Fang Huaifang, Zeng Zhaorui, Liu Lan
Department of Chemistry, Wuhan University, Wuhan 430072, China.
Anal Chem. 2006 Sep 1;78(17):6043-9. doi: 10.1021/ac060360q.
Although sample stacking has enjoyed some degree of success in electrophoretic separation techniques, there is still a major problem with complex matrix sample as it suffers tremendously from sample matrix effects. A novel method that combines two concentration techniques, centrifuge microextraction (CME) and on-line back-extraction field-amplified sample injection (OLBE-FASI), is used to determine trace ephedrine derivatives in urine and serum by capillary zone electrophoresis. The CME, integrating the sample cleanup and preconcentration into a single step, is a promising sample preparation method for biological samples. The CME technique provided 9-14-fold enrichment within 10 min. The OLBE-FASI eliminated the need to perform solvent exchange and provided a further concentration of the analytes. Using CME coupled with OLBE-FASI, over a 3800-fold increase in sensitivity could be obtained as compared with the normal hydrodynamic injection without sample stacking. For a 1-mL urine sample, the linear range was 5/10-200 ng/mL with the square of the correlation coefficients (r(2)) ranging from 0.9988 to 0.9994. Detection limits were from 0.15 to 0.25 ng/mL using a photodiode array UV detection at wavelength 192 nm. The possibility of this method to determine ephedrine derivatives in 20-muL serum samples was also demonstrated.
尽管样品堆积在电泳分离技术中取得了一定程度的成功，但对于复杂基质样品仍存在一个主要问题，即它深受样品基质效应的影响。一种结合了两种浓缩技术的新方法，即离心微萃取（CME）和在线反萃取场放大进样（OLBE-FASI），被用于通过毛细管区带电泳测定尿液和血清中的痕量麻黄碱衍生物。CME将样品净化和预浓缩整合为一个步骤，是一种很有前景的生物样品制备方法。CME技术在10分钟内实现了9至14倍的富集。OLBE-FASI消除了进行溶剂交换的需要，并进一步浓缩了分析物。与不进行样品堆积的正常流体动力学进样相比，使用CME与OLBE-FASI相结合可使灵敏度提高3800倍以上。对于1 mL尿液样品，线性范围为5/10 - 200 ng/mL，相关系数的平方（r²）在0.9988至0.9994之间。使用波长为192 nm的光电二极管阵列紫外检测，检测限为0.15至0.25 ng/mL。该方法测定20 μL血清样品中麻黄碱衍生物的可能性也得到了证明。
