啤酒和腊肠中N,N-二甲基亚硝胺的测定

目的建立气相色谱-质谱法(gas chromatography-mass spectrometry,GC-MS)测定啤酒和腊肠中N,N-二甲基亚硝胺的方法。方法试样经二氯甲烷超声提取、离心,SILICA/PSA玻璃柱净化后气相色谱/质谱仪直接测定,D6-N,N-二甲基亚硝胺内标法定量。结果加标回收率范围为66.9%~103.4%,相对标准偏差(RSD)在2.5%~7.7%。将该方法用于实际样品分析,30份啤酒中均未检出N,N-二甲基亚硝胺,8份腊肠样品中检出2份阳性样品,含量均低于肉制品中N,N-二甲基亚硝胺限量值3.0μg/kg。结论此方法简便快速,灵敏度较高,可以用于啤酒和腊肠中N,N-二甲基亚硝胺的准确定量。     

气相色谱-质谱联用法测定肉制品中的4种N-亚硝胺类

本文建立了气相色谱质谱(GC-MS)快速测定肉制品中4种N-亚硝胺含量的分析方法,4种亚硝胺分别为N-二甲基亚硝胺(NDMA)、N-二乙基亚硝胺(NDEA)、N-二丙基亚硝胺(NDPA)、N-二甲基吡咯烷(NPYR)。样品经二氯甲烷提取后经固相萃取柱(SPE)净化,采用DB-1701柱分离,选择离子法(SIM)进行定性定量检测,4种亚硝胺在0.05~10μg/m L质量浓度范围内线性关系良好,相关系数均可达0.995以上,检出限0.06~0.1μg/kg,方法回收率75%~80%,标准偏差小于10%,此方法适用于肉制品中4种亚硝胺的测定。     

肉制品中N-二甲基亚硝胺测定及不确定度评定

建立气相色谱/三重四级杆质谱法测定肉制品中N-二甲基亚硝胺的方法,并对测定过程中可能引入的不确定度进行分析和评定。试样经QuEChERS方法提取后采用MRM模式进行定性定量;建立不确定度评定的数学模型,确定并简化不确定度来源,计算合成不确定度和扩展不确定度。加标回收率范围为87.8%~115.3%,相对标准偏差(RSD)在4.3%~6.2%,线性相关系数达0.999 5,实际分析15份样品中检出5份阳性样品,含量均低于国家限量值3.0μg/kg;测定3.0μg/kg时,N-二甲基亚硝胺的含量是(3.0±0.18)μg/kg,相对扩展不确定度为6.0%。该试验方法步骤简单、有机溶剂用量少、灵敏度高,重现性好,满足国家限量检测的要求;本方法适用于GC-MS/MS测定肉制品中N-二甲基亚硝胺的不确定度评定。     

气相色谱-质谱法测定肉制品中的亚硝胺

利用二氯甲烷提取肉制品中的3种挥发性亚硝胺,即:N-二甲基亚硝胺(NDMA)、N-二乙基亚硝胺(NDEA)、N-二丙基亚硝胺(NDPA)。利用气质联用仪采用选择离子法(SIM)进行定性定量检测。本检测方法前处理简单快捷,易于操作,线性相关系数分别可达0.9991、0.9991、0.9995;线性范围分别可达0~250μg/mL;方法重现性良好,其RSD可达1.44%~1.99%;回收率可达90%~105%;灵敏度高,检测限分别为0.04μg/kg、0.025μg/kg、0.01μg/kg。     

气相色谱-质谱法测定肉制品中的9种挥发性N-亚硝胺类物质

研究建立一种适用于肉制品中9种挥发性N-亚硝胺含量的气质联用快速检测方法。实验优化提取溶剂和色谱柱对提取和分离检测影响的条件,同时考察4种固相萃取单柱(酸性氧化铝、C18、活性炭、PSA)和1种双填料的混合固相萃取柱(PSA-C18)的净化效果。结果表明:本检测方法的线性系数均可达到0.999 2以上;线性范围为0~10μg/m L;重现性良好,相对标准方差均≤3.2%;回收率为85%~98%;检测限分别为N-亚硝基二甲基胺1.0μg/kg、N-亚硝基甲基乙基胺2.1μg/kg、N-亚硝基二丁基胺0.8μg/kg;其他均为0.5μg/kg。该方法能够满足测定肉及肉制品中N-亚硝胺的残留含量的需要。     

腊肉加工过程中N-亚硝胺的分析

为了解腊肉中N-亚硝胺的形成及水平状况,利用气相色谱法(FID氢火焰检测器)对腊肉中的N-二甲基亚硝胺(NDMA)和N-二乙基亚硝胺(NDEA)的含量进行跟踪分析。结果表明:烤制阶段N-亚硝胺急速增加,且NDEA最大含量几乎是NDMA的2倍。经过腌制后NDMA含量为4.06μg/kg,烤制结束增加到9.23μg/kg,NDEA含量腌制结束时为4.26μg/kg,烤制第1天就增加到7.90μg/kg,烤制结束时达到16.20μg/kg,烘烤是影响腊肉中N-亚硝胺形成的重要环节。成熟阶段增加速度相对平缓,成熟12 d,NDMA和NDEA含量分别为10.52μg/kg和20.25μg/kg。     

