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。     

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。     

Results of a proposed breath alcohol proficiency test program

Although proficiency test programs have long been used in both clinical and forensic laboratories, they have not found uniform application in forensic breath alcohol programs. An initial effort to develop a proficiency test program appropriate to forensic breath alcohol analysis is described herein. A total of 11 jurisdictions participated in which 27 modern instruments were evaluated. Five wet bath simulator solutions with ethanol vapor concentrations ranging from 0.0254 to 0.2659 g/210 L were sent to participating programs, instructing them to perform n = 10 measurements on each solution using the same instrument. Four of the solutions contained ethanol only and one contained ethanol mixed with acetone. The systematic errors for all instruments ranged from -11.3% to +11.4% while the coefficient of variations ranged from zero to 6.1%. A components-of-variance analysis revealed at least 79% of the total variance as being due to the between-instrument component for all concentrations. Improving proficiency test program development should consider: (1) clear protocol instructions, (2) frequency of proficiency testing, (3) use lower concentrations for determining limits-of-detection and -quantitation, etc. Despite the lack of a biological component, proficiency test participation should enhance the credibility of forensic breath test programs.     

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。     

The Contribution of Body Mass and Volume of Distribution to the Estimated Uncertainty Associated with the Widmark Equation

The Widmark equation is used forensically for the determination of the amount of ethanol (alcohol) that may have been consumed and also to determine the blood alcohol concentration (BAC) of an individual at a specific time. It is important to be able to estimate the uncertainty associated with Widmark equations. To date, there has been no detailed determination of contribution to the final uncertainty of Widmark calculations of the volume of distribution of ethanol (V_d), using anthropometric equations, or the contribution of an individual’s body mass. Using published data, published literature, and freedom of information data, we determined that the variability (%CV) associated with V_d was ~10% (Watson et al. and Forrest anthropometric equations) and that the %CV associated with estimated body mass was ~15% compared to ~3% when body mass was directly measured. These data allow an estimation of the overall uncertainty of Widmark calculations using general error propagation. The estimated total uncertainty for BAC calculations increased from ~11% (volume consumed) and ~22% (BAC) to ~19% (volume consumed) and ~37% (BAC) when using measured body mass compared to estimated body mass. These results demonstrate that forensic practitioners should be mindful of the increase in estimated uncertainty in calculated Widmark equation results when estimated body mass is used rather than measured body mass. These data further improve the knowledge around the uncertainty of results calculated with the Widmark equation.     

Identification of 1‐(2,3‐dihydro‐1H‐inden‐5‐yl)‐2‐(ethylamino)pentan‐1‐one (bk‐IVP) in a Seized Drug Exhibit

To circumvent the law by evading regulation and obscuring their identities in routine analyses, numerous substituted cathinones have entered the illicit drug market. These compounds have been coined “bath salts” by users. In the described case, the laboratory received an unknown white powder for controlled substances identification. The sample could not be immediately identified using standard methods and procedures. Ultimately, the structure was elucidated using GC‐MS, NMR, FTIR, GC‐SPIR, UV, and color tests to be 1‐(2,3‐dihydro‐1H‐inden‐5‐yl)‐2‐(ethylamino)pentan‐1‐one (bk‐IVP), a cathinone analog with a rarely observed nonoxygenated bicyclic ring system. Features of spectra and chemical tests are reported that distinguish this class of cathinones from heterocyclic analogs.     

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.     

Internal Morphological Analysis for Age Estimation of Blow Fly Pupae (Diptera: Calliphoridae) in Postmortem Interval Estimation*

Abstract: Larvae and pupae of blow fly species are frequently used in postmortem interval estimation, their age indicating minimum time since death. Most studies have considered age estimation of larvae, neglecting study of pupae. Relative development of external pupal features is useful, but there are also internal changes during metamorphosis that may be indicators of age, utilizing histological techniques. This study aimed to optimize preservation and histological analysis of blow fly pupae, specifically Calliphora vicina Robineau‐Desvoidy and Lucilia sericata (Meigen), and to examine internal features with potential for age estimation. Effect of hot‐water‐killing and different preservatives were examined. It was determined that blow fly pupae should be pierced through the three tagma, hot‐water‐killed, and preserved in 80% ethanol as the optimal preservation for subsequent analyses. Hematoxylin and eosin stained pupal sections revealed differences in brain and thoracic muscle development throughout the pupal stage with potential for age estimation.     

