HPLC测定工作场所空气中3,4-苯并(a)芘的不确定度评估

为建立高效液相色谱测定工作场所空气中3,4-苯并(a)芘的不确定度评定方法,依据JJF1059-1999《测量不确定度评定与表达》~([1])分析并识别测定过程中的不确定度的主要来源,评定结果表明不确定度主要来源工作曲线拟合,配制标准溶液和采集样品过程中,该不确定度评价方法对HPLC测定工作场所空气中3,4-苯并(a)芘的质量控制有实际意义。     

高效液相色谱法测定植物油中苯并(a)芘含量的不确定度评定

结合CNAS—GL06《化学分析中不确定度的评估指南》和JJF 1059.1—2012《测量不确定度评定与表示》,建立高效液相色谱法测定植物油中苯并(a)芘含量的数学模型,全面分析不确定度来源并进行评估计算。实验结果显示影响测量结果不确定度的因素主要有标准溶液的浓度、样品定容和样品测试重复性等几个方面。植物油中苯并(a)芘测测定结果可表示为(5.03±0.42)μg/kg,包含因子k=2。     

气相色谱法测定汽油中苯含量的测量不确定度评定

本文分析了气相色谱法测定汽油中苯含量的过程中引入的不确定度来源为样品、标准物质、测量重复性和实验准确度,并逐一对各不确定度分量进行了评定,得出苯含量检测结果的相对合成标准不确定度和扩展不确定度.     

气相色谱法测定室内空气中三苯浓度的不确定度评定

根据GB11737-89《居住区大气中苯、甲苯、二甲苯卫生检验标准法气相色谱法》建立了气相色谱法测定室内中三苯的不确定度数学模型,从测定程序分析了不确定度的来源,并计算各不确定度分量,得出合成不确定度、扩展不确定度。为该检验方法的不确定度评定提供一个参考。     

气袋采样-热脱附-气相色谱/质谱法测定汽车内饰材料中7种苯系物挥发量的不确定度评定

依照JJF 1059.1-2012《测量不确定度评定与表示》,对气袋采样-热脱附-气相色谱/质谱法测定汽车内饰材料中7种苯系物挥发量的结果进行不确定度评定。分析了测量过程中引入的不确定度来源,包括采样过程、标准物质、标准曲线拟合、测量重复性等分量引入的不确定度及其计算方法,最后合成标准不确定度,通过乘以95%概率下的扩展因子2,获得测量结果的扩展不确定度。结果显示,不确定度主要来源于标准曲线拟合和测量重复性,可采取相关方法确保不确定度在适当范围内,提高测定结果的准确性。     

气相色谱法测定车用汽油中苯含量的不确定度评定

通过分析气相色谱法测定车用汽油中苯含量的方法,对车用汽油中苯含量的测量不确定度进行了评定,不确定度主要来源于标准样品配置和测试时体积引入的不确定度、标准物质苯和内标物（4-甲基-2-戊酮）纯度以及气相色谱仪器本身和微量进样器引入的不确定度。     

固相微萃取— 气相色谱联用法测量痕量苯不确定度的评定

通过建立数学模型,对固相微萃取—气相色谱联用法测量痕量苯的测量结果不确定度进行了评定。通过对影响不确定度的各分量进行分析,得出固相微萃取—气相色谱联用法测量痕量苯的测量结果不确定度为4. 8%。通过对各不确定度分量的分析可以得知气相色谱仪及色谱条件对测量结果的不确定度影响最大。     

气相色谱法测定茶叶中乐果残留量的不确定度评定

本文以测定茶叶中乐果的含量为例,评定了气相色谱法测定乐果的不确定度。建立数学模型,分析各不确定度分量,将不确定度分量合成,并计算其测定结果的扩展不确定度。为实验室在该类测量过程中不确定度的评定提供参考。     

GC-MS测定塑料玩具产品中多环芳烃的不确定度评定

本文按照SN/T 1877.2-2007《塑料原料及其制品中多环芳烃的测定方法》对测定塑料玩具中多环芳烃含量的不确定度进行了评定,分析和量化了影响测定结果的不确定度分量,将不确定度分量合成,得到了16种多环芳烃中日常检出频率较高的萘、蒽和苯并[a]芘含量的扩展不确定度分别为0.216mg/kg、0.162mg/kg和0.058mg/kg。     

气相色谱法测定水中百菌清含量的不确定度评定

介绍了气相色谱测定水中百菌清含量的不确定度评定方法,分析了测量程序中不确定度的各项来源,包括样品采集、标准溶液制备、校准曲线回归、样品稀释过程、前处理方法、样品回收率等因素引入的不确定度及其计算方法。     

Urinary benzo[a]pyrene and its metabolites as molecular biomarkers of asphalt fume exposure characterized by microflow LC coupled to hybrid quadrupole time-of-flight mass spectrometry

