元素分析-同位素比质谱法测定食醋总碳同位素比值

本文建立了一种利用元素分析-同位素比质谱法(Elemental analyzer-Isotope ratio mass spectrometry,EA-IRMS)测定食醋总碳同位素比值的方法,并对食醋进行聚类分析。优化了样品稀释倍数及进样量。2 g芳香醋用4 m L超纯水进行稀释,2 g糯米酿造食醋用2 m L超纯水进行稀释,苹果醋、配制白醋不稀释,进样量均为1μL,样品分析时间为670 s。结果显示:芳香醋、糯米酿造食醋、苹果醋及配制白醋的δ~(13)C值范围分别为-26.94‰~-23.46‰、-25.06‰~-22.40‰、-27.99‰~-22.76‰、-19.06‰~-13.74‰,聚类分析可将不同产地、不同原料、不同生产方式的食醋进行初步归类,并且该方法可鉴别出芳香醋和掺入≥4%糯米酿造食醋、≥6%苹果醋、≥2%配制白醋的芳香醋混合样品。食醋及质控样品(咖啡因)的测试精度(SD)在0.02‰~0.25‰(n=6)之间,均小于0.3‰,满足方法检测分析要求。结果表明,所建EA-IRMS方法结合聚类分析可用于食醋分类及掺假鉴别。     

基于氮稳定同位素比例质谱和液相色谱-高分辨质谱的有机番茄鉴别

为了解决有机食品鉴别需要多种参数指标进行综合判定,制样过程繁琐,判别正确率偏低的问题,本研究提出一种基于稳定同位素比例质谱和液相色谱-高分辨质谱分析技术,结合偏最小二乘法判别分析(partial least squares-discriminant analysis,PLS-DA)的有机番茄鉴别方法.将采集的94个番茄...     

C/C pattern of honey from Turkey and determination of adulteration in commercially available honey samples using EA-IRMS

Honey adulteration particularly by adding cheap sugars such as High Fructose Corn Syrup (HFCS) and cane sugar syrup into natural honey is widespread. This study reports (¹³C/¹²C, ‰) patterns of 31 authentic honey samples obtained from different sources and regions of Turkey as well as 43 commercial honey samples to determine the adulteration using mass spectrometer coupled to elemental analyzer (EA-IRMS). The analyses indicated that the ranges of (¹³C/¹²C, ‰) values of honey and protein fractions of Turkish honey are from −23.30 to −27.58‰ and −24.13 to −26.76‰, respectively. These values for commercial honey samples were determined to range from −11.28 to −25.54‰ and −19.35 to −25.61‰, respectively. The numbers of adulterated commercial honey samples were found to be 10, which corresponds to 23% of the total number of the samples. Diastase activity, HMF content, electrical conductivity and moisture content of honey samples were also determined. Method validation and uncertainty budget calculations were also reported.     

气相色谱-燃烧-同位素比质谱法测定鱿鱼中甲醛稳定碳同位素比值

建立了一种气相色谱-燃烧-同位素比质谱法(GC/C/IRMS)测定鱿鱼中甲醛(FA)稳定碳同位素比值的方法。鱿鱼样品经水充分提取后,高速离心除油脂,上清液与2,4-二硝基苯肼在酸性、60℃条件下发生液相衍生化反应1 h,衍生液经正己烷萃取,氮吹干后复溶即可进行稳定碳同位素测试。二氯甲烷、甲醇、正己烷、乙腈均可作为衍生产物甲醛2,4二硝基苯腙的同位素测试的溶剂。甲醛的衍生化反应未发生碳同位素分馏,由质量平衡方程计算得到的衍生产物甲醛2,4二硝基苯腙的δ¹³C值与实测值差值的标准偏差为0.215‰。分析9个市售不同产地鱿鱼中甲醛的含量为0.341~39.132 mg/kg,内脏部分含量较高。甲醛含量较高的2、3、4、5号样品δ¹³C值差异高达23.653‰。水产品中甲醛稳定碳同位素指纹特征可作为其来源解析的特征性指标。     

