An analytical method for prohexadione in Chinese cabbage and apple.

A residual determination method as a regulatory residue method was developed using HPLC-UVD for prohexadione residues in Chinese cabbage (Brassica pekinensis) and apple (Malus domestica). The developed method consisted of solid-liquid extraction with acidic acetonitrile and ion-suppression liquid-liquid partitioning, followed by anion exchange cartridge cleanup. The limits of detection and quantitation for the method were 0.005 and 0.02 mg/kg, respectively. The method gave good linearity in the range of 0.02-2.5 mg/kg. Accuracy and precision ranged from 84.1 to 94.1% and from 2.4 to 6.9%, respectively. Additionally, the confirmative conditions of LC-MS/MS for prohexadione were set in negative electrospray ionization mode with transitions of m/z 211.4 → 167.5 and m/z 211.4 → 123.5 in the selected reaction monitoring mode. The applicability of the method was demonstrated by analyzing real samples collected from local markets in Seoul, Republic of Korea. This developed method fully deserves consideration in accordance with its sensitivity, accuracy and precision required for residue analysis of prohexadione in Chinese cabbages and apples.

Simultaneous determination of anti-diabetes/anti-obesity drugs by LC/PDA, and targeted analysis of sibutramine analog in dietary supplements by LC/MS/MS.

The safety of dietary supplements is questionable as there have been occasional reports of products contaminated with illegal adulterants. The present study was carried out to develop trustworthy methodologies to screen for six anti-diabetic drugs (phenformin, rosiglitazone, glipizide, glimepiride, glybenclamide and gliclazide) and six anti-obesity drugs (ephedrine, fenfluramine, T3, T4, fluoxetine and sibutramine) in dietary supplements. A simultaneous determination method of the 12 drugs by liquid chromatography coupled with a photodiode array (LC/PDA) was established and was validated for linearity (r(2) > 0.99), precision (RSD <13.3%), recoveries (88.8-115.9%) and reproducibility. Sibutramine and its analogs, N-desmethylsibutramine, were subject to further investigation by LC/MS/MS because they were one of the major illegal adulterants. Our proposed method to monitor illegal drug adulterations in dietary supplements using LC/PDA is a simple and reliable, and therefore applicable to routine drug-adulteration screening.

Determining dioxin-like compounds in selected Korean food.

To measure the levels of dioxin-like compounds, pork, mackerel, cheese and milk were analyzed. The food samples were obtained at three different markets in Seoul. All the samples were animal origin and their lipid contents ranged from 4% to 34%. After extraction, extracts were cleaned up by sulfuric acid impregnated silica gel, purified on a series of silica gel, alumina, carbon column chromatography and then analyzed by high resolution gas chromatography/high resolution mass spectrometry. The levels of polychlorinated dibenzo-p-dioxins/furans for pork, mackerel, cheese and milk were 0.0008, 0.8663, 0.002 and 0.0236 pgTEQ/g wet weight, respectively. In addition, the levels of non-ortho coplanar polychlorinated biphenyls for pork, mackerel, cheese and milk were 0.0041, 1.5781, 0.0259 and 0.0353 pgTEQ/g wet weight, respectively. Among food samples analyzed, pork showed the lowest level of dioxin-like compounds.