Multiplex PCR system to track authorized and unauthorized genetically modified soybean events in food and feed

A diverse range of genetic elements has been used to develop genetically modified organisms (GMOs) over the last 18 years. Screening methods that target few elements, such as the Cauliflower Mosaic Virus 35S promoter (P-35S) and Agrobacterium tumefaciens nopaline terminator (T-nos), are not sufficient to screen GMOs. In the present study, a multiplex PCR system for all globally commercialized GM soybean events was developed to easily trace the events. For this purpose, screening elements of 24 GM soybean events were investigated and 9 screening targets were selected and divided into three individual triplex PCR systems: P-35S, ribulose-1,5-bisphosphate carboxylase small subunit promoter of Arabidopsis thaliana, T-nos, T-35S, pea E9 terminator, open reading frame 23 terminator of A. tumefaciens, proteinase inhibitor II terminator of potato, acetohydroxy acid synthase large subunit terminator of A. thaliana, and the revealed 3′ flanking sequences of DP-305423-1. The specificity of the assays was confirmed using thirteen GM soybean events as the respective positive/negative controls. The limit of detection of each multiplex set, as determined using certified reference materials of specific GM events, ranged from 0.03 to 0.5%, depending upon target. Furthermore, 26 food samples that contained soybean ingredients, which were purchased from the USA, China, Japan, and Korea, were analyzed, 17 of which contained one or more GM soybean events. These results suggest that the developed screening method can be used to efficiently track and identify 24 GM soybean events in food and feed.     

Aflatoxin B1 degradation by culture and lysate of a Pontibacter specie

The presence of aflatoxin B₁ (AFB₁) along the food chain poses a significant threat, thus propelling the need for an effective approach to control it. This study was therefore, aimed at investigating AFB₁ degradation of liquid cultures and lysates of an isolated Pontibacter sp. (VGF1). Liquid cultures, lysed bacterial cells in the absence (uninhibited lysates) and presence of protease inhibitors (protease inhibited lysates) were respectively incubated with AFB₁ for 3, 6, 12, 24 and 48 h. AFB₁ degradation was monitored during this period on high performance liquid chromatography (HPLC) and results obtained revealed that after 6 h of incubation, the protease inhibited (PI) lysates yielded a 65% AFB₁ degradation, whereas after 12 h, no residual AFB₁ was detected. Conversely, after 48 h of incubation, a significantly (p≤0.05) lower AFB₁ degradation of 50 and 36% by the liquid culture and uninhibited lysate, respectively, were noted. It was further confirmed that the degradation mechanism was enzymatic. Data from cytotoxicity studies against human lymphocytes further demonstrated that extracts of biotransformed AFB₁ were less toxic when compared to that of AFB₁. Findings from this study have demonstrated an alternative approach for the decontamination and biocontrol of AFB₁ in various agricultural commodities.     

Low temperature cleanup combined with magnetic nanoparticle extraction to determine pyrethroids residue in vegetables oils

To quantify trace pesticide residue in vegetable oil rapidly, low temperature cleanup combined with magnetic nanoparticle based solid phase extraction was developed to determine eight pyrethroids in vegetable oils, including tetramethrin, fenpropathrin, cypermethrin, decamethrin, fenvalerate, acrinathrin, permethrin and bifenthrin. Polystyrene coated magnetic nanoparticles were synthesised by a modified chemical coprecipitation combined with emulsion polymerisation method. The nanoparticles were afterwards characterised by Fourier transform-infrared spectroscopy, X-ray diffraction, transmission electron microscopy as well as vibrating sample magnetometer, and successfully employed as adsorbents for the magnetic solid phase extraction of pyrethroids which were cleaned up using low temperature approach in advance. Critical impact factors on the efficiency of the extraction method such as the mass of adsorbents used, volume and type of eluent solvent, extraction time as well as elution time were optimised subsequently. Regression analysis of the calibration curves of the eight pyrethroids yielded satisfactory correlation coefficients within the range of 0.980–0.998. Limit of detection and limit of quantification were calculated to be between 0.0290-0.0658 and 0.0890–0.1994 ng g⁻¹, respectively. Intra-day and inter-day reproducibility at different concentration levels also produced satisfactory recovery rates of 83.18–112.79% with relative standard deviations not exceeding 10.84% and 12.01%, respectively, suggesting desirable stability of the proposed method.     

超高压液相色谱-高分辨质谱快速筛查和确证食用贝类中多种原多甲藻酸贝类毒素

建立超高压液相色谱-高分辨质谱快速筛查和确证贻贝、牡蛎、蚌类、扇贝等食用贝类及其制品中3 种天然形式的原多甲藻酸贝类毒素的检测方法。样品中的原多甲藻酸采用乙腈-水体系均质提取,应用改进型QuEChERS技术净化,在乙腈-水（含5 mmol/L醋酸铵和0.1%甲酸）体系经Acquity HSS T3柱（150 mm×2.1 mm,1.8 μm）梯度洗脱,实现了3 种原多甲藻酸贝类毒素的基线分离。该方法基于电喷雾正离子模式,采用高分辨质谱一级全扫描和数据依赖扫描,对食用贝类及其制品样品中的原多甲藻酸贝类毒素进行检测。3 种贝类毒素的定量限均为10 μg/kg（RSN＞10）;在10～500 μg/L范围内线性关系良好,相关系数（R2）均大于0.99。应用该方法对国内外多个地区的贝类产品进行了筛查及确证,其中部分样品检出原多甲藻酸贝类毒素。该方法灵敏度高,重复性好,操作简便、快捷,适用于食用贝类及其制品中多种原多甲藻酸贝类毒素的筛查分析。     

