REMEDIUMREMEDIUM1561-59362658-3534Joint-Stock Company Chicot207210.32687/1561-5936-2026-30-3-293-299Original ArticleDirect UV detection in the chromatographic analysis of amino acids: potential, limitations, and evaluation of method applicability for the quality control of a multicomponent drugPaskarNikita G.paskar_nikita@farmoborona.ruPyatigorskayaNatalya V.pyatigorskaya_n_v@staff.sechenov.ruZyryanovOleg A.zyryanov_o_a@staff.sechenov.ruLosevaSofia A.loseva_s_a@staff.sechenov.ruSechenov First Moscow State Medical University, Moscow, Russia, Research and testing center "Farmoborona" LLC, Korolyov, Russia, 2Sechenov First Moscow State Medical University, Moscow, Russia, Pacific State Medical University, Vladivostok, Russia, 3, 4Sechenov First Moscow State Medical University, Moscow, Russia2809202630329329929092026Copyright © 2026,2026Introduction. Direct UV detection of amino acids without a derivatization step is of interest for pharmaceutical analysis, as it simplifies sample preparation and eliminates an additional reaction step. This study involved the development and evaluation of an ion-pair HPLC method with direct UV detection for the determination of five amino acids in a multicomponent drug product with the INN Ketoanalogues of Amino Acids. The aim of the study was to develop and evaluate the applicability of an HPLC method with direct UV detection for determining five amino acids (histidine, threonine, tyrosine, tryptophan, and lysine) in a multicomponent drug product with the INN Ketoanalogues of Amino Acids. Materials and methods. Chromatography was performed using an Agilent 1260 Infinity II chromatograph equipped with a UV-spectrophotometric detector. A YMC-Triart C18 column (250 × 4.6 mm, 5 μm, 120 Å) was used. The flow rate was 1.0 mL/min, the column oven temperature was 25 °C, the injection volume was 10 μL, and the total analysis time was 40 min. During method development, the detection wavelength was varied; initially, detection was performed at 200 nm. Results. The selected conditions ensured the separation of the target amino acids in the standard solution. However, when analyzing the test solution, method specificity was not achieved due to the co-elution of matrix components in the lysine elution region, a finding confirmed by peak spectral purity assessment. Conclusion. HPLC with direct UV detection demonstrated analytical potential for the separation of amino acids; however, the method proved to have limited applicability for the multicomponent drug product under investigation due to insufficient specificity. The results confirm the need for more selective approaches, specifically methods involving derivatization.amino acidsHPLCdirect UV detectionion-pair chromatographyketoanalogues of amino acidsmulticomponent drugspecificityquality controlаминокислотыВЭЖХпрямое УФ-детектированиеион-парная хроматографиякетоаналоги аминокислотмногокомпонентный лекарственный препаратспецифичностьконтроль качества1.Wahl O., Holzgrabe U. Amino acid analysis for pharmacopoeial purposes. Talanta. 2016;154:150—163.2.Fialaire A., Postaire E., Prognon R., Pradeau D. Bioavailability prediction of amino acids and peptides in nutritive mixtures by separation on non-polar stationary phases by high-performance liquid chromatography and direct UV detection at 210 nm. J. Liq. Chromatogr. 1993;16(14):3003—3015.3.Schuster R. Determination of free amino acids by high performance liquid chromatography. Anal. Chem. 1980;52(4):617—620.4.Yokoyama Y., Tsuji S., Sato H. Simultaneous determination of creatinine, creatine, and UV-absorbing amino acids using dual-mode gradient low-capacity cation-exchange chromatography. J. Chromatogr. A. 2005;1085(1):110—116.5.Epshtein N. A. Validation of chromatographic methods: checking the peak purity and the specificity of methods with diode array detectors. Drug Development & Registration. 2020;9(3):129—136. doi: 10.33380/2305-2066-2020-9-3-129-136 (In Russ.)