同位素模拟-气相色谱-串联质谱法测定邻苯二甲酸二（2-乙基）己酯在茶汤中的浸出率

在排查茶叶冲泡和样品前处理过程中邻苯二甲酸二（2-乙基）己酯（di-(2-ethylhexyl) phthalate,DEHP）背景污染基础上,采用同位素模拟-气相色谱-串联质谱法研究茶汤中DEHP的浸出率。结果表明,有机试剂、实验器皿以及旋转蒸发浓缩过程会产生DEHP污染,背景污染造成DEHP在茶汤中的浸出率偏高,为13%～400%。同位素DEHP-D4模拟冲泡实验结果表明,DEHP-D4在茶汤中的浸出率为4.5%～11.9%,浸出率与茶叶中DEHP-D4质量浓度相关性较小,但与茶叶种类、冲泡方式和冲泡次数相关。该研究结果为茶叶中DEHP风险评估提供技术支撑,为制定茶叶中DEHP最大残留限量标准提供基础数据。     

应用电感耦合等离子体质谱法快速检测葡萄酒中57种矿质元素

为减少葡萄酒复杂基体对测定结果的影响,用矿质元素含量很低的玫瑰蜜(Vitis vinifera,L.Rose Honey)葡萄酒做溶剂配置标准溶液,样品直接用5%(v/v)硝酸稀释,建立了电感耦合等离子体质谱法(ICP-MS)快速检测葡萄酒中57种矿质元素的方法。该方法中各元素的检出限在0.002(硼)～23.10ng/L(硒)之间,相对标准偏差5.00%,加标回收率为81.15%～108.6%,能够满足多元素同时分析的要求。应用该法检测了酒精发酵结束后的霞多丽、西拉和美乐3个单品种酒中矿质元素含量,结果显示,3个单品种酒中均可检测到上述57种元素,不同品种酒之间锂(Li),铝(Al),钪(Sc),钒(V),镍(Ni),锗(Ge),钇(Y),钼(Mo),锑(Sb),镱(Yb),钨(W),铅(Pb)和铀(U)含量有显著性差异,葡萄酒中主要的重金属锌(Zn)、砷(As)、铅(Pb)、镉(Cd)均低于OIV的限量。     

Improvement of accuracy for the determination of vitamin A in infant formula by isotope dilution-liquid chromatography/tandem mass spectrometry

Analysis of vitamin A in food has been an intricate subject due to its labile properties. In this study, an isotope dilution-liquid chromatography/mass spectrometric (ID-LC/MS) method was established as a candidate reference method for the accurate determination of vitamin A in infant formula. We found that the oxidative degradation of vitamin A in sample preparation processes is a key fact that hampers reliability of measurement results. Therefore, sample preparation processes were carefully designed to minimise oxidative degradation of vitamin A by preventing sample from exposure to air. Similar cautions were applied for the preparation of calibration solutions. Both within-day repeatability and among-day reproducibility tests of the ID-LC/MS method showed less than 1.0% of relative standard deviation, and the measurement uncertainty by this method is estimated to be less than 1.0%. The newly designed method showed greatly improved performance compared to methods reported in other literatures.     

高效液相色谱-质谱法测定白酒中的氨基甲酸甲酯

建立了高效液相色谱-电喷雾质谱测定白酒中氨基甲酸甲酯农药残留的检测方法.酒样用旋转蒸发器在50℃水浴上浓缩,以乙腈-0.1%乙酸为梯度流动相,Eclipse XDB-C18(150mm×4.6mm,5 μm)柱高效液相色谱分离.电喷雾正离子模式,选择质子化氨基甲酸甲酯分子离子[M H] 为定量离子进行MS测定.结果表明,氨基甲酸甲酯的检测限为7.6 ng,方法的平均加标回收率为80.7%～97.0%,相对标准偏差为5.4%～9.2%.该方法的灵敏度高、操作简便、快速,满足白酒中痕量氨基甲酸甲酯农残的高灵敏分析.     

