Calibration in Analytical Chemistry

In measurement sciences, calibration is an operation that establish a relationship between an output quantity, qouU with an input quantity, q m for a measuring system under specified conditions (qin qout) The result of calibration is a model that may have the form of a conversion factor, a mathematical equation, or a graph. By means of this model, then it is possible to estimate q -values from measured q0Ut-values (qout qin) as can be seen in an abstracted form in Fig. 6.1. 

From the information-theoretical point of view, calibration corresponds to the coding of the input quantity into the output quantity and, vice versa, the evaluation process corresponds to decoding of output data. From the mathematical viewpoint, qin is the independent quantity in the calibration step and qout the dependent one. In the evaluation step, the situation is reverse qout is the independent, and qin the dependent quantity. From the statistical standpoint, qout is a random variable both in calibration and evaluation whereas qin is a fixed variable in the calibration step and a random variable in the evaluation step. This rather complicated situation has some consequences on which will be returned in Sect. 6.1.2. 

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ISO Guide 32 (1997) Calibration in analytical chemistry and use of certified reference materials. International Organization for Standardization, Geneva. 

Danzer K, Currie LA (1998) IUPAC, Analytical Chemistry Division, Commission on General Aspects of Analytical Chemistry Guidelines for calibration in analytical chemistry part 1. Fundamentals and single component calibration (Recommendations 1998), Pure Appl Chem 70 993... 

Calibration in analytical chemistry relates mostly to quantitative analysis of selected species and, therefore, to calibration functions of the kind y = f(x). 

IUPAC (2004) Analytical Chemistry Division Guidelines for calibration in analytical chemistry. Part 2. Multispecies calibration (IUPAC Technical Report). Prepared for publication by K Danzer, M Otto, LA Currie. Pure Appl Chem 76 1215... 

R. Brereton, Introduction to multivariate calibration in analytical chemistry. Analyst, 125, 2000, 2125-2154. 

K. Danzer and L. A. Currie, Guidelines for Calibration in Analytical Chemistry, Pure Appl. Chem. 1998, 70, 993. 

Marschal A (1994) Traceability and calibration in analytical chemistry. Proc Symposium EUROLAB, Florence, Italia... 

ISO (1996) Calibration in analytical chemistry using reference materials. ISO Guide 32... 

Before assessing the other validation parameters (trueness, recovery, precision, selectivity, specificity, detection capability, stability, and applicability/mgged-ness), the appropriateness of the calibration model should be evaluated. The correctness of the analytical determination of elements in food and food products depends indeed on the choice and the evaluation of the calibration model. The calibration model gives the mathematical relationship between the signal of the measuring system and the concentration in the sample. Several authors have published guidelines concerning calibration in analytical chemistry [5-7]. 

Quantitative modelling. Almost all experiments, ranging from simple linear calibration in analytical chemistry to complex physical processes, where a series of... 

The PLS method was developed by H. Wold [71] and has been further developed and extended to chemical systems by S. Wold [72], A tutorial paper on the method is given in [73]. An important area of application of PLS is in the field of quantitative structure-activity relations [64a, 74]. The applications of PLS for multivariate calibration in analytical chemistry has been thoroughly treated by Martens and Naes [75]. As we shall see, PLS is also a very useful in organic synthesis. 

Calibration in Analytical Chemistry and Use of Certified Reference Materials 32 1st ed. 

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