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  • Author or Editor: Huitao Liu x
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Summary

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%.

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Abstract

A simple capillary electrophoresis (CE) method with ultraviolet (UV) detection was developed for the determination of hexachlorophene (HCP) in cosmetics. Separation conditions were obtained in 20 mM Na2B4O7, 10% MeOH (pH 9.20), with 25 kV applied voltage and UV detection at 208 nm. Under the selected conditions, electrophoretic analysis was completed in about 4 min, with limit of detection (LOD) of 0.06 µg·mL−1 for HCP. The method was successfully applied to determine HCP in three kinds of cosmetics with relative standard deviations (RSD) of 0.52–3.02% and recoveries from 90.0 to 96.4% for the spiked samples. The results indicated that the proposed method was reliable. Comparative experiments were also carried out with high-performance liquid chromatography (HPLC)-UV method described in National Standards of People's Republic of China. The validation results of the two methods are comparable, but the proposed CE method is simple, rapid, which makes separation and analyte quantification in shorter time with much less reagent consumption.

Open access

Abstract  

A simple method for preparing F-doped anatase TiO2 nanoparticles with high visible light photocatalytic activity was developed using TiCl4 and HF as TiO2 and fluorine precursors in HCl solution by a one-step hydrothermal treatment without any organic species. The presence of HF plays an important role in the formation of the F-doped shuttle-like anatase TiO2 nanostructures. XRD analysis showed that the F could prevent the transformation of anatase to rutile in HCl solution. Compared with ordinary TiO2, the F-doped TiO2 nanoparticles synthesized at 180 °C exhibited better photocatalytic activity for the degradation of rhodamine B under visible light irradiation. Possible formation mechanism of F-doped anatase TiO2 under hydrothermal conditions was discussed.

Restricted access

Abstract

A simple capillary electrophoresis (CE) method with ultraviolet (UV) detection was developed for the determination of hexachlorophene (HCP) in cosmetics. Separation conditions were obtained in 20 mM Na2B4O7, 10% MeOH (pH 9.20), with 25 kV applied voltage and UV detection at 208 nm. Under the selected conditions, electrophoretic analysis was completed in about 4 min, with limit of detection (LOD) of 0.06 µg·mL−1 for HCP. The method was successfully applied to determine HCP in three kinds of cosmetics with relative standard deviations (RSD) of 0.52–3.02% and recoveries from 90.0 to 96.4% for the spiked samples. The results indicated that the proposed method was reliable. Comparative experiments were also carried out with high-performance liquid chromatography (HPLC)-UV method described in National Standards of People's Republic of China. The validation results of the two methods are comparable, but the proposed CE method is simple, rapid, which makes separation and analyte quantification in shorter time with much less reagent consumption.

Open access

Abstract

A sweeping micellar electrokinetic chromatography (sweeping-MEKC) enrichment model was established for the determination of three chlorophenols (CPs) in cosmetics, namely, bithionol, pentachlorophenol (PCP), and 2,4,6-trichlorophenol (2,4,6-TCP). The optimum electrophoretic conditions were 20 mM NaH2PO4-80 mM sodium dodecyl sulfate (SDS) and 30% (v/v) acetonitrile (pH 2.3). The optimum on-line concentration conditions were as follows: sample matrix, 100 mM NaH2PO4; pressure injection at 20.67 kPa (3 psi) for 25 s. The linear range of bithionol, PCP, and 2,4,6-TCP are 0.20–4.00 μg mL−1, 0.10–2.00 μg mL−1, and 0.05–2.00 μg mL−1 respectively, with correlation coefficient (r) over 0.9972. The limits of detection (LOD) based on three times the signal-to-noise ratio (S/N = 3) are in the range of 0.0061–0.024 μg mL−1. Recoveries for the three CPs in powder and lotion samples are between 79.7 and 110.2% with relative standard deviation (RSD) of 1.38–5.54% and 92.2–121.3% with RSD of 0.72–6.09%, respectively. The proposed method can provide reference for the determination of trace CPs in different sample matrix.

Open access