These criteria Description of all of the details is beyond the scope of this include the patient cohort and setting in which the test is to chapter and only some highlights will be discussed. Review of be used, as well as the outcome measures to be considered. The Clinical Question and Criteria for Until recently, methodologists interested in systematic of Studies reviews have focused on studies of the effects of interventions, Among the steps in conducting a systematic review of a especially drugs, on patient outcomes.
Their work is generally diagnostic test Box 1-I , the most important is the identifica- applicable to systematic reviews of diagnostic tests that start tion of the clinical question for which the test result is required with a question of the second type above.
Unfortunately for to give an answer and thus formulation of the question that systematic reviews of diagnostic tests, it is unusual at present forms the basis of the review.
Two types of questions can be to find more than one study on any combination of a test and addressed in a systematic review in diagnostic medicine: one an outcome. We therefore focus on systematic reviews of the type is related to the diagnostic accuracy of a test and the other diagnostic accuracy of tests.
When the questions to be addressed are defined, the review The questions that arise are similar in structure, but require group must agree on the scope of the review. The review group different approaches. It may be possible to undertake a meta- Explore the effect of variability in study and analysis if data are available from a number of similar studies other characteristics setting, type of populxion, i.
Meta-analyses can subgroup analysis or modeling. For guidelines on conduct accuracy to different settings and the effect of study design of meta-analyses of RCTs, see the Quality of Reporting of and inherent patient characteristics such as age, sex, and Meta-analyses QUOROM statement at www.
It is usual to search both Medline and enable the clinician to calculate the posttest probability if the Embase because the overlap between the two can be as low as pretest probability is known? Searching of databases is a detailed exercise and the help of a librarian or information scientist is recommended. Guidance that is tailored to searching for studies of diagnostic.. For Glasziou www. Although the Additional studies may be found in the "gray" literature of direct laboratory costs are small in comparison, the tests have a profound influence on medical decisions and therefore total -uncover.
A hierarchy of evidence regarding clinical tests begins with Data Extraction and ritical Appraisal of Studies assessment of the test's technical performance and proceeds Identified papers should be read independently by two persons through the study of the test's diagnostic performance to an and data extracted according to a template. A checklist of identification of potential benefits and thus to economic eval- items to extract from primary studies in preparing a systematic uation.
This hierarchy of evidence can also be seen in the review on test accuracy is available online. It therefore lies at the heart the template. The quality of studies must be assessed as part of the sys- Economic evaluation provides a means of evaluating the tematic review.
The study design is an important consider- comparative costs of alternative care strategies. For many questions related to outcomes, an RCT will be the highest quality design. For studies of diagnostic accu- Methodologies for racy, studies of consecutive series of patients will rank above Health economics is concerned with the cost and consequences studies using historical controls.
Of course, a study may use a of decisions made about the care of patients. It therefore good design but suffer from serious drawbacks in other dirnen- involves the identification, measurement, and valuation of sions; for example, many patients may have been lost to follow- both the costs and the consequences. The process is complex up or the studied test performed poorly during the study as and is an "inexact science. Thus adequate grading uation include 1 cost minimization, 2 cost benefit, 3 cost of the quality of studies must go beyond the categorization of effectiveness, and 4 cost utility analysis Table Cost-minimizatim analysis determines the costs of alterna- tive approaches that produce the same outcome.
It can be Summarizing the Data considered the simplest but least informative type of economic The characteristics and data from critically appraised studies evaluation. In the area of diagnostic testing, it is applicable to should be presented in tables. The data of studies of diagnostic the cost of alternative suppliers of the same test, device, or accuracy should include sensitivities, specificities, and likeli- instrument. It is therefore a technique that is limited to the hood ratios wherever possible.
These can then be summarized procurement process where the specifications of the service are in plots that provide an indication of the variation among already established and the outcomes clearly dehed. It might studies. The summary should also include an assessment of the be considered as providing the "cost per test," an often quoted quality of each study, using an explicit scoring system.
