An optimised HS-SPME-GC-MS method for the detection of volatile nitrosamines in meat samples

A method to detect volatile nitrosamines in meat samples was developed using headspace sampling by solid-phase microextraction (HS-SPME), with analysis by GC-MS. A 50/30 µm divinylbenzene/carboxen/polydimethylsiloxane fused silica fibre was selected to extract a total of nine volatile nitrosamines: N-nitrosodimethylamine, N-nitrosomethylethylamine, N-nitrosodiethylamine, N-nitrosodi-n-propylamine, N-nitrosomorpholine, N-nitrosopyrrolidine, N-nitrosopiperidine, N-nitrosodi-n-butylamine, and N-nitrosodiphenylamine. Extraction at 65°C for 45 min with 36% (w/v) NaCl were the optimal conditions determined for the extraction of nine nitrosamines. Excellent linearity was obtained for all analytes with determination coefficients greater than 0.997. Recovery rates were between 92 and 113%. The relative standard deviation ranged from 0.81 to 8.0% for six of the nine compounds, and from 16 to 32% for the other three. For seven out of nine nitrosamines, limits of detection were below 3.6 µg kg^?1 and the limits of quantification were below 12 µg kg^?1. The nitrosamine levels in four varieties of processed meat products were investigated to assess the applicability of the method. Based on the results, the developed HS-SPME-GC-MS method proved to be a simple and efficient technique to detect seven out of nine nitrosamines in meat products with adequate sensitivity, accuracy and precision.     

蓝莓对蒸煮火腿中亚硝酸盐和亚硝胺的抑制作用研究

目的研究15种不同品种蓝莓果对肉制品加工过程中亚硝酸盐残留量和亚硝胺生成量的抑制作用。方法 以蒸煮火腿加工工艺为基础,对15种不同品种蓝莓果进行实验,依据GB 5009.33-2010测定肉制品中亚硝酸盐的含量,采气相色谱质谱联用技术(GC-MS)测定肉制品中的8种亚硝胺[N-亚硝基二甲基胺(NDMA)、N-亚硝基甲乙胺(NMEA)、N-亚硝基二乙基胺(NDEA)、N-亚硝基吡咯烷(NPYR)、N-亚硝基二丙基胺(NDPA)、N-亚硝基哌啶(NPIP)、N-亚硝基二丁基胺(NDBA)、N-亚硝基二苯基胺(NDphe A)]。结果 15种蓝莓果对亚硝酸盐的抑制率在6.27%~38.11%之间,平均值为25.17%,对亚硝胺的抑制率在53.64%~71.54%之间,平均值为63.01%。结论 蓝莓果对肉制品加工过程中亚硝酸盐和亚硝胺的含量具有显著抑制作用。     

Occurrence and source of nitrosamines and secondary amines in groundwater and its adjacent Jialu River basin, China

The presence of mutagenic and carcinogenic nitrosamines in groundwater is of great concern. In this study, eight nitrosamines including N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosomethylethylamine (NMEA), N-nitrosopyrrolidine (NPYR), N-nitrosomorpholine (NMOR), N-nitrosopiperidine (NPIP), N-nitrosodi-n-propylamine (NDPA), and N-nitrosodi-n-butylamine (NDBA) and corresponding secondary amines were investigated in shallow groundwater, river water, and wastewater samples collected from the Jialu River basin. The total concentrations of nitrosamines and secondary amines in groundwater were ND-101.1 ng/L and 0.36-4.38 μg/L, respectively. NDMA and its secondary amine DMA (44.7%/40.1%) were the predominant compounds in groundwater, followed by NDEA/DEA (21.7%/29.3%) and NDBA/DBA (26.4%/27.4%). Relatively high concentrations of these six compounds were also observed in river water that was influenced by the direct discharge of industrial and domestic wastewater. Using acesulfame as a quantitative population marker, the contribution of domestic sources to the concentrations of nitrosamines and secondary amines was 39-85% in downstream reaches of the Jialu River, and that of industrial sources was estimated to be 65-98% in other sites of the area. Both on-site leakage of domestic and industrial wastewater and leaching from river water would contribute to the occurrence of target pollutants in groundwater. The target pollutants posed a cancer risk of 4.12 × 10(-5) to the local populations due to the direct usage of groundwater as potable water.     