顶空气相色谱内标法测定人血中乙醇含量的不确定度评定

目的建立顶空气相色谱内标法测定人血中乙醇含量的不确定度评定的方法。方法结合顸空法乙醇含量测定的全部过程,假设传播系数为1,则对产生不确定度的各分量因子进行分析计算与合成。结果不确定度因素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、使用标准物质的标示值的不确定度和使用的量器、容量器皿等的不确定度。结论本评定方法得出检测的最大误差来自于两个平行样品检测时所产生的误差值。     

A New Method for the Removal and Analysis of Small Particles Adhering to Carpet Fiber Surfaces,,

Fibers are a commonly encountered evidence type and fiber comparisons are routinely conducted. When the characteristics of questioned and known fibers correspond, the probative value is limited because the characteristics compared are determined by their manufacture. It would be valuable to test the hypothesis that questioned fibers originated from a specific carpet. One means of testing this is to analyze fine particles on the fibers. A procedure was developed for removing adhering particles from fibers and preparing them for scanning electron microscopy/ energy dispersive X‐ray spectrometry (SEM/EDS) analysis. The efficacy of several fluids (acetone, ethanol, hexanes, aqueous ethanol, aqueous sodium hexametaphosphate) and agitation methods (sonication and vortexing) for removing particles from fibers was evaluated. The most effective method evaluated was sonication in ethanol for 10 min. The recovered particles were filtered onto a polycarbonate filter and analyzed by automated SEM/EDS analysis to generate data on the particle assemblage. This method makes possible future research to test the within‐item and between‐item variability of particle assemblages on fibers.     

GC/MS和GC法定性定量分析可卡因

目的建立用于可卡因案件检验鉴定的GC和GC/MS定性、定量分析方法。方法通过选择和优化,建立GC、GC/MS法检验可卡因的最佳分析条件;用分别含0.6mg/ml地西泮为内标的0.10、0.20、0.40、0.60、0.80、1.00、1.20mg/ml可卡因标准品乙醇液,考察线性范围和方法检测限。结果分析方法线性方程:GC/FID,Y=1.055X-0.0021,R2=0.9999,GC/NPD,Y=0.556X-0.0016,R2=0.9996;可卡因检测限:GC/FID法10ng,GC/NPD法2ng;分别以所建GC/FID、GC/NPD分析方法和内标法对案件中缴获的可卡因毒品进行定量分析,结果为72%±2.3%,且两方法定量重现性良好。结论本文所建方法可以用于可卡因涉毒案件的检验鉴定。     

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。     

Correction of the alkylnitrite method for the detection of ethanol in blood taking into account toxico-kinetic and anthropometric data

The correction coefficient for the systemic inaccuracy arising during determination of blood ethanol by alkylnitrite gas chromatography and concomitant calibration of aqueous solutions was estimated to equal 0.82; this finding was confirmed by the results of the toxico-kinetic assay for the measurement of total body water (TBW) from the kinetic curve characterizing the time dependence of ethanol concentration in the exhaled air, saliva, capillary and venous blood in combination with 4 anthropometric methods and (in several cases) direct physical detection of TBW. When detecting the blood ethanol level with a correction coefficient of 0.82, the mutual position of the kinetic curves for ethanol concentrations in the blood and the exhaled air (recalculated for the blood level with a coefficient of 2100) as well as in the blood and saliva agreed with that reported in the available literature; it significantly differed from the position of the curves obtained with a correction coefficient of 0.95. The causes accounting for the systematic inaccuracy and erroneous values of the correction coefficients in earlier studies are discussed.     

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。     

Driving Under the Influence of Synthetic Cannabinoid Receptor Agonist XLR‐11

The case of a 22‐year‐old male Caucasian driver is presented. He was involved in a traffic collision. At the roadside, he displayed blank stare and mellow speech with a barely audible voice. A DRE found low body temperature, rigid muscle tone, normal pulse, lack of horizontal and vertical gaze nystagmus, nonconvergence of the eyes, dilated pupil size, and normal Pupillary reaction to light. A standard toxicology DUID protocol was performed on the driver's whole blood including ELISA and GC‐MS drug screens with negative results. Additional drug screening was undertaken for bath salts and synthetic cannabinoid receptor agonists by LC‐MS/MS by a commercial laboratory and identified the synthetic cannabinoid receptor agonist XLR‐11 in the driver's blood. XLR‐11 was subsequently quantified at 1.34 ng/mL. This is the first documented case involving a driver operating a motor vehicle under the influence of the synthetic cannabinoid receptor agonist XLR‐11.     