液相色谱-串联质谱法测定糖果中2-(4-甲氧基苯氧基)-丙酸钠甜味抑制剂

建立了高效液相色谱-串联质谱法检测糖果中的2-(4-甲氧基苯氧基)-丙酸钠的方法。采用水溶液(pH8.0):乙腈=1.5:1 (V/V)作为提取溶剂,然后用正己烷去除油脂,取水层清液过膜,进行检测。采用电喷雾负离子模式(ESI-)和选择反应监测扫描(SRM)模式,外标法定量。结果表明,该方法在6.25~100 μg/L范围内线性关系良好(相关系数r=0.9998),检出限为8.0 μg/kg,定量限为20.0 μg/kg。回收率为82.7%~90.7%,相对标准偏差为2.5%~4.2%。该方法前处理简单、重现性好、灵敏度高,为糖果中的2-(4-甲氧基苯氧基)-丙酸钠的检测提供一种新的选择。     

Mass spectrometric determination of waxy corn (Maize) starch in glutinous (waxy) rice cake by use of 13C/12C ratio

Glutinous (waxy) rice cake is a popular New Year food in Japan. Economic incentives exist for rice cake producers to adulterate the products and mislabel them. Stable carbon isotope ratios (¹³C/¹²C) in rice cake products were determined by mass spectrometry to detect such adulteration. Since the ¹³C/¹²C ratios in rice (δ¹³C value of ca - 25 ppt, parts per thousand are different from those of corn (maize) starch (ca ?9 ppt), the presence of added waxy corn (maize) starch in rice cake could be detected.     

Multi-Element (C,N, H,O) Stable Isotope Ratio Analysis for Determining the Geographical Origin of Pure Milk from Different Regions

In order to identify the geographical origin of pure milk, different proteins and milk water were extracted from pure milk originated from Australia and New Zealand, Germany and France, the USA, and China. Then, δ ¹³C and δ ¹⁵N values of the extracted proteins and δ ²H and δ ¹⁸O values of milk water were determined by element analyzer-isotope ratio mass spectrometry (EA-IRMS). The results indicated that pure milk from these regions could be potentially discriminated by using analyte δ ¹³C, δ ¹⁵N, δ ²H, and δ ¹⁸O. The P value analysis of them was highly significant (P?<?0.01) considering the origins. 3D distribution of δ ¹³C, δ ¹⁵N, δ ²H, and δ ¹⁸O can also clearly present regional concentration phenomena according to the regions of pure milk. Therefore, it can be concluded that δ ¹³C, δ ¹⁵N, δ ²H, and δ ¹⁸O analysis could potentially be rapid and routine for origin discrimination of pure milk.     

基于电感耦合等离子体质谱仪分析矿物元素含量的大豆产地溯源

为表征相似地域特性的溯源指标,提高矿物元素对大豆产地溯源的准确性及稳定性。采用电感耦合等离子体质谱仪分析黑龙江省北安市9个农场及黑河市嫩江县6个农场共42个大豆样品中矿物元素含量,对所得的矿物元素含量数据进行方差分析、主成分分析和判别分析。结果显示:北安市和黑河市嫩江县矿物元素溯源指标,第1主成分主要由V、Fe、La、Ce、Pr、Nd、Dy、Er、Yb 9种元素构成,贡献率最大,为28.390%;第2主成分主要由As、Se、Lu、Ir、Au 5种元素构成,贡献率为14.435%;第3主成分主要由Ca、Ni、Cd、Ba 4种元素构成,贡献率为10.881%。利用大豆中矿物元素含量的分析,实现了省内大豆主产区产地溯源,并获得了黑龙江省两个大豆主产区溯源指标,分别为Na、K、Mn、Rb、Ba和Au 6种元素。综合2个主产区42个大豆样品矿物元素分析结果,实现了对黑龙江省两大主产区大豆产地溯源的准确判别,正确判别率为100%。     

A new selective liquid membrane extraction method for the determination of basic herbicides in agro-processed fruit juices and Ethiopian honey wine (Tej) samples

Supported liquid membrane (SLM) extraction was optimised for trace extraction and enrichment of selected triazine herbicides from a variety of agro-processed fruit juices and Ethiopian honey wine (Tej) samples. In the extraction process, a 1:1 mixture of n-undecane and di-n-hexylether was immobilised in a thin porous PTFE membrane that forms a barrier between two aqueous phases (the donor and acceptor phases) in a flow system. The extracts constitute the selectively enriched analytes collected from the acceptor phase and were analysed by transferring to a HPLC-UV system using a diode array detector at 235?nm. High enrichment factors were obtained with very good repeatability of results, and the detection limit was lower than 3.00?µg l^?1 for ametryn in apple juice. The optimised method showed very good linearity of over 50–500?µg l^?1 with a correlation coefficient of >0.990 or better for triplicate analysis. All chromatograms gave well resolved peaks with no interfering peaks at the retention times of the selected triazines, showing high selectivity of the SLM extraction method in combination with HPLC-UV for the selected matrices. The optimised method can be used as an alternative solventless extraction method for microgram-level extraction of other triazine herbicides and a variety of pesticides from liquid and semi-liquid environmental, biological and food matrices.     

