高效液相色谱法测定海洛因含量的不确定度评定

目的建立高效液相色谱法测定海洛因含量的不确定度评定的方法。方法结合海洛因含量测定的全部过程,假设传播系数为1,对产生不确定度的各分量因子进行分析计算与合成。结果不确定度的来源主要包含样品检测时产生的误差值、检测仪器的精密度、天平和使用的容量器皿等的不确定度。结论本评定方法得出检测的误差来自于两个平行样品检测时产生的误差值。     

自动顶空GC/MS测定血液中乙醇含量不确定度评定

目的评定自动顶空—气相色谱—质谱法(GC/MS)测定血液中乙醇含量的不确定度。方法从分析测量过程着手,依据不确定度评定的指导性文件,分析了不确定度来源,量化不确定度分量,计算检测结果的合成标准不确定度和扩展不确定度。结果血液样本两次测定结果平均值为0.738mg/mL的扩展不确定度为0.084mg/mL。结论血液中乙醇含量的不确定度主要来源于样品检测、乙醇标准溶液和标准曲线。     

HS-GC内标曲线法测定血中乙醇含量的不确定度评估

目的建立自动顶空-气相色谱(HS-GC)内标曲线法测定血中乙醇含量的不确定评估方法。方法从分析测定程序着手,依据不确定度评定的指导性文件,分析不确定度来源,量化不确定度分量,计算检测结果的合成标准不确定度和扩展不确定度。结果各相对不确定度来自于检材重复性检测为3.4%,乙醇标准溶液为0.71%,检材为0.61%,叔丁醇内标溶液为0.41%,标准曲线为1.1%,气相色谱仪为1.3%,血液中乙醇的相对扩展不确定度为3.9%。结论血液中乙醇含量的不确定度主要来源于检材重复性检测、气相色谱仪、乙醇标准曲线。     

气相色谱法测定人血中乙醇的不确定度评估

本文建立了气相色谱法测定人血中乙醇含量的不确定度评定方法,考虑不确定度的来源主要包括仪器的精密度、标准物质标称值的不确定度、样品及标准物质体积的不确定度等。假定传播系数为1,对各分量进行计算与合成。经实验验证,理论推导的结果与实验结果基本吻合。     

氢化物原子荧光法测定人发中砷含量的不确定度评定

目的评定氢化物原子荧光法测定人发中砷含量的不确定度。方法以人发标准样品为分析对象,依据化学分析中不确定度的评估指南等指导性文件,分析测定过程中砷含量测定值（C）、样品处理后的总体积（V）、样品称量值（m）以及重复测量（rep）等多个不确定度分量,计算检测结果的合成标准不确定度和扩展不确定度。结果本文方法测定人发中砷含量的不确定度评定结果为：人发样品中砷的含量为（0.57±0.06）mg/kg,置信概率（p）=95%,自由度（υeff）=4。结论本文方法测量不确定度的主要来源是重复性和校准曲线,测定结果在标准物质给出的含量范围之内。     

GC/MS测定尿液中氯胺酮含量不确定度评定

目的评定气相色谱—质谱法（GC/MS）测定尿液中氯胺酮含量的不确定度。方法依据不确定度评定的指导性文件,从测定程序分析了不确定度的来源,量化不确定度分量,计算检测结果的合成标准不确定度和扩展不确定度。结果尿液检材中测定结果平均值为0.257μg/mL的扩展不确定度为0.016μg/mL。结论尿液中氯胺酮含量的不确定度主要来源于标准品纯度和标准曲线。     

毛发中甲基苯丙胺含量的测量不确定度评定

对涉嫌吸毒人员毛发样本中的甲基苯丙胺含量进行测量不确定度评定。将毛发样本清洗、定量称取、研磨提取后，采用液相色谱-串联质谱仪（LC-MS/MS）分析甲基苯丙胺含量。基于样本处理程序及外标单点定量法数学模型，分析毛发中甲基苯丙胺含量的不确定度来源，并进行分量评定及合成不确定度计算。本方法检测毛发中甲基苯丙胺含量为0.264 ng/mg，结果的合成相对不确定度为4.0%，引入各项不确定度分量的因素贡献大小顺序为：甲基苯丙胺标准工作溶液浓度>检测重复性>标准工作溶液移取体积>提取溶剂移取体积>检材称取质量。本研究从人员操作、仪器设备和实验环境等方面评定了毛发中甲基苯丙胺含量的不确定度，提高了检验结果科学性和表述严谨性，有利于为涉毒案件的执法和审判提供坚实科学证据。     

直接进样气相色谱内标工作曲线法测定血液中乙醇的不确定度评估

测量不确定度的评估是评价测量结果的有效方法，是测量结果质量的定量表征，是实验室认可评审的重要内容。近年来，实验室认可评审在公安系统陆续开展，我所也于去年10月份通过CNAS认可，在认可过程中进行了血液中乙醇定量项目的不确定度评估。本文以此为例，探讨血液中乙醇含量气相色谱内标法检测结果的不确定的评估过程，以保证检测数据更加准确可靠、有效。     

气相色谱法测定海洛因含量的测量不确定度评定

目的探讨气相色谱法测定海洛因含量的测量不确定度评定。方法从测定程序分析不确定度来源,并计算各不确定度分量及合成不确定度,得出总不确定度。结果重复性测定不确定度分量最大,气相色谱仪误差次之,而玻璃容量器具天平及对照品所引起的不确定度分量对总不确定度的影响可忽略不计。结论气相色谱法测定海洛因含量的测量不确定度主要来源于重复性测定的误差及气相色谱仪的误差。     