A review indicator that is not, however, a true economic evaluation should also present critical analysis of the data highlighted in because it does not identify an outcome except the provision the review. Cost-benefit analysis determines whether the value of the able to produce a demonstrably greater benefit if spent benefit exceeds the cost of the intervention and therefore on a different intervention or test whether the intervention is worthwhile.
The value of the con- sequence or benefit is assessed in monetary terms; this can be Perspectives of quite challenging because it may require the analyst to equate The perspective from which an economic evaluation is a year of life to a monetary amount. There are a number of performed affects the design, conduct, and results of the evalu- methods, including the "human capital approach," which ation. The perspective may, for example, be that of a patient, assesses the individual's productivity in terms of earnings , a payer government health agency or health insurance and the "willingness to pay approach," which assesses how company , or society.
The perspective may he long term or much individuals are prepared to pay. The questions below illustrate the importance of Cost-effectiveness analysis looks at the most efficient way of The effects are measured in terms of What is the cost of the test result produced on analyzer a natural unit, such as a year of life or the number of strokes A compared with analyzer B?
Surrogate measures with clear relationships to rnor- What is the cost of the test result produced by bidity and mortality have also been used e. When assessing an intervention, the number of cases What is the cost of the test result produced by POCT of disease prevented may he used as a measure of benefit. Cost-utility analysis includes the quality and the quantity of Will provision of rapid blood testing for the the health outcome, or in other words looking at the quality emergency department reduce the length of patients' of the life-years gained.
The cost of the intervention is assessed stays in the department and thus decrease cost for the in monetary terms, but the outcomes are expressed in "quality- hospital? Cost-utility analysis has been Will rapid HbA,, testing in a clinic rather than in a used to assess the utility of some screening programs. Will it save and benefit. A cost-effectiveness studyL0 of screening for money for the patients' employers by reducing colorectal cancer versus no screening showed that the "least employees' time away from work to go to repeated expensive" strategy was a single sigmoidoscopy at 55 years of physician appointments?
Will it life-year saved. Will it save money for the health system by When tests increase both the cost and benefit, decisions improving glycemic control and thus decreasing about their use will depend on factors such as willingness to hospitalizations related to poor glycemic control!
This reflects a decision by the U S. Congress increasing patients' functioning and contributions to to approve dialysis treatment for end-stage renal failure, a societv? The first scenario is the type of evaluation made when There are four possible findings from cost-utility analyses making a deal and is a simple procurement exercise. The and corresponding possible decisions: outcome is the same--the provision of a given test result, to a Test more costly but providing greater benefit-possibly given standard of accuracy and precision within a given time introduce depending on overall gain the specification.
The second question might appear to be Test more costly but providing less b e n e f i t d o not the same, but it is not and will undoubtedly have to take into introduce test account other issues, namely the logistical issues associated Test less costly but providing greater benefit-introduce with sample transport or the level of communication support test provided by the laboratories. The implications of the remaining questions. Note that the clinical complications of poor The oatient-centered eoals of evidenced-based laboratorv u glycemic control are largely long term and may be beyond the medicine cannot be reached by primary studies and systematic time frame of the financial interests of those performing an reviews alone.
The results of these investigations must be economic analysis. Indeed, rigorous long-term economic eval- turned into action.
Increasingly, health systems and profes- uations of the use of tests are rare. Guidelines are a tool to facilitate imple- mentation of lessons from primary studies and systematic Criteria for evaluating an economic study of a diagnostic test reviews. Important motivations for development of guidelines include: have been to decrease variability in practice and improve the Clear definition of economic question including use of best practices and to decrease the often prolonged perspective of the evaluation e.
The focus of modern clin- these criteria. The tools of EBM and clinical The stream of new tests in laboratory medicine requires epidemiology allow the guidelines to be developed in a more frequent decisions about whether or not to implement transparent way from well-conducted studies and systematic them.
Economic evaluations can help in making these deci- reviews. The finite resources for healthcare require use of a n objective means of determining how resources are allocated and how the efficiency and effectiveness of service delivery can be improved. In the absence of a transparent process for development of a Economic evaluations can be important for laboratories.
