微生物降解体系中反-4-甲基-环己烷酸的气相色谱-质谱法测定

Quantification of Trans-4-methyl-1-cyclohexane Carboxylic Acid in Culture Media for Microorganisms by GC-MS

建立了微生物降解体系中反-4-甲基-环己烷酸(4MCCA)的气相色谱-质谱测定方法。分别采用孔径为0.45和0.22μm滤膜对微生物降解体系中的4MCCA样品进行减压过滤,去除菌体;用0.1 mol/L H2SO4调节滤液至pH 2～3;二氯甲烷萃取定容。利用气相色谱-质谱的选择离子模式检测,外标法定量。本方法的线性范围为0.10～100 mg/L,相关系数为0.9994,检出限和定量限分别为0.10 ng和0.34 ng,日内和日间精密度分别为2.7%～6.6%和1.5%～11.3%。采用本方法测定了150 mg/L 4MCCA在微生物降解体系中的降解情况,24,48和96 h时4MCCA的降解率分别为24.7%,51.8%和55.0%。

An analytical method was developed for the determination of a candidate naphthenic acid compound using GC-bIS, specifically trans-4-methyl-l-cyclohexane carboxylic acid （4MCCA） in culture media. The methods for removal of bacteria from the media and pH condition for extraction 4MCCA were optimized. Effective removal of bacteria from 4MCCA-containing media was achieved by vacuum filtration using a 0.45-μm filter and a 0.22-μm filter separately under a pressure of 0. 1 kPa. The ideal acidic range for extraction 4MCCA was pH 2-3. Under the optimized conditions, the samples of 4MCCA were extracted using a liquid-liquid extraction process by dichloromethane. The 4MCCA was determined by external standard method under the SIS mode by GC-MS. The linear range was 0. 10-100 mg/L （R2 = 0. 9994）. The limit of detection and quantification were 0.10 ng and 0. 34 ng. The precision of inner-day and inter-day was 2. 7% - 6.6% and 1.5% - 11.3%, respectively. This method was applied to monitor biodegradation for 150 mg/L 4MCCA. The rates of biodegradation of 4MCCA were 24.7%, 51.8% and 55.0% by 24, 48, and 96 h, respectively.