气相色谱法测定果汁饮料中甜蜜素含量的不确定度评定

采用气相色谱法测定果汁饮料中甜蜜素的含量,对测定结果的不确定度进行了分析,对各不确定度分量进行了评定和量化,计算了合成标准不确定度和扩展不确定度。不确定度主要来自量器校准和标准曲线引入的不确定度。果汁饮料中甜蜜素的含量结果表示为（0．350±0．023）g／kg,k=2。     

高效液相色谱法测定啶虫脒含量的不确定度评定

按照HG 3754—2004《啶虫脒可湿性粉剂》对啶虫脒含量进行了测定,通过建立数学模型,对测量不确定度来源进行了分析、评定和量化。当啶虫脒含量为102．1g／kg时,合成不确定度为2．1g／kg,扩展不确定度为4．2g／kg（k=2）。     

钢铁及其合金中铬含量测定结果的不确定度评定

对用GB／T223、11—1991《过硫酸铵氧化容量法测定铬量》的方法测定钢铁及合金中铬含量测量结果的不确定度进行了评定。对样品测量过程中的不确定度分量进行了分析和量化，求得铬含量测定结果的标准不确定度和扩展不确定度分别为0．06％和0．12％。     

高效液相色谱法测定榨菜中柠檬黄的不确定度评定

根据JJF1059～1999《测量不确定度评定与表示》对高效液相色谱法测定榨菜中柠檬黄含量的测定不确定度进行评定。通过对实验过程中样品的取样称量、使用仪器、标准物质、测试过程中的随机因素以及标准工作曲线的拟合等因素进行分析,计算了不确定度分量和合成不确定度。榨菜中柠檬黄含量的测定结果为（0．0375±0．0050）g／kg,k=2。     

原子吸收法测定蔬菜罐头中铜含量的测量不确定度评定

对GB／T 5009．13－1996《食品中铜的测定方法》中火争原子吸收法测定蔬菜罐头中铜含量的测量不确定度进行评定，根据JJF1059－1999《测量不确定度评定与表示》技术规范的要求，分析了该测量过程的测量不确定度来源，建立了数学模型，并利用标准样品对测量不确定度的各个分量进行计算，计算得该测定水平下铜含量测定结果的扩展不确定度为0．2mg/kg.     

石墨炉原子吸收光谱法测定虾粉中镉含量的不确定度评定

对石墨炉原子吸收光谱法测定虾粉中镉含量进行了不确定度评价。分析了整个测试过程中不确定度的来源,并对各不确定度分量进行了计算,当虾粉中镉的含量为0．389mg／kg时,扩展不确定度为0．008mg／kg（k=2）。     

柠檬酸含量测量不确定度的评定

分析了测定柠檬酸含量测量不确定度的来源，评定了柠檬酸含量测定过程中测量重复性、天平、滴定管、标准溶液浓度等因素对柠檬酸含量测量不确定度的影响，计算得柠檬酸含量测定结果的扩展不确定度为0．36％。在柠檬酸含量的测定过程中，滴定管的准确度是影响柠檬酸含量测量不确定度的主要因素。     

鸡精调味料中谷氨酸钠含量测量不确定度的评定

分析鸡精调味料中谷氨酸钠含量测量不确定度的影响因素,建立数学模型,对各不确定度分量进行了分析和计算。当鸡精调味料中谷氨酸钠的含量为49．15％时,谷氨酸钠含量测定结果的扩展不确定度为0．34％(k=2)。     

复混肥料中氯离子含量测量不确定度的评定

对硫氰酸铵滴定法测定复混肥料中氯离子含量的测量不确定度进行了评定。分析了测量重复性、滴定管、标准溶液浓度等因素对氯离子含量测量不确定度的影响。计算得复混肥料中氯离子含量测定结果的扩展不确定度为0．049％。     

分光光度法测定磷的测量不确定度的评定

按照国家标准GB／T7730．3-1997中的方法I进行锰铁中磷含量的测定，对涉及的玻璃器皿和仪器设备进行不确定度来源分析和评定。不确定度主要来自于重复性测定、天平、250mL容量瓶、25mL移液管、分光光度计及测定过程。分光光度法测定磷的扩展不确定度U=0．007％，有效自由度veff=50，置信水平为95％。     

离子色谱法测定卷烟主流烟气中氨含量的不确定度评定

根据《测量不确定度评定与表示》对离子色谱法测定卷烟主流烟气中氨含量的不确定度进行评定,通过分析得出,测量重复性、线性回归方程以及标准溶液的配制是不确定度的主要来源.分析结果结果表明,当卷烟样品主流烟气中氨释放量为12.04μg/支时,扩展不确定度为0.40μg/支,k=2.     

