ANALYTICAL GOALS

Analytical goals related to biological variation have attracted considerable interest. Originally, focus was on imprecision, and Cotlove et aF suggested that the analytical 

TABLE 14-4 Hierarchy of Procedures for Setting Analytical Quality Specifications for Laboratory Methods 

Data from EQA/proficiency testing scheme B. Data from current publications on methodology 

In addition to imprecision, goals for bias should also be considered. Gowans et related the allowable bias to the width of the reference interval, which is determined by the combined within- and between-subject biological variation in addition to the analytical variation. On the basis of considerations concerning the included percentage in an interval in the presence of analytical bias, it was suggested that  

Thus the bias should desirably be less than a fourth of the combined biological standard deviation. One may further extend the suggested relationships to comprise an optimum relation corresponding to a factor 0.125 and a minimum relation with a factor 0.375. Given a normal distribution of reference values, the desirable relationship corresponds to maximum deviations for proportions outside the interval from the expected 2.5% at each side to 1.4% and 4,4%. This gives an overall deviation of 0.8% from the expected total of 5%, corresponding to a relative deviation of 16%, which may be considered acceptable.  

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Im summary, it was not possible to achieve all analytical goals in this study of AN/S polymerizations. We were unable to approximate total solids contents directly because of presence of insoluble polymer. Circumstantial evidence sug-... 

Medical significance, indications for use, and analytic goals for the test. 

EXMAT - A Linked Network of Expert Systems for Materials Analysis. Seven individual expert systems comprise EXMAT (1) problem definition and analytical strategy (2) instrumental configuration and conditions (3) data generation (4) chemometric/search algorithms (5) results (6) interpretation (7) analytical goals. Dynamic headspace (DHS)/GC and pyrolysis GC (PGC)/concentrators... 

Figure 5.34 shows the FT-NIR predictive models for total vol% paraffins, isoparaffins, naphthenes and aromatics and carbon number distribution for a typical naphtha dataset. Since NIRS can be demonstrated to have sufficient hydrocarbon speciation capability to reproduce the analyzis with the same precision as the GC method, but in a fraction of the time, then a useful process analytical goal has been achieved. 

The aim of this chapter is to translate such different analytical goals into objective functions, i.e. into different criteria which can be the objective goals of an optimization process. 

Analytical goals, by contrast to those of preparative separation, are based upon the information generated in the process of separation, or realized by... 

The sequence, position, and distribution of separated components contain a good deal of information on the mixture. If properly measured and interpreted, this can serve many analytical goals without further tests. The quality of this information naturally improves as the system is better understood, characterized, and controlled. Informational content is greatest when, through theory and/or calibration, one can identify zones or peaks located at defined positions in the sequence with specific molecular species At that point, using a suitable sensor (detector), both qualitative and quantitative analyses follow. One can, at the same time, often measure certain physicochemical constants for the components, such as partition coefficients and diffusion constants. 

If peaks can be adequately distinguished (depending on analytical goals and methods) at some Rs value less than one, then more peaks can be crowded into the separation space and nc increases in accordance with the equation... 

Bowers, L.D. Analytical goals in therapeutic drug monitoring. Clin. Chem. 44, 375-380... 

When using such a system, the analytical goals for the separation must be defined. The following conditions were chosen ... 

Optical rotation has the dual advantages of historical use and widespread recognition in the compendia. For an enantiopure material, it defines its configuration when used in conjunction with other valid chemical tests. However, optical rotation has been used ineffectively when the primary analytical goal is the determination of stereochemical purity. The limits selected for the specification seem to be unrelated to the purity required by other methods. For example, the compendial monograph for naproxen requires that the drug substance meet a specification of "between -f-63.0 and -1-68.5"" in a chloroform solution. Based on the published specific rotation, this corresponds to a stereochemical purity of 95.5 to 103.7%, compared to the assay limits of 98.5 to 100,5%, determined by titration with sodium hydroxide (5). 

Sylvestre, E. (1979). Development of analytical goals for the Kodak Ektachem GLU/BUN analyzer. 3rd Europ. Congr. Clin. Chem., Brighton, 3-8 June, 43, Abstr. 

MALDI-TOF precludes many previously mentioned problems and limitations of the ESI-MS technique. However, it is important to note that MALDI-TOF and ESI-MS are complementary, not alternative, techniques. Depending of the analytical goal, either one of these two methods can be more effective. MALDI-TOF technique was described in detail in the literature [282]. Fig. (21) shows a negative mode MALDI-TOF spectrum of an HA fraction composed of three individual oligomers 30-mer, 32-mer, and 34-mer [286]. In general, chemical structure, ionization, end groups, etc. are usually characterized by means of the MALDI-TOF detector [282]. 

Keywords Validation Lithium Performance Proficiency testing Analytical goals... 

In evaluation of the performance characteristics of a candidate method, precision, accuracy (trueness), analytical range, detection limit, and analytical specificity are of prime importance. The sections in this chapter on method evaluation and comparison contain a detailed outline of these concepts and their assessment. The estimated performance parameters for a method can then be related to quality goals that ensure acceptable medical use of the test results (see section on Analytical Goals), From a practical point of view, the ruggedness of the method in routine use is of importance. Reliable performance when used by different operators and with different batches of reagents over longer time periods is essential. 

Fraser CG. Generation and application of analytical goals in laboratory medicine, Annali dell Instituto Superiore di Sanita 1991 27 369-376. 

In the planning phase of a method comparison study, one should consider the size of the medicaUy significant difference or critical difference that should be detected at a given concentration TO-i jjgetc (see Analytical Goals)... 

Gowans EMS, Petersen PH, Blaabjerg 0> Horder M. Analytical goals for the acceptance of common reference intervals for laboratories throughout a geographical area. Scand J Chn Lab Invest 1988 48 757-64. 

Ross JW, Lawson NS. Analytical goals, concentration relationships, and the state of the art for clinical laboratory precision. Arch Pathol Lab Med 1995 119 495-513. 

Data from studies of biological variation may be used to assess the importance of changes in test values within an individual from one occasion to another, determining the appropriateness of reference intervals and, in conjunction with data from analytical variation, establish laboratory analytical goals. Application by cHnicians of information on biological variability could enhance their ability to precisely identify important changes in test results in their patients. 

Fuentes-Arderiu X, Fraser CG. Analytical goals for interference. Ann Clin Biochem 1991 28 393-5. 

Multiple analytical goals have been proposed for the performance of glucose meters. The rationale for these is not always clear. In 1987 the ADA recommended a goal of total error (in the hands of users) of less than 10% at glucose concentrations of 30 to 400mg/dL 100% of the time. The... 

An analytical goal, or quality specification, for between-day imprecision, expressed as the CV, is 0.9% or less based on within-person biological variation. Current methods are capable of achieving a between-day CV of 1.5% or less. 

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