Determination of the Composition of Commercial Tannin Extracts by Liquid Secondary Ion Mass Spectrometry (LSIMS)

The composition of various commercial tannin extracts were determined by liquid secondary ion mass spectrometry (LSIMS). Spectra were obtained directly from tannin extracts without any pre-separation. Eight different tannin powders were analysed: three gallotannins (Chinese, Turkish, tara), three ellagitannins (sweet chestnut, pendunculata oak, sessile oak), one mixed hydrolysable tannin (myrabolans) and one proanthocyanidin (grape seeds). This method enabled the main molecules in these powders to be identified.     

Overview of the Applications of Tandem Mass Spectrometry (MS/MS) in Food Analysis of Nutritionally Harmful Compounds

Tandem mass spectrometry (MS/MS) has proved to be a useful and a time saving analytical tool, with many applications of direct detection of target molecules in food samples. When coupled with chromatographic techniques, it combines the separation capabilities of chromatography and the power of MS/MS as an identification and confirmation method. This article reviews the use of tandem mass spectrometry in the determination of various food contaminants such as alkaloids, pesticides (carbamates, s-triazines, phenylureas, N-methylcarbamates), marine toxins, mycotoxins, arsenosugars, antibiotics, dioxins, polychlorinated biphenyls, and acrylamide. Experimental conditions and the main spectral patterns for the recognition of these compounds are presented.     

Overview of the Applications of Tandem Mass Spectrometry (MS/MS) in Food Analysis of Nutritionally Harmful Compounds

Tandem mass spectrometry (MS/MS) has proved to be a useful and a time saving analytical tool, with many applications of direct detection of target molecules in food samples. When coupled with chromatographic techniques, it combines the separation capabilities of chromatography and the power of MS/MS as an identification and confirmation method. This article reviews the use of tandem mass spectrometry in the determination of various food contaminants such as alkaloids, pesticides (carbamates, s-triazines, phenylureas, N-methylcarbamates), marine toxins, mycotoxins, arsenosugars, antibiotics, dioxins, polychlorinated biphenyls, and acrylamide. Experimental conditions and the main spectral patterns for the recognition of these compounds are presented.     

微乳液溶剂热法微/纳米草酸钐的合成与表征

采用微乳液溶剂热法,在CTAB/正辛烷/正丁醇/硝酸钐水溶液（草酸钾水溶液）所形成的反相微乳液体系中,合成不同尺寸的棒状微/纳米Sm2（C2O4）3.利用X射线衍射（XRD）、透射电子显微镜（TEM）、扫描电子显微镜（SEM）对Sm2（C2O4）3的形貌和尺寸进行了表征.结果表明,微/纳米Sm2（C2O4）3的尺寸随着水与CTAB的摩尔比（ω）、反应时间的增大而增大.     

液相色谱-四级杆/线性离子阱复合质谱法分析恩诺沙星在海参体内的代谢产物

为鉴定恩诺沙星给药后其在海参(Stichopus japonicas)体内的主要代谢产物,取药浴后均质的海参样品,经酸化乙腈提取、浓缩、正己烷净化后,利用液相色谱-四级杆/线性离子阱复合质谱法进行分析。采用电喷雾离子源在正离子模式下进行多反应选择监测结合实时触发增强子离子模式(MRM-IDA-EPI)扫描,分析恩诺沙星在海参体内的代谢产物。实验结果表明,给药6 h后海参体内共鉴定出10种恩诺沙星代谢产物,包括恩诺沙星异构化产物(M3)、脱乙基产物环丙沙星(M1)及其异构体(M2)、加氢还原产物及其异构体(M4、M5和M6)、羟基化恩诺沙星及其异构体(M7和M8)和加氧恩诺沙星及其异构体(M9和M10)。恩诺沙星在海参体内的代谢产物M2~M5以峰面积计,均高于环丙沙星(M1)。研究发现恩诺沙星在海参体内主要发生脱乙基反应和加氢还原反应,其主要代谢产物为M2和M4。