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The Most Common Grades of Reagents and Chemicals

It is imperative that everyone in the custody supply chain know and understand the different grades of reagents and chemicals used in the laboratory and their uses.

Aaron Schieving is the founder and managing director at ABS Testing Solutions. He has about 20 years of medical device, pharmaceutical, biopharmaceutical, organ and tissue, cell therapy and regenerative medicine...

Chemicals and reagents play a critical role in the manufacturing and testing of pharmaceutical products, medical devices, biologics, cell- and tissue-based products, and many other health care-related solutions. Laboratories and researchers who use chemicals and reagents trust that their manufacturers have properly identified the grades of each chemical and ensured that the chemicals have met all regulatory and compliance standards for their intended use. It is imperative that everyone in the custody supply chain know and understand the different grades of reagents and chemicals and their uses, which are explained in this article.

Grades of reagents and chemicals used in the laboratory

When making a solution, the manufacturer must first decide what degree of chemical purity is needed based on the intended use. The following list describes the seven most common grades of reagents and chemicals , from highest to lowest grade/purity:

• ACS grade meets or exceeds purity standards set by the American Chemical Society (ACS). This grade is acceptable for food, drug, or medicinal use and can be used for ACS applications or for general procedures that require stringent quality specifications and a purity of ≥95%.
• Reagent grade is generally equal to ACS grade (≥95%) and is acceptable for food, drug, or medicinal use and is suitable for use in many laboratory and analytical applications.
• USP grade meets or exceeds requirements of the United States Pharmacopeia (USP). This grade is acceptable for food, drug, or medicinal use. It is also used for most laboratory purposes, but the USP being followed should always be reviewed prior to beginning to ensure the grade is appropriate for that methodology.
• NF grade meets or exceeds requirements of the National Formulary (NF). The USP and the NF (USP– NF) jointly publish a book of public pharmacopeial standards for chemical and biological drug substances, dosage forms, compounded preparations, excipients, medical devices, and dietary supplements. The listings here should be reviewed to determine which would be considered equivalent grades.
• Laboratory grade is the most popular grade for use in educational applications, but its exact levels of impurities are unknown. While excellent for teaching and training, it is not pure enough to be offered for food, drug, or medicinal use of any kind.
• Purified grade , also called pure or practical grade, meets no official standard; it is not pure enough to be offered for food, drug, or medicinal use of any kind.
• Technical grade is used for commercial and industrial purposes; however, like many others, it is not pure enough to be offered for food, drug, or medicinal use of any kind.

ACS, Reagent, and USP-NF grades are typically equivalent and interchangeable but, even so, appropriateness should always be confirmed before application. This can be done by reviewing the applicable regulatory requirements.

Lab, purified, and technical grades of reagents and chemicals have their own uses. For example, lab-grade chemicals, because of their low cost and good chemical purity, are used widely in educational applications, such as teaching laboratories at both the secondary school and college levels; however, lab-grade chemicals would not be appropriate for use in the quality control laboratory of a pharmaceutical or medical device manufacturer. ACS-, USP-, or reagent-grade chemicals should be applied in this setting, because they have fewer impurities that could ultimately impact patients taking the drugs made with those chemicals.

With seven different and inequivalent grades of reagents and chemicals, it is crucial to understand how they can impact products. Using a lower-purity grade than a product’s intended use requires could be a costly mistake. Similarly, using a higher-purity grade when not required could result in unnecessary costs. Add in the increased regulatory scrutiny and it becomes even more important to have a complete understanding of the components that your process requires.

Grades of reagents and chemicals: Frequently Asked Questions

Q: What is LR and AR grade?

A: LR grade chemicals refer to chemicals that meet the specifications outlined by the Laboratory Reagent (LR) grade. LR grade chemicals are often used in laboratory settings for analytical and research purposes. These chemicals are of high purity, with impurities specified and controlled to ensure accuracy and reliability in experimental work. 

AR grade chemicals, also known as Analytical Reagent grade chemicals, are chemicals that meet the specifications outlined for analytical applications in laboratories. These chemicals are of high purity, typically exceeding 95 percent, with impurities specified and controlled to ensure accuracy and reliability in analytical procedures. AR grade chemicals are suitable for a wide range of analytical techniques, including titrations, spectrophotometry, chromatography, and other analytical methods. They are often used in research, quality control, and educational laboratories where precise and consistent results are essential.

Q: What is the most acceptable chemical grade?

A:  The most acceptable chemical grade depends on the specific requirements of the intended application. However, in many cases, the highest purity grade available is preferred to ensure accuracy, reproducibility, and reliability of results. For most laboratory analytical work, the highest grades such as ACS (American Chemical Society) grade, AR (Analytical Reagent) grade, or equivalent are typically considered the most acceptable. These grades offer the highest level of purity and are suitable for a wide range of analytical techniques and applications.

It's important to note that the choice of chemical grade should be based on the specific needs of the experiment or process. For some applications where extreme levels of purity are not necessary, lower grades such as LR (Laboratory Reagent) grade may be acceptable and more cost-effective. Ultimately, selecting the appropriate chemical grade involves considering factors such as purity requirements, budget constraints, and the intended use of the chemicals.

Q: What do I need to consider when purchasing different grades of chemicals?

A:  While there are a variety of considerations when purchasing different grades of chemicals for your lab, here are five important ones:

• Specifications:  Review the specifications provided by the supplier for each grade of chemical. Pay attention to impurity levels, assay values, and other relevant parameters to ensure they meet your requirements.
• Application compatibility: Ensure that the grade of chemical you choose is compatible with your specific application. Some applications may require higher purity grades to avoid interference or contamination.
• Regulatory compliance:  Consider any regulatory standards or guidelines that apply to your industry or application. Choose chemicals that comply with relevant regulations and safety standards.
• Budget: Evaluate the cost differences between different grades of chemicals. Balance the need for high purity with budget constraints to find the most cost-effective option.
• Supplier reliability:  Choose a reputable supplier known for providing high-quality chemicals and reliable service. Consider factors such as reputation, certifications, and customer reviews when selecting a supplier.