As a step to study the health effects of asphalt fume exposure, an analytical method was developed to characterize benzo[a]pyrene and its hydroxy metabolites in the urine of asphalt fume-exposed rats. This method is based on microflow liquid chromatography (LC) coupled to hybrid quadrupole orthogonal acceleration time-of-flight mass spectrometry (Q-TOFMS). Twenty-four female Sprague-Dawley rats were used in the experiment, with 8 as controls and 16 exposed to asphalt fumes in a whole-body inhalation chamber for 10 days (4 h/day). Generated at 150 degrees C, the asphalt fume concentration in the animal exposure chamber ranged 76-117 mg/m(3). In the urine of the asphalt fume-exposed rats, benzo[a]pyrene and its metabolites of 3-hydroxybenzo[a]pyrene, benzo[a]pyrene-7,8-dihydrodiol(+/-), and benzo[a]pyrene-7,8,9,10-tetrahydrotetrol(+/-) were identified, and their concentrations were determined at 2.19 +/- 0.49, 16.17 +/- 0.3, 6.28 +/- 0.36, and 29.35 +/- 0.26 ng/100 mL, respectively. The metabolite concentrations from the controlled group, however, were either under the detection limits or at a relatively very low level (0.19 +/- 0.41 ng/100 mL for benzo[a]pyrene-7,8,9,10-tetrahydrotetrol metabolite). The results clearly indicate that the benzo[a]pyrene and its hydroxy metabolites were significantly elevated (p < 0.001) in the urine of asphalt fume-exposed rats relative to controls. The study also demonstrated that the combination of microflow LC separation and collision-induced dissociation leading to a characteristic fragmentation pattern by hybrid Q-TOFMS offers a distinct advantage for the identifications and characterizations of the benzo[a]pyrene metabolites.     

气相色谱法测定食品包装中残留1,1-二氯乙烷含量的不确定度评定

在气相色谱法测定食品包装中残留的1,1-二氯乙烷含量过程中,对可能引入的不确定度进行了评定,并分析量化了不确定度来源。结果显示:由标准溶液产生的不确定度分量最大,其次是用标准曲线求1,1-二氯乙烷含量,再次是测量重复性,这三项是该法测定结果不确定度的重要来源。当1,1-二氯乙烷测量结果为23.6mg/kg时,其扩展不确定度为2.1334mg/kg(k=2)。     

Picogram quantitation of polycyclic aromatic hydrocarbons adsorbed on aerosol particles by two-step laser mass spectrometry

Polycyclic aromatic hydrocarbons (PAHs) are emitted into the atmosphere mostly by anthropogenic combustion sources. Because of their carcinogenic and mutagenic properties, PAHs are often analyzed in air quality measurements. Atmospheric concentrations of PAHs, typically in the nanograms-per-cubic-meter range, require significant effort for sample collection and processing when conventional methods such as gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry are used. In contrast, two-step laser mass spectrometry (L2MS) is highly sensitive and selective for PAHs and requires almost no sample preparation. Here, we present for the first time a method based on L2MS to quantify PAHs adsorbed on aerosol particles collected on a filter. Linear ranges for quantitation were determined for five different PAHs in the mass range of 178-276 Da (i.e., phenanthrene, pyrene, chrysene, benzo[e]pyrene, benzo[ghi]perylene) covering more than 2 orders of magnitude with detection limits between 50 and 300 pg of a single PAH on a whole filter sample. A quantitative comparison with GC/MS was performed using model aerosols consisting of benzo[e]pyrene adsorbed on inorganic salt aerosol particles. On average, 25% less benzo[e]pyrene was determined with GC/MS than with L2MS, with a variability between the two methods of +/-68%. The general lower amount measured with GC/MS is attributed to losses during the sample preparation for the GC/MS measurements.     

The determination of volume ratios by gas depletion through multiple expansions

We present a new technique for the determination of the volume ratio of two vacuum chambers connected through a valve. The method is based on the measurement of the pressure in a chamber filled with a gas that is repeatedly depleted by expansion in a second chamber that was previously evacuated. Our calculation shows that under the reported measurement conditions, this technique has an uncertainty comparable to that obtained from the gas accumulation technique [Elliott KWT, Clapham PB.The accurate measurement of the volume ratios of vacuum vessels. NPL Report MOM 28, January 1978]. An excellent equivalence between the results obtained with this new technique and the measurements obtained by the gas accumulation technique is demonstrated.     

气相色谱内标法测定塑料制品中乙苯和苯乙烯含量的不确定度评定

目的 对气相色谱内标法测定塑料制品中乙苯和苯乙烯含量进行不确定度评定，为塑料制品中乙苯、苯乙烯含量测定的准确性提供参考。方法 依据GB 31604.16—2016采用气相色谱内标法对塑料制品中乙苯和苯乙烯含量进行测定，根据相应的测量模型，分析不确定度主要影响因素的来源，并对各影响因素引入的相对标准不确定度进行评估。结果 测量塑料制品中乙苯、苯乙烯的扩展不确定度分别为(23.83±1.50)、(23.90±1.26)mg/kg(P=95%、k=2)。结论 结果表明，混标工作液配制、试样重复测量、气相色谱仪性能是影响乙苯和苯乙烯含量测量不确定度的主要因素，应选择精度高且量程合适的量具，加强气相色谱仪的期间核查，提高实验人员操作的熟练水平，进一步减小测量不确定度，使测量结果更为准确、可靠。     

