Perchlorate in honey from China: Levels, pollution characteristics and health risk assessment.

The release and accumulation of perchlorate into the environment have raised concerns about safety to food, however, the dietary risk of perchlorate in honey have not yet received attention. Herein, we investigated the pollution characteristics and assessed the human health risks of perchlorate in honey from China. A total of 151 honey samples collected from 20 provinces of China were analyzed, and overall detection frequencies was 95.4 %. The levels of perchlorate ranged from below limit of quantitation to 612 µg/kg, with a mean value of 34.5 µg/kg. Lychee honey samples had the highest mean perchlorate concentration (163 µg/kg). The mean concentration of perchlorate in the honey samples produced in South China was significantly higher than that in honey from Southwest China, East China and North China (P < 0.05). The health risk assessment showed that mean hazard quotient (HQ) values of different honey for children (ranged from 0.0108 to 0.400) and adults (ranged from 0.0123 to 0.453) were less than 1. This result indicated that mean pollution levels of perchlorate in various honey were unlikely to pose health risk. However, perchlorate concentrations in two lychee honey samples had associated HQ values were >1, suggesting potential health risks. This work not only offers valuable information for honey consumer, but also important reference for comparison of honey samples in the future. ENVIRONMENTAL IMPLICATION: Perchlorate contamination has become a hot environmental issue in connection with human health due to its potential thyroid toxicity and widespread occurrence in environment and foods. Honey not only was widely beloved by consumers worldwide but also considered a potential indicator of environmental pollution. Here, a national investigation and risk assessment of perchlorate levels in different types of honey from China was conducted. The results describe the perchlorate contamination were extensive in honey samples, mean levels of perchlorate in various honey were unlikely to cause health risks. However, significantly high level of contamination in lychee honey should be of concern.

Occurrence and Risk Assessment of Fluoroquinolone Residues in Chicken and Pork in China.

Antibiotics, especially fluoroquinolones, have been exhaustively used in animal husbandry. However, very limited information on the occurrence and exposure assessment of fluoroquinolone residues in chicken and pork in China is available to date. Thus, a total of 1754 chicken samples and 1712 pork samples were collected from 25 provinces in China and tested by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for residual determination of six common fluoroquinolones. The results revealed that the detection frequencies of fluoroquinolone residues were 3.99% and 1.69% in chicken and pork samples. The overall violation frequencies were 0.68% and 0.41% for chicken and pork. Enrofloxacin and its metabolite ciprofloxacin were found to be the most predominant fluoroquinolones. The occurrence of these antibiotics in different sampling regions and market types was analyzed. The %ADI values of enrofloxacin and ciprofloxacin were far less than 100, indicating the health risk associated with the exposure to these aforementioned fluoroquinolone residues via chicken and pork for Chinese children, adolescents, and adults was acceptable. The results provided useful references for Chinese consumers, and helped to appropriately use these antibiotics in poultry and livestock industry.

Capillary electrochromatographic fast enantioseparation based on a chiral metal-organic framework.

Metal-organic frameworks (MOFs) have received great attention because of their unusual properties and fascinating structures in separation sciences. However, to the best of our knowledge, there has been no attempt to utilize chiral MOFs as stationary phases in packed-CEC. Here, a chiral MOF [In3 O(obb)3 (HCO2 )(H2 O)]·solvent (4,4'-oxybisbenzoic acid) was explored as the chiral stationary phase in packed-CEC for separation of chiral compounds and isomers. The fabricated [In3 O(obb)3 (HCO2 )(H2 O)]·solvent packed capillary columns gave fast enantioseparation of (±)-hydrobenzoin, (±)-1-phenyl-1,2-ethanediol, and clenbuterol within 3 min in CEC. Besides, the baseline separations of nitrophenol isomers within 6 min were also achieved. The RSDs for the retention time of run-to-run, day-to-day, and column-to-column reproducibility were 1.51-3.63, 1.83-3.98, and 3.42-5.66%, respectively. These results demonstrate that chiral MOFs are promising for enantioseparation in CEC.

Experimental comparison of chiral metal-organic framework used as stationary phase in chromatography.

Chiral metal-organic frameworks (MOFs) are a new class of multifunctional material, which possess diverse structures and unusual properties such as high surface area, uniform and permanent cavities, as well as good chemical and thermal stability. Their chiral functionality makes them attractive as novel enantioselective adsorbents and stationary phases in separation science. In this paper, the experimental comparison of a chiral MOF [In3O(obb)3(HCO2)(H2O)] solvent used as a stationary phase was investigated in gas chromatography (GC), high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC). The potential relationship between the structure and components of chiral MOFs with their chiral recognition ability and selectivity are presented.

Chiral metal-organic framework used as stationary phases for capillary electrochromatography.

Metal-organic frameworks (MOFs) have received great attention as novel media in separation sciences because of their fascinating structures and unusual properties. However, to the best of our knowledge, there has been no attempt to utilize chiral MOFs as stationary phases in capillary electrochromatography (CEC). In this study, a homochiral helical MOF [Zn2(D-Cam)2(4,4'-bpy)]n (D-Cam=D-(+)-camphoric acid, 4,4'-bpy=4,4'-bipyridine) was explored as the chiral stationary phase in open tubular capillary electrochromatography (OT-CEC) for separation of chiral compounds and isomers. The MOFs coated column has been developed using a simple procedure via MOFs post-coated on the sodium silicate layer. The baseline separations of flavanone and praziquantel were achieved on the MOFs coated column with high resolution of more than 2.10. The influences of pH, organic modifier content and buffer concentration on separation were investigated. Besides, the separations of isomers (nitrophenols and ionones) were evaluated. The relative standard deviations (RSDs) for the retention time of run-to-run, day-to-day and column-to-column were 1.04%, 2.16% and 3.07%, respectively. The results demonstrated that chiral MOFs are promising for enantioseparation in CEC.