Additional resources:

• Lab Manager Safety Digital Summit
• “Running a Safe Lab” Big Picture Series
• Lab Manager Academy: Lab Safety Management Certificate

Chemical Grades

What are chemical grades?

What are the different grades of chemicals, what is ar/or, what is a reagent how many types of reagents are there, what is the most acceptable chemical grade, what do some of laballey’s chemical grades mean, what are some recommended grades for household and industrial use.

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• v.26(3); 2015 Jul

Grading Evidence for Laboratory Test Studies Beyond Diagnostic Accuracy: Application to Prognostic Testing

Andrew c. don-wauchope.

1 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada

2 Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada

Pasqualina L. Santaguida

3 Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Ontario, Canada

Evidence-based guideline development requires transparent methodology for gathering, synthesizing and grading the quality and strength of evidence behind recommendations. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) project has addressed diagnostic test use in many of their publications. Most of the work has been directed at diagnostic tests and no consensus has been reached for prognostic biomarkers.

Aim of this paper

The GRADE system for rating the quality of evidence and the strength of a recommendation is described. The application of GRADE to diagnostic testing is discussed and a description of application to prognostic testing is detailed. Some strengths and limitations of the GRADE process in relation to clinical laboratory testing are presented.

Conclusions

The GRADE system is applicable to clinical laboratory testing and if correctly applied should improve the reporting of recommendations for clinical laboratory tests by standardising the style of recommendation and by encouraging transparent reporting of the actual guideline process.

INTRODUCTION

The Grading of Recommendations Assessment, Development and Evaluation (GRADE) project was initiated to standardise the grading of guideline recommendations ( 1 ). The GRADE system addresses both the quality of evidence as well as the level of recommendation ( 2 ). Numerous systems exist for grading the evidence and recommendations, generated by a range of organisations representing professional societies and national/provincial/international bodies amongst others ( 3 ). The GRADE project has published two sets of papers with the most recent series still appearing in the literature ( 4 ). These provide a combination of general guidance and examples of specific application to a range of areas in medicine. This article will briefly describe the GRADE approach to evaluating the quality of evidence for diagnostic testing with a focus on laboratory tests. Figure 1 gives an overview of how this fits into the overall GRADE process that includes a number of other factors in the formation of a recommendation classified as strong or weak. Subsequently, we will describe how this can be applied to prognostic testing using our previous work on natriuretic peptides as the example. Finally, the strengths and limitations of the GRADE approach will be considered in the context of laboratory medicine.

The GRADE domains – the basis for the evaluation of quality of evidence

OVERVIEW OF THE GRADE SYSTEM OF RATING THE QUALITY OF THE EVIDENCE

The GRADE system uses four major domains to evaluate the quality of the evidence for a research question ( Figure 1 ). Typically research questions would be expected to follow the Population-Intervention-Comparator-Outcome (PICO) format ( 5 ). There are four major domains and several minor domains that can be considered as modifiers of the final quality of evidence ( 6 ).

The first major domain investigates the risk of bias or limitations of primary papers that are considered for answering the specific PICO research question behind the guideline recommendations ( 7 ). This is based on evaluation of the study design (i.e. cohort or randomized trials), the application of the study design (identification of any threats to internal validity), the reporting and analysis of the results and the conclusions presented. There are a range of validated tools available to assist researchers and guideline teams to evaluate the risk of bias in the primary papers. Systematic reviewers should include their GRADE assessment and the supporting data in the results of the systematic review.

The second major domain investigates the inconsistency of the evidence ( 8 ). This domain considers all the primary papers related to each outcome (defined in the PICO) and evaluates the direction of the effect for consistency. The presence of inconsistency in the direction or magnitude of the effect (i.e. specificity) would result in a downward grading of the evidence for the outcome. It is evaluated by considering the range of point estimates, the confidence interval around each point estimate and the statistical testing for heterogeneity. When several outcomes are considered, inconsistency is evaluated separately for each outcome.

The third major domain investigates the indirectness of evidence in relation to outcomes ( 9 ). This domain considers the plausible or proved link between the factor (e.g. the diagnostic intervention) being considered and the outcome being evaluated. This requires consideration of the potential differences in population, type of intervention, outcome measures and the comparisons made. The overall indirectness needs to be judged based on the PICO and if present would downgrade the quality of evidence. Similar to inconsistency, each outcome is evaluated for indirectness.

The fourth major domain is about the imprecision of the evidence ( 10 ). Ideally, this domain evaluates outcomes for which a summary pooled estimate is calculated in a meta-analysis to provide a measure of overall effect across different studies. The width of the 95% CI in this context would give an estimate of the imprecision of the summarised data. If an intervention is being compared to a control then the 95% CI of the individual point estimates for each included study would be precise if there was no overlap, and imprecise if there was overlap. When the study effects cannot be meta-analyzed a number of factors (such as sample size) are considered across the literature being evaluated and graded for imprecision.

There are several minor domains that can also be considered when grading evidence and recommendations. One minor domain is publication bias ( 11 ). This domain is generally evaluated using statistical techniques to assess the probability of publication bias. There must be sufficient number of studies included so that the statistical test has validity. In the case where there are too few studies, one may likely assume that publication bias is likely present. Other aspects to consider when assessing publication bias are small numbers of studies with small populations and predominate funding from industry sponsors whose role within the study is not specified. Other minor domains include any evidence for dose response, the magnitude of the effect size and plausible residual confounding ( 12 ).

