气相色谱法测定蔬菜中甲胺磷农药残留量的测量不确定度评定

通过对气相色谱法定量测定蔬菜中甲胺磷农药残留量的检验过程进行研究，分析确定该检测过程的测量不确定度来源，进而求出各不确定度分量对总测量不确定度的相对贡献，并对测量结果进行表述。     

气相色谱法测定蔬菜中16种有机磷农药残留量的测量不确定度评定

目的:评定气相色谱法测定蔬菜中有机磷农药残留量的测量不确定度,为客观分析蔬菜中多组分农药残留检测结果的可靠性提供参考。方法:以NY/T 761-2008第一部分方法二的标准方法为研究对象,分析有机磷农药残留量测定的全过程,从标准溶液、样品制备、重复性、标准曲线拟合和回收率等五个方面对检测方法的测量不确定度进行了评定,确认不确定度的来源和大小,合成标准不确定度,计算扩展不确定度并报出结果。结果:蔬菜中16种有机磷农药的含量范围为0.100~0.339 mg/kg,扩展不确定度范围在0.016~0.052 mg/kg之间(P=95%,k=2)。结论:气相色谱法测定蔬菜中有机磷农药残留量的测量不确定度主要来源为标准曲线拟合,其次为回收率,可通过选择合适的标准溶液浓度制作标准曲线、优化前处理方法、质控样品等措施减少不确定度,保证检测结果的准确、可靠。     

高效液相色谱法测定酱腌菜中苯甲酸的不确定度评定

目的评定高效液相色谱法测定酱腌菜中苯甲酸含量的不确定度。方法按照GB 5009.28-2016《食品安全国家标准食品中苯甲酸、山梨酸和糖精钠的测定》测定酱腌菜中苯甲酸,根据JJF 1059.1-2012《测量不确定度评定与表示》的方法,建立高效液相色谱法测定酱腌菜中苯甲酸不确定度评定的数学模型,分析并量化其中各来源的不确定度分量,最终合成酱腌菜中苯甲酸含量的不确定度。结果在95%的置信区间下,酱腌菜中苯甲酸含量测定结果可表示为(0.214±0.00624) g/kg,k=2。结论引入不确定度的主要分量是重复性测定及标准曲线的拟合过程等。     

固相萃取高效液相色谱-串联质谱联用法测定蔬菜及其制品中苯甲酰脲类农药残留的不确定度评估

目的对蔬菜及其制品中苯甲酰脲类农药残留的不确定度进行评定。方法通过高效液相色谱-串联质谱联用法对蔬菜及其制品中苯甲酰脲类农药残留量测定过程进行分析,对数学模型中的各不确定度分量进行识别和量化,最后计算出相对合成标准不确定度和扩展不确定度。结果当蔬菜及其制品中除虫脲、灭幼脲和氯吡脲的浓度为10.4、9.98、9.74μg/kg时,其扩展相对不确定度分别为3.5%、1.8%和2.2%(k=2)。测量不确定度来源主要由标准溶液的配制的准确度、方法的准确度和测量的重复性组成。结论该评估模型为高效液相色谱-串联质谱联用法对蔬菜及其制品中苯甲酰脲类农药残留量的不确定度提供了参考依据。     

气相色谱法测定大豆油中有机氯农药残留的不确定度评定

目的建立气相色谱法(gas chromatography,GC)测定大豆油中有机氯农药残留结果的不确定度评定的数学模型。方法依据JJF 1059.1-2012《测量不确定度评定与表示》,全面考虑测量过程中的不确定度来源,对大豆油中有机氯农药残留的不确定度进行评定。结果当取样量为1.0 g,k=2(置信度为95%)时,检测出大豆油中六六六(hexachlorocyolohexane,HCH)和滴滴涕(dichlorodiphenyltrichloroethane,DDT)含量。α-HCH、β-HCH、γ-HCH、δ-HCH、o,p'-DDT和p,p'-DDT的含量分别为:(0.66±0.090)、(1.32±0.104)、(0.52±0.074)、(0.35±0.066)、(0.12±0.032)和(0.051±0.014)mg/kg。结论 GC法测定大豆油中有机氯农药残留的不确定度主要来源于测定结果重复性,其次为标准工作液的配制及色谱峰面积引起的不确定度,其他因素的影响相对较小。     

