收集提取“物证”样本规范化研究——以物证鉴定样本为切入点

物证是证据种类之一,而物证鉴定样本是在物证鉴定过程中,为了实现物证的种属认定与同一认定而依法提取和保存的、供比对的已知证据材料。物证鉴定样本因鉴定而成为证据,是鉴定意见的重要组成部分。物证鉴定样本在诉讼中具有重要作用。当前,样本收集、提取存有许多不足,需采取行之有效的收集提取方法,以助于物证鉴定制度在内的整个证据制度的完善。     

气相色谱-串联质谱法分析尿和血中除草剂百草枯

目的建立尿和血中百草枯的离子交换固相萃取-气相色谱-串联质谱分析方法。方法尿样加内标乙基百草枯,用732阳离子交换树脂提取;血样加内标乙基百草枯,用三氯乙酸凝聚蛋白质后取上清液用732阳离子交换树脂提取。提取物用硼氢化钠在水溶液中碱性条件下还原,还原物用有机溶剂提取进行气相色谱-串联质谱法分析。结果尿和血中百草枯的提取率分别为76％和74％,检测限分别为2ng／mL和10ng／mL,尿添加百草枯100ng／mL和血添加百草枯500ng／mL水平的回收率分别为99．6±5．6％和99．3±7．6％（Mean±CV）。结论本文建立的分析方法灵敏度高,能够满足中毒致死案件检验及临床毒物检验的需要。     

3种方法联合运用提取人体脱落上皮细胞DNA

目的寻求提高法医物证检验中附有人体脱落细胞载体检材的DNA检出率的方法。方法根据案件检材的具体条件．选择3种提取方法即Chelex-100法、Chelex-100联合有机法和Chelex-100联合磁珠法。结果采用了分步提取DNA法,可充分、有效地提取微量DNA,提高了人体脱落上皮细胞有效DNA的检出率。结论根据第一步提取方法的检测结果,来调整下一步的提取策略,如是否加以纯化浓缩,可增加人体脱落上皮细胞有效DNA的检出率。     

Extraction of high quality DNA from biological materials and calcified tissues

Calcified tissues, such as bone and tooth, and some other sample types, such as those containing adhesive, present a challenge to standard extraction protocols. We have developed a lysis reagent, BTA™ lysis buffer, which is designed for use with PrepFiler™ Kit reagents. The BTA™ lysis buffer disrupts calcified tissue matrices and achieves effective extraction of DNA from pulverized bone and tooth samples. In addition, the BTA™ lysis buffer mildly but efficiently extracts DNA from challenging substrates like tape, chewing gum, and cigarette butts and, as with bone and tooth, DNA from these lysates is purified using established PrepFiler™ reagent extraction protocols.We successfully extracted DNA from powdered human bone samples, chewed gum and smoked cigarettes using BTA™ lysis buffer. Extraction yields for bone, gum and cigarette samples tested were consistent and reproducible. This extraction method efficiently removed potential PCR inhibitors from all samples tested, and C_T values for the internal PCR control of Quantifiler^® Human DNA Quantification Kit were consistent and within the normal range. The DNA extracted from these samples also provided conclusive profiles that were free of PCR artifacts when amplified using the AmpF?STR^® Identifiler^® PCR Amplification Kit. The protocol is easily adapted for automation.     

Case report of a homicide resolved 15 years later: The robustness of Chelex extraction

DNA typing techniques is one of the most advanced tools for human identification. During the last 10 years, a great number of methods for DNA extraction and analysis have been introduced to forensic genetic, with considerable success but also with considerable controversy. The success and validation of a criminal investigation are very closely related to the process used for obtaining and preserving biological evidence.We report the strategy that we employed to analyze evidences belonging to a homicide happened in Brescia (Italy) in 1992, not resolved at that time, with the forensic genetic analysis. After 16 years the analysis were conducted on DNA samples extracted with Chelex maintained at −80 °C, bloodstain, and biological specimens of perpetrators. Standard autosomal and Y-chromosome STR analysis identified the persons involved and victim's profiles. This case is of interest as a demonstration of a more successful application of DNA typing in well conserved DNA samples than in bloodstains kept in the Court Office.     

LC-MS／MS测定尿液中可卡因及其代谢物苯甲酰爱康宁

目的建立尿液中可卡因(cocaine,COC)及其代谢物苯甲酰爱康宁(benzoylecgonine,BZE)的液相色谱-串联质谱分析方法。方法尿液经固相萃取后,用AllurePFP丙基柱分离,以V(甲醇):V(20mmol/L乙酸胺和0.1%甲酸的缓冲溶液)=80∶20为流动相,采用二级质谱多反应监测模式检测COC和BZE。按10mg/kg的剂量对豚鼠腹腔注射可卡因,给药后收集7d尿液。结果尿液中COC和BZE在2.0～100ng/mL质量浓度范围内线性关系良好(r=0.9995),最低检测限(LOD)为0.5ng/mL;回收率大于90%;日内和日间精密度均小于6%;豚鼠尿液中主要检测目标物是BZE,且BZE检测时限也较COC长。结论所建方法灵敏度高,选择性好,适用于尿液中可卡因和苯甲酰爱康宁的检测。     