Photochemical attenuation of N-nitrosodimethylamine (NDMA) and other nitrosamines in surface water

The aqueous photolysis of seven alkyl nitrosamines was studied by irradiation in a solar simulator. Nitrosamines included N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodi-n-propylamine (NDPA), N-nitrosodi-n-butylamine (NDBA), N-nitrosopiperidine (NPip), and N-nitrosopyrrolidine (NPyr). Direct photolysis at irradiations of 765 W/m2, representing Southern California midsummer, midday sun, resulted in half-lives of 16 min for NDMA and 12-15 min for the other nitrosamines. The quantum yield for NDMA was determined to be phi = 0.41 and phi = 0.43-0.61 for the other nitrosamines. Quantified products of NDMA photolysis included methylamine, dimethylamine, nitrite, nitrate, and formate, with nitrogen and carbon balances exceeding 98 and 79%, respectively. Indirect photolysis of nitrosamines in surface water was not observed; increasing dissolved organic carbon (DOC) slowed the NDMA photolysis rate because of light screening. Removal of NDMA measured in tertiary treated effluent flowing in a shallow, sunlit engineered channel agreed with photolysis rates predicted based on the measured quantum yield and system parameters. Because biodegradation is relatively slow, aquatic photolysis of NDMA is generally expected to be more significant even at relatively low levels of solar irradiation (t(1/2) = 8-38 h at 244-855 W/m2, 51 degrees N latitude, 1 m depth).     

Characterization of new nitrosamines in drinking water using liquid chromatography tandem mass spectrometry

N-Nitrosodimethylamine (NDMA), a member of a group of probable human carcinogens, has been detected as a disinfection byproduct (DBP) in drinking water supplies in Canada and the United States. To comprehensively investigate the occurrence of possible nitrosamines in drinking water supplies, a liquid chromatography-tandem mass spectrometry technique was developed to detect both thermally stable and unstable nitrosamines. This technique consisted of solid-phase extraction (SPE), liquid chromatography (LC) separation, and tandem quadrupole linear ion trap mass spectrometry (MS/MS) detection. It enabled the determination of sub-ng/L levels of nine nitrosamines. Isotope-labeled N-nitrosodimethylamine-d6 (NDMA-d6) was used as the surrogate standard for determining recovery, and N-nitrosodi-n-propylamine-dl4 (NDPA-dl4) was used as the internal standard for quantification. The method detection limits were estimated to be 0.1-10.6 ng/L, and the average recoveries were 41-111% for the nine nitrosamines; of these, NDMA, N-nitrosopyrrolidine (NPyr), N-nitrosopiperidine (NPip), and N-nitrosodiphenylamine (NDPhA) were identified and quantified in drinking water samples collected from four locations within the same distribution system. In general, the concentrations of these four nitrosamines in this distribution system increased with increasing distance from the water treatment plant, indicating that the amount of formation was greater than the amount of decomposition within this time frame. The identification of NPip and NDPhA in drinking water systems and the distribution profiles of these nitrosamines have not been reported previously. These nitrosamines are toxic, and their presence as DBPs in drinking water may have toxicological relevance.     

An examination of some foodstuffs for the presence of volatile nitrosamines

Over 500 samples of foodstuffs, including meat, fish and dairy products, vegetables, fruit and soups have been examined for the presence of volatile nitrosamines. Cooked complete meals were studied in order to assess the possibility of interactions of the constituents which could result in nitrosamine formation. The extracts of foods were subjected to gas chromatography and the presence of nitrosamines confirmed using on-line high resolution mass spectrometry. The most frequently occurring nitrosamines were N-nitrosodimethylamine and N-nitrosopyrrolidine which were present in many cooked bacon samples. N-nitrosodimethylamine also occurred in some other meat products, but other nitrosamines were rarely found. N-nitrosodimethylamine also occurred in fish and cheese, but neither this nitrosamine nor any other was found above the detection limit of 1 μg/kg in any of the other foods.     

