Caffeine Quantification Via High-Precision Coulometric Titration

Caffeine has traditionally been used to assess and control the metrological characteristics of liquid chromatographs. In recent years, with increasing requirements for the traceability of measurement results, the use of caffeine as a reagent for verification, calibration, and type approval tests has started to contradict the effective regulations governing measurement uniformity. This study aims to develop and test a procedure of caffeine quantification in caffeine via primary coulometric titration for the metrological support of high-performance liquid chromatography (HPLC) with an accuracy of no more than 1 % abs. In the course of work, a detailed analysis of methods for determining caffeine content in various matrices was carried out; in addition, a procedure for determining caffeine mass fraction in caffeine via coulometric titration was developed and tested. A comparison of the obtained results with caffeine mass fraction measurements performed using HPLC confirmed the commutativity of coulometric titration and HPLC. The developed procedure of caffeine quantification in caffeine via primary coulometric titration employing GET 176 can be used to develop a caffeine composition reference material and to provide metrological traceability of HPLC measurements on its basis to state primary standards reproducing the «mass fraction of components» and to SI units (Systeme international d’unites, SI).