Using the GRADE approach, the quality of evidence is reported as one of 4 levels: High (++++); Moderate (+++o); Low (++oo); or Very Low (oooo) ( 13 ). The use of symbols to convey the strength of evidence is becoming more apparent in clinical practice guidelines and assists readers in quickly assessing the quality upon which the recommendations are based. The definitions of these categories have been well described for therapeutic interventions ( 13 ) and we have suggested some additional descriptions applicable to diagnostic accuracy and prognostic studies. Table 1 (on the next page) is an adaptation of the practical interpretation of the quality of the evidence when considering intervention ( 13 ), diagnostic accuracy ( 14 ), and prognostic studies ( 15 ).

Interpretation of the quality of evidence for GRADE

GRADE FOR DIAGNOSTIC TESTING USING LABORATORY TESTS

Diagnostic testing was considered a separate category when the GRADE project published the first set of articles describing the process for evaluating quality of the evidence and recommendations ( 16 ). This was received with some scepticism from the laboratory community but has been successfully applied in some situations with a number of limitations. The challenge to diagnostic testing is often in the nature of the study design providing data to support the PICO question. The Oxford Centre for Evidence-Based Medicine (CEBM) has articulated this well in their table for levels of evidence in diagnostic accuracy testing ( 17 ). Within this hierarchy, the highest order (i.e. most rigorous and valid) of study are cohort and case-control studies and thus quite different from therapeutic interventions where randomised controlled trials are considered the highest order of study design. This is noted in the GRADE description for diagnostic test strategies, where exception is made for diagnostic accuracy studies that would include cross-sectional or cohort designs as an acceptable study type with no downgrading based on for the domain of study limitations. However, the evidence is quickly down-ranked when considering the indirectness and imprecision often associated with these study design types. As more experience with the use of GRADE was gained, the approach to evaluating diagnostic accuracy studies was further developed ( 18 , 19 ).

The same general principles and categories apply and it remains essential to set the question well with consideration of the PICO elements. There is some evidence to suggest that many clinical questions posed in diagnostic test studies do not distinguish between the population being tested and the problem (disease) of interest ( 20 ).

The PICO format for interventions typically combines the problem with population while for diagnosis it may be important to separately define these two components. For diagnostic accuracy studies the outcomes are typically the classification of the results into the proportion of true positive, true negative, false positive and false negative ( 21 ). This assumes that the patient-relevant clinical outcome is the correct diagnosis, and this encourages focus on diagnostic accuracy data. However, there is debate about what is considered the most appropriate clinical outcome of testing and that more emphasis should be placed on the role of testing in clinical pathways, and that the purpose of the test (diagnosis, monitoring, screening, prognosis, risk stratification and guiding therapy) and the clinical effectiveness of testing should be considered in the wider context of health care and the role for diagnostic testing ( 22 ). If the clinically important outcome includes appropriate management and improvement in patient health, then there is great difficulty in linking the diagnostic test to the health outcome directly and the assessment of imprecision requires that multiple other factors are considered ( 22 , 23 ). There are a number of outcome options that could be considered for diagnostic testing and the most appropriate of these should be defined as part of the PICO ( 22 , 24 ).

Thus far most of the published literature has focused on diagnostic accuracy studies. The STARD document has helped improve the reporting of diagnostic accuracy studies ( 25 ). The comparator could be a “gold” standard test but this may not be available and other options are mentioned in the STARD document. This concept has been explored further by the Agency for Health Care Research and Quality (AHRQ) in their methods guide for medical test reviews ( 26 ). Other parts of the extended PICO question definition may include the timing and setting for the question (i.e. PICOTS) ( 27 ). Timing is one aspect that is often considered critical for diagnostic testing as the time between the test being investigated and the comparator test is essential. Timing plays an important role, particularly if the investigators are not blinded to the index and reference test results are not masked. It is also important if the two tests are carried out at different time points in the disease process. For index tests and reference tests, that require samples or procedures other than blood (for example tissue or diagnostic imaging), then the two tests must be conducted in a time frame in which change in the disease process would not impact the interpretation of the test result. For laboratory testing based on blood samples the ideal situation is collection of all samples at the same point in time. The setting often helps defines the population more clearly. When the prevalence of the diagnosis is changed because of the setting (e.g. primary care versus specialist clinic), it becomes an important component as consideration of prevalence will impact the diagnostic accuracy data. This can be illustrated by two of the questions asked in the AHRQ comparative effectiveness review on the use of Natriuretic peptides in Heart Failure ( 28 , 29 ). Two diagnostic settings were considered and this allowed for the primary papers to be grouped correctly and evaluated in the appropriate context ( Table 2 ).

Grading of evidence for the diagnostic use of B-type Natriuretic peptides

Assessing risk of bias for diagnostic accuracy studies is discussed extensively in the GRADE papers as this is seen as particularly challenging ( 18 , 30 ). The AHRQ Methods Guide describes the challenges of assessing risk of bias in more detail ( 31 ). Validated tools such as the QUADAS II( 32 ) tool or its predecessor the QUADAS( 33 ) can be helpful to carefully consider a range of important factors that impact on the evaluation of risk of bias. For any new systematic reviews or clinical practice guidelines the use of QUADAS II would be recommended as it has improved from the earlier version. QUADAS II focuses on 4 aspects of risk of bias (patient selection, conduct or interpretation of the index test, conduct or interpretation of the reference test, flow and timing of the tests) and four aspects of applicability (whether the study is applicable to the population and settings of interest). In the AHRQ Methods Guide, the domain of indirectness, which is the link between diagnostic accuracy and clinical outcome, and the domain of imprecision were identified as challenging to assess ( 34 ).

This section provides an overview of the theoretical framework to identify ways in which the domains of risk of bias/study limitations, inconsistency, indirectness, imprecision and publication bias can be considered for evaluating the evidence for diagnostic tests. This has been successfully applied to diagnostic applications of laboratory tests and Table 2 provides an example of how GRADE was applied in the recent AHRQ systematic review for Natriuretic peptides in the diagnosis of heart failure ( 28 , 29 ).