人体内乙醇含量检测的影响因素分析

人体内乙醇含量检测不仅是法医鉴定工作中常规检测项目,也是交通肇事案件最终的仲裁依据,其检测结果直接影响着受检人员的责任判罚。本文根据乙醇的毒理特征及在人体内的代谢过程,就不同检材、送检时效性、尸体腐败、血液检品中不同成分和保存方式、以及检测结果的不确定度等对乙醇含量检测结果的影响进行分析,以利于对受检者是否饮酒及其程度做出科学、公正的判定。     

Breath alcohol test precision: an in vivo vs. in vitro evaluation

Random error is associated with breath alcohol measurements, as with all analytical methods. The total random uncertainty of a group of n measurements is typically determined by computing the standard deviation and requiring it to be less than some appropriate level (i.e., +/- 0.0042 g/210 l). The total random uncertainty has two primary sources; the instrumental method and the sample source. These are typically inseparable values. In breath alcohol testing the two primary sample sources are simulators and human breath. The present study evaluates ten groups of simulator samples consisting of ten measurements each on BAC Verifier Datamaster instruments. The data also includes ten breath alcohol measurements from each of 21 individuals following alcohol consumption. The range of standard deviations for the simulator samples was 0.0003-0.0022 g/210 l. The range of standard deviations for the human breath samples was 0.0015-0.0089 g/210 l. Two statistics that test for homogeneity for variances were applied. The simulator samples resulted in a Cochran's C test of 0.5000 and an Fmax test of 48.9. The human breath samples resulted in a Cochran's C test of 0.1519 and an Fmax test of 27.3. All were significant at P less than 0.001. The statistical tests demonstrated that the intragroup variability among the human subjects was comparable to the intragroup variability among the simulator samples. The data also demonstrates that the sample source (simulator or human) is probably the largest contributor to total random uncertainty. Therefore, when duplicate breath alcohol testing from individuals shows variability in the second decimal place the cause is differences in breath samples provided and not instrumental imprecision.     

The influence of alcohol content variation in UK packaged beers on the uncertainty of calculations using the Widmark equation

It is common for forensic practitioners to calculate an individual's likely blood alcohol concentration following the consumption of alcoholic beverage(s) for legal purposes, such as in driving under the influence (DUI) cases. It is important in these cases to be able to give the uncertainty of measurement on any calculated result, for this reason uncertainty data for the variables used for any calculation are required. In order to determine the uncertainty associated with the alcohol concentration of beer in the UK the alcohol concentration (%v/v) of 218 packaged beers (112 with an alcohol concentration of ≤5.5%v/v and 106 with an alcohol concentration of >5.5%v/v) were tested using an industry standard near infra-red (NIR) analyser. The range of labelled beer alcohol by volume (ABV's) tested was 3.4%v/v – 14%v/v. The beers were obtained from a range of outlets throughout the UK over a period of 12?months. The root mean square error (RMSE) was found to be ±0.43%v/v (beers with declared %ABV of ≤5.5%v/v) and ±0.53%v/v (beers with declared %ABV of >5.5%v/v) the RMSE for all beers was ±0.48%v/v. The standard deviation from the declared %ABV is larger than those previously utilised for uncertainty calculations and illustrates the importance of appropriate experimental data for use in the determination of uncertainty in forensic calculations.     

GC/MS法测定人体血液和肾、肝组织中的丙泊酚

目的 采用气相色谱/质谱法检测人体血液和肾、肝组织中的丙泊酚.方法 心血和肾、肝组织中的丙泊酚经环己烷提取,采用气相色谱/质谱法,丙泊酚选择m/z 163、178,内标百里香酚选择m/z 150、135进行测定;并考察方法专属性、线性范围、定量线与检出限、回收率与精密度.结果 丙泊酚的保留时间为8.17min,与内标百里香酚分离良好;其在心血和肾、肝组织中的检测浓度线性关系良好,r值均大于0.992,最低检测质量浓度分别为0.05 μg/mL、0.10μg/g及0.05 μg/g,方法回收率90％ ～ 110％,日内、日间RSD均小于7％.结论 本文方法简便、灵敏、快速,其准确度、精密度和回收率均可满足生物检材中丙泊酚浓度的测定,可在相关研究及实践中选用.     

The statistical variability of blood alcohol concentration measurements in drink-driving cases

Like many other places in the world, Hong Kong has drink-driving legislation which prohibits a driver from having in his blood alcohol exceeding a prescribed limit while in control of a motor vehicle. The accuracy of measuring this alcohol concentration is obviously of prime concern as an erroneous result can avert the administration of justice. The common practice is to deduct all errors from the measured value and compare the deducted value with the prescribed limit, so that the benefit of all errors of the measurement is given to the driver. It is therefore important for any laboratory responsible for measuring blood alcohol concentrations to identify and quantify all errors associated with the measurement. The present study examined 900 blood alcohol determinations carried out by the Hong Kong Government Laboratory (HKGL) on cases of suspected drink driving. The determinations were performed by 5 different analysts with two different sets of instruments during 1995-1997. Statistical analysis indicated that the instruments had no bearing on the random error or variability and that even though analyst was a significant factor on variability, the deviation from the mean so caused was only 0.3% and of no practical significance. When the systematic error introduced by the tolerance limits of the certified alcohol standards (purchased from the Laboratory of Government Chemists, UK) was taken into account, the total uncertainty (random plus systematic errors) of an alcohol determination at 99.5% confidence level was found to be 4%. It is recommended that laboratories engaged in blood alcohol determination should adopt similar statistical treatment of their analytical results to find out the error and to ensure that the results are independent of analyst and instrument used.