气相色谱法测定鲜枸杞中氧乐果农药残留量的不确定度评定

目的 评定气相色谱法测定鲜枸杞中氧乐果含量的不确定度。方法 参考JJF 1059.1-2012《测量不确定度评定与表示》,应用国家农业行业标准NY/T 761-2008《蔬菜和水果中有机磷、有机氯、拟除虫菊酯和氨基甲酸酯类农药多残留的测定》对鲜枸杞中氧乐果农药残留进行检测,并对其测定过程的不确定度进行了评定和分析。结果 在鲜枸杞中的氧乐果含量测定中,当样品的氧乐果含量为0.045 mg/kg时,其扩展不确定度为0.006 mg/kg(k=2),结果表示为(0.045±0.006)mg/kg。结论 鲜枸杞中氧乐果农药残留测量结果的主要不确定度来自样品重复测量,标准溶液配制,样品前处理、定容,标准溶液重复测定,样品称量5个因素,其中样品重复测量引入的相对标准不确定度分量贡献最大,而由样品称量引入的相对标准不确定度分量最小。     

气相色谱法测定粮食中4种有机磷农药残留量的不确定度评定

目的 对气相色谱法测定粮食中乐果、杀螟硫磷、对硫磷、马拉硫磷农药残留量的方法进行不确定度评估。方法 依据JJF 1059.1-2012《测量不确定度评定与表示》和JJF 1135-2005《化学分析测量不确定度评定》中有关规定, 建立了用气相色谱法测定粮食中4种有机磷农药残留量的不确定度评估数学模型, 对测定中的不确定度来源进行分析和评估。结果 当粮食中乐果、杀螟硫磷、对硫磷、马拉硫磷的残留量分别为0.10、0.19、0.095、0.093 mg/kg时, 扩展不确定度分别为: 0.01、0.01、0.010、0.006 mg/kg, 4种有机磷残留量分别表示为: (0.10±0.01) mg/kg (k=2)、(0.19±0.02) (k=2)、(0.095±0.006) mg/kg (k=2)、(0.093±0.007) mg/kg (k=2)。 结论 实验过程中的不确定度主要来源于标准物质配制和样品稀释过程, 本评估方法可为气相色谱法检测多组分农药残留量的不确定度评估提供依据。     

酱腌菜中食盐含量测量不确定度的评估研究

根据GB/T 5009.54-2003《酱腌菜卫生标准的分析方法》,采用摩尔法,用硝酸银标准溶液测定酱腌菜中的食盐含量。通过对酱腌菜中食盐含量测量不确定度的评估实验,建立了一种简单、适用的测量不确定度评估方法。     

气相色谱法测定果蔬汁中甲氰菊酯和林丹残留量的不确定度评定

目的评定采用气相色谱法(gas chromatography,GC)测定果蔬汁中甲氰菊酯和林丹含量的测量不确定度。方法建立测定果蔬汁中2种农药残留量的数学模型,采用乙腈对样品进行提取,弗罗里矽柱净化,用气相色谱仪进行分析。结果果蔬汁中甲氰菊酯和林丹的扩展不确定度分别为0.0053 mg/kg和0.0045 mg/kg。结论不确定度主要来源于标准溶液的配制、测量重复性和标准曲线拟合。     

电感耦合等离子体发射光谱法测定酱腌菜中钠含量的不确定度评定

评定电感耦合等离子体发射光谱仪测定酱腌菜中钠含量的不确定度, 提高实验结果准确性。方法 依据 CNAS-GL006:2019《化学分析中不确定度的评估指南》和 JJF 1135-2005 《化学分析测量不确定度评定》,采用电感耦合等离子体发射光谱仪 (ICP-OES) 法测定酱腌菜中钠含量,建立了不确定度评定的数学模型,对不确定度的来源进行了全面分析,通过计算得到扩展不确定度。结果 在酱腌菜的钠含量测定中, 当样品的钠含量为 3148 mg/100g, 其扩展不确定度为 430 mg/100g (k=2), 结果表示为(3148±430) mg/100g（k=2）。结论 用ICP–OES 进行测量时, 主要不确定度来源于标准溶液配制、其次为样品的重复性测定和回收率, 通过降低可控不确定度来提高测量结果的准确度, 该质量控制手段可用于合理地体现测定结果的可靠程度。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status