APPLICATION OF GRADE TO PROGNOSTIC TESTING

Although the GRADE has been widely adopted for assessing the quality of the evidence in both studies of interventions and diagnostic accuracy, it has not yet been applied to studies evaluating prognosis. In large part, this is because GRADE has not reached consensus on how to apply the criteria in the four major domains and in the minor domains specific to prognosis research.

Prognosis is defined as the probable course and outcome of a health condition over time. A prognostic factor is any measure in people with a health condition that from a specific start point is associated with subsequent clinical outcome (endpoint) ( 35 ). Prognostic factors, if well established, function to stratify individuals with the health condition into categories of risk or probability for the outcomes of interest. Research into prognostic factors aims to establish which factors are modifiable, which should be included in more complex models predicting outcome, monitor disease progression, or show differential responses to treatment.

We had the opportunity to explore the application of the GRADE approach in a systematic review in which 3 prognostic questions were addressed ( 36 ). In the diagnostic examples ( Table 2 ), we considered the use of natriuretic peptides with respect to diagnosing heart failure. In addition, our systematic review considered natriuretic peptides as potential markers predicting mortality and morbidity in both acutely ill and chronic heart failure patients( 37-40 ). as well as in the general population ( 41 ). Our review showed that both BNP and NT-proBNP generally functioned as an independent predictor of subsequent mortality and morbidity at different time frames.

Huguet et al.(2013) have recently proposed some guidance for adapting GRADE for prognostic studies based on their work in identifying factors associated with chronic pain ( 15 ). The main differences from GRADE applied to intervention studies, occur with respect to study limitations and to factors that may increase overall quality. With regards to study limitations, there is consideration of the phases of prognostic research. This differs from evaluating evidence from intervention and diagnostic accuracy studies, where the type of specific design (e.g. RCT or cohort study) is given specific weighting. In the context of prognostic studies, there is no consensus on the taxonomy for phases of prognosis research ( Table 3 ). The simplest approach considers three phases of prognostic research. At the lowest level of prediction (PHASE 1), prognosis studies are designed to identify potential associations of the factors of interest and are termed “exploration” ( 42 ) or “predictor finding” ( 43 ) or “developmental studies” ( 44 ) PHASE 2 explanatory studies typically establish or confirm independent association between prognostic factors and outcomes, and are also labelled as “validation” studies ( 44 ). The highest level of evidence is from PHASE 3 studies where the prognosis study attempts to evaluate the underlying processes that link the prognostic factor with the outcome. High quality evidence is likely found in PHASE 3 studies ( 15 ); conversely, moderate to very low quality evidence is based on PHASE 1 and 2 studies.

Frameworks for sequential development of prediction models that assess the contribution of potential prognostic factors

In prognostic research, setting the clinical question is still the most important aspect as patient important outcomes need to be addressed in the appropriate context. Using the PICOTS format is central to this process to adequately define the population, the intervention, the timing and the setting. The comparator and the outcome are also critical but often challenging to define. The comparator test could be a wide range of items when it comes to delineating probable course and outcome. In our examples we included a full range of reported comparators in the form of any type of diagnosis of heart failure.

This could prove to be challenging if one form of confirmation is clearly better than another or if the different confirmatory tests include different sub-populations. For the heart failure populations we did not attempt to divide these out, apart from the division between acute decompensated and chronic stable heart failure. However, we could have tried to use different diagnostic criteria such as echocardiography findings to delineate severity and diastolic from systolic dysfunction.

As discussed in the diagnostic accuracy section the range of clinically relevant outcomes can be quite diverse. For prognostic outcomes the use of clinical pathways and clinically effectiveness should be considered in additional to the more traditional mortality and morbidity outcomes. The length of time from the test to the evaluation of the outcome status may be an important consideration as this may change with differing lengths of time. Bearing all these concepts in mind is important when defining the outcome as the applicability of the findings will be dependent on patient important outcomes.

Risk of bias for the prognostic studies in the natriuretic peptide systematic review was evaluated using the underlying principles of the Quality in Prognosis Studies (QUIPS) tool ( 45 ). The elements of the QUIPS tool had been previously published and we adapted these very slightly for the prognostic questions in our study ( 46 ). This considers 6 domains that may impact bias of a prognostic study: participation; attrition; prognostic factor measurement; confounding measurement and control; outcome measurement; and analysis and reporting ( 45 ). The type of study design for prognostic evaluation is largely cohort studies and these are primarily prospective in nature. However, in many reports the original study was a prospective or randomised controlled trial and the analysis of the prognostic factor was done as an afterthought and hence the study design should be classified as retrospective cohort. There are randomised controlled trials that could be considered as true evaluations of prognostic testing but these are rare.

One additional advantage of using the QUIPS is that there is a thorough assessment of the potential for confounding bias. When applying the GRADE to intervention studies, where the presence of plausible confounding in cohort studies can be expected to reduce the effect size observed, the study limitations can be upgraded. However, this assumption may not be applicable to prognostic studies which are predominately observational in design; residual confounding can effect predictions in either direction (over or under estimation of the predictive strength) or have no effect at all ( 15 ). Our systematic review for natriuretic peptides and heart failure showed that most studies had many plausible confounders (biases) that were not accounted for in the adjusted analysis (i.e. residual confounders) ( 38 , 40 ). The methods used in our comparative effectiveness review attempted to establish a minimum of three critical confounders; age, renal function, BMI (or other measure of height and weight) considered in the study design or in the analysis. As an example to evaluate confounding from renal function we considered multiple terms to identify the tests and conditions ( Table 4 ). Our findings showed consistent problems with studies measuring these three plausible confounders, not considering several other potential confounders. However, it was not clear which if any of these affected our estimates of prediction or the direction of impact. The domain of confounder measurement and control is essential in prognostic studies because the link between the prognostic test and the outcome is most often not direct and thus consideration of all other known factors that influence the outcome need to be taken into account. This evaluation of primary papers allowed us to judge the overall bias for the papers included for each sub-question that we addressed as well as obtain some insight into the other relevant domains of GRADE. Huguet et al (2013) have also made use of the QUIPS tool in their experience with chronic pain systematic reviews ( 15 ).