When guidelines are developed dently of the other costs of healthcare. This is often referred by a professional group such as specialist physicians or to as "silo budgeting.
Second, achieve- suspected of promoting the welfare of the professional group. Third, the introduction of a new test measures that may harm patients.
In the latter setting, a key or testing modality e. For medical intervention may be interpreted as proof of absence of example, the D-dime test has been used to exclude diagnoses benefit. This approach works only if clini- evelopment of Gui cians actually consider the D-dimer results and stop ordering The development of guidelines is best undertaken with a the expensive imaging tests when the D-dimer result and the step-by-step plan. One such scheme is shown in Figure , clinical findings indicate that they are not needed.
Finally, only selected issues of which will be discussed here. For a even if the desired cost savings are achieved, silo budgeting more detailed discussion, see Bruns and Oosterhuiss or ensures that the savings are seen in a budget different from the Oosterhuis et aLL9 laboratory's, and the laboratory budget shows only an increased cost.
Fortunately the drawbacks of silo budgeting are being Selection and Refinement of a Topic recognized, and a broader view of health economics seems to The critical importance of this first step is analogous to the be developing in some healthcare settings. High-grade evidence for all recommendations? Consultation, peer review, wnsenws conference,. Figure Steps in development 8 Presentation of gutdelino I 1 of a clinical piactice guideline. Evidence-based pidelines in laboratory medicine: principles and methods.
Clin Chem ; T h e scope must not exceed the capabilities Refinement of the topic ideally involves a multidisciplinary in time, funding, and expertise of the group, the topic must group that includes clinicians, laboratory experts, patients, and not be without evidence or the guideline will lack credibility , likely users of the guidelines. T h e scope will be affected by the and the area must be one requiring attention or the guideline support staff if any and financial support available to the will have little value.
T h e cost is usually underestimated. Guidelines can address clinical conditions such as diabetes and liver disease , symptoms chest pain , signs abnormal Determination of Ta el. Group and Establishment bleeding , or interventions, whether therapeutic coronary of a Multidisciplinary Guideline Development Team angioplasty and aspirin or diagnostic cardiac markers.
T h e The intended audience must be identified: Is it nurses, general priority for a guideline should be: Is there variation in practice practice physicians, clinical specialty physicians, laboratory that suggests uncertainty! Is the issue of public health impor- specialists, or patients! T h e team should include representatives of all key groups Is there a perceived necessity for cost reduction!
OAL J. Where no systematic reviews exist, the group effectively must undertake to produce one. The level of evidence supporting each conclusion in the review will affect the recommendations made in the guidelines.
Translating Evidence into a Guideline and Grading the Strength of Recommendations The processes for reaching recommendations within an expert group are poorly understood.
For clinical practice guidelines, the process may involve balancing of costs and benefits after values are assigned and the strength of evidence is weighed. Conclusive evidence for recommendations is only rarely avail- able.
Authors of guidelines thus have an ethical responsibility to make very clear the level of evidence that supports each recommendation. Various schemes are available for grading the level of evi- dence, and one of them should be adopted and used explicitly.
A rather simple one, with a rather typical four levels A through D , is shown inTable A morecomplex scheme is shown in Box For a recent and different approach, see Atkins et al. For methodologists for expertise in statistics, literature search, example, multiple studies supporting use of a drug may have critical appraisal, and guideline development , and those who been done well and a competent systematic review may be deliver services such as nurse practitioners and patients for available,so that the evidence may be graded as high.
However, guidelines on home monitoring of glucose; laboratory techni- if the studies were done in adults and the guideline is for chil- cians and managers for a guideline that addresses turnaround dren, the strength of the recommendation may be low. The highest level of evidence is rare in guidelines on the Potential conflicts of interest of all members must be noted. In most such guidelines, the majority of The role, if any, of sponsors commercial or nonprofit in the the recommendations are based on expert opinion.
