比色法测定人参中人参总皂苷的含量

目的：建立人参中人参总皂苷的含量测定方法。方法：采用比色法测定。结果：比色法测定的线性范围为15．0～75．0μg，相关系数γ=0．9997；平均回收率为100．61％，RSD为1．51％(n=6)。结论：本法简便、准确、灵敏度高、重复性好，可用于人参药材及含人参制剂的含量测定。     

大孔树脂联合Sephadex LH-20葡聚糖凝胶纯化蜂胶总黄酮工艺研究

目的 优选大孔树脂联合Sephadex LH-20葡聚糖凝胶分离纯化蜂胶总黄酮的最佳工艺参数.方法 采用硝酸铝-醋酸钾比色法定量,通过比较9种大孔吸附树脂对蜂胶总黄酮的吸附率和解吸率,筛选出最佳大孔吸附树脂型号,通过动态吸附与解吸试验优选大孔树脂最佳纯化工艺参数,采用Sephadex LH-20葡聚糖凝胶进一步纯化.结果 优选大孔树脂型号为HPD-722型.最佳纯化工艺:上样液浓度2.5 mg/mL,比上样量0.43 g/g(药材/湿树脂),上样容积流量为每小时2倍床体积(bed volume,BV),径高比1:9;先以30％乙醇3 BV除杂,再用80％乙醇4 BV洗脱,洗脱容积流量1 BV/h,洗脱液浓缩、干燥,得蜂胶总黄酮Ⅰ,纯度为41.42％;取蜂胶总黄酮Ⅰ1.2 g,用少量甲醇超声溶解,上样于Sephadex LH-20层析柱,以甲醇洗脱,洗脱流速0.75 mL/min,7.5 mL作为一个流份收集,以三氯化铝为显色剂,聚酰胺薄层色谱检识各流份,合并、干燥得蜂胶总黄酮Ⅱ,纯度为68.48％.结论 HPD-722型大孔吸附树脂联合Sephadex LH-20葡聚糖凝胶可有效纯化蜂胶总黄酮.     

Heat Induced Changes to Dental Resin Composites: A Reference in Forensic Investigations?*

The objective was to investigate color change and surface damage in dental resin composites exposed to high temperatures over different time intervals for comparative purposes. Samples were prepared using two resins - Z100(R) (R1) and Charisma (R2), heated at the following temperatures: 200 degrees C, 400 degrees C, 600 degrees C, 1000 degrees C, for 15, 30 and 45 min (n = 104 for each resin sample). Color (DeltaE) and brightness (DeltaL) changes were analyzed by spectrophotometry using the CIE Lab system and surface changes by Scanning Electron Microscopy (SEM). R1 showed more intense color changes after heat exposure than R2. DeltaL values were found to be the best parameter for evaluation of light and color change. A biphasic pattern after thermal exposure was detected, from dark brown to light white. SEM showed more intense alterations in R2 than in R1. These results indicate that the parameters observed in both resins are useful as a guide in forensic analyses.     

Age determination of ballpoint pen ink by thermal desorption and gas chromatography-mass spectrometry

Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography-mass spectrometry (GC-MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed.     

氨基树脂漆的傅立叶变换红外光谱分析

根据红外谱图的相似程度决定两种涂料是否属同一种类的涂料是最基本也是最初级的检验方法,不可避免地带有极大的盲目性,只有把握了特征峰所代表的基团的振动形式,才能准确地识谱,正确地鉴别.本文介绍了氨基树脂漆的傅立叶变换红外光谱分析及谱图解释.     

汽车罩光漆的ATR-FTIR法检验

目的通过对油漆样品罩光漆成膜物质的检验以区分不同汽车厂家的油漆样品。方法采用衰减全反射红外光谱法（Fourier Transform Infrared Spectroscopy Attenuated Total Reflection Spectroscopy,ATR-FTIR）研究15个汽车厂家提供的356份油漆样品的罩光漆成膜物质。结果在所有油漆样品中,丙烯酸漆出现的频率最高,氨基漆出现的频率最低;在所有厂家中,使用丙烯酸漆的厂家最多,使用氨基氨酯混合漆的厂家最少;在使用相同罩光漆的不同厂家的油漆样品中,通过比较红外谱图可以对样品进一步区分。结论 ATR-FTIR法能够在一定程度上区分不同汽车厂家的油漆样品,从而大大缩小侦查范围,对于涉车案件的快速侦破具有非常重要的作用。     

Potency of delta 9-THC and other cannabinoids in cannabis in England in 2005: implications for psychoactivity and pharmacology

Gas chromatography was used to study the cannabinoid content ("potency") of illicit cannabis seized by police in England in 2004/5. Of the four hundred and fifty two samples, indoor-grown unpollinated female cannabis ("sinsemilla") was the most frequent form, followed by resin (hashish) and imported outdoor-grown herbal cannabis (marijuana). The content of the psychoactive cannabinoid delta 9-tetrahydrocannabinol (THC) varied widely. The median THC content of herbal cannabis and resin was 2.1% and 3.5%, respectively. The median 13.9% THC content of sinsemilla was significantly higher than that recorded in the UK in 1996/8. In sinsemilla and imported herbal cannabis, the content of the antipsychotic cannabinoid cannabidiol (CBD) was extremely low. In resin, however, the average CBD content exceeded that of THC, and the relative proportions of the two cannabinoids varied widely between samples. The increases in average THC content and relative popularity of sinsemilla cannabis, combined with the absence of the anti-psychotic cannabinoid CBD, suggest that the current trends in cannabis use pose an increasing risk to those users susceptible to the harmful psychological effects associated with high doses of THC.     

Applications of Blue Light‐curing Acrylic Resin to Forensic Sample Preparation and Microtomy

This study discusses the results of an evaluation of a one‐part blue light‐curing acrylic resin for embedding trace evidence prior to the preparation of thin sections with a microtome. Through a comparison to several epoxy resins, the physical properties relevant to both trace evidence examination and analytical microscopy in general, including as viscosity, clarity, color, hardness, and cure speed, were explored. Finally, thin sections from paint samples embedded in this acrylic resin were evaluated to determine if, through smearing or impregnation, the resin contributed to the infrared spectra. The results of this study show that blue light‐curing acrylic resins provide the desired properties of an embedding medium, generate high‐quality thin sections, and can significantly simplify the preparation of paint chips, fibers and a multitude of other types of microscopic samples in the forensic trace evidence laboratory.     

Fluorescence and Structural Degradation in Composite Resins as a Function of Temperature*

Abstract: Detecting composite resin upon postmortem examination can be difficult. Ultraviolet illumination has been suggested to ease location of this material; however, this may not be advisable in incineration situations. Understanding of the chemical and physical properties of resin as a function of temperature is an important parameter in identification of this material in incineration circumstances. Twenty-seven discs of resin, Quixx (Dentsply), Filtek Supreme (3 M), and Tetric Ceram (Ivoclar) were prepared and exposed to increasing heating conditions of 200°C–900°C in 100°C increments for 30 min. Analysis was performed with Fourier transform infrared spectroscopy, ultraviolet-visible light spectrophotometry, scanning electron microscopy/energy dispersive X-ray spectroscopy, optical microscopy, and UV illumination. Characterization of the material occurred at each temperature range. The organic components and the fