Dual pH-optimized HPTLC method for simultaneous quantification and enhanced fluorescence detection of triamterene and losartan in human plasma: Toward achieving maximum separate fluorescence intensity.

A novel and selective High Performance Thin Layer Chromatographic (HPTLC) method was developed for the simultaneous determination of triamterene (TRM) and losartan (LOS) in their pure forms and spiked human plasma using fluorescence detection. The challenge of differing optimal pH values for maximum fluorescence in TRM and LOS detection was addressed by devising a strategy for detection in various pH media. TRM was measured in a neutral medium and achieved maximum fluorescence at 540 nm upon excitation at 365 nm, with a 66.7-fold sensitivity increase compared to previous methods. LOS, which exhibited weak fluorescence in a neutral medium, showed maximum fluorescence in a strong acidic environment. After perchloric acid treatment, LOS achieved maximum response at 400 nm after excitation at 260 nm, with an 83.3-fold sensitivity increase. Pre-coated silica gel 60-F254 was used as the stationary phase, with a mobile phase of toluene: ethyl acetate: methanol: acetone: ammonia (6:1.5:1.5:0.9:0.1, v/v/v/v/v). Rf values for LOS and TRM were 0.16 and 0.32, respectively. The method exhibited good linearity for TRM (3–150 ng/band) and LOS (6–150 ng/band), with LODs of 0.70 and 1.41 ng/band and LOQs of 2.13 and 4.26 ng/band. The technique demonstrated excellent compliance with ICH guidelines for accuracy, precision, repeatability, and robustness. The method achieved high recovery percentages and low standard deviations in analyzing both bulk drug and plasma samples. The current work is a valuable tool for routine clinical laboratory use, enabling efficient monitoring of TRM and LOS from a single sample preparation.