原料及加工工艺对包馅鱼肉卷N-亚硝胺含量的影响

为评价原料及加工工艺对包馅鱼肉卷中N-亚硝胺含量的影响,分别测定包馅鱼肉卷馅和皮加工过程中9 种挥发性N-亚硝胺含量、亚硝酸盐含量、硫代巴比妥酸反应物（thiobarbituric acid reaction substances,TBARs）值以及挥发性盐基氮（total volatile nitrogen,TVB-N）含量的动态变化。结果表明：经过加工后鱼肉卷馅和皮中的TVB-N含量均下降,TBARs值和亚硝酸盐含量均上升;鱼肉卷馅的各种原料中含有不等量的N-二甲基亚硝胺（N-nitrosodimethylamine,NDMA）（0～27.51 μg/kg）、N-二乙基亚硝胺（N-nitrosodiethylamine,NDEA）（0～3.39 μg/kg）、N-甲基乙基亚硝胺（N-nitrosoethylmethylamine,NMEA）（0.11～4.33 μg/kg）以及N-亚硝基二苯胺（N-nitrosodiphenylamine,NDPheA）（0～0.82 μg/kg）;在鱼肉卷皮原料中检出了NDEA（0～12.56 μg/kg）、NMEA（0.08～15.26 μg/kg）以及N-亚硝基哌啶（N-nitrosopiperidine,NPIP）（0～8.13 μg/kg）;馅中NDMA、NMEA、NDEA及皮中NDMA、NMEA主要在盐擂期间形成,并在加工后期逐渐下降;NDPheA及NPIP含量在馅和皮的加工过程中始终低于检出限;鱼肉卷成品馅料中NDMA含量为（1.9±0.2） μg/kg,低于国家标准中的限量,而皮中未检出NDMA。     

在线固相萃取-液相色谱-串联质谱法测定鸡肉和鸡蛋中5 种抗病毒类药物残留量

建立鸡肉和鸡蛋中阿比多尔、金刚烷胺、金刚乙胺、美金刚、奥司他韦的在线固相萃取-液相色谱-串联质谱检测方法。样品采用1.0%甲酸-乙腈提取，经MCX在线固相萃取小柱净化，用XBridge C18色谱柱分离，使用电喷雾离子源正离子模式监测，以内标法定量。结果表明：5 种抗病毒类药物在0.05～100 ng/mL范围内线性关系良好；检出限为0.05～0.10 μg/kg，定量限为0.10～0.20 μg/kg；方法回收率范围为80.03%～93.96%，相对标准偏差低于10%。该方法分析速度快、灵敏度高，可用于鸡肉和鸡蛋中5 种抗病毒类药物的定性、定量分析。     

固相萃取结合超高效液相色谱-质谱法测定畜禽肉及肉制品中肾上腺素和多巴胺的残留量

建立畜禽肉及肉制品中2种儿茶酚胺类化合物(肾上腺素和多巴胺)的超高效液相色谱-质谱联用检测方法.样品采用10?mmol/L磷酸二氢钾溶液提取,WCX固相萃取柱净化,Waters?Acquity?BEH?C18柱分离,采用电喷雾离子源,正离子多反应模式监测,基质匹配内标法定量.结果表明:肾上腺素和多巴胺在0.5～50?n...     

