ABSTRACT
A method was developed for the determination of N-acetyl-S-( N-methylcarbamoyl ) cysteine ( AMCC) in human urine by online solid-phase extraction ( SPE )-high performance liquid chromatography ( HPLC ) . The separation of AMCC from the urine matrix was performed on AmoniPac PA Solid phase Extraction ( SPE ) column with 5 mmol/L KH2 PO4 as the mobile phase by left pump. Then the time was controlled to switch the valve to make only the section of sample containing AMCC transferred into the analytic column-Acclaim PAⅡ C18 . The determination was performed using gradient elution of 0. 1% H3 PO4 (containing 5% acetonitrile) and acetonitrile by right pump. The results showed that AMCC present good linear correlation in the range of 1 . 0-100 mg/L with a correlation coefficient of above 0 . 999 , the quantitation limit of the method was 0. 2 mg/L (with the sample inject volume =10 μL), the recoveries of spiked samples were in the range of 82 . 9%-85 . 9%, and the relative standard deviation ( n=6 ) of retention time and peak area were 0. 2% and 4. 0% respectively. Compared with offline SPE-HPLC, the proposed method was convenient, environmentally friendly, efficient and stable, and feasible for the detection of AMCC in 7 human urine samples.
ABSTRACT
An accurate, fast and sensitive method based on high performance liquid chromatography was established for the simultaneous determination of eleven ultra-violet absorbents in cosmetics. Eleven ultra-violet absorbents were baseline separated on an Acclaim C18 column within 11. 5 min using acetonitrile-0. 1%formic acid in water ( V/V) mobile phase, and detected at 361 nm with UV detection. Under the optimized conditions, the relative standard derivations ( RSDs) of the eleven ultra-violet absorbents were all less than 0. 1% for retention time, and less than 1. 2% for peak area; good linearity was obtained from 5 to and 500 mg/L with the correlation coefficients of above 0 . 9990 for these analytes; the recoveries spiked in a cosmetic sample were in the range of 77% -116%. Benzophenone-3, butylmethoxydibenzoylmethane, ethylhexylsalicylatec and homosalate were found in the detected cosmetic samples, and the concentration of homosalate was the highest. The results indicated that this method had potential for applications due to its convenience, accuracy and sensitivity. Oxybenzone, butylmethoxydibenzoylmethane, 2-ethylhexyl salicylatec and homosalate were found in the detected cosmetic samples, and the concentration of homosalate was the highest.