Quantitative determination of endogenous compounds in biological samples using chromatographic techniques

Chromatographic methods are increasingly being used for the quantitative determination of endogenous compounds in biological samples. This article presents an overview of the specific issues, which have to be taken into account for the development, validation and application of these methods. The usual lack of analyte-free samples of the biological matrix implies that alternative strategies for calibration have to be followed. This article compares and discusses the advantages and disadvantages of two strategies – the use of the authentic analyte in a surrogate matrix and the use of a surrogate analyte in the authentic matrix. In addition, it highlights important aspects of the validation of chromatographic methods for endogenous analytes.