As more guideline development process must be agreed upon and studies are published on the diagnostic accuracy of tests and reported. Ideally, staff support is available for arranging meet- on the relationship of tests to outcomes, the dependence of ings and conference calls and assisting with publication and guidelines on "opinion" should decrease.
For analytical goal setting or "quality specifications" for A minimum group size of six has been recommended. Sizes analytical methods in guidelines, randomized controlled larger than 12 to 15 persons can inhibit the airing of each clinical trials outcomes studies are rarely available. A differ- person's views. A recommended tool is the use of subgroups to ent hierarchy of evidence Table may be useful for grading focus on specific questions, with a steering committee respon- of such laboratoqvrelated recommendations.
The highest level sible for coordination and the production of the final guideline. It is conceiv- Other ways of using subgroups can be envisioned. For example, a modeling study can show how rates of the question misclassification of cardiac risk are increased when cholesterol assays have analytical bias.
Level 1B in Table refers primarily to the concepts of. Thus, when a test is used to rnonitor a patient's condition, analytical practice applyto variability is not an important concern. Similarly, the goal for bias is to make bias small compared with the variation among individuals.
Thus, reference intervals formerly called "normal ranges" for a test in a given reference group will be unaffected critically appraise by the small amount of analytical error or bias.
Use of this type evidence of quality specification for imprecision and bias appears appro- priate in guidelines. In fact, failure to use this approach is difficult to justify because data on within-person and among- Figure The audit cycle. From Price CP. Evidence-based person biological variation are available for virtually all corn- laboratory medicine: supporting decision-making.
Clin Chem monly used tests. The ability to use assays for monitoring and ZOOQ All of the audit activities are found in the oractice of completeness of literature review and the evidence-based laboratory medicine. In many cases reviews. Each of these reviews can add value. As part of the guideline development process, a plan for In such cases, the first step of an auditing process is to establish updating should be developed. T h e importance of this step is a specification.
Such a specification may then generate obser- underscored by the finding that one of the most common vations, which can lead to the creation of a standard. A t the reasons for nonadherence to guidelines is that the guidelines outset it provides the comparative measure against which to are outdated. About half of published guidelines are outdated judge the performance data collected. These findings suggest that the time collecting data o n aspects of the process that are considered to interval between completion and review of a guideline should have an influence o n the outcome with the goal of identifying be short.
T h e clinical audit can improve clinical practice, although the effects are modest. A more general role for audit, Audit to Monitor orkload and Demand however, is that it can be used as part of the wider management T h e true demand for a test will depend o n the number of exercise of benchmarking of petformance with the use of patients and the spectrum of disease in the group for which the relevant performance indicators against the performance of test is appropriate.
When conducting an audit of workload for peers. These questions, which in practice have been accomnmdated in the clinic andlor ward can be asked by questionnaire, include: routines.
What clinical question is being asked? Audit to Monitor Adherence to What action will be taken following the decision? This is the scenario that probably best reflects the way in which What risks are associated with not receiving the the "clinical audit" was first envisaged and practiced. Typically, result? This approach is the most likely to identify when a setting? With the advent of electronic requesting and the electronic patient record, it is possible to build this approach into a routine practice.
The principles provide An algorithm may be embedded in the electronic requesting the logic on which all of the elements of practice are founded. The application of evidence-based practice is far Audit to Monitor the lntro more complex for laboratory medicine than for therapeutic An audit can be used to ensure 1 that the change in practice interventions but critical for success. The development of any new test should lead related to this chapter. Atkins D. BMJ ; Bissel MG. Laboratory related measures of patient outcomes: an Identification of any algorithm into which the test introduction.
Randomisrd comparisons of with other tests, signs, or symptoms mcdical tests: sometimes invalid, not alwaysefficient. Lancet Identification of the decision s likely to be made on ; Towmds complete and accuiatc rcporring of studies of receipt of the result diagnostic accuracy: thc STAKD initiative. Standards for Reporting of Identification of the likely outcome s Diagnostic Accuracy. The STARD statement for reporting studies of of a new test diagnostic accuiacy: explanation and elaboration.
