No abstract

It is difficult to detect biogenic amines (BAs) in biological fluids because of their very low concentrations. In this paper, we reported an on-line sample preconcentration method in CE-amperometric detection (CE-AD) based on a dynamic pH junction, and a concentration enhancement of approximately 100-fold was achieved compared with the classical CE-AD methods in the simultaneous analysis of six BAs in urine (dopamine, epinephrine, norepinephrine, tyramine, tryptamine, and serotonin). The technique is proposed based on the sharp pH change generated at the boundary between an acidic sample and the basic BGE zone. Under optimized conditions, all analytes were successfully focused and well separated within 20 min with high efficiency and sensitivity (LODs at S/N = 3 ranging from 5.34 to 68.3 nM). For the analysis of urine samples by this method, satisfactory recoveries were obtained without a complicated pretreatment step or derivatization process. Therefore, it is self-evident that this approach for the analysis of real biological samples has great potential in the future.

No abstract

No abstract

A novel method of CE coupled with dual electrochemical detection has been developed for the determination of pathological metabolites of phenylalanine in urine samples. Factors influencing the separation and detection were examined and optimized. Five aromatic acid metabolites and a major coexisting interfering compound uric acid could be well separated within 23 min at a separation voltage of 16 kV using a 35 mmol/L SDS/60 mmol/L H(3)BO(3)-Na(2)B(4)O(7) running buffer (pH 8.2). Highly linear response was obtained for these five biomarker compounds over three orders of magnitude with detection limits ranging from 6.6 to 0.064 μg/mL (S/N=3). The average recovery and RSD were within the range of 92.6-121.0 and 1.0-12.0%, respectively. The proposed method has been used to detect the unconjugated aromatic acids simultaneously in urine samples with the advantages of obtaining more information about target analytes and avoiding redundant measurements and high assay cost, thus could find potential applications involving assays of biomarker compounds for the purpose of fast diagnose of some metabolic diseases including phenylketonuria.