Yufang Zheng

Artificial neural network classification based on high-performance liquid chromatography of urinary and serum nucleosides for the clinical diagnosis of cancer.

Nucleosides in human urine and serum have frequently been studied as a possible biomedical marker for cancer, acquired immune deficiency syndrome (AIDS) and the whole-body turnover of RNAs. Fifteen normal and modified nucleosides were determined in 69 urine and 42 serum samples using high-performance liquid chromatography (HPLC). Artificial neural networks have been used as a powerful pattern recognition tool to distinguish cancer patients from healthy persons. The recognition rate for the training set reached 100%. In the validating set, 95.8 and 92.9% of people were correctly classified into cancer patients and healthy persons when urine and serum were used as the sample for measuring the nucleosides. The results show that the artificial neural network technique is better than principal component analysis for the classification of healthy persons and cancer patients based on nucleoside data.

Determination of arsenic species by capillary zone electrophoresis with large-volume field-amplified stacking injection.

Determination of arsenic species by large‐volume field amplified stacking injection‐capillary zone electrophoresis (LV‐FASI‐CZE) is reported in this paper. Whole column injection was employed. The optimum buffer pH for the separation of weak acids was discussed. It was found that the optimum buffer to analyze the stacked arsenate (As(V)), monomethylarsonate (MMA), and dimethylarsinate (DMA) was 25 mM phosphate at pH 6.5. However, the optimum buffer to analyze the concentrated arsenite (As(III)) was 20 mM phosphate – 10 mM borate at pH 9.28. The limits of detection of the method developed were 0.026 mg/L for As(III), 0.023 mg/L for As(V), 0.043 mg/L for MMA, and 0.018 mg/L for DMA. An enrichment factor of 34–100 for several arsenic species was obtained. In the end, this method was applied to determine the arsenic concentration in the environmental reference materials to show the usefulness of the method developed.

Capillary electrophoretic analysis of arsenic species with indirect laser induced fluorescence detection

The development of a method for determining arsenic species by capillary zone electrophoresis (cze) with indirect laser-induced fluorescence (lif) is described in this paper. the buffer ph, the concentration of fluorescein, the nature and the concentration of the background electrolytes (bges) were defined. when 2.0 mm nahco3 (ph 9.28) with 10(-7) m fluorescein was used as the buffer, arsenite (as(lll), dimethylarsonic acid (dma), monomethylarsonic acid (mma), and arsenate (as(v)) were all separated from one another. the limits of detection for the four arsenic species were p p in the range of 0.12-0.54 mg/l. this method was used in the analysis of spiked arsenic species in tap and mineral water to demonstrate its usefulness. the results showed that both the recovery and the reproducibility of the developed method were acceptable.