Bossuyt PM. The qualicy of reporting in diagnostic test research: getting expected better, still not optimal. Analysis and prcscmation of data. Evidence-based laboratory medicine: from and reduction in laboratory workload principles to ourcomes. This "summary of use" and portfolio of evidence forms the 8. From evidencc to guidelines. Evidence-based laboratory medicine from basis of the "standard operating procedure" for the clinical use principles to outcomes.
Systematic rcviews in health care: systematic reviews of service, and the basis for conducting the audit. Before auditing the introduction of a new test, it is obvi- Cat-activeness of ously important to have ensured that a full program of educa- screening for colorectal canccr in the general population, JAhilA tion of users has been completed and that any other changes ; Guyatt GH, Rrnnie D, eds.
Users' guides to the medical literature: a Clin Chem Systematic reviews in laboratory ; JAMA Horvath AR, Pewsnrr D. Systematic reviews in laborarmy medicine: ; Clin Chim Acta Evidence-based guidelines in laboratarv medicine:.
Updated6 Getting better but still not good. JAMA January 4, Guidelines for meta-analyses evaluating diagnostic tests. Evidence-based medicine: what it is and what it isn't. Empirical evidence of designmlated bias in developing guidelines. BM] ; JAMA ; Dilution: The process diluting of reducing the 4.
List the different available pipettes, based on their use, type, and concentration of a solute by adding additional solvent. Ergonomics: The study of capabilities in relationship to 5. Understand centrifugation and balances and the terminology related work demands by defining postures which minimize to each and calculate RCF and rpm when given the appropriate unnecessary static work and reduce the forces working- on information.
Describe an atom and define atomic number, mass number, isotope, Exposure Control Plan: A set of written instructions half-life, and nuclide.
Define radioactive decay. List four types of radioactive decay, the type of particle produced by pathogens. State the principles of autoradiography and scintillation counting. Gravimetry: The process of measuring the mass weight of List two types of scintillation counters and their uses in the laboratory. Describe the hazards of radiation and the risks of radiation exposure. Half-Life: The time period required for a radionuclide to Recognize and interpret various laboratory hazard signage and state decay to one-half the amount originally present.
State the purpose of an ergonomics program. Primary Reference Material: A thoroughly characterized, Analysis: The procedural steps performed to determine the stable, homogeneous material of which one or more kind or amount of an analyte in a specimen. Used for calibration of definitive methods; in the Balance: An instrument used for weighing.
Bloodborne Pathogens: Pathogenic microorganisms that are Radioactivity: Spontaneous decay of atoms radionuclides present in human blood. These pathogens include, but are that produces detectable radiation. Buffer: A solution or reagent that resists a change in pH Reference Material: A material or substance, one or more upon addition of either an acid or a base. Certified, primary, and contained in the laboratory. Used primarily for and are frequently referred to as analytes or measurands.
A internal and external quality assurance purposes. A clinical laborato- Systkme International d'Unites SI : An internationally rian is concerned primarily with the measurement of gases or adopted system of measurement. The units of the system solids in liquids, where there is always a relatively large amount are called SI units. However, the Systkme International d'Unit6s semiqualitative, quantitative, or semiquantitative SI recommends the use of moles of solute per volume of procedure for detecting the presence or measuring the solution for analyte concentrations substance concentrations quantity of an analyte in a specimen.
Universal Precautions: A n approach to infection control. Although considered incorrect and inappropriate by metrolo- According to the concept of Universal Precautions, all gists, mass concentration also is reported in terms of grams human blood and certain human body fluids are treated as percent or percent.
This is typically how concentrations of if known to be infectious for HIV, HBV, and other ethanol in blood are expressed. This terminology indicates an bloodborne pathogens. The following equations define the expressions of concen In laboratory practice, solutes are typically measured number of kilograms of solvent.
