Metabolism Study on Tobacco-specific N-Nitrosamines in Rabbit by Solid-phase Extraction and Liquid Chromatography-electrospray Ionization-mass Spectrometry Method

Metabolism of four tobacco-specific N-nitrosamines （TSNAs）, N＇-nitrosonornicotine （NNN）, N＇-nitrosoanatabine （NAT）, N＇-nitrosoanabasine （NAB） and 4-（methyl nitrosamino）-1- （3-pyridyl）-1-butanone （NNK） was studied by solid-phase extraction （SPE） and liquid chromato- graphy-electrospray ionization-mass spectrometry （LC-ESI-MS）. SPE and LC-ESI-MS method was evaluated to be rapid, simple, sensitive and selective for analysis of TSNAs in rabbit serum. The doses of TSNAs administrated were 4.666 μg/kg and 11.665 μg/kg according to different levels in cigarettes. Metabolic curves of four TSNAs and 4-（methyl nitrosamino）-1-（3-pyridyl）- 1-butanone （NNAL）, the metabolite of NNK, were obtained.

Modifying NaY Zeolite with Metal Oxide by Microwave Irradiation:Influence on the Adsorption and Decomposition of N-nitrosamines

Coating MgO.br ZrO2 on zeolite NaY accelerated decomposition of N-nitrosodimethylamine and N-nitrosopyrrolidine, resulting from variation of the surface state such as generation of basic sites.

Rapid and Simple Extraction Method for Volatile N-Nitrosamines in Meat Products

A new methodology for extraction, pre-concentration and analysis of volatile nitrosamines in meat-derived products was developed and compared with conventional methods (Distillation and two-step solid-phase extraction). The samples (canned sausages, cured meat, luncheon and smoked meat) were treated with an aqueous sodium hydroxide (NaOH) by autoclaving at 121°C for 10 min and extracted by liquid-liquid extraction with dichloromethane, then the nitrosamines were pre-concentrated using activated silica. Then, gas chromatography coupled with flame ionization detector was used for the separation and determination of the different nitrosamines contained in a real sample and gas chromatography with mass spectrometry detection was used as the confirmation technique. The newly invented autoclaving method allowed the determination of nitrosamine compounds at trace levels with limit of detection ranged from 0.077 to 0.18 ppb and quantitation limits were from 0.26 to 0.6 ppb for all nitrosamines, and found to be superior to the conventional ones, yielding approximately about 10%-20% increasing in the recovery compared with the mean recovery obtained when applying conventional methods.

Determination of Seven Volatile N-Nitrosamines in Fast Food

In this study, various fast food samples, including raw meat, cured meat, grilled meat, fried meat, smoked meat and canned meat products, were analyzed for the determination of the seven volatile N-nitrosamines. The samples were treated with an aqueous sodium hydroxide (NaOH) by autoclaving at 121°C for 10 min and extracted by liquid-liquid extraction with dichloromethane, and then the nitrosamines were pre-concentrated by using activated silica. Then, gas chromatography coupled with flame ionization detector was used for the separation and determination of the different nitrosamines contained in a real sample. The applied method allowed the determination of nitrosamine compounds at trace levels with limit of detection ranging from 0.077 to 0.18 ppb, and quantitation limits were from 0.26 to 0.60 ppb for all nitrosamines. The total concentrations of the seven nitrosamines in the studied meat samples ranged from 2.60 to 13.28 μg/kg.

THE N-NITROSAMINES IN TOBACCO SMOKE AND ITS ADSORPTION AND DEGRADATION

N-nitrosamines are strong carcinogens for humans. This paper gives an overview of the nitrosmaines in cigarette smoke including the formation, the harmfulness, the analytical methods of the nitrosmaines and the adsorptions and degradations of N –nitrosamines.

A Rapid, Validated RP-HPLC Method for the Determination of Seven Volatile N-Nitrosamines in Meat

The present work reports a rapid reversed-phase high-performance liquid chromatography (RP-HPLC) method for the determination of seven volatile N-nitrosamines namely N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodiproylamine (NDPA), N-nitrosodi butylamine (NDBA), N-nitrosopiperidine (NPIP) and N-nitrosopyrrolidine (NPYR) for monitoring food safety. A strategic experimental approach was implemented for the method development. The desired chromatographic separation was achieved on a Symmetry C18 (4.6 × 150 mm, 5 μm) column using gradient elution. The optimized mobile phase consisted of the 10 mM ammonium hydroxide pH = 8.9 and acetonitrile. The eluted compounds were monitored at 231 nm wavelength using spectrophotometric detector. The developed method separated seven compounds from each other within a run time of 10 min. The method is effective for the determination of presence of these carcinogenic compounds. The average extraction recovery of seven nitrosamines was found 84.5%;the precision of method was found less than 2.7% and accuracy was found between 95%-102.5%. The assay could be applied in food monitoring safety.

