The application of amino acid racemization in the acid soluble fraction of enamel to the estimation of the age of human teeth

Estimation of age-at-death for skeletonised forensic remains is one of the most significant problems in forensic anthropology. The majority of existing morphological and histological techniques are highly inaccurate, and show a bias towards underestimating the age of older individuals. One technique which has been successful in forensic age estimation is amino acid racemization in dentine. However, this method cannot be used on remains where the post-mortem interval is greater than 20 years. An alternative approach is to measure amino acid racemization in dental enamel, which is believed to be more resistant to change post-mortem. The extent of amino acid racemization in the acid soluble fraction of the enamel proteins was determined for modern known age teeth. A strong correlation was observed between the age of the tooth and the extent of racemization. No systematic bias in the direction of age estimation errors was detected. For the majority of teeth analyzed, the presence of dental caries did not affect the results obtained. In a minority of cases, carious teeth showed a higher level of racemization than would be expected given the age of the individual. These results indicate that amino acid racemization in enamel has the potential to be used in age estimation of skeletal remains.     

"Life expectancy" of "ecstasy" tablets in Israel in the years 2001-2003

3,4-Methylenedioxymethamphetamine (MDMA) tablets known as "ecstasy" became a very popular drug amongst Israeli youth in the last decade. The ecstasy tablets have a simple design impressed on them (logos) making it relatively easy to distinguish between various logos. The life expectancy of ecstasy tablet logos, defined as the period between the first seizure by the police of a certain logo until the last seizure of the same logo, was monitored during the years 2001-2003. During this time interval, 58 different tablet logos were seized. A total of 26 logos, defined as common logos with at least 10 independent seizures, were observed. At any given time interval during this period, 8-10 common logos were found with an average life expectancy of approximately 9 months. Five of the observed 26 common logos were defined as the most common logos that appeared in at least 200 independent seizures each. Plots of the number of seizures and number of tablets seized as a function of time are presented and discussed as well as explanations for the high turnover rate of any given logo.     

Age estimation using the racemization of amino acid in human dentin

This study was made to improve the validity of age estimation from teeth using amino acid racemization. The correlation between actual age and the D/L ratio of aspartic acid was investigated by analyzing not only the total amino acid but also its fractionated substances, insoluble collagen and soluble peptide. The coefficient values of correlation between the D/L ratio and actual age in adult lower central incisors were 0.996 (sigma = +/- 1.0 year) for the total amino acid, 0.988 (sigma = +/- 1.8 years) for insoluble collagen, and 0.997 (sigma = +/- 0.9 years) for soluble peptide. The corresponding figures in adult first premolars were 0.991 (sigma = +/- 1.6 years), 0.988 (sigma = +/- 1.9 years), and 0.994 (sigma = +/- 1.4 years), respectively. The reactive velocity of aspartic acid racemization was highest for soluble peptide in both the lower central incisors and first premolars and approximately three times as rapid as that for total amino acid. As a result, age estimated from the analysis of soluble peptide was most accurate. The velocity for insoluble collagen was slightly lower than that for total amino acid. Age estimation was attempted from the teeth of an unknown body. These results suggest that the analyses, not only of total amino acid in dentin but also of its fractionated and extracted substances, can lead to higher reliability in age estimation. Soluble peptide, in particular, has been found to be most effective.     

A new approach to amino acid racemization in enamel: testing of a less destructive sampling methodology

Aspartic acid racemization has been found to be an accurate measure of age at death for recent forensic material. This paper examines the practicality of using acid etching of the tooth surface to extract amino acids from the enamel for racemization analysis. By serial etching of the tooth and contamination of the teeth with bovine serum albumin prior to etching, the ability of etching to remove contamination was assessed. The destructiveness of the method was visualized and quantified using micro-computed tomography (micro-CT). By bleaching the teeth and by deeper etching it was possible to obtain more consistent values. While etching had little effect on the enamel at the macroscale, it did have an impact at the microscale. The quantities of enamel removed varied depending upon the tooth morphology, but were not large. Acid etching of enamel thus appears to be a promising new method for extracting proteins for amino acid racemization age estimation noninvasively.     