Edward R. Powsner and John C. Widman on - number of gram equivalents of solute which theMeasurement ofRadioactivity portionof this chapter number of liters of solution is based. A molal solution contains 1 mol of solute General laboratory techniques and procedures. In: Burtis CA, in 1 kg of solvent. Molality is properly expressed as mollkg.
Tietz textbook of clinical chem- In the past, milliequivalent mEq was used to express the istry and molecular diagnostics, 4th ed. Philadelphia: W. Now, the recommended Saunders, For example, if a or derived. A t present only the radian for plane angles and sample contains mg of Na per liter, the molar concentra- the steradian for solid angles are classified this way.
Liter is the name of the submultiple cubic decimeter of the SI unit of In clinical laboratory practice, a titer is thought of as the lowest volume, the cubic meter. Considering that 1 cubic meter rep- dilution at which a particular reaction takes place.
Nevertheless, the IU. Regarding gases in solution, Henry's law states that the CGPM recommends that such exceptional units as the liter solubility of a gas in a liquid is directly proportional to the should not be combined with SI units and preferably should pressure of the gas above the liquid at equilibrium.
Thus as the he replaced with SI units whenever possible. The The minute, hour, and day have had such long-standing use relationship between pressure and solubility varies with the in everyday life that it is unlikely that new SI units derived nature of the gas. When several gases are dissolved at the same from the second could supplant them. Some other non-SI units time in a single solvent, the solubility of each gas is propor- are still accepted, although they are rarely used by most indi- tional to its partial pressure in the mixture.
T h e solubiliq of viduals in their daily lives, but have been very important in most gases in liquids decreases with an increase in temperature some specialized fields. Details of the SI system are found in an and indeed boiling a liquid frequently drives out all dissolved expanded version of this chapter. A meaninpful measurement is exmessed with both a number and a unit. The unit identifies the dimension-mass, volume, or concentration-of a measured property.
The number indi- Many international clinical laboratory organizations and cates how many units are contained in the property. The United States is one of the few coun- been made in metric units.
In the early development of the tries who have yet to accept SI units. A comparison of results metric system, units were referenced to length, mass, and time.
T h e first absolute systems were based on the centimeter, gram, and second CGS and then the meter, kilogram, and second MKS. The SI is a different system that was accepted internationally in The units of the system are called SI units.
Base, derived, and supplemental units are the three classes of SI units. A deriued unit is derived mathematically from two or more base units Table Version 2. A similar standard, known as T o describe test results properly, it is important that all neces- CEN ENV , is being developed by the European Com- sary information be included in the test description. The name of the system or its abbreviation 2. A dash two hyphens 3.
The name of the analyte never abbreviated with an initial capital letter 4. A comma 5. The quantity name or its abbreviation 6. A n equal sign 7. The numerical value and the unit or its abbreviation. The quality of the analytical results produced by the laboratory is a direct indication of the purity of the chemicals used as analytical reagents. The availability and quality of the refer- ence materials used to calibrate assays and to monitor their analytical performance also are important.
Laboratory chemicals are available in a variety of grades. The solutes and solvents used in analytical work are reagent grade chemicals, among which water is a solvent of primary importance. IUPAC has established criteria for "primary stan- dards. Such water is most conveniently prepared nccls. Deioniza- medicine.
OH- ions for the impurities present in ionized form in the irmm. The preparation of many reagents and solutions used in the A single-bed deionize1 generally is capable of clinical laboratory requires "pure" water. In ties. Although the process is inadequate for producing reagent practice, water is filtered before any of these processes are grade water for the laboratory, it may be used as a preliminary used.
Distillation Ultraviolet Oxidation Distillation isthe process of vaporizing and condensing a liquid Ultraviolet oxidation is another method that works well as part to purify or concentrate a substance or to separate a volatile of a total system. T h e use of ultraviolet radiation at the biocidal substance from less volatile substances.
It is the oldest method wavelength of nanometers eliminates many bacteria and of water purification. Problems with distillation for preparing cleaves many ionizing organics that are then removed by reagent water include the carryover of volatile impurities and deionization. This will result in contamination of the distil- uality, Use, and Storage of Reagent Grade Water late with volatiles, sodium, potassium, manganese, carbonates, Type water may be used for glassware washing.
