Chemometric and ultraviolet-visible spectrometric methods for simultaneous determination of caffeine, trigonelline, and chlorogenic acid in instant coffees

New methods for simultaneous determination of caffeine (CAF), trigonelline (TRIG), and chlorogenic acid (CGA) in instant coffees using UV-Vis spectrometry and multivariate calibration (full-PLS, iSPA-PLS, and SPA-MLR) algorithms are presented. Instant coffees were analyzed using the reference HPLC method to determine CAF, TRIG, and CGA concentrations. The dataset, comprising UV-Vis spectra and reference HPLC concentrations, was split into calibration (71 samples) and prediction (47 samples) sets; cross-validation was performed within the calibration set. The proposed methods yielded RPD_pred > 3 for TRIG and CAF determinations, indicating excellent performance, and RPD_pred ≤ 2 for CGA, suggesting poor performance or suitability for screening. This work offers an innovative, green, fast, and low-cost alternative to HPLC for complementary screening or routine analyses. This alternative requires no organic solvents and generates no waste. Moreover, it uses an inexpensive instrument that records the spectrum in just 1 s, whereas the HPLC run takes 20 min.