시료 희석 직접 주입 LC-MS/MS를 이용한 법화학 수용액 시료 중카페인 신속 분석

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for thedetermination of caffeine in forensic aqueous sample. The centrifuged sample (100 μl) was diluted 50-fold with distilledwater. The diluted sample (400 μl) was then diluted further with 200 μl of 0.1% formic acid solution and 400 μl of acetonitrilecontaining 500 ng of caffeine-(3-methyl-13C3) prior to LC-MS/MS analysis. The mobile phase was composed of 0.1% formicacid in distilled water (A) and acetonitrile (B). Chromatographic separation was performed by using a Zorbax SB-C18 (100mm×2.1 mm i.d., 3.5 μm) column and caffeine was eluted within 1.1 min. Linear least-squares regression with a 1/x weightingfactor was used to generate a calibration curve with the coefficients of determination (r2=0.9983). The lower limit ofquantification was 25 ng/ml for the analyte. The process efficiency was 98.6~100.1%. Intra- and inter-day precisions werenot more than 2.1% and 1.7%, while intra- and inter-day accuracies were ranged from −6.8 to 4.5%, respectively. The suitabilityof the method was examined by analyzing unknown forensic aqueous samples.