Analyte subtraction method

The analyte addition method (AAM) involves adding the sample solution to a standard solution of the determinand, whereas in the analyte subtraction method (ASM) the sample is added to a standard solution of an ion that reacts stoichiometrically with the test substance and is sensed by an ISE. These methods are advantageous for determinations on small samples for which microelectrodes would otherwise have to be used. pH adjustment and masking of interferents in the sample is unnecessary because all these operations can be done beforehand on the standard solution. Furthermore, the analyte subtraction method widens... 

In addition techniques, the test substance concentration is determined from the difference in the ISE potentials obtained before and after a change in the sample solution concentration. The main advantage Ues in the fact that the whole measurement is carried out in the presence of the sample matrix, so that results with satisfactory accuracy and precision can be obtained even if a substantial portion of the test substance is complexed. Several addition techniques can be used, namely, single, double or multiple known addition methods, in which the sample concentration is increased by additions of a test substance standard solution single, double or multiple known subtraction methods, in which the sample concentration is decreased by additions of a standard solution of a substance that reacts stoichiometrically with the determinand and analyte addition and subtraction methods, in which the sample is added to a test substance solution or to a reagent solution. 

The tasks formulated above have determined the structure of the book, the first six chapters of which are devoted to accounts of the main chemical methods (preliminary processing of samples, kinetic methods, pyrolysis GC, determination of carbon skeleton, subtraction method, chemically selective stationary phases, elemental analysis). The last two chapters are devoted to the solution of two tasks that are most important in analytical chemistry nowadays the determination of impurities (Chapter 8) and the identification of components of complex mixtures by fimctional group analysis (Chapter... 

The subtraction method is a valuable technique for solving the two principal problems in analytical chemistry identification of compounds (chromatographic zones) and impurity analysis. The subtraction method is a simple and efficient means of analytical investigation to apply it, no special equipment is required, and part of the column can be... 

Table 13.3 Comparison of different analytical derivative methods for the calculation of nuclear magnetic shielding constants a (in ppm) (Gauss, 1992, 1993, 1994 Gauss and Stanton, 1995, 1996) The experimental data (Gauss, 1992 Wasylishen and Bryce, 2002) are extrapolated to the equilibrium geometry by subtracting calculated ro-vibrational corrections from the experimental values.

The analysis involved deconvolution by iterative reconvolution, background subtraction, and optional correction for shift of the instrument response function. Statistical tests included chi-square, the Durbin-Watson test, the covariance matrix, a runs test, and the autocorrelation function [6]. An alternative form of data analysis involves distributions of lifetimes rather than a series of exponentials. Differentiation of systems obeying a decay law made up of three discrete components from systems where there exists a continuous distribution of lifetimes, or a distribution plus one or more discrete components, is a nontrivial analytical problem. Methods involving the minimization of the chi-square parameter are commonly used, but recently the maximum entropy method (MEM) has gained popularity [7]. Inherent in the MEM method is the theoretical lack of bias and the potential for recovering the coefficients of an exponential series with fixed lifetimes which are free of correlation effects and artificial oscillations. Recent work has compared the MEM with a new version of the exponential series method (ESM) which allows use of the same size probe function as the MEM and found that the two methods gave comparable results [8]. 

Two methods are commonly used to correct for the residual current. One method is to extrapolate the total measured current when the analyte s faradaic current is zero. This is the method shown in the voltammograms included in this chapter. The advantage of this method is that it does not require any additional data. On the other hand, extrapolation assumes that changes in the residual current with potential are predictable, which often is not the case. A second, and more rigorous, approach is to obtain a voltammogram for an appropriate blank. The blank s residual current is then subtracted from the total current obtained with the sample. 

Mixtures can be identified with the help of computer software that subtracts the spectra of pure compounds from that of the sample. For complex mixtures, fractionation may be needed as part of the analysis. Commercial instmments are available that combine ftir, as a detector, with a separation technique such as gas chromatography (gc), high performance Hquid chromatography (hplc), or supercritical fluid chromatography (96,97). Instmments such as gc/ftir are often termed hyphenated instmments (98). Pyrolyzer (99) and thermogravimetric analysis (tga) instmmentation can also be combined with ftir for monitoring pyrolysis and oxidation processes (100) (see Analytical methods, hyphenated instruments). 

Rows 1-7, item Titr 0.5% subtracted typical of temporary change in the production process, calibration procedure, or analytical method, especially if values 1-7 were obtained in one production campaign or measurement run. 

Determine the actual cavity volume and surface area within the Delaunay tetrahedra The overlap of the exclusion spheres with the relevant Delaunay tetrahedra is subtracted analytically, leaving only the actual cavity volume and surface area. This nontrivial calculation is from the multiple overlap of exclusion spheres, but a systematic method for carrying it out is available.70 71... 

A method blank is a sample containing all components except analyte, and it is taken through all steps of the analytical procedure. We subtract the response of the method blank from the response of a real sample prior to calculating the quantity of analyte in the sample. A reagent blank is similar to a method blank, but it has not been subjected to all sample preparation procedures. The method blank is a more complete estimate of the blank contribution to the analytical response. 

Terminology. Dietary fiber is the accepted terminology in the United States for nutritional labeling. Total dietary liber (TDF) and its subtractions, insoluble dietary fiber (IDF) and soluble dietary fiber (SDF). are defined analytically by official methods. 

TNT, Sb sulfide and Pb thiocyanate are detd as described in Ref 13, while the remaining ingredient K chlorate + gum is calcd by subtracting from 100 the sum of other ingredients Refs l)Faber 3(1919), 141-50 2)C.A.Taylor Wm. H, Rinkenbach, "Explosives , USBur-MinesBull 219(1923), 32-6(Analysis of commercial K chlorate) 142-3(Detn of K chlorate in dynamites) 3)Scott. Furman (1939), 274-6, 861-70, 1677 2160 4) Treadwell Hall, vols 1 2(1942) 4a) Kast-Metz(1944), 373-80(Analysis of commercial K chlorate) 5)Anon, "Control Laboratory Manual , Expls Proplnts Branch, PicArsn, Dover,. NJ (1956) Method No 501.1(Analysis of M31 Igniting Mixture) Method No 502.1 (Analysis of PA-100 Primer Mixture) Method No 503.1(Analysis of Standard Primer Mixture) 6)M.Halik R.Croom, PATR 2430(1957)(U) (Flame spectrophotometric method for detg Na chlorate in K chlorate) 7)Anon, "Analytical Methods for Powders and Explosives ,... 

Single nucleotide polymorphisms (SNPs), 218 Software, 43-46 for aggregate subtraction, 137 for cell cycle analysis, 135-137 for spectral compensation, 79 Soluble analytes, 218-220 Sorting, 159-173 accuracy of, 166, 168 alternate methods for, 170-172 batch, 170-171 break-off point, 161-163 efficiency of, 168-170, 169f for prenatal diagnosis, 221 high speed, 165-166, 169-170, 172, 215, 225... 

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