Development and evaluation of pulsed - Post column derivatization in liquid chromatography as a concept to minimize reagent consumption

In the current article, we propose an alternative approach to reduce the consumption of the reagents in liquid chromatography coupled to on-line post column derivatization. In our proposal post column reagents do not flow continuously but they are instead introduced as well-defined pulses (at microliter levels) that are merged on-line with the eluted analytes through precise tuning (Pulsed-Post Column Derivatization, Pulsed-PCD). The profiles of the pulses in terms of time and flow rate were investigated visually using caffeine as model compound (at 274 nm). The robustness of the procedure was evalu-ated by Monte Carlo simulations and was verified taking into account the precisions of typically used propulsion systems. As a proof of concept, we selected the determination of histidine in human urine af-ter separation by cation exchange chromatography and Pulsed-PCD derivatization with o-phthalaldehyde. The consumption of the derivatizing reagent was downscaled to the microliter level per run, while the analytical results were within the expected ranges (110 - 1520 mu mol L -1) and with good agreement with the corroborative method based on classic HPLC-PCD. (c) 2023 Elsevier B.V. All rights reserved.

Automated summary

In this article, a new approach to reduce the consumption of reagents in liquid chromatography coupled to online post column derivatization is proposed. The proposed method, called Pulsed-Post Column Derivatization (Pulsed-PCD), introduces reagents as well-defined pulses at microliter levels. The robustness of the procedure was evaluated and the method was successfully applied to determine histidine in human urine.