Example of the range of terms used to identify renal dysfunction in the prognostic evaluation of natriuretic peptides

Inconsistency can be estimated from the summary tables with the point estimates and 95% CI from odds ratio (OR), hazards ratio (HR) and relative risk (RR). This follows the description from the GRADE group and application of this category does not differ from tests of intervention or diagnostic tests ( 8 ).

The proposed adaptation of the GRADE to prognostic studies for indirectness asks raters to consider this domain in the context of the population, the prognostic factor, and the outcome. The less generalizable the results for each of these contexts, the higher the likelihood of down-rating this category increases. Indirectness is typically present when one considers prognostic use of a test as there is very seldom a direct link between the test and the outcome of interest. There are typically numerous steps in the process and many of these are completely independent of the test being evaluated. If the factors described by the GRADE group (population; intervention, outcome and comparator) are well described in the PICOTS then it may be possible to find a group of primary studies that match all factors in the same way. If such a group of studies could be found then indirectness may not be present. In the natriuretic peptide systematic review primary studies differed in outcome and comparators that clearly made the evidence-to-outcomes link indirect ( 38 , 40 ).

Imprecision has some interesting difference between application in guidelines and systematic reviews ( 10 ). For systematic reviews the goal is estimating the effect size while for guidelines the goal is to support a recommendation. Thus in a systematic review the precision will be interpreted on the width of the 95% CI while in guidelines it would be interpreted on the ability to separate from the comparator. When possible the pooled effect size and confidence limit would be the ideal tool to evaluate imprecision. Consideration should also be given to the sample size of studies ( 10 ). However meta-analysis is not always available as the appropriate application of meta-analysis requires that the studies being included match the PICOTS closely. When meta-analysis is not possible the range of effect size and the spread of 95% CI need to be considered.

Publication bias will follow the same principles described in the GRADE papers ( 11 ). Although the issue has been noted in recent literature, in the context of prognostic studies ( 47 ), there is currently no registry of studies, or studies related to laboratory testing. Thus it is difficult to make informed judgements about the likelihood of publication bias.

Careful consideration and description of all the GRADE domains need to be made by the guideline developers or systematic reviewers. This should be documented and written up as an appendix to allow users of the guideline to consider the details used by the guideline writers and to allow methodologists the opportunity to further develop the concepts around evaluation of diagnostic tests.

STRENGTHS AND LIMITATIONS OF GRADE FOR LABORATORY TESTS

The major strengths when using the GRADE approach for the evaluation of the strength of evidence and recommendations is the explicitness and reproducibility of the process ( 48 ). An advantage is the requirement to define a useful and appropriate clinical question that includes the necessary components of PICOTS. The GRADE system takes into account key domains to assess quality and strength of evidence. The process of GRADE allows for transparency when users of the guideline review the evidence behind the recommendations ( 49 ).

Limitations can be grouped in a number of areas. Firstly guideline writers often do not fully understand the GRADE system. Methodological experts are most often aware of the system but many of them invited to participate in the guideline team will not have had sufficient exposure to GRADE or training to incorporate the GRADE assessment of the strength of evidence strength or to the process for making recommendations. The GRADE system has been available for a number of years but as it continues to develop it can be difficult for non-methodologists to keep pace with the changes. The application of GRADE requires judgment of the evidence in the domains as well as judgement of the factors that help form the recommendation. This judgment is often construed as expert opinion and this has formed the core of clinical practice guidelines in many instances. The GRADE process is designed to move away from expert opinion alone to one that includes an evidence-formed judgement. If the team is well versed in the GRADE literature and suitably trained then the judgement aspect will be a strength; however, it could be a limitation if the team is not able to sufficiently consider the evidence and be unduly influenced by their own expert opinion.

The second group of limitations relates to the challenges guideline teams face in meeting the explicit criteria required for developing structured clinical questions and for the evaluation of the evidence as described in the GRADE process. Although the domains of GRADE and how to apply these are well defined, the heterogeneity of evidence presents practical challenges to guideline development teams. For example, defining the appropriate type of study design for the highest rank of evidence can be challenging. As noted previously, the designs that are considered to have greater rigour (i.e. higher form of evidence) will depend on the actual purpose of the study. For diagnostic testing and prognostic testing these will be different and these nuances require careful reflection from the guideline developers. Initially the researchers may consider using the currently published models (for example CEBM tables and Table 3 ) and use these if seen as appropriate ( 17 , 42-44 ). If an alternative system is used it should be justified in the method description. The aspects of PICOTS require careful consideration to make the question applicable to the target audience. This is reasonably straightforward for diagnostic testing ( 19 ). but definitions may be more challenging in prognostic questions as the distinction between population and disease become even more important. Often more than a single outcome should be considered in order to capture the complexity of the contribution of diagnostic testing in relation to patient important outcomes. There are practical challenges when judgements are based on patient-relevant versus a test accuracy perspective ( 19 ). Similarly, there are some challenges to adequately judge imprecision as statistical approaches are somewhat limited for assessing heterogeneity in diagnostic tests. The complexity and diversity of clinical care pathways may complicate the assessment of indirectness. Here the factors that may impact the clinical care pathway need to be accounted for when the directness or indirectness of the evidence is rated. The choice of outcome measures will further influence the considered judgement process of the GRADE approach.

CONCLUSIONS

The GRADE system can be used to rate the evidence for diagnostic and prognostic use of laboratory testing. There are numerous challenges and the results may not always be seen as consistent between different guideline groups. However, the GRADE evidence rating system allows users of the guideline to compare and contrast guidelines covering the same or similar content. The transparency of the approach also allows better-informed adaptation and implementation of guideline recommendations to local practice.