固相萃取-气相色谱/质谱联用法测定卷烟主流烟气中的香兰素和乙基香兰素

采用固相萃取-气相色谱/质谱联用技术,建立了一种同时测定卷烟主流烟气中香兰素和乙基香兰素的方法。方法优化了萃取条件,考察了萃取溶剂、萃取时间对检测结果的影响。通过硅藻土固相萃取柱净化并浓缩后,选取DB-HeavyWAX毛细管柱进行目标物分离,以香兰素-d3作为内标,对香兰素和乙基香兰素进行定量分析。结果表明,香兰素和乙基香兰素在浓度0.2~20.0 mg/L范围内具有良好的线性关系,其检出限分别为9.1 ng/支和6.5 ng/支,回收率均在96.3%~107.7%之间。     

Analysis of pyridines in mainstream cigarette smoke

A new technique has been developed for the quantitative analysis of pyridines in mainstream cigarette smoke using a GC-MS technique. For analysis, 10 cigarettes are smoked using conditions based on US Federal Trade Commission recommendations. The smoke is collected in a water trap and analyzed using a GC-MS technique. A standard or a fast GC separation can be applied for the analysis. The standard separation was followed by MS detection using selected ion monitoring (SIM) acquisition on a quadrupole instrument. The fast GC was followed by MS detection with total ion acquisition on a time-of-flight instrument. The levels of pyridine depend on the type of cigarette: for a full flavor cigarette pyridine is as high as 18.0 microg/cigarette (cig.). and for an ultra light cigarette is about 3.0 microg/cig. Substituted pyridines vary between 5.0 microg/cig. to 0.1 microg/cig. for a full flavor cigarette, and between 0.2 microg/cig. and a few ng/cig. for an ultra light cigarette. The reproducibility of the technique is very good, with less than 7-8% RSD in both separation procedures for most of the analyzed compounds.     

Quantification of 16 polycyclic aromatic hydrocarbons in cigarette smoke condensate using stable isotope dilution liquid chromatography with atmospheric‐pressure photoionization tandem mass spectrometry

A stable isotope dilution liquid chromatography tandem mass spectrometry method for the analysis of 16 polycyclic aromatic hydrocarbons in cigarette smoke condensate was developed and validated. Compared with previously reported methods, this method has lower limits of detection (0.04–1.35 ng/cig). Additionally, the proposed method saves time, reduces the number of separation steps, and reduces the quantity of solvent needed. The new method was applied to evaluate polycyclic aromatic hydrocarbon content in 213 commercially available cigarettes in China, under the International Standardization Organization smoking regime and the Health Canadian intense smoking regime. The results showed that the total polycyclic aromatic hydrocarbon content was more than two times higher in samples from the Health Canadian intense smoking regime than in samples from the International Standardization Organization smoking regime (1189.23 versus 2859.50 ng/cig, p < 0.05). Meanwhile, the concentration of individual polycyclic aromatic hydrocarbons (and total polycyclic aromatic hydrocarbons) increased with labeled tar content in both of the tested smoking regimes. There was a positive correlation between total polycyclic aromatic hydrocarbons under the International Standardization Organization smoking regime with that under the Health Canadian intense smoking regime. The proposed liquid chromatography tandem mass spectrometry method is satisfactory for the rapid, sensitive, and accurate quantitative evaluation of polycyclic aromatic hydrocarbon content in cigarette smoke condensate, and it can be applied to assess potential health risks from smoking.     

Gas chromatographic-mass spectrometric analysis of acrylamide and acetamide in cigarette mainstream smoke after on-column injection

A method is described for the simultaneous determination of two short-chained amides, acrylamide and acetamide (classified by the International Agency for Research on Cancer as probable and possible human carcinogens, respectively), in total particulate matter using gas chromatography-on-column injection and mass spectrometric detection. Sample preparation is kept to a minimum, and the proposed analytical procedure proves to be fast, sensitive, and precise. Validation studies show good linearity with a regression coefficient of r2=.000 for both compounds. Quantitation limits are 32 ng/mL for acrylamide and 70 ng/mL for acetamide. In the particulate phase of mainstream smoke from the University of Kentucky Reference Cigarette 2R4F, 2.3 microg/cig acrylamide and 4.7 microg/cig acetamide are found; no acetamide and only .0074 microg/cig acrylamide is found in the gas phase. Possible mechanisms of formation in cigarette smoke are discussed.     

卷烟主流烟气中8种羰基化合物的超高效液相色谱测定

建立了超高效液相色谱(UPLC）对卷烟主流烟气总粒相物中甲醛、乙醛、丙酮、巴豆醛等8种羰基化合物的测定方法。采用经2,4-二硝基苯肼酸性溶液处理过的剑桥滤片捕集烟气,再用含2%(体积分数）吡啶的乙腈溶液进行萃取,以KinetexTM C18(150 mm×2.1 mm,2.6 μm）为色谱柱,水-乙腈(35∶65）和水-乙腈-四氢呋喃-异丙醇(59∶30∶10∶1）为流动相梯度洗脱,采用二极管阵列检测器进行检测,分析时间为20 min。结果表明,该方法的相关系数r2≥0.999 97,检出限为25.81~67.74 ng/cig,平均加标回收率为95%~99%,相对标准偏差为1.4%~5.8%。各组分峰分离度高、分析时间短、流动相耗量少、结果准确可靠。用该方法对20种不同卷烟牌号样品中8种羰基化合物的含量进行测定,结果满意。     

