2012—2014年青岛、深圳、大连三口岸282份进口水果和蔬菜中农药残留监测

目的掌握和了解进口水果和蔬菜中农药残留污染状况,为国家制定和完善相关标准和采取相关措施提供科学依据。方法本文采用GB/T 19648—2006《水果和蔬菜中500种农药及相关化学品残留量的测定气相色谱-质谱法》和GB/T 20769—2008《水果和蔬菜中450种农药及相关化学品残留量的测定液相色谱-串联质谱法》分析方法,对2012—2014年从青岛、深圳、大连三个主要水果和蔬菜进口口岸采集的282份水果和蔬菜样品进行了666种农药残留的检测。结果对282份水果和蔬菜样品进行农药残留测定和技术分析:未检出农药残留样品31份,占11.0%;检出农药残留样品251份,占89.0%。共检测出农药52种,频次702次。结合中国、欧盟、日本的农药最大残留限量标准,对获得的数据进行了科学的分析:进口香蕉、榴莲、火龙果、草莓的农药残留水平整体处于安全水平,应加强进口龙眼、樱桃、葡萄中农药残留的检测和监管。结论进口水果和蔬菜的农药残留检出率较高,达到89.0%,但超出中国最大残留限量标准的样品较少,只占1.1%,说明进口水果和蔬菜中农药残留整体处于安全水平。     

《食品安全现代化法案》有关第三方审核机制的研究和应对

美国是我食品的主要出口地区,近年来出口贸易额保持快速增长的态势。但随着美国《食品安全现代化法案》以及配套法规的出台实施,特别是第三方认证机构审核机制的出台,对我输美食品企业在生产环境、投入品使用、包装和供应商审核等方面提出更高的要求,不仅加重了相关企业的负担,同时也可能对我现行出口食品检验监管制度与体制造成冲击。本文通过分析该法规的适用范围、主要参与主体、法规的主要内容及要求,研究该法规对我国第三方认证市场、输美企业以及对我国出口食品质量提升等方面造成的影响,提出加强沟通合作促进体系对接、学习借鉴相关理念和制度设计等对策措施,并对提高我国出口食品质量和完善我国进出口食品安全监管体系提供一定参考。     

气相色谱-三重四极杆质谱法测定液体乳及乳粉中的17种邻苯二甲酸酯类增塑剂

目的建立气相色谱-三重四极杆质谱法(gas chromatography-tandem mass spectrometry,GC-MS/MS)同时测定液体乳及乳粉中17种邻苯二甲酸酯类增塑剂的含量。方法样品经乙腈超声提取,凝胶渗透色谱(gel permeation chromatography,GPC)净化后用GC-MS/MS分析,外标法定量。结果该方法线性关系良好,相关系数为0.9956～0.9999;方法的检出限(S/N=3)为3～60μg/kg;定量限(S/N=10)为10～200μg/kg;在50、200、500μg/kg添加水平下的平均回收率为78.2%～115.4%,相对标准偏差为2.65%～9.95%。结论本研究建立的方法样品处理简单快速、净化效果好、灵敏度和选择性高,适用于日常检测工作。     

Rapid screening and quantification of multi-class multi-residue veterinary drugs in royal jelly by ultra performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry

A simple and rapid multi-class multi-residue analytical method was developed for the screening and quantification of veterinary drugs in royal jelly by ultra performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS). A total of 90 veterinary drugs investigated belonged to more than 14 families such as lincomycins, macrolides, sulfonamides, quinolones, tetracyclines, β-agonists, β-lactams, sedatives, β-receptor antagonists, sex hormones, glucocorticoids, nitroimidazoles, benzimidazoles, nitrofurans, and the others. A modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) procedure was used for the sample preparation without solid-phase extraction step. The linearity, sensitivity, accuracy, repeatability, and reproducibility of the method were fully validated. The response of the detector was linear for each target compounds in wide concentration range (at least, two orders of magnitude) with correlation coefficient (R²) of 0.9921–0.9999. The range of the limit of quantification for these compounds in the royal jelly ranged from 0.21 to 20 μg/kg. The repeatability and reproducibility were in the range of 3.01–11.6% and 5.97–14.9%, respectively. The average recoveries ranged from 70.21 to 120.1% with relative standard deviation of 1.77–9.90% at three concentration levels. For the screening method, the data of the precursor and product ions of the target analytes were simultaneously acquired under the All Ions MS/MS mode in a single run. A homemade database including the elemental composition, accurate masses, retention time, isotopic pattern data of the target ions the characteristic in-source fragment ions was utilized for the confirmation and identification of the target compounds. The applicability of the screening method was verified by applying to real royal jelly samples, and certain veterinary drugs were detected in some cases.     