衍生化在气相色诤-质谱法检测苯丙胺类毒品中的应用进展

衍生化是气相色谱-质谱法检测苯丙胺类毒品的重要步骤。衍生化可改善苯丙胺类化合物的色谱行为,增加其质谱分析的质量和特征离子峰,使质谱更加独特,提高了苯丙胺类毒品的检测灵敏度,从而为检验鉴定提供准确可靠的实验结果。本文综述了衍生化在气相色谱-质谱法检测苯丙胺类毒品中的应用进展。     

TOXI-LAB系统对尿液中吗啡进行复核检验的可行性探讨

目的　考查TOXI LAB毒物分析实验室系统对吸毒嫌疑人尿液中毒品进行快速复核检验的可行性。方法　应用TOXI LAB系统对吸毒嫌疑人阳性尿液中吗啡进行快速复核检验 ,同时进行GC/NPD、GC/MS验证。　结果　TOXI LAB方法在检测吸毒嫌疑人尿液中吗啡时其特异性为 10 0 %。　结论　该方法对吸毒嫌疑人尿液中毒品进行快速复核检验是可行的。     

血液中氯胺酮的GC／MS／MS分析

目的建立血液中氯胺酮的定性分析方法;方法采用串联质谱法分析;结果选择氯胺酮的特征离子m/z180为母离子,CID电压为0.5v进行MS/MS分析;结论此检验方法能有效的消除来自人体血液的干扰物质,方法快速、灵敏、准确。     

GC／MS同时分析头发中大麻酚类和△^9-四氢大麻酸

目的建立同时分析毛发中THC、CBN、CBD和大麻主要代谢物THC-COOH的方法.方法头发检材去污处理后,加入内标氯灭酸,经NaOH水解和正己烷:乙酸乙酯(9:1)提取,吹干后衍生化,利用GC/MS-SIM方法分析.结果THC、CBN和THC-COOH的最低检出限分别为0.01、0.05和0.01ng/mg.10例阳性头发中均检出THC成分,THC浓度范围为0J 1～8.84ng/mg,有3例未检出THC-COOH,检出者的量亦低于定量下限.结论同时分析头发中的大麻酚类和△9-四氢大麻酚是可行的,头发中THC-COOH浓度明显都低于THC浓度.     

GC/MS衍生化测定精浆中游离支链氨基酸和果糖

目的 建立人精浆中支链氨基酸和果糖的气相质谱衍生化分析方法.方法 精液样本液化离心后,按精子活率的临床标准分为正常组和非正常组,经TMS微波衍生化,GC/MS分析两组支链氨基酸、果糖衍生物含量差异.结果 正常组与非正常组的缬氨酸,亮氨酸,异亮氨酸在相对含量上均有一定差异.正常组3种氨基酸相对含量高于非正常组.果糖分析观察到同样的特征,正常组相对含量高于非正常组.结论 精子活率低的精浆样本仍可检出支链氨基酸和果糖,其差异有助于无精子、少精子精斑的法医学鉴别.     

Simultaneous analysis of six amphetamines and analogues in hair, blood and urine by LC-ESI-MS/MS: Application to the determination of MDMA after low Ecstasy intake

A rapid and sensitive method using LC-MS/MS triple stage quadrupole for the determination of traces of amphetamine (AP), methamphetamine (MA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA, “ecstasy”), 3,4-methylenedioxyethamphetamine (MDEA), and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine (MBDB) in hair, blood and urine has been developed and validated. Chromatography was carried out on an Uptisphere ODB C₁₈ 5 μm, 2.1 mm × 150 mm column (Interchim, France) with a gradient of acetonitrile and formate 2 mM pH 3.0 buffer. Urine and blood were extracted with Toxitube A^® (Varian, France). Segmented scalp hair was treated by incubation 15 min at 80 °C in NaOH 1 M before liquid–liquid extraction with hexane/ethyl acetate (2/1, v/v). The limits of quantification (LOQ) in blood and urine were at 0.1 ng/mL for all analytes. In hair, LOQ was <5 pg/mg for MA, MDMA, MDEA and MBDB, at 14.7 pg/mg for AP and 15.7 pg/mg for MDA. Calibration curves were linear in the range 0.1–50 ng/mL in blood and urine; in the range 5–500 pg/mg for MA, MDMA, MDEA and MBDB, and 20–500 pg/mg for AP and MDA. Inter-day precisions were <13% for all analytes in all matrices. Accuracy was <20% in blood and urine at 1 and 50 ng/mL and <10% in hair at 20 and 250 pg/mg. This method was applied to the determination of MDMA in a forensic case of single administration of ecstasy to a 16-year-old female without her knowledge during a party. She suffered from hyperactivity, sweating and agitation. A first sample of urine was collected a few hours after (T + 12 h) and tested positive to amphetamines by immunoassay by a clinical laboratory. Blood and urine were sampled for forensic purposes at day 8 (D + 8) and scalp hair at day 60 (D + 60). No MDMA was detected in blood, but urine and hair were tested positive, respectively at 0.42 ng/mL and at 22 pg/mg in hair only in the segment corresponding to the period of the offence, while no MDA was detectable. This method allows the detection of MDMA up to 8 days in urine after single intake.     

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。     

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。