Analytical Factors

Since many ion exchange columns exhibit mixed-mode interactions with analytes, factor analysis has been found to be useful in optimization.84 A 3-year, comprehensive review of inter-laboratory errors in determinations of the anions chloride, nitrate, and sulfate and the cations sodium, potassium, magnesium, and calcium suggested that multipoint calibration is essential and nonlinear calibration desirable.102 The need for nonlinear calibration was confirmed by an extended quality assurance study of chloride, sulfate, and nitrate in rainwater.103... 

Factor 2 contained those variables which related to casing. These included MDS dimension 1 and analytical factor 2. Plots of factors 1 and 2 (Fig. 10) showed that these analytical/sen-sory factors contain both tobacco type and casing information. 

Unlike the pre-analytical factors, analytical factors are more readily controlled within the individual laboratory. Analytical variables that are associated with the demonstration of the antigen include antibody specificity and sensitivity, dilution, detection system, and antigen retrieval. 

It has been suggested that validation exercises may not be necessary if a validated commercial method is employed and the vendor s protocol carefully followed. This clearly is not true as pre-analytical factors are so different between laboratories that standardization of the staining method is not a guarantee of uniformity of sensitivity. 

Irjala KM, Gronroos PE. Preanalytical and analytical factors affecting laboratory results. Ann Med 1998 30 267-72. 

A number of analytical factors must be considered when assessing the status of each nutrient. They include reference intervals, concentrations of markers in plasma and tissue, and their measurement in urine. 

Analytical factors that have to be considered in the measurement of trace elements include (1) specimen requirements, (2) preanaiytical factors, (3) collection equipment, and (4) analytical methodology. 

Markert and Frei have reviewed Biochemical Events Related to Phagocytosing Cells. The clinical chemist is required more and more to deal with isolation and measurement of components in leukocytes. These authors have considered the techniques for isolation of the cells and their subcellular components as well as the biochemical mechanisms involved in phagocytosis in both normal and pathological situations. Alkaline phosphatase has been of considerable interest to clinical chemists for more than 50 years Posen and Doherty have reviewed The Measurement of Serum Alkaline Phosphatase in Clinical Medicine and, in a detailed fashion, have outlined available information regarding the significance of serum alkaline phosphatase in a variety of disease states as well as the many physiological and analytical factors affecting the activity of this enzyme. 

Pre-analytic, analytic, and post-analytic factors can significantly alter hormone receptor results. 

Variability of results is caused by both analytical factors and biological factors. 

Statland, B.E. and Winkel, P. (1977). Effects of non-analytical factors on the intraindividual variation of analytes in the blood of healthy subjects Consideration of preparation of the subject and time of venipuncture. CRC Critical Reviews in Clinical Laboratory Science 8, pp. 105-144. 

This method measures the UV change induced by ionization instead of the volume of titrant necessary to change pH. Spectrophotometric titration is a powerful technique that works with relatively low concentrations of analyte (factor 10—Slower compared to potentiometric titration), thus preventing sample precipitation for a larger proportion of the samples. The interpretation of experimental data is relatively easy when one considers a single ionization. It becomes significantly more complex if the molecule has several ionizable centers, and even more if they overlap. In this case sophisticated numerical procedures like target factor analysis have to be used. ... 

Tatsumoto and Snavely (1969) lead extraction by volatilization below the melting point with other analytical factors as given in Table 18. 

This paper analytical factors as given in reference 1 above. K-feldspar separates were provided by C. L. Sainsbury for Alaska and Peter Lipman for Nevada both donators are from the U.S. Geological Survey. 

These two exercises introduce the notion of gravimetric factor or analytical factor. It is defined as the ratio of the analyte mass and the mass of the compound that is weighed. In the first example, the analytical factor was 1 [M(Cl)/M(AgCl)], and in... 

Description of the most important analytical factors for selecting an ICP-MS system, taking into consideration more recent application demands... 

Internal standards can also be used directly for quantitation without the creation of a working curve. This approach is less accurate than fiiU calibration but is convenient under conditions where exact measure is not required. In this case, the response area of a single concentration, usually in the mid-range of the expected concentrations, is measured and its area ratioed against the internal standard to obtain an analytical factor that can then be used to convert future measured ratios into the desired concentration units, assuming a linearity of instrument response. 

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