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Analytical Research: What is it, Importance + Examples

Finding knowledge is a loose translation of the word “research.” It’s a systematic and scientific way of researching a particular subject. As a result, research is a form of scientific investigation that seeks to learn more. Analytical research is one of them.

Any kind of research is a way to learn new things. In this research, data and other pertinent information about a project are assembled; after the information is gathered and assessed, the sources are used to support a notion or prove a hypothesis.

An individual can successfully draw out minor facts to make more significant conclusions about the subject matter by using critical thinking abilities (a technique of thinking that entails identifying a claim or assumption and determining whether it is accurate or untrue).

What is analytical research?

This particular kind of research calls for using critical thinking abilities and assessing data and information pertinent to the project at hand.

Determines the causal connections between two or more variables. The analytical study aims to identify the causes and mechanisms underlying the trade deficit’s movement throughout a given period.

It is used by various professionals, including psychologists, doctors, and students, to identify the most pertinent material during investigations. One learns crucial information from analytical research that helps them contribute fresh concepts to the work they are producing.

Some researchers perform it to uncover information that supports ongoing research to strengthen the validity of their findings. Other scholars engage in analytical research to generate fresh perspectives on the subject.

Various approaches to performing research include literary analysis, Gap analysis , general public surveys, clinical trials, and meta-analysis.

Importance of analytical research

The goal of analytical research is to develop new ideas that are more believable by combining numerous minute details.

The analytical investigation is what explains why a claim should be trusted. Finding out why something occurs is complex. You need to be able to evaluate information critically and think critically. 

This kind of information aids in proving the validity of a theory or supporting a hypothesis. It assists in recognizing a claim and determining whether it is true.

Analytical kind of research is valuable to many people, including students, psychologists, marketers, and others. It aids in determining which advertising initiatives within a firm perform best. In the meantime, medical research and research design determine how well a particular treatment does.

Thus, analytical research can help people achieve their goals while saving lives and money.

Methods of Conducting Analytical Research

Analytical research is the process of gathering, analyzing, and interpreting information to make inferences and reach conclusions. Depending on the purpose of the research and the data you have access to, you can conduct analytical research using a variety of methods. Here are a few typical approaches:

Quantitative research

Numerical data are gathered and analyzed using this method. Statistical methods are then used to analyze the information, which is often collected using surveys, experiments, or pre-existing datasets. Results from quantitative research can be measured, compared, and generalized numerically.

Qualitative research

In contrast to quantitative research, qualitative research focuses on collecting non-numerical information. It gathers detailed information using techniques like interviews, focus groups, observations, or content research. Understanding social phenomena, exploring experiences, and revealing underlying meanings and motivations are all goals of qualitative research.

Mixed methods research

This strategy combines quantitative and qualitative methodologies to grasp a research problem thoroughly. Mixed methods research often entails gathering and evaluating both numerical and non-numerical data, integrating the results, and offering a more comprehensive viewpoint on the research issue.

Experimental research

Experimental research is frequently employed in scientific trials and investigations to establish causal links between variables. This approach entails modifying variables in a controlled environment to identify cause-and-effect connections. Researchers randomly divide volunteers into several groups, provide various interventions or treatments, and track the results.

Observational research

With this approach, behaviors or occurrences are observed and methodically recorded without any outside interference or variable data manipulation . Both controlled surroundings and naturalistic settings can be used for observational research . It offers useful insights into behaviors that occur in the actual world and enables researchers to explore events as they naturally occur.

Case study research

This approach entails thorough research of a single case or a small group of related cases. Case-control studies frequently include a variety of information sources, including observations, records, and interviews. They offer rich, in-depth insights and are particularly helpful for researching complex phenomena in practical settings.

Secondary data analysis

Examining secondary information is time and money-efficient, enabling researchers to explore new research issues or confirm prior findings. With this approach, researchers examine previously gathered information for a different reason. Information from earlier cohort studies, accessible databases, or corporate documents may be included in this.

Content analysis

Content research is frequently employed in social sciences, media observational studies, and cross-sectional studies. This approach systematically examines the content of texts, including media, speeches, and written documents. Themes, patterns, or keywords are found and categorized by researchers to make inferences about the content.

Depending on your research objectives, the resources at your disposal, and the type of data you wish to analyze, selecting the most appropriate approach or combination of methodologies is crucial to conducting analytical research.

Examples of analytical research

Analytical research takes a unique measurement. Instead, you would consider the causes and changes to the trade imbalance. Detailed statistics and statistical checks help guarantee that the results are significant.

For example, it can look into why the value of the Japanese Yen has decreased. This is so that an analytical study can consider “how” and “why” questions.

Another example is that someone might conduct analytical research to identify a study’s gap. It presents a fresh perspective on your data. Therefore, it aids in supporting or refuting notions.

Descriptive vs analytical research

Here are the key differences between descriptive research and analytical research:

The study of cause and effect makes extensive use of analytical research. It benefits from numerous academic disciplines, including marketing, health, and psychology, because it offers more conclusive information for addressing research issues.