姜黄挥发油抗痤疮丙酸杆菌作用的研究

目的:了解姜黄挥发油对痤疮丙酸杆菌的抑制作用,选出新的天然抗痤疮丙酸杆菌药物。方法:采用药物成分钢杯法抑菌实验来验证其效果。结果:痤疮丙酸杆菌对姜黄挥发油中等敏感,强于公认的抗厌氧菌感染药物甲硝唑。结论:姜黄挥发油具有较好的抑制痤疮丙酸杆菌的作用,为临床治疗痤疮提供了一个新的选择。

荧光分光光度法测定饮用水中挥发酚类的研究

〔目的〕分析 4-氨基安替比林氯仿萃取分光光度法、直接荧光分光光度法、正丁醇萃取荧光分光光度法三种方法测定水中挥发酚的优缺点及适用范围 ,旨在找出一个更好的检测方法测定饮用水中挥发酚。〔方法〕使用此三种方法分别测定样品及标准中的挥发酚的含量 ,比较其相关系数、线性范围、灵敏度、回收率与检出限。〔结果〕以上三种方法的相关系数分别为 0 .9988、0 .9998、0 .9994,线性范围分别为 0 -0 .0 40mg L、0 -0 .0 40mg L、0 -0 .0 2 0mg L ,平均回收率分别为 95 .9%、10 0 .2 %、96.9% ,检出限分别为 0 .0 0 2mg L、0 .0 0 10 7mg L、0 .0 0 0 3 3mg L ,灵敏度分别为 11.177、3 2 61.9、3 745 6。〔结论〕正丁醇萃取荧光分光光度法有很好的灵敏度、回收率、检出限和相关系数 ,方法较简单且试剂毒性小 ,适合饮用水中挥发酚测定的国家标准要求 ,可以取代 4-氨基安替比林氯仿萃取分光光度法成为国家标准方法。

五种植物挥发油霜抗人体蠕形螨作用的研究

目的:观察五种不同的植物挥发油霜对人体蠕形螨杀灭作用的情况,筛选出新的天然杀螨药物。方法:在室温18℃～26℃,相对湿度为60%～70%的条件下,从我科门诊患者和健康人群的额部、双颊、鼻部、鼻唇沟取蠕形螨,立即加入不同植物挥发油霜,显微镜下观察蠕形螨的存活情况,筛选出此五种植物挥发油中杀螨效果最佳者,又对其进行不同浓度抗蠕形螨作用的显微镜观察。结果:姜黄、丁香、桉叶、珊瑚姜、木姜子这五种植物的挥发油霜均有不同程度的杀灭人体蠕形螨作用,随着药物作用时间的延长,螨虫死亡率明显增高,而其中姜黄油霜的杀螨效果最强,加药后2h螨虫死亡率有显著性差异(P<0.05,与基础霜比;P<0.05,与木姜子油霜比;P>0.05,丁香、桉叶、珊瑚姜、木姜子这四种植物挥发油霜的螨虫死亡率差别无显著性)。桉叶油霜及新肤螨灵霜的杀螨作用次强(P<0.05,与基础霜比)。而且,随着加药时间的延长,姜黄油霜组螨虫形态结构发生变化与基础霜比差异有显著性(P<0.05),而其他的各组与基础霜比差异无显著性(P>0.05)。结论:姜黄、丁香、桉叶、珊瑚姜、木姜子这五种植物挥发油霜有抗人体蠕形螨的作用,其中以姜黄挥发油霜的作用最强。我们的研究为临床治疗蠕形螨的天然药物开发打下了一个基础。

茂名市近海养殖区海水挥发酚与氰化物的测定

用定时多点取样和分光光度测定法,对茂名市近海养殖区海水挥发酚和氰化物含量等指标进行了检测。测定结果表明;各水样中挥发酚含量都在0.014～0.026mg/L之间,而氰化物含量在0.00780 ～0.00873mg/L之间,分别接近国家规定的四级标准和三级标准,两者都大大超出了国家规定的优良海水水质标准,表明茂名市近海水域水质环境污染较为严重,应当引起高度重视。

果蔬香精回收装置和技术

设计了一种改进的天然香精回收装置,该装置可用于果蔬汁生产中挥发性芳香物质的回收.对该装置的设计原理、操作方法、回收天然香精的工艺条件和回收率分别进行了探讨,结果表明,在该工艺条件下,以丁酸乙酯和乙酸乙酯为内标物,其回收率分别为90.1%和98.7%,脱香果汁加入质量分数1%的100倍香精复香,感官评定与新鲜果汁比较无显著差异.

