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1

Determination of formaldehyde in aquatic products by micellar electrokinetic capillary chromatography with 2,4-dinitrophenylhydrazine derivatization

Xu L. N, Gai F. Y, Mu G. F, Gao Y., Liu C. J., Luan F.

Acta Chromatographica

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2012

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Vol. 24, no. 4

519--528

EN

Formaldehyde in aquatic products was determined by micellar electrokinetic capillary chromatography (MEKC) after derivatization with 2,4-dinitrophenylhydrazine. Separation was carried out at 25 °C and 25 kV, using a fused silica capillary (75 µ internal diameter; 50.5 cm effective length) and an ultraviolet detector set at 360 nm. The optimal background electrolyte was 20 mM sodium tetraborate and 20 mM sodium dodecyl sulfate at pH 9.0 with 3 s hydrodynamic injection at 30 mbar. Electrophoretic analysis took approximately 6.5 min. The correlation coefficient of the calibration curve was 0.999 over the concentration range 2.0–100.0 mg L-1 and the LOD and LOQ values were 0.57 and 1.89 µg mL-1, respectively. The recoveries were from 83.7% to 97.2% with steam distillation as the sample pretreatment method.

2

Analysis of alkaloids in pharmaceutical preparations containing Kushen by capillary electrophoresis with application of experimental design and a quantitative structure-property relationship approach

Wen Y., Liu H., Tian L, Han P., Luan F.

Acta Chromatographica

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2010

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Vol. 22, no. 3

445--457

EN

A simple and rapid capillary electrophoretic procedure for analysis of matrine and oxymatrine in Kushen medicinal preparations has been developed and optimized. Orthogonal design was used to optimize the separation and detection conditions for the two active components. Phosphate concentration, applied potential, organic modifier content, and buffer pH were selected as variable conditions. The optimized background electrolyte contained 70 mM sodium dihydrogen phosphate and 30% acetonitrile at pH 5.5; the separation potential was 20 kV. Each analysis was complete within 5 min. Regression equations revealed linear relationships ( r > 0.999) between peak area and amount for each component. The detection limits were 1.29 μg mL -1 for matrine and 1.48 μg mL -1 for oxymatrine. The levels of the two active compounds in two kinds of traditional Chinese medicinal preparation were easily determined with recoveries of 96.57–106.26%. In addition, multiple linear regression and a non-linear model using a radial basis function neural network approach were constructed for prediction of the migration time of oxymatrine. The predicted results were in good agreement with the experimental values, indicating that a radial basis function neural network is a potential means of prediction of separation time in capillary electrophoresis.

3

Analysis of food additives by capillary electrophoresis

Liu H., Wen Y., Luan F., Gao Y.

Acta Chromatographica

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2008

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Vol. 20, no. 2

239-246

EN

A simple and rapid capillary zone electrophoretic method is proposed for the analysis of antioxidants and preservatives in food. The important factors affecting separation and detection, for example pH, and concentration of the buffer electrolyte and organic modifier, were investigated in detail. Separation of five antioxidants (propyl gallate, gallic acid isoamyl ester, gallic acid n-octyl ester, nordihydroguaiaretic acid, and trihydroxybutyrophenone) and one preservative (benzoic acid) was achieved in a 50.5 cm (effective length) × 75 µm i.d fused-silica capillary, with 15 mmol L-1 borate buffer, pH 9.18, containing 25% (v/v) acetonitrile as separation buffer. UV detection was at 219 nm and the applied potential was 25 kV. Regression analysis revealed linear relationships between peak area and amount of each additive from 10 to 1000 µg mL-1 (R = 0.9992-1.0000). RSD of retention time and peak area were 0.44-0.74% and 1.25- 4.31%, respectively. The method was successfully used for simultaneous analysis of the six compounds in food with the recoveries from 89.3 to 115.8%.