采用QuEChERS结合UHPLC-MS/MS定量分析热加工肉制品中的三种胺类物质

本文采用QuEChERS技术结合超高效液相色谱-串联质谱（UHPLC-MS/MS）技术建立同时检测丙烯酰胺（AA）、亚硝胺（NAs）和杂环胺（HAAs）含量的方法，用于分析热加工肉制品中产生的胺类物质。结果表明:该方法检测出的三类成分20种胺类物质在相应浓度范围内显示出良好的线性关系（R2>0.991），检测限和定量限分别为0.01~1.6 ng/g和0.03~4.8 ng/g，日内回收率介于66.3%~116.5%之间，日内精密度介于0.78%~9.0%之间。每个胺类物的5×LOQ加标水平计算的日间精度范围为3.4%~9.4%。该方法应用于煎烤的四种肉制品中AA、NAs和HAAs的分析，共检测出9种胺类物质，浓度范围为0.03~31.26 ng/g。     

Biotransformation of nitrosamines and precursor secondary amines under methanogenic conditions

The biotransformation potential of six nitrosamines and their precursor secondary amines by a mixed methanogenic culture was investigated. Among the six nitrosamines tested, N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), and N-nitrosopyrrolidine (NPYR) were almost completely degraded but only when degradable electron donors were available. On the contrary, N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA), and N-nitrosodibutylamine (NDBA) were not degraded. Three precursor secondary amines, corresponding to the three biodegradable nitrosamines, were also completely utilized even with very low levels of available electron donors. The secondary amine precursors of the three, nonbiodegradable nitrosamines were also recalcitrant. A bioassay conducted to elucidate the biotransformation pathway of NDMA in the mixed methanogenic culture using H(2) as the electron donor showed that NDMA was utilized as an electron acceptor and transformed to dimethylamine (DMA), which in turn was degraded to ammonia and methane. The H(2) threshold concentration for NDMA bioreduction ranged between 0.0017 and 0.031 atm. Such a high H(2) threshold concentration suggests that in mixed methanogenic cultures, NDMA reducers are weak competitors to other, H(2)-consuming microbial species, such as homoacetogens and methanogens. Thus, complete removal of nitrosamines in anaerobic digestion systems, where the H(2) partial pressure is typically below 10(-4) atm, is difficult to achieve.     

LLE-GC-MS-SIM检测白酒中9 种微量功能成分

应用液液萃取（liquid-liquid extraction,LLE）结合气相色谱-质谱-选择离子扫描（gas chromatography-mass spectrometry-selective ion monitoring,GC-MS-SIM）技术检测20 种白酒中D-柠檬烯、对伞花烃、叶绿醇、4-甲基愈创木酚、4-乙基愈创木酚、麝香草酚、异丁香酚、四甲基吡嗪及亚油酸乙酯含量。该方法回收率在81.80%～109.30%之间,精密度均小于6.00%;检测范围内,线性关系良好（R2＞0.999 0）,检出限和定量限分别为0.17～0.91 μg/L和0.58～3.04 μg/L。LLE-GC-MS-SIM法对9 种功能成分的定量检测结果表明,3 种萜烯类物质在浓香型酒样中含量较高,且山庄酒厂酒样含量普遍高于市售酒样;芝麻香型白酒中酚类物质含量最高,其中酒样W09中4 种酚类物质质量浓度高达4 301.61 μg/L;四甲基吡嗪在酱香型酒样中质量浓度为2 379.65～2 985.09 μg/L,远高于芝麻香型酒样的1 116.80～1 309.66 μg/L及浓香型酒样的245.40～555.76 μg/L;亚油酸乙酯在不同酒样中含量差异较大,除市售酒样W17、W19和W20外,其余酒样质量浓度为1 951.96～7 183.35 μg/L。     

Further Studies on the Formation of Nitrosamines in Cured Pork Products Packaged in Elastic Rubber Nettings

Traces of N-nitrosodi-n-butylamine (NDBA) and N-nitrosodiethylamine (NDEA) can form in cured pork products packaged in elastic rubber nettings due to the interaction of nitrite in meat and amines in the rubber. Studies were carried out to determine whether taking nettings off immediately after processing or placing a layer of collagen as a barrier between nettings and meat could prevent or minimize formation of the above nitrosamines. None was effective. However, cured pork products packaged in a reformulated rubber netting, made with different amine additives, contained either none or only negligible levels of NDBA or NDEA, but, instead, contained 8–104 ppb levels of a new nitrosamine, N-nitrosodibenzylamine which is reported to be noncarcinogenic.     

