HF-LLLME-CE法测定偶氮染料氧化降解生成的有机酸

采用纤维膜三相液相微萃取(HF-LLLME)和毛细管电泳技术,对偶氮染料氧化降解过程中可能产生的小分子羧酸甲酸、乙酸、草酸、乳酸、丁二酸、柠檬酸、苹果酸进行了测定。以pH值为7.2的230 mmol/L磷酸二氢钠、115 mmol/L四硼酸钠和0.5 mmol/L十六烷基三甲基溴化铵(CTAB)溶液为缓冲液,分离电压-12 kV,检测波长200 nm的条件下,10 min内达到基线分离。三相液相微萃取以磷酸三丁酯(TBP)为有机相,供体相pH为2.5,接收相pH为12.0,萃取时间为45 min,将萃取接收相直接进行毛细管电泳(CE)测定,富集倍数在7~67之间。样品相中7种有机酸的质量浓度在5 mg/L~1 000 mg/L的范围内与电泳峰面积呈良好线性(r2>0.999 1),方法的检出限为0.09 mg/L~0.54 mg/L。运用该法对TiO2光催化降解偶氮染料过程中产生的有机酸进行测定,检测到的4种羧酸的投加回收率在93%~110%之间。

Determination of Organic Acids Generated from Degraded Azo Dyes by Three Phase Liquid Phase Microextraction with Capillary Chromatography

A noval method of capillary electrophoresis(CE)coupled with hollow fiber three phase liquid phase microextraction(HF-LLLME)was developed for determination of 7 low molecular mass organic acids including formic acid,acetic acid,oxalate,succinic acid,citric acid,malic acid,tartaric acid and lactic acid which may be the degradation products of Reactive Brilliant Red X-3B.Baseline separation of 7 organic acids was achieved within 10 min by using 230 mmol/L NaH2PO4,115 mmol/L Na2B4O7 and 0.5 mmol/L CTAB at pH 7.2 with a constant temperature of 25 ℃,detection wavelength 200 nm and separation voltage-12 kV.Under the optimized LPME condition,tri-butyl-phosphate(TBP)as organic phase,donor phase pH 2.5,acceptor phase pH 12.0,without addition of salt,an enrichment factors ranged from 7 to 67 could be achieved within 45 min extraction.The receiving phase could be used for capillary electrophoresis analysis without any further treatment.Calibration curves for 7 organic acids were well correlated within the range of 5 mg/L~1 000 mg/L,and detection limits were in the range of 0.09 mg/L~0.54 mg/L.This proposed method was validated in analyzing organic acids produced from TiO2/UV degradation of azo dye Reactive Brilliant Red X-3B,and the spiked recoveries ranged from 93% to 110%.