海产品中副溶血性弧菌免疫磁分离和环介导等温扩增快速检测方法的建立

采用纳米免疫磁珠分离副溶血性弧菌,建立副溶血性弧菌环介导等温扩增检测方法。方法 采用副溶血性弧菌单克隆抗体,制备纳米免疫磁珠,特异性吸附副溶血性弧菌,结合环介导等温扩增技术,建立副溶血性弧菌快速检测方法。结果 副溶血性弧菌纳米免疫磁珠在菌体浓度为10³cfu/ml水平时,对副溶血性弧菌的捕获率达到74%。免疫磁分离结合环介导等温扩增技术,在纯培养、无需增菌情况下,检测灵敏度达到140cfu/ml增菌液;通过对134株副溶血性弧菌和74株非目标菌的测试,环介导等温扩增技术具有良好的特异性;食品基质添加试验中,在增菌时间缩短至8h的条件下,其检测限为2cfu/25g样品。结论 副溶血性弧菌免疫纳米磁珠结合环介导等温扩增技术,有效缩短了增菌时间,适用于副溶血性弧菌的快速检测。     

HS-SPME-GC-MS结合自动解卷积技术分析阿胶中的挥发性成分

建立了顶空固相微萃取—气相色谱—质谱(headspace solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS)结合自动解卷积技术检测阿胶中挥发性物质的分析方法。以总峰面积和总出峰数为考察指标,通过单因素和正交试验对萃取条件进行优化,以期得到HS-SPME-GC-MS分析阿胶挥发性物质的较优条件。结果显示,萃取温度对总出峰数和总峰面积的影响较大,所得优化萃取条件为样品量5g、50/30μm DVB/CAR/PDMS萃取头、萃取温度70℃、平衡时间10 min、萃取时间50 min、解吸时间5min。该条件下,鉴定出阿胶挥发性成分41种,分别为吡嗪类10种、醛类8种、酯类5种、酮类6种、13种其他类化合物,其中相对含量较高的为吡嗪类48.95%和醛类26.37%。挥发性成分绝对峰面积的相对标准偏差的平均值为6.25%,该方法重复性较好。     

液相色谱-四极杆-飞行时间质谱法筛查食品中6 种人工合成甜味剂

应用高效液相色谱-四极杆-飞行时间质谱建立固体样品中甜味剂的筛查。样品经前处理后采用Eclispe XDB-C18色谱柱,以0.1%甲酸-10 mmol/L甲酸铵溶液-甲醇为流动相,梯度洗脱,电喷雾负离子模式分析检测。在 全扫描采集模式下,以准分子离子峰的峰面积定量,以化合物精确分子质量定性。各化合物在0.02～2.0 mg/L范围 内均呈现良好的线性关系,相关系数均大于0.998。样品平均添加回收率为74.5%～120.1%,相对标准偏差均小于 10.4%。本方法可满足现行法规的限量要求。     

中欧美食品接触用塑料材料及制品法规差异分析

着眼于食品接触用塑料材料及制品管理要求、合规测试、产品信息传递,对比分析了当前阶段中欧美食品接触用塑料材料及制品在监管法规构成、原料管理、成型品管理、回收塑料管理、食品分类和食品模拟物、迁移试验条件、食品接触面积与食品模拟物体积比、符合性声明、标签标识等方面的差异,提出欧美法规对我国食品接触用塑料材料和制品法规的借鉴与参考,旨在进一步提升我国食品接触用塑料材料及制品标准水平。     

国内钢铁分析研究进展

综述了最近20年国内在钢铁分析研究中的进展,包括原子光谱分析、分子光谱分析、离子色谱分析以及电化学分析等方法,并对各种分析方法的特点作了比较。     

Layered mixed-anion compounds: Epitaxial growth,active function exploration,and device application

Optoelectronic properties and device applications of layered mixed-anion compounds such as oxychalcogenide LaCuOCh (Ch = chalcogen) and oxypnictide LaT_MOPn (T_M = 3d transition metal, Pn = pnicogen) are reviewed. Several distinctive functions have been found in these materials based on our original material exploration concept. Fabrication of high-quality epitaxial films of LaCuOCh leads to clarifying the excellent electrical and optical properties such as high hole mobility of 8 cm²/(V s) and heavy hole doping at >10²¹ cm^?3 in LaCuOSe, and sharp and tunable-wavelength photoluminescence in the solid–solution systems in LaCuOCh. In addition, a room temperature operation of a light-emitting diode is demonstrated using LaCuOSe as a light-emitting layer. These results suggest that the layered oxychalcogenides have potential for light-emitting layers as well as transparent hole-injection layers in organic/inorganic light-emitting diodes. Furthermore, by extending the material system from the copper-based oxychalcogenides to isostructural compounds, transition metal-based oxypnictides LaT_MOP (T_M = Fe, Ni), we have found novel superconductors, LaFeOP and LaNiOP.