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A guide to Chemical Grades

• Reagent A.C.S. - This designates a high quality chemical for laboratory use. The abbreviation "A.C.S.," means the chemical meets the specifications of the American Chemical Society. A Certificate of Analysis is available upon request.
• Guaranteed Reagent (GR) - Suitable for use in analytical chemistry, products meet or exceed American Chemical Society (ACS) requirements where applicable. (EMD trademark)
• AR - The standard Mallinckrodt grade of analytical reagents; suitable for laboratory and general use. If the reagent also meets the requirements of the American Chemical Society Committee on Analytical Reagent, it will be denoted as an AR (ACS) reagent. (MBI trademark)
• Primary Standard - Analytical reagent of exceptional purity that is specially manufactured for standardizing volumetric solutions and preparing reference standards.
• Reagent - The highest quality commercially available for this chemical. The American Chemical Society has not officially set any specifications for this material.
• OR - Organic reagents that are suitable for research applications.(MBI trademark)
• Purified - Defines chemicals of good quality where there are no official standards. This grade is usually limited to inorganic chemicals.
• Practical - Defines chemicals of good quality where there are no official standards. Suitable for use in general applications. Practical grade organic chemicals may contain small amounts of isomers of intermediates.
• Lab Grade - A line of solvents suitable for histology methods and general laboratory applications.
• USP - Chemicals manufactured under current Good Manufacturing Practices and which meet the requirements of the US Pharmacopeia.
• USP/GenAR - A line of chemicals manufactured under cGMP, meet the requirements of the 1995 USP 23, meet European Pharmacopeia (PhEur, EP) and British Pharmacopeia (BP) specifications where designated, and are Endotoxin (LAL) tested where appropriate. (MBI trademark)
• NF - Chemicals that meet the requirements of the National Formulary.
• FCC - Products that meet the requirements of the Food Chemical Codex.
• CP (Chemically Pure) - Products of purity suitable for use in general applications.
• Technical - A grade suitable for general industrial use.
• OmniTrace Grade Acids - Higher purity than Reagent Grade, suitable for trace metals analysis. Acids are analyzed for a minimum of 33 different metals. Trace metals are typically in the ppb range. (EMD trademark)
• Tracemetal - Acids manufactured to achieve very low metal contamination in ppb range. Primarily used in digestion of samples prior to ICP analysis. Each lot is analyzed for 32 metals by ICP/MS. (Tedia designation)
• Tracemetal Plus - For critical trace metal analyses, the acids are manufactured by double sub-boiling distillation to achieve low metal contamination in ppt range. Each lot is analzed for 32 metals by ICP/MS. (Tedia designation)
• Suprapur Grade Acids - High purity grade acid produced by E. Merck. Suitable for sensitive instrumental methods. Trace metals in low ppb range, frequently less than detection limits. This grade applies to acids and salts. (EMD trademark)
• AR Select - A line of acids specifically developed for trace metal analysis; analyzed for up to 28 metals in the 0.05 to 0.0005 ppm range. (MBI trademark)
• AR Select Plus - The purest grade of Mallinckrodt acids. AR Select Plus acids are manufactured utilizing sub-boiling point, quartz-lined stills and are packaged in fluoropolymer bottles to maintain purity. These products are tested for 45 elements in the 3.5 to 0.005 ppb range, ensuring low background interference. (MBI trademark)
• Environmental Grade - Extremely high purity acids refined through a single sub-boiling distillation process. (Anachemia trademark)
• Environmental Grade Plus - Acids produced by distilling Environmental Grade acids a second time. This product is double sub-boiling distilled acid and is of the highest purity available. (Anachemia trademark)

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What Do The Different Grades Of Chemical Mean?

• The Chemistry Blog
• Posted on August 19, 2020
• by Lucy Bell-Young

There are many different types of chemical grades, which determine where and how a chemical product can be used. Generally speaking, the different grades of chemicals refer to how pure and free from contaminants they are. While each country, lab and organisation have their own ways of classifying chemical products, they are usually based on similar principles and regulations. 

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Buy different grades of chemicals from leading UK chemical supplier, chemicals.co.uk

What are the different chemical grades.

Classifying chemicals based on purity and quality is essential to determine which type of chemical to use for a particular purpose, such as laboratory experiments or industrial processes. In the UK, we have our own set of standards for different grades of chemicals. Other countries may have similar standards, but there will be some variations. Each company may also have slightly different specifications.

Here are some of the most common chemical grades in the UK for general chemical products:

• Technical Grade: This is the lowest grade of chemical in terms of purity level and quality. The chemical products that belong in this category are intended for industrial applications, where the high purity of chemical reagents and precursors is not completely essential, as long as the intended reactions occur.
• GRG: General Reagent Grade, or General Grade chemicals, are those that are suitable for laboratory use and household purposes. Chemicals under this category have a high purity level of up to 99.9%. However, no specific standard test is conducted to determine if there are contaminants in GRG mixtures. 
• BP Grade: Otherwise known as pharmaceutical grade chemicals, this category is very similar to the American USP Grade. BP Grade chemical products conform to the standards established by the British Pharmacopoeia, which are based on the level of purity and lack of contaminants in a substance. Chemical products that are able to comply with these standards are given a certificate of analysis or conformity. Since BP grade chemicals are commonly used in manufacturing cosmetic products, this certification is necessary in order to prove that a product has undergone the required testing and verification.
• Analytical Research Grade: Chemical products under this category are considered very high quality, and are designed for specialist analytical laboratory testing. The high degree of purity of the products is necessary for accurate and precise testing. This is because if a product contained contaminants in this setting, it could skew the results of the test. 

Specific categories of chemicals also have their own separate classifications. For instance, in the United States, acids have grading levels that are based on purity and intended use. These are some of the common classifications of acid grades :

• Omni-trace grade acids: Acids under this category have higher purity than reagent grade acids. Omni-trace grade acids are excellent for analysing the presence of at least 33 different types of metals in trace amounts, with a parts per billion range.
• Trace metal grade: Acids that are manufactured under this grade have a very low level of metal contamination. Trace metal grade acids are used in inductively coupled plasma mass spectrometry (ICP-MS) tests to prepare samples.
• Supra pure grade acids: Acids under this category are suitable for use with analytical instruments. Trace metal contents in these acids are so low that they can hardly be detected. The grade also applies to the salts produced by the acid reactions.
• Environmental grade: Acids with this grade level are highly pure. This is because they undergo a single sub-boiling distillation process to remove impurities.

What Are Analytical Grade Chemicals?

Various industry-leading chemical companies have their own definitions of chemical grades based on government regulations. Therefore, there can be some very specific differences between classifications. Something that most companies in various countries agree on, however, is that analytical grade chemicals are the highest graded products in terms of purity and lack of contaminants. 