Analysis of pain management drugs, specifically fentanyl, in hair: application to forensic specimens

This article discusses the immunoassay screening of pain management drugs, and the mass spectrometric confirmation of fentanyl in human hair. Hair specimens were screened for fentanyl, opiates (including oxycodone), tramadol, propoxyphene, carisoprodol, methadone, and benzodiazepines and any positive results were confirmed using gas chromatography or liquid chromatography with mass spectral detection. The specific focus of the work was the determination of fentanyl in hair, since autopsy specimens were also available for comparison with hair concentrations. Using two-dimensional gas chromatography with electron impact mass spectrometric detection, fentanyl was confirmed in four of nine hair specimens collected at autopsy. The accuracy of the assay at 10 pg/mg was 95.17% and the inter-day and intra-day precision was 5.04 and 13.24%, respectively (n=5). The assay was linear over the range 5-200 pg/mg with a correlation of r(2)>0.99. The equation of the calibration curve forced through the origin was y=0.0053x and the limit of quantitation of the assay was 5 pg/mg. The fentanyl concentrations detected were 12, 17, 490, and 1930 pg/mg and the results were compared with toxicology from routine post-mortem analysis. The screening of pain management drugs in hair is useful in cases where other matrices may not be available, and in routine testing of hair for abused drugs.     

Ethyl glucuronide: unusual distribution between head hair and pubic hair

Ethyl glucuronide (EtG) is a minor metabolite of ethanol that can be detected in hair. In some specific situations, head hair can be missing, and therefore, alternative anatomical locations of hair are of interest. In this study, paired hair specimens (head hair and pubic hair) from eight social drinkers were analyzed for EtG. Each sample was decontaminated by two dichloromethane bathes (5 ml) for 2 min. After cutting into small pieces, about 50 mg of hair was incubated in 2 ml water in the presence of 10 ng of EtG-d5, used as internal standard and submitted to ultra-sonication for 2 h. The aqueous phase was extracted by SPE using Oasis MAX columns. The hair extract was separated on an ACQUITY BEH HILIC column using a gradient of acetonitrile and formate buffer. Detection was based on two daughter ions: transitions m/z 221-85 and 75 and m/z 226-75 for EtG and the IS, respectively. This laboratory is using a positive cut-off at 50 pg/mg. All eight head hair specimens were negative for EtG at a limit of quantitation fixed at 10 pg/mg. Surprisingly, EtG was identified at high concentrations in pubic hair, in the range 12-1370 pg/mg. It appears, therefore, that it is not possible to document the drinking status of a subject by simply switching from head hair to pubic hair.     

Hair analysis to document non-fatal pesticide intoxication cases

We reported two non-fatal cases of intoxication with pesticides namely alachlor and carbofuran. Hair stand samples were collected from two men approximately 1 year after alachlor intoxication for case 1, and 14 days after the last exposure for case 2. Hair analysis was performed using a liquid chromatography-tandem mass spectrometry method. In case 1, alachlor was detected in the 5 analysed hair segments (concentrations between 12 and 136 pg/mg) and its metabolites were not detected. In case 2, carbofuran and its main metabolite (3-hydroxycarbofuran) were detected in the hair strand (global analysis) at the concentrations of 207 and 164 pg/mg, respectively. However, additional data are required in order to interpret such results.     

Application of discriminant analysis to differentiate between incorporation of cocaine and its congeners into hair and contamination

The requirement to differentiate between incorporation and external contamination of drugs into hair is undisputed, in particular when dealing with compounds which are administered by sniffing or inhalation (e.g. cocaine). With the aim of making this discrimination, hair samples from cocaine (COC) users (group IN) and seized cocaine samples (group OUT) were compared regarding the parameters benzoylecgonine (BZE), ecgonine methyl ester (EME), ecgonine (ECG), anhydroecgonine methyl ester (AEME), cocaethylene (CE) and norcocaine (NCOC). Since most of these compounds may be minor by-products of COC or be formed by biotransformation or chemical degradation, the stability of each substance was carefully examined. COC was found to be converted into significant amounts of BZE, EME and ECG even under mild extraction conditions, while traces of NCOC proved to be a ubiquitous by-product of COC. Cocaine positive hairs and seized cocaine samples (diluted to relevant concentrations) were equally preprocessed and analyzed by LC-MS-MS. Out of the metabolites listed above, NCOC, CE and AEME (each normalised to COC) were significantly increased in the incorporation group (i.e. hair samples from cocaine users). Based on this approach, a statistical discriminant analysis enabled us to make a prediction (and estimation of uncertainty) for each cocaine positive hair sample as to its likelihood of belonging to the group of cocaine users or of being contaminated.