Determination of benzo[a]pyrene sulfate conjugates from benzo[a]pyrene-treated cells by continuous-flow fast atom bombardment mass spectrometry

The level of certain water-soluble hydrocarbon conjugates, such as benzo[a]pyrene sulfates (BP-SO4), is a direct measure of carcinogenic polycyclic aromatic hydrocarbon metabolism and an indication of exposure. A new method, based on continuous-flow high-resolution fast atom bombardment mass spectrometry, has been developed for the analysis of BP-SO4 in the medium of cell cultures treated with benzo[a]pyrene. An organic solvent extract of medium from cultures of the human hepatoma cell line (HepG2) was fractionated by reversed-phase SEP-PAK chromatography and microbore high-performance liquid chromatography (HPLC). The HPLC fraction containing BP-SO4 was collected, dried, and injected into a stream of acetonitrile/water/glycerol that was continuously flowing to the tip of the sample probe which was being bombarded continuously by a beam of high-energy xenon atoms. Molecular anions of BP-SO4 (m/z 347) desorbed from the liquid were analyzed by a high-resolution (m/delta m 5000) mass spectrometer and recorded as a function of time. As little as 1.5 pg of BP-SO4 could be detected with a S/N ratio of 8. The mass spectrometer response was linear with respect to the quantity of BP-SO4 injected over the range from 15 to 625 pg. The results obtained with this method show that the HepG2 cultures metabolized 3% of the benzo[a]pyrene into the BP-SO4 conjugate in 24 h. This procedure, which was used to detect and quantify directly BP-SO4 in culture medium without the use of a radiolabeled precursor, should be generally applicable for analyses of sulfated conjugates resulting from the metabolism of different hydrocarbons.     

Development of a room-temperature phosphorescence fiber-optic sensor

The design of a new fiber-optic sensor based on solid-surface room-temperature phosphorimetry is presented for the analyses of polycyclic aromatic hydrocarbons in water samples. Analytical figures of merit are given for several compounds of environmental importance. Limits of detection at the nanograms per milliliter level were estimated for pyrene, benzo[e]pyrene, benzo[ghi]perylene, 1,2:3,4-dibenzanthracene, coronene, and 2,3-benzofluorene. The linearity of response of the phosphorescence sensor was evaluated, showing a fairly linear behavior for quantitative analysis. Finally, the feasibility of monitoring polycyclic aromatic hydrocarbons in aqueous media was illustrated by identifying pyrene in a contaminated groundwater sample.     

Cement-based stabilization/solidification of oil refinery sludge: Leaching behavior of alkanes and PAHs

Stabilization/solidification is a process widely applied for the immobilization of inorganic constituents of hazardous wastes, especially for metals. Cement is usually one of the most common binders for that purpose. However, limited results have been presented on immobilization of hydrocarbons in cement-based stabilized/solidified petroleum solid waste. In this study, real oil refinery sludge samples were stabilized and solidified with various additions of I42.5 and II42.5 cement (Portland and blended cement, respectively) and subject to leaching. The target analytes were total petroleum hydrocarbons, alkanes and 16 polycyclic aromatic hydrocarbons of the EPA priority pollutant list. The experiments showed that the waste was confined in the cement matrix by macroencapsulation. The rapture of the cement structure led to the increase of leachability for most of the hydrocarbons. Leaching of n-alkanes from II42.5 cement-solidified samples was lower than that from I42.5 solidified samples. Leaching of alkanes in the range of n-C(10) to n-C(27) was lower than that of long chain alkanes (>n-C(27)), regardless the amount of cement addition. Generally, increasing the cement content in the solidified waste samples, increased individual alkane leachability. This indicated that cement addition resulted in destabilization of the waste. Addition of I42.5 cement favored immobilization of anthracene, benzo[a]anthracene, benzo[b]fluoroanthene, benzo[k]fluoroanthene, benzo[a]pyrene and dibenzo[a,h]anthracene. However, addition of II42.5 favored 5 out of 16, i.e., naphthalene, anthracene, benzo[b]fluoroanthene, benzo[k]fluoroanthene and dibenzo[a,h]anthracene.     

连续流动法测定烟草中总氮含量的不确定度评定

本文结合实验室的实际情况,对连续流动法测定烟草中总氮含量的测量不确定度进行评定,分析了总氮含量检测误差的影响因素,计算了不确定度分量及合成不确定度,并得出测量结果扩展不确定度为0.04%,为测量结果提供了可信度和可信区间。     

火焰原子吸收分光光度法测定低合金钢中镍含量的不确定度评价

依据GB/T 223.54—1987利用火焰原子吸收分光光度法对低合金钢中镍进行了测定,对测定过程中不确定度的来源进行了分析,并对测定过程中的不确定度分量进行了合理评定,评定了测量结果的不确定度。找出了影响检测的主要因素,测量不确定度主要来源于试样称量、试样溶液定容和试样溶液质量浓度测定三方面,试样溶液质量浓度上机测定引入的不确定度主要来源于校准溶液配制、校准曲线拟合及重复性测定等,通过分析,明确了提高测量准确度的方法,给出了评定方法、步骤及结果。