Monthly survey of N-nitrosamine yield in a conventional water treatment plant in North China

A sampling campaign was conducted monthly to investigate the occurrence of N-nitrosamines at a conventional water treatment plant in one city in North China.The yield of N-nitrosamines in the treated water indicated precursors changed greatly after the source water switching.Average concentrations of N-nitrosodimethylamine（NDMA）,N-nitrosomorpholine（NMOR）,and N-nitrosopyrrolidine（NPYR） in the finished water were6.9,3.3,and 3.1 ng/L,respectively,from June to October when the Luan River water was used as source water,while those of NDMA,N-nitrosomethylethylamine（NMEA）,and NPYR in the finished water were 10.1,4.9,and 4.7 ng/L,respectively,from November to next April when the Yellow River was used.NDMA concentration in the finished water was frequently over the 10 ng/L,i.e.,the notification level of California,USA,which indicated a considerable threat to public health.Weak correlations were observed between N-nitrosamine yield and typical water quality parameters except for the dissolved organic nitrogen.

Simultaneous removal of ammonia and N-nitrosamine precursors from high ammonia water by zeolite and powdered activated carbon

When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products（DBPs） may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine（NDMA）, may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes.The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon（PAC） sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than67% ammonia and 70%–100% N-nitrosamine precursors were removed by Mordenite zeolite（except 3-（dimethylaminomethyl）indole（DMAI） and 4-dimethylaminoantipyrine（DMAP））. PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors（dimethylamine（DMA）, ethylmethylamine（EMA）, diethylamine（DEA）, dipropylamine（DPA）, trimethylamine（TMA）, DMAP, and DMAI） during the alum coagulation process.

Detecting N-nitrosamines in water treatment plants and distribution systems in China using ultra-performance liquid chromatography-tandem mass spectrometry

N-nitrosodimethylamine （NDMA） and several other N-nitrosamines have been detected as disinfection by-products in drinking waters in many countries around the world. An ultra-performance liquid chromatography- tandem mass spectrometry method with solid phase extraction sample preparation was developed to study the occurrence of N-nitrosamines in several water treatment plants and distribution systems in China. Isotope labeled N-nitrosodi-n-propylamine-dl4 （NDPA-dl4） was selected as the internal standard for quantification. The solid phase extraction procedures including pH, enrichment process and MS/MS parameters including capillary voltage, cone gas flow, cone voltage, collision energy were optimized to give average recoveries of 26% to 112% for nine N- nitrosamine species. The instrument detection limits were estimated to range from 0.5 to 5μg.L-1 for the nine N- nitrosamine species. NDMA and several other N-nitrosa- mines were found at fairly high concentrations in several water treatment plants and distribution systems. NDMA was found in all locations, and the highest concentrations in cities B, G, T, and W were 3.0, 35.7, 21.3, and 19.7 ng. L 1, respectively. A wide range of N-nitrosamines concentrations and species were observed in different locations. Higher concentrations of N-nitrosamines were detected in distribution systems that were further away from the treatment plants, suggesting that the contact time between the residual disinfectant and natural organic matter may play an important role in the formation of these compounds.

Characterization of dissolved organic matter as N-nitrosamine precursors based on hydrophobicity, molecular weight and fluorescence

It is very important to identify the dominant precursors for N-nitrosamine formation from bulk organic matter, to enhance the understanding of N-nitrosamine formation pathways in water treatment plants and allow the development of practical treatment technologies. In this study, dissolved organic matter （DOM） from two source waters was fractionated with XAD resins and ultra- filtration membranes. The N-nitrosamine formation potential （FP） （ng of N-nitrosamines formed per mg of dissolved organic carbon （DOC）） from raw water and each fraction were measured and correlated with the fluorescence excitation-emission matrix （EEM）, molecular weight （MW） and other assays. The results showed that the hydrophilic fraction had N-nitrosamine FP 1.3 to 3.5 times higher than the hydrophobic fraction from both source waters. The DOM fraction with low MW was the dominant fraction in these two source waters and contributed more precursors for N-nitrosamine formation than the larger MW fraction. The EEM spectra indicated there were notable amounts of soluble microbial products （SMPs） and aromatic proteins in the two studied rivers, which probably originated from wastewater discharge. The SMPs tended to be more closely correlated with N-nitrosodimethylamine formation potential than the other DOM components. Higher N-nitrosamine FP were also related to fractions with lower DOC/DON ratios and lower SUVA254 values.