The high quality of analytical grade chemicals make them ideal for laboratory analytical purposes. They are used for testing other chemicals, including biochemical products such as enzymes and hormones. 

Analytical grade chemicals are also used for calibrating laboratory instruments. For example, they are used in the following processes to compare the sample value with the standard value:

• Capillary electrophoresis
• Chromatography
• Electrochemistry
• Microbiology
• Spectroscopy

High levels of precision and accuracy of measurements in laboratory analyses are possible because of analytical grade chemicals. In turn, these measurements serve as the basis for creating new materials that can be manufactured into more high quality products.

What Are Lab Grade Chemicals?

Compared to analytical grade chemicals and reagent chemicals , lab grade chemicals are less pure. However, while their levels of impurities are usually not specified, they don’t contain excessive amounts of contaminants. Instead, their quality is considered to be upper-intermediate. 

Lab grade chemicals are typically used for educational purposes in school chemistry labs for a wide range of experiments, such as titration. This is because school-based experiments are intended as a demonstration of concepts, not for carrying out ultra-precise sample analysis. The important thing is that students are able to learn chemistry principles and methodologies, and lab grade chemicals are ideal for this. 

What Are Food Grade Chemicals?

Food grade chemicals are food ingredients that are compliant with health and safety regulations and international standards, such as the Food Chemicals Codex (FCC). These chemicals are manufactured in bulk and sold either in large wholesale containers or in retail packs.

Food grade chemicals refer to non-organic or organic chemical additives that are added to food in order to make it last longer, taste better, and look better, among other reasons. These chemicals are processed and mass produced by companies either for use by food companies, or for direct household use. Some examples of food grade chemicals are:

• Antioxidants
• Food preservatives
• Artificial food colouring
• Artificial flavouring
• Vitamins and minerals

These chemicals are added to processed foods to extend their shelf lives and provide a wide range of flavourings. Certain types of processed foods are also fortified with vitamins and other micronutrients. Some food grade chemicals, like citric acid and baking soda, are also commonly used in households for baking and cooking. 

What Are GPR Grade Chemicals?

GPR grade chemicals are referred to in several ways, including guaranteed pure reagent grade chemicals, and also general pure reagent chemicals. These are laboratory grade chemicals that can have a purity rating of up to 99.9%. 

However, these products do not undergo strict testing for contaminants. This makes them suited for general laboratory use only, again as in school chemistry experiments, or testing for chemical reactions .

As reagents, GPR grade chemicals can also be used to maintain the quality of certain products. For example, reagents are efficient at testing for the presence of contaminants. They are also used to test the level of chemical reactions in a large batch of products, like beer and other manufactured beverages.

What Is Reagent Grade Water?

Reagent grade water is usually distilled water intended for specific laboratory testing procedures. When used as a reagent, it is important that water does not significantly interfere with the procedure or chemical reactions being tested. 

Ideally, it should contain as few contaminants as possible. This includes impurities like dissolved minerals, which can react with other chemicals in a solution and affect test results. In titration procedures , for example, pure water is necessary to gain accurate calculations of the molarity of the acid and base substances.

Reagent grade water has three general levels of classifications, depending on purity:

• Type 1: This classification is necessary for critical laboratory applications, like DNA sequencing. The water reagent is prepared by distillation , deionisation , and filtration.
• Type 2: General analytical laboratory procedures require this classification of reagent grade water. It is crucial that it is free from organic chemicals in these settings, where it is used for buffers , pH solutions, and microbial preparations.
• Type 3: This is the lowest laboratory water grade recommended for rinsing laboratory glassware, heating baths, and filling autoclaves.

What Does USP Grade Mean?

USP grade means United States Pharmacopeia grade . USP is a non-profit scientific convention whose standards are accepted in more than 140 countries. The USP standards are mainly focussed on food, drugs, and medical-grade chemicals.

In the United States, USP does not have the power to legally enforce its standards. The U.S. Food and Drug Administration (FDA) and other related government agencies are the ones responsible for the enforcement of laws and regulations.

The different grades of chemicals ensure that quality standards and product safety are followed. These grades serve as guidelines about the appropriate quality of chemicals that should be used.

The blog on chemicals.co.uk and everything published on it is provided as an information resource only. The blog, its authors and affiliates accept no responsibility for any accident, injury or damage caused in part or directly from following the information provided on this website. We do not recommend using any chemical without first consulting the  Material Safety Data Sheet  which can be obtained from the manufacturer and following the safety advice and precautions on the product label. If you are in any doubt about health and safety issues please consult the Health & Safety Executive ( HSE ).

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Analytical Grade Solvents

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There are different grades of solvents available on the market to cater to the needs of different laboratory research applications. Normally, the qualities of solvents are set by international organizations such as ASTM International or the American Chemical Society (ACS). Thermo Fisher Scientific offers a wide range of analytical grade solvents for research applications.

ACS grade solvents

Our ACS grade solvents are manufactured under specific quality control parameters. The Committee on Analytical Reagents of the ACS is the first of its kind to set the quality requirements for each solvent and develop a validated method to ascertain purity. These solvents are widely used in research laboratories in academic and industrial settings. Certificates of Analysis and MSDS are available upon request.

Anhydrous solvents

Anhydrous solvents are highly pure solvents made with low water content. Anhydrous solvents produced in laboratories use complex and difficult processes to reduce the moisture content. To minimize the moisture content, we use various dehydration methods, such as column distillation, addition of molecular sieves, and distillation over metallic catalyst.

Commercially available anhydrous solvents can be directly used in reactions, as further purification is not required. These anhydrous solvents are used in moisture-sensitive reactions in both organic and inorganic synthesis and in analytical laboratory applications where yields are maximized by reducing side reactions.

Anhydrous solvents normally have less than 50 ppm of water content. Care should be taken while opening the anhydrous solvents at ambient temperature as they tend to absorb moisture from the atmosphere.

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