NIST Mass Spectrometry Data Center standard reference libraries and software tools: Application to seized drug analysis

The standard reference libraries and associated custom software provided by the National Institute of Standards and Technology's Mass Spectrometry Data Center (NIST MSDC) are described with a focus on assisting the seized drug analyst with the identification of fentanyl-related substances (FRS). These tools are particularly useful when encountering novel substances when no certified sample is available. The MSDC provides three standard reference mass spectral libraries, as well as six software packages for mass spectral analysis, reference library searching, data interpretation, and measurement uncertainty estimation. Each of these libraries and software packages are described with references to the original publications provided. Examples of fentanyl identification by gas chromatography–mass spectrometry (GC–MS) and by direct analysis in real-time (DART) mass spectrometry are given. A link to online tutorials is provided.     

Estimating the degree of ethanol intoxication from analysis of cerebro-cranial hematomas

314 cases of combined cerebro-cranial trauma and posttraumatic intracranial hematomas were identified of which ethanol was detected in 114 hematomas. The other investigative group was 103 hospitalized patients who had hematomas evacuated during neurosurgical procedures. In 62 of these cases ethanol was detected. Blood and urine samples were also collected and the alcohol concentration was determined in all specimens by GC and ADH. The ethanol elimination rate for autopsy and operative intracranial hematomas was approximately 0.07–0.08‰/h(±0.034‰/h). The elimination rate of ethanol from blood (β₆₀) was about two or three times greater as that from hematomas. Because of the different water content of intracranial hematomas from blood, it was necessary to adjust the ethanol concentration for water content. On the basis of the corrected ethanol concentrations and the elimination rates for both tissues it was possible to estimate the ethanol concentration at the time of injury. Intracranial hematomas are tissues of possible value in the determination of alcohol intoxication especially in alcoholism. Ethanol can be found in hematomas even after 72 h from head injury.     

A Method for Estimating Sex Using Metric Analysis of the Scapula*

Abstract: The most accurate and precise methods for the assessment of age and stature often require knowledge of sex. Thus, being able to correctly identify sex from skeletal remains is critical in the forensic context. The presence of the os coxae or skull can never be guaranteed, making the development of reliable methods of sex estimation using other skeletal elements necessary. Using a 724 individual calibration sample from the Hamann‐Todd collection, this study identifies sexual dimorphism in the human scapula, and presents a new five‐variable discriminant function for sex estimation. The overall accuracy of this method proved to be 95.7% on the cross‐validated calibration sample, 92.5% on an 80 individual test sample from the Hamann‐Todd collection, and 84.4% on a 32 individual test sample from the skeletal collection of the Wichita State University Biological Anthropology Laboratory. Additionally, a slightly less accurate two‐variable model was developed and has cross‐validated accuracy of 91.3%.     

Detection of Cutting Agents in Drug‐Positive Seized Exhibits within the United States

The following report summarizes a study performed on seized drug exhibits collected in two U.S. states to evaluate the presence and identification of cutting agents. Aliquots of seized drug materials from Kentucky (n = 200) and Vermont (n = 315) were prepared using a dilute‐and‐shoot procedure. Initial analysis was performed using gas chromatography–mass spectrometry (GC‐MS) followed by analysis using liquid chromatography quadrupole time‐of‐flight mass spectrometry (LC‐QTOF). Active compounds detected overall included caffeine (31.0%), quinine/quinidine (24.7%), levamisole (11.6%), acetaminophen, (8.2%) and procaine (8.2%). These compounds were found with several drugs of abuse, such as heroin, fentanyl, methamphetamine, and cocaine. This novel information about cutting agents used to dilute or alter drugs of abuse is important to criminal investigations and in the management of acute intoxications at health centers. However, common methodologies for analysis and standard reporting practices frequently do not include cutting agents, resulting in lacking or inadequate information regarding prevalence of these substances.