Novel strategy for fluorescence determination of glibenclamide in samples with high concentration of caffeine based on a low-pressure flow injection chromatography system

Abstract

In this work, a new low-pressure flow injection chromatography (FIA-C) system with fluorescence detection was developed for the toxicological control of glibenclamide in beverages with high caffeine content. As caffeine quenched the fluorescence signal of glibenclamide, a separation of the analyte from the sample matrix was proposed as a simple and rapid strategy. The separation was performed in a commercially available monolithic column (RP-18e, 25 mm × 4.6 mm i.d.) inserted in a flow injection system. The mobile phase used for analysis was acetonitrile/acetic acid (50:50 v/v), with a flow rate of 1.03 mL min−1. For each analysis, only 5.2 mL of mobile phase was used. After the optimization of the variables of the system, a calibration curve with a linear range between 0.50 and 10.0 mg L−1 was obtained (R2 = 0.997). The precision of the proposed method was evaluated in terms of the relative standard deviation obtaining 0.58 and 1.68% for the intra-day precision and inter-day precision, respectively. The detection limit was 0.10 mg L−1 and the sample throughput, taking into account the whole procedure, was 12 h−1. The method was applied to fortified real samples with satisfactory recovery values (90.4–103.7%). On the other hand, samples adulterated with commercially GLB pills were also analyzed with very good results (96.5–104.5%).