氢氧化钡处理-活性炭柱固相萃取/GC-MS/MS检测腌制蔬菜中7种挥发性N-亚硝胺

建立氢氧化钡处理,活性炭柱固相萃取,气相色谱-串联质谱法(GC-MS/MS)检测腌制蔬菜中挥发性N-亚硝胺的新方法。将10 g腌制蔬菜样品加入N-二甲基亚硝胺-d6和N-二丙基亚硝胺-d14内标于50 mL离心管中,经80℃密闭处理1h,离心分离,活性炭柱固相萃取,以DB-1701柱(30 m×0.25 mm×0.25μm)气相色谱分离,串联质谱多重反应监测模式进行检测。结果表明,本法可实现对批量腌制蔬菜样本中7种N-亚硝胺的检测,其中N-二丙基亚硝胺(NDPA)的检出限和定量限分别≤0.08 ng/g和≤0.2 ng/g,N-二甲基亚硝胺(NDMA)等其它6种N-亚硝胺检出限和定量限分别≤0.04 ng/g和≤0.1 ng/g;考察质量浓度范围内(1～100 ng/mL),线性良好,R2≥0.9993;0.1,1.0和5.0 ng/g三水平的加标回收率为82.1%～125.6%,相对标准偏差为0.10%～11.8%。对超市腌制蔬菜的抽样(n=46)监测表明,NDMA、N-亚硝基吗啉(NMOR)和N-亚硝基吡咯烷(NPYR)检出率为100%,N-二乙基亚硝胺(NDEA)、NDPA、N-亚硝基哌啶(NPIP)的检出率为71%～88%,N-甲乙基亚硝胺(NMEA)未检出;除NPYR含量较高,最高值为4.71 ng/g外,其它N-亚硝胺含量均在1 ng/g以下;腌制蔬菜中N-亚硝胺处于较安全水平。     

快速水蒸气蒸馏-气相色谱热能分析仪法测定肉制品和水产制品中13种N-亚硝胺

建立快速水蒸气蒸馏结合气相色谱-热能分析仪技术测定肉制品和水产制品中13种N-亚硝胺化合物的方法。快速水蒸气蒸馏仪能以较高效率提取样品中亚硝胺类化合物,采用N-亚硝基二异丙胺作为内标可有效提高方法稳定性和回收率。结果表明:在0～1.00μg/mL质量浓度范围内,13种N-亚硝胺标准曲线线性良好,线性相关系数均可达0.995以上,当取样量为200 g,浓缩体积为1.0 mL时,13种亚硝胺方法检出限为0.05μg/kg～0.18μg/kg,定量限为0.17μg/kg～0.59μg/kg,添加回收率为80.1%～112.9%,相对标准偏差为1.88%～7.16%。将该方法应用于16个实际样品检测,发现水产制品类样品中N-二甲基亚硝胺检出较多,部分样品含量超过国家限量标准,其他N-亚硝胺化合物偶有检出,含量相对较低。     

浓缩条件对于N-二甲基亚硝胺测定结果稳定性的影响

N-二甲基亚硝胺具有致癌性,在熏肉制品等腌制食品中广泛存在,目前是国际上公认的致癌物。GB2762-2012《食品中污染物限量》规定肉制品中N-二甲基亚硝胺限量为3.0μg/kg。按照国家标准方法检验N-二甲基亚硝胺时结果波动幅度较大。本文探究了不同浓缩条件对N-二甲基亚硝胺检测结果的影响,发现浓缩条件是制约结果稳定性的重要因素之一。     

气相色谱-热能分析仪测定水产品中N-亚硝胺

用水蒸气蒸馏-二氯甲烷萃取的方法提取水产品中四种挥发性N-亚硝胺,即N-二甲基亚硝胺(NDMA)、N-二乙基亚硝胺(NDEA)、N-亚硝基吡咯烷(NPYR)和N-二丙基亚硝胺(NDPA)。利用气相色谱-热能分析仪联用进行定性定量检测。本检测方法线性相关系数分别可达0.999 4、0.999 1、0.999 2和0.998 7;线性范围可达0.2μg/m L~4.0μg/m L;方法重现性良好,其RSD可达2.48%~3.56%;回收率可达75.2%~88.9%。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

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

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press     

INFOPRINT 2014 was Successfully Held in Dongguan

Sponsored by Printing and Printing Equipment Industries Association of China （PEIAC） and organized by Print China magazine, the Seventeenth Beijing International Printing Information Conference （INFOPRINT 2014） was successfully held on 11th Dec. 2014 at Dongguan Exhibition International Hotel.