刺激剂浓度对橡胶树胶乳挥发脂肪酸值的影响

研究了不同乙稀利浓度刺激橡胶树所采集的鲜胶乳挥发脂肪酸值(VFANo.)的贮存变化,结果表明刺激强度对胶乳VFANo.的影响极大。

Analysis of <i>N</i>-Nitrosamine Migration from Rubber Teats and Soothers

A testing method for N-nitrosamines and N-nitrosatable substances in rubber teats and soothers was modified. N-Nitrosamines are generally analyzed using either a nitrogen chemiluminescence detector (NCD) or a thermal energy analyzer (TEA). However, because few testing laboratories are equipped with these devices, it is difficult to conduct these tests. Therefore, an analysis method for N-nitrosamines using the more widespread gas chromatography-mass spectrometry (GC-MS) method was improved. In addition, EN 12868 was used to prepare the test solutions because of its worldwide use and compliance with EU regulations. Using GC-MS, EN 12868 method targeting ten kinds of N-nitrosamines was modified. The determination limits of the method were 1.0 -1.5 μg/kg for N-nitrosamines and 4 -6 μg/kg for N-nitrosatable substances. Quantification was possible at 1/5 or less and 1/15 or less, respectively, of the regulation values listed in EU Directive 93/11/EEC. In terms of application, there were no problems with the selectivity of the detector. The recoveries were 58% -109% for N-nitrosamines and 59% -102% for N-nitrosatable substances. Screening and verification were possible by measuring the amount of secondary amines in the boiled solution and migration solution.

气质联用法测定生食水产品中的挥发性N-亚硝胺

利用二氯甲烷提取腌制生食水产品中的挥发性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)、N-二丙基亚硝胺(ND-PA)。利用气质联用仪采用选择离子法(SIM)进行定性定量检测。结果表明,该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、0.9990、0.9995;线性范围分别可达0～250μg/mL;方法重现性良好,其RSD可达1.49%～1.94%;回收率可达90%～105%;灵敏度高,检测限分别为0.04,0.025,0.05,0.01μg/kg。

Electrochemical Reduction Determination of N-Nitrosodiphenylamine in Food Based on Graphene Electrode Material

As a group of the most notorious carcinogens,N-nitrosamines(NAs)are highly toxic and usually involved in healthy issue of human daily life.An electrochemical sensor for N-nitrosodiphenylamine(NDPhA)detection was constructed based on graphene electrode material.The graphene was facilely obtained by direct reduction of graphene oxide(GO)with hydrazine hydrate,and further coated on the surface of the glassy carbon electrode(GCE)to fabricate the electrochemical sensor for NDPhA analysis in food samples.The present sensor showed excellent sensitivity and selectivity for the electrochemical determination of NDPhA under a reduction manner with the detection limit of 0.6μmol/L.It was also successfully used in beer and ham food samples with satisfactory recovery results.

Strong selective adsorption of N-nitrosamines on zeolites

With the functional group of -N-N=O, N-ni-trosamines are well known to constitute a serious health risk[1]. These toxicant chemicals not only give rise to poisoning sometimes[2], but also play an important role in causing cancer in almost all organs of experimental animals and are therefore likely to be related to human beings, since they have the similar metabolism and meta-balin to those animals[3]. Gaseous nitrogen oxides like NO2, N2O3 and N2O4 are reportedly to react with-secondary amines and form N-nitrosamines in environment[4], and some foods, such as beer and salted fish, contain a high concentration of N-nitrosamines and their precursors. However, tobacco and cigarette smoke are believed to be the largest N-nitrosamines pollution for human beings besides the industrial working place. N-nitrosamines are considered important contributors to the total burden of carcinogens resulting from tobacco, especially tobacco smoke, because they can be deposited directly into the blood following inhalation