Quality Assessment of Spectroscopic Methods in Clinical Laboratories

This chapter describes procedures and protocols that have been developed for the quality assessment of the different spectroscopic methods used for the analysis of a variety of metabolites, electrolytes, hormones, vitamins, and plasma proteins/peptides in human body fluids. For spectrophotometry in particular, basic technical prerequisites for instrument performance surveillance and preclusion of sample-dependent variations are described in detail. These include the serum index determination, liquid level and clot detections, and instrument validations such as absorbance limit check, antigen excess check, substrate deletion check, and linearity measurements. But the regulatory protocols for quality assessment, which have been established in many countries during the past three decades, are also described. These define procedures that are suitable to assess nearly all relevant aspects of the analytical performance criteria of spectroscopic methods. Quality checks optimize the analytical process for clinical chemistry parameters that are relevant to the majority of clinical diagnoses and, thus, ameliorate the patient outcome. The contemporary organizational concept of quality assessment schemes for clinical chemical analyses, which are mandatory in Germany, are further outlined for spectroscopic techniques such as UV-Vis, fluorescence, and infrared spectroscopy, as well as flame atom emission and absorption spectrometry.