顶空-气相色谱法测定5种挥发性消毒副产物在饮用水加热前后的含量变化

目的建立顶空气相色谱法测定生活饮用水在加热前后5种挥发性消毒副产物三氯甲烷、四氯化碳、一溴二氯甲烷、二溴一氯甲烷、三溴甲烷含量的变化。方法取出厂水、末梢水、煮沸的开水、敞口持续煮沸1 min的开水各10 mL于顶空瓶中70℃顶空平衡15 min,取上层气体进样进行气相色谱分析, HP-5毛细管色谱柱分离,电子捕获检测器检测,外标法定量。结果 5种挥发性消毒副产物在不同的浓度下线性关系良好,相关系数为0.9992～0.9996;加标回收率为83.3%～101.8%。其中三氯甲烷在4种样品中检出浓度为0.717～44.9μg/L;四氯化碳、一溴二氯甲烷、二溴一氯甲烷均有不同程度检出,三溴甲烷均未检出。结论经过氯化消毒的自来水煮沸后,挥发性消毒副产物含量大幅降低,其中以开盖持续煮沸1min的开水中含量最低,因此建议饮用自来水需要提前煮沸。     

2013年滁州市食源性致病菌监测分析

目的了解和掌握滁州市食品中食源性致病菌污染状况,为开展食品安全风险评估和确定高危食品种类、分布提供科学依据。方法按照《2013年国家食品污染和有害因素风险工作手册》中的标准操作程序,对市售10类食品进行金黄色葡萄球菌、沙门氏菌、志贺氏菌、单增李斯特菌、蜡样芽胞杆菌、阪崎肠杆菌、致泻大肠埃希氏菌、铜绿假单胞菌共8种食源性致病菌的检测。结果共抽检169份样品,检出致病菌17株,总检出率10.06%。其中蜡样芽胞杆菌12株、铜绿假单胞菌3株、致泻性大肠埃希氏菌2株。结论滁州地区市售食品存在不同程度的食源性致病菌污染,有一定的食品安全风险。其中婴幼儿食品、乳制品和桶装水等污染较为严重,主要污染菌为蜡样芽胞杆菌、铜绿假单胞和致泻性大肠埃希氏菌。     

Reduction of Escherichia coli O157, Listeria monocytogenes and Salmonella enterica sv. Typhimurium populations on fresh-cut bell pepper using gaseous ozone

Bacterial contamination is the main cause of food poisoning which can lead to diarrhoea, abdominal cramp, vomiting as well as death. Bacterial contamination can potentially be controlled by application of gaseous ozone due to its antibacterial activity. Therefore, the objective of this study was to investigate the efficacy of gaseous ozone for reducing food-borne pathogens such as Escherichia coli O157, Listeria monocytogenes and Salmonella enterica sv. Typhimurium on fresh-cut bell pepper. Efficacy of gaseous ozone to reduce bacterial populations was investigated in vitro and in vivo. Results showed that optimum effect of ozone on reducing bacterial populations was achieved with short term exposures of less than 6 h. Ozone reduced the bacterial population by disrupting bacterial cell structure, which lead to cellular death. Results also showed that bacterial cells have different resistance to ozone where ozone was more effective against L. monocytogenes, followed by E. coli O157 and Salmonella Typhimurium. Optimal reduction of the bacterial population on fresh-cut bell pepper was achieved with exposure to 9 ppm ozone for 6 h. This treatment reduced 2.89, 2.56 and 3.06 log of E. coli O157, Salmonella Typhimurium and L. monocytogenes populations, respectively. In conclusion, exposure to 9 ppm ozone for 6 h helps in reducing food-borne pathogen on fresh-cut bell pepper and has high potential to be an alternative sanitization treatment to reduce pathogen population on fruit.     

气相色谱-质谱联用法快速检测食物中毒 案例中的克百威农药

目的通过气相色谱-质谱联用法(gas chromatography-mass spectrometry,GC-MS)快速检测食物中毒案例的样品中克百威农药。方法使用丙酮快速提取样品,离心后取上清液,上机待测。运用全扫描方式监测,通过全扫描提供的质谱图由谱库检索出可疑物质,再根据保留时间和质谱图中特征离子准确定性。配制标准系列通过选择离子扫描模式监测方式,外标法定量。结果在导致食物中毒的现场采集的样品中检出致毒因子杀虫剂农药克百威。配制克百威标准浓度为0.10~2.00 mg/L范围内呈良好的线性关系,相关系数(r~2)=0.9989,加标回收率为86%~101%,相对标准偏差(relative standard deviation,RSD)为2.2%~5.8%。样品中克百威的含量最高达到了232 mg/kg。结论此方法操作简单、易行,是快速、有效的一种毒物分析方法。