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Ethane-1,2-diamine (EA) and hexane-1,6-diamine (HA) are two important plastic restricted substances commonly existing in food contact materials. A capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C 4 D) method has been developed for direct determination of above analytes, and the detection sensitivity has been significantly improved based on electromembrane extraction (EME). Under the optimum conditions, EA and HA could be well separated from their aliphatic diamine homologs as well as the common inorganic cations within 25 min. The limits of detection could reach sub-ng/mL level, and good linearity ( r > 0.998) between peak area and analyte concentration could be obtained at three orders of magnitude. This EME/CE-C 4 D method provided a novel application for determining these plastic restricted substances in different bottled soft drinks, providing an alternative for the sensitive analyses of diamine substances.

A novel miniaturised capillary electrophoresis with electrochemical detection (mini-CE-ED) method has been developed for fast determination of formaldehyde (FA) and acetaldehyde (AA) in several food products without preconcentration. Because FA and AA usually exist as uncharged molecules with zero electrophoretic mobility, plus the fact that these two compounds lack of chromophore for sensitive ultraviolet (UV) detection, effective and sensitive determination of FA and AA in real samples is often a challenging task. In this work, an electroactive compound 2-thiobarbituric acid (TBA) was selected as the ideal derivatisation reagent to facilitate the electrochemical determination of FA and AA. Under the optimum conditions, FA-TBA and AA-TBA adducts can be well separated by mini-CE-ED with low detection limit of 9.10 × 10 −9 g/mL (13.2 fg) for FA (S/N = 3). The proposed method should find a wide range of analytical applications in food products as an alternative to conventional and microchip CE approaches.

A high-performance micellar electrokinetic capillary chromatography with amperometric detection (MECC–AD) method for the fast determination of melamine (MM), occasionally used to increase the apparent protein content of milk products, has been developed. Method development involved optimisation of the working electrode, the running buffer system and acidity, the concentration of sodium dodecyl sulphate (SDS), the separation voltage, the applied potential and the sample injection time. Under the optimum conditions, MM can be well separated from its co-existing interferences in real-world samples within 9 min at the separation voltage of 20 kV in a 8 mmol/L SDS/20 mmol/L H 3 BO 3 –Na 2 B 4 O 7 running buffer (pH 7.4). Satisfactory recovery (83.3–105.5%), repeatability of the peak current (3.2%) and migration time (3.8%), and the limit of detection (2.1 × 10 −6 g/mL) for the method were achieved. This proposed procedure has been successfully used for the determination of MM in milk products.

A new and efficient method for the determination of synthetic phenolic antioxidants (SPAs) has been developed by using micellar electrokinetic capillary chromatography (MECC) with electrochemical detection. Under the optimum conditions, all analytes were successfully separated within 13 min at the separation voltage of 18 kV in a 20 mmol/L borate running buffer (pH 7.4) containing 25 mmol/L sodium dodecyl sulfate. The excellent linearity was obtained in the concentration range from 5.0 × 10 −4 to 2.0 × 10 −6 mol/L and the detection limits ( S / N = 3) of propyl gallate (PG), tert -butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) range from 2.9 × 10 −7 to 2.7 × 10 −6 mol/L. This method has been proved to be effective and successfully applied for the determination of SPA in food products, providing a promising and convenient entry to monitor the superscale use of phenolic antioxidants.

Simultaneous determination of daidzein and genistein in soy products by capillary electrophoresis with electrochemical detection (CE–ED) was reported. The effects of working electrode potential, running buffer pH, separation voltage and injection time on CE–ED were investigated. Under the optimum conditions, the analytes could be separated in a 100 mmol/l borate buffer (pH 11.0) within 20 min. A 300 μm diameter carbon disk electrode has a good response at +0.70 V (vs. SCE) for the analytes. The response was linear over three orders of magnitude for the analytes. This method has been satisfactorily used for the determination of daidzein and genistein in several actual soy samples.

A method based on capillary electrophoresis with electrochemical detection (CE–ED) was developed for the determination of trans -Resveratrol in wines, Chinese medicinal herb Polygonum cuspidatum Sied. et Zucc., and Zijin capsule. The effects of some important factors such as injection time, and applied potential to working electrode were investigated. Operated in a wall-jet configuration, a 300 μm diameter carbon-disk electrode was used as the working electrode, which exhibits good response at +0.85 V (vs. SCE) for trans -Resveratrol. Linearity was obtained in the concentration range from 1.0×10 −4 to 5.0×10 −7 g/ml. The detection limit (S/N=3) was 5.96×10 −8 g/ml. This proposed method has been successfully applied to analyze several actual samples with satisfactory assay results.