A method for the determination of volatile N-nitrosamines in food by HS-SPME-GC-TEA

A method for the determination of volatile nitrosamines in sausages was developed using headspace sampling by solid-phase microextraction and gas chromatography with thermal energy analyzer detection (HS-SPME-GC-TEA). Two fused silica fibers, one coated with polydimethylsiloxane-divinylbenzene (PDMS-DVB) and another with poliacrylate (PA) were evaluated. A factorial fractional design was employed in order to evaluate the influence of the equilibrium time, ionic strength, extraction time and temperature for the extraction of N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosopiperidine and N-nitrosopyrrolidine in sausages. The method was validated and applied for the determination of nitrosamines in sausages. The described method is simple, rapid, with adequate accuracy, selectivity, sensitivity and precision.     

气相色谱-同位素稀释质谱法测定肉中多环芳烃含量

采用分子印迹固相萃取技术,建立肉中多环芳烃残留的气相色谱-同位素稀释质谱检测方法。以萘-D8为内标、正己烷-二氯甲烷（7∶3,V/V）混合溶液为提取试剂,经过匀浆、超声提取、离心、分子印迹固相萃取等步骤,在优化仪器条件下进行定性、定量分析。在5～100 ng/mL范围内,16 种多环芳烃峰面积与内标物峰面积的比值均与质量浓度的比值呈良好的线性关系,线性相关系数不小于0.999 9,肉及肉制品中检出限为0.125～0.625 μg/kg。3 个加标水平下的样品回收率在85.7%～109%之间,相对标准偏差（n=6）在0.75%～4.90%之间。该方法前处理效率高,定量法灵敏、准确,适合于监控肉类中多环芳烃的含量。     

改进的QuEChERS-气相色谱-质谱法测定中式腊肉中8 种挥发性N-亚硝胺

基于改进的QuEChERS法建立测定中式腊肉中8 种挥发性N-亚硝胺的气相色谱-质谱检测方法,并应用于市售样品的初步风险评估。样品经乙腈超声提取、冷冻和N-丙基乙二胺净化后水浴氮吹浓缩定容至微量体积;目标物经极性毛细管柱分离后以选择离子监测模式和外标法定量。结果表明,8 种N-亚硝胺在对应质量浓度范围内线性关系良好（R2＞0.997）,基质效应为0.86～0.98;检出限为0.05～0.14 μg/kg,定量限为0.15～0.47 μg/kg;低、中、高3 个含量（0.3、1.0、3.0 μg/kg）加标回收实验的平均回收率为71.3%～94.1%,相对标准偏差（n=6）为0.4%～11.2%;12 份代表性市售样品中仅1 份样品的N-亚硝基二乙胺含量（3.06 μg/kg）超标,其余均低于单项和总挥发性N-亚硝胺的限量水平（3.0 μg/kg和10.0 μg/kg）。该方法净化效果好、成本低,检测灵敏、结果准确,适用于中式腊肉中8 种挥发性N-亚硝胺的检测;目前市售中式腊肉中N-亚硝胺的风险水平整体较低。     

超高效液相色谱-串联质谱法测定动物性食品中8 种抗病毒类药物残留量

建立同时测定鸡肉、猪肉、鸡肝和猪肝中阿比朵尔、金刚烷胺、金刚乙胺、泛昔洛韦、帕拉米韦、咪喹莫特、奥司他韦、拉米夫定8?种抗病毒药物残留的超高效液相色谱-串联质谱的检测方法。样品采用乙腈-0.1%甲酸溶液（9∶1,V/V）经一次性振荡提取,用MCX固相萃取柱净化,内标法定量。结果表明：8?种抗病毒药物的检出限均低于1.0?μg/kg,定量限均低于3.0?μg/kg,空白鸡肉、鸡肝、猪肉、猪肝中分别添加5.0、10.0?μg/kg和20.0?μg/kg,8?种抗病毒药物的回收率均在70%～120%之间。该方法基质干扰小、灵敏度高、回收率好,可用于日常动物性样品中抗病毒类药物的残留检测。     

