[Amlodipine assay conditions and stability in biological material]

The objective of the study is to determine amlodipine assay conditions and stability in biological material. Thin layer chromatography (TLC), gas chromatography-mass spectrometry (GC-MS) and UV-spectrophotometry were used for identification. Amlodipine was recovered from biomaterial by double (30 min each) infusing with acetone at the ratio of recovery solution and sample 2:1 (w/w). The purification was carried out by extraction and chromatography in a semi-preparative column with reverse-phase packing material Silasorb C-18 using acetone/water eluent (8:2). Amlodipine assay was performed by TLC [Sorbfil plates, butanol/acetone (5:5) as a mobile phase], GC-MS (HP-5 ms Ultra inert column (30 m×0.25×0.25 μm) with stationary phase of 5% phenyl-95% dimethyl polysiloxane), UV-spectrophotometry (95% ethanol as a solvent). The proposed assay method for amlodipine in biomaterial (liver tissue) is validated for linearity, selectivity, accuracy and precision. The amlodipine stability in model mixtures with liver tissue was studied. It was shown that the analyte stability in biological material decreases with increasing temperature. Amlodipine is stable at -25 °C, 0-2 °C, 8-10 °C, 18-22 °C, and 36 °C for 120, 112, 105, 91, and 77 days, respectively.