Final rinsing, and sulfates. As a result, water treated by distillation alone does however, should be done with the water grade suitable for the not meet the specific conductivity requirement of type I intended glassware use. It may also be used for certain qualita- water. Type 11 water is used for general laboratov testingnot requir- eferenee Materials ing type I water. Storage should be kept to a minimum; storage Primary reference materials are highly purified chemicals that and delivery systems should be constructed to ensure a are directly weighed or measured to produce a solution whose minimum of chemical or bacterial contamination.
These highly purified chemicals may bc weighed out directly Such procedures include trace metal, enzyme, and electrolyte for the preparation of solutions of selected concentration or for measurements, and preparation of all calibrators and solutions the calibration of solutions of unknown strength.
They are of reference materials. This water should be used immediately supplied with a certificate of analysis for each lot. These chem- after production. No specifications for storage systems for type icals must be stable substances of definite composition that can I water are given because it is not possible to maintain the high be dried, preferably at "C to "C, without a change in resistivity while drawing off water and storing it. They must not be hygroscopic, so that water is not absorbed during weighing.
Secondary reference materials are solutions whose concen- Testing for Water Purity trations cannot be prepared by weighing the solute and dissolv- A t a minimum, water should be tested for microbiological ing a known amount into a volume of solution. T h e content, pH, resistivity, and soluble silica,' and the maximum concentration of secondary reference materials is usually deter- interval in the testing cycle for purity of reagent water should mined by analysis of an aliquot of the solution by an acceptable be 1 week.
It should be noted that measurements taken at the reference method, using. For example, if the water is piped a long distance, con- Certified Reference Standards Standard Reference Materials, sideration must be given to deterioration en route to the site SRMs for clinical laboratories are available from the N E T of use.
T o meet the specifications for high-performance liquid and the IRMM. Examples of such standards available sary to add a final 0. Not all standard reference materials have the properties an ultraviolet UV detector. No peaks exceeding the analyti- and the degree of purity specified for a primary standard, but cal noise of the system should be found. These may then be used to characterize other materials. These are available in two forms: 1 lot-analyzed reagents, in cal, electrophoretic, mass spectrometric, enzymatic, and immu- which each individual lot is analyzed and the actual amount noassay techniques.
These techniques are discussed in detail in of impurity reported, and 2 maximum impurities reagents, for Chapters Here we discuss the basic techniques of volu- which maximum impurities are listed. These reagent grade chemicals are of very high purity and are recommended for quantitative or ampling and Dispensing qualitative analyses. Clinical chemistry procedures require accurate volumetric measurements to ensure accurate results.
For accurate work, only Class A glassware should be used. Class A glassware is certified to conform to the specifications outlined in NIST Many analytical techniques require reagents whose purity circular Manu- facturers offer selected chemicals that have been especially Pipettes purified to meet specific requirements.
There is no uniform Pipettes are used for the transfer of a volume of liquid from one designation for these chemicals and organic solvents.
Molecular Diagnostics: Promises and Possibilities. Molecular Diagnostics of Infectious Diseases. Textbook of Clinical Trials, 2nd Edition. Essential Clinical Anatomy, 4th Edition. Textbook of Clinical Hemodynamics.
Abeloff's Clinical Oncology, 4th Edition. Clinical Nuclear Medicine 4th Edition. Textbook of Clinical Trials. Molecular Quantum Mechanics, 4th Edition. Textbook of Clinical Neurology. Textbook of Clinical Neuropsychiatry, 2nd edition. Basic Clinical Radiobiology, 4th edition. The appendix contains the previous edition, a new two-colour design is used to useful reference interval tables for many analytes, with highlight illustrations, tables and chapter headings.
The both US and SI units given. It also has very useful sections on perhaps splitting the analytical and clinical topics. In point-of-care testing and laboratory automation. There are over 10, printed references, which could and update of existing chapters. However, this edition but not with this new one at the time of writing.
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