基于气相色谱-三重四极杆质谱联用法测定葡萄果实与葡萄酒中挥发性酚

利用固相萃取结合气相色谱-三重四极杆质谱联用技术，建立测定葡萄与葡萄酒中19 种挥发性酚的多反应监测方法。该方法分别在葡萄汁与葡萄酒2 种基质中验证，方法检出限为0.02～1.01 μg/L，定量限为0.08～3.36 μg/L，具有较广线性范围且R2大于0.99，加标回收率在81.99%～122.72%范围内。具有较高的灵敏度、准确性和精密度。该方法应用于10 个葡萄果实样品和10 款葡萄酒中挥发性酚的检测，在所有样品中均能检测到19 种挥发性酚，其中香草酸、香草醛和4-乙烯基苯酚是葡萄果实含量较高的3 种挥发性酚；4-乙基苯酚、3-乙基苯酚和4-乙烯基苯酚是葡萄酒中含量较高的3 种挥发性酚。所测样品中目标物质含量范围均在方法线性范围内，该方法具有普遍适用性。     

桑椹多酚对广式腊肠风味的影响

植物多酚因能有效抑制肉制品的过氧化近年来备受关注,然而由此造成肉制品风味的变化还鲜有报道。鉴于此,将不同剂量的桑椹多酚提取物（0.5 g/kg和1.0 g/kg）加入到肉糜中,制成广式腊肠,分析多酚添加前后广式腊肠的挥发性风味、游离脂肪酸、游离氨基酸的组成和含量变化,以及桑椹多酚对广式腊肠感官评价的影响。研究发现,添加桑椹多酚后,腊肠中挥发性风味物质由空白组的49种减少到32种,腊肠游离脂肪酸的含量明显下降。值得注意的是,由于蛋白质水解增强,添加桑椹多酚后,腊肠中呈味氨基酸（Glu和Arg）的释放得到促进。储藏末期（10 d）,添加1.0 g/kg桑椹多酚的腊肠游离氨基酸的含量达到5904.91 mg/100 g,较对照组提高了10.82%。总体而言,桑椹多酚的添加会抑制腊肠中某些挥发性风味物质的形成,抑制腊肠中的肉腥味,促进呈味氨基酸的释放,但对腊肠游离脂肪酸组成的影响并不显著。     

超高效液相色谱-串联质谱法测定肉制品中的虾过敏原

目的：建立超高效液相色谱-串联质谱（ultra performance liquid chromatography-tandem mass spectrometry,UPLC-MS/MS）法检测肉制品中虾过敏原的定量方法。方法：选取基质较为复杂的肉制品（西式火腿、香肠和肉丸）作为研究对象。样品经磷酸盐缓冲液（Phosphate buffer solution,PBS）超声提取30 min,离心（10000 r/min,15℃,10 min）后加入乙腈去除脂肪,取样液加入内标肽段（2.5μmol/L,40μL）和胰蛋白酶（1 mg/mL,10μL）在37℃下酶解16 h后上液质进行分析,样品经T3柱进行分离,0.1%甲酸-水溶液和乙腈梯度洗脱,多反应监测（multiple reaction monitoring,MRM）正离子模式采集数据,内标法定量。结果：采用该方法测定肉制品中虾过敏原蛋白含量,其中定量肽段在0.001～2.0μmol/L范围内,线性关系良好,决定系数R2为1.0000,检出限为0.67 mg/kg,定量限为2.00 mg/kg;在三个加标浓度水平下,回收率为83.2%...