实时荧光单引物等温扩增检测阪崎克罗诺杆菌方法的建立

目的建立实时荧光单引物等温扩增(SPIA)检测阪崎克罗诺杆菌的方法。方法本文以阪崎克罗诺杆菌Omp A基因特异序列为靶序列,设计RNA-DNA组合引物和链终止序列,优化反应体系,对4株不同来源阪崎克罗诺杆菌和21株其他食源性致病菌进行实时荧光SPIA特异性分析,通过不同浓度梯度阪崎克罗诺杆菌菌悬液灵敏度的检测和添加有阪崎克罗诺杆菌的婴儿配方奶粉样品检出限的确定,评价方法的准确度。结果除4株阪崎克罗诺杆菌外,其他细菌均未出现特异性荧光扩增曲线,具有良好的特异性。在40 min内,实时荧光SPIA检测阪崎克罗诺杆菌纯培养基因拷贝灵敏度为每反应1 copies,相应活菌数为1.6×10-1cfu/ml;对婴儿配方奶粉模拟样品中阪崎克罗诺杆菌的检出限是1.5×100cfu/100 g。结论本研究建立的方法具有灵敏度高、特异性强、耗时短、操作简单等优点,适用于实验室快速检测阪崎克罗诺杆菌Omp A基因。     

高温燃烧红外光谱法与库仑滴定法测煤中硫的区别

从工作原理、称样质量、试验是否需要催化剂、燃烧所需气体及燃烧温度等方面论述了高温燃烧红外光谱法和库仑滴定法之间的区别。     

流式细胞术在微生物快速检测领域的研究进展

概述了流式细胞术的发展历史、工作原理及其在微生物快速检测方面的应用。     

赤霞珠干红葡萄酒中重金属含量分析

研究分析了我国赤霞珠干红葡萄酒中重金属的含量及其受污染情况.使用湿法消解法处理葡萄酒样,火焰原子吸收法检测了铜、铁、锰、锌,石墨炉原子吸收法检测铅和镉,结果表明,样品预处理方式合理,检测方法准确可靠.检测结果说明不同企业生产的葡萄酒中重金属的含量存在差异.试验所检测的商品葡萄酒中重金属含量均未超过国家标准.     

流式细胞技术快速检测果汁中的霉菌、酵母菌

研究应用流式细胞技术（flow cytometry,FCM）快速检测果汁饮料中霉菌、酵母菌的方法。通过正交实验和方差分析,对样品前处理技术条件进行优化,去除了影响FCM检测的基质颗粒,使FCM检测限达到101cfu/mL数量级,检测时间从5d缩短到100min。从绘制的标准曲线可以看出,FCM与平板法线性相关,符合性好。FCM将以更加灵敏、准确、快速、操作简便的优点成为一种可替代平板法来检测果汁中霉菌、酵母菌的自动化仪器检测新技术。     

Preparation and research of waterborne polyurethane phase change material

ABSTRACT

This paper first designed the molecular structure of the water-soluble polyurethane phase change material. Taking HDI (hexamethylene diisocyanate), PEG (polyethylene glycol), chain extender (DMPA (dimethylolpropionic acid), BDO (1,4- butanediol), EDA (ethylenediamine)), catalyst (DBTDL (February acid dibutyl tin)), neutralizing agent (TEA (triethylamine)) as the raw material, the paper then prepared the waterborne polyurethane phase change material, which is available for wet spinning process. The particle size, appearance, storage stability, water absorption, tensile strength and elongation at break of the WPUPCM emulsion were then tested. Moreover, the influences of reaction temperature, reaction time, R value (ie -NCO / -OH molar ratio), PEG relative molecular mass and DMPA content on the WPUPCM performance indicators were investigated. The study indicated that reaction temperature, reaction time, R value, PEG relative molecular mass and DMPA content show various influences on WPUPCM performance indicators. Therefore, in order to meet the requirements of practical application and determine optimal formulation and process parameters, further relevent studies based on comprehensive considerations of all factors are needed.