Analysis of cigarette mainstream smoke for 1,1-dimethylhydrazine and vinyl acetate by gas chromatography-mass spectrometry

1,1-Dimethylhydrazine, also known as unsymdimethylhydrazine (UDMH) and vinyl acetate (VA), are both classified by the International Agency for Research on Cancer as 2B carcinogens (possibly carcinogenic to humans) and listed as cigarette smoke constituents; however, there is little or no quantitative data available on them. For UDMH in cigarette smoke, neither a yield nor a method has been published. For VA, the most recent information on yields dates back to 1965. To bridge this gap, we have developed new gas chromatographic-mass spectrometric methods for both compounds to determine their yields in cigarette smoke. UDMH is determined by derivatization with 2-nitrobenzaldehyde in methanol and is not found in cigarette smoke at levels above the detection limit of 19 ng/cig. In further experiments, when UDMH is added to the smoke stream or air stream of lit or unlit cigarettes, the derivative 2-nitrobenzaldehyde-2,2-dimethylhydrazone is found only in the air stream of the unlit cigarettes. From this, we conclude that UDMH is either not formed during smoking at all or, if it is, it reacts immediately and quantitatively with other smoke constituents (e.g., aldehydes) and is therefore not detectable in cigarette smoke. VA is determined by trapping in acetone at -78 degrees C and is found at a concentration of 270 ng/cig for a standard reference cigarette with a cellulose acetate filter (the reference cigarette 1 R4F). In the literature, VA is reported at concentrations of 1.6 microg/cig for a cigarette with a cellulose acetate/charcoal filter and 4 microg/cig for a cigarette with a cellulose acetate filter and for an unfiltered cigarette.     

卷烟主流烟气中碳中心自由基的自旋标记荧光表征

以自旋标记荧光探针4-((9-acridinecarbonyl)amino)-2,2,6,6-tetramethylpiperidin-1-oxyl(TEMPO-9-AC)研究了卷烟主流烟气中的碳中心自由基。以吸烟机抽吸卷烟,以弱荧光的TEMPO-9-AC作为捕集剂捕集卷烟主流烟气中的碳中心自由基,生成稳定的强荧光的碳中心自由基捕集加合物,以高效液相色谱-三重四极杆串联质谱联用仪(HPLC-MS/MS)对其结构进行了确认,并建立了高效液相色谱-荧光检测(HPLC-FLD)的定量方法。结果表明,方法的检出限为0.318 nmol/cig,相对标准偏差(RSD)为3.5%～9.7%;利用TEMPO-9-AC捕集体系鉴别出了10种碳中心自由基;对5种代表性卷烟烟气中的碳中心自由基进行了定量计算,获得了它们在主流烟气中碳中心自由基的含量数据,并发现碳中心自由基总量与焦油释放量之间具有高度的相关性。本法检出限低,重复性好,适用于卷烟主流烟气中碳中心自由基的结构验证及释放量的检测分析。     

甲醇溶液直接吸收-离子液体富集-气相色谱-质谱法测定卷烟主流烟气中吡啶、喹啉和苯乙烯

建立了一种收集检测卷烟主流烟气中吡啶、喹啉和苯乙烯的方法,以甲醇(CH3OH)溶液为吸收液,直接收集吸烟机抽吸的卷烟主流烟气,采用[BMIM]PF6离子液体萃取富集,气相色谱-质谱联用(GC/MS)技术定量分析卷烟主流烟气中的吡啶、喹啉和苯乙烯3种半挥发性物质,测定过程简便快速,结果准确可靠。本方法的线性关系良好,相关系数(r2)大于0.9995,吡啶、苯乙烯和喹啉的检出限分别为24.9,9.34和4.05ng/cig(每支烟),相对标准偏差(RSD)小于6.0%,加标回收率在90.6%～107.4%之间。     

7种生物碱在不同粒径卷烟主流烟气气溶胶中的分布研究

建立了烟气气溶胶中7种生物碱的气相色谱-质谱(GC-MS)测定方法,并采用电子低压撞击器(ELPI)分12级捕集烟气气溶胶粒相物,研究了卷烟主流烟气气溶胶中7种生物碱含量和浓度的粒径分布。捕集的气溶胶样品加入氢氧化钠溶液和二氯甲烷进行碱法提取,提取液经DB-5MS弹性毛细管柱分离,选择离子监测模式测定,内标法定量。结果表明:该法检测主流烟气气溶胶中7种生物碱的相对标准偏差(RSD)为2.1%~6.4%,检出限为0.39~14.84 ng/cig,加标回收率为85.5%~124.8%。7种生物碱主要分布于0.144~0.722μm的中等粒径气溶胶粒相物中,在粒径0.431μm的粒相物中含量最高,与捕集的粒相物质量分布一致。7种生物碱在不同粒径气溶胶粒相物中的浓度基本趋于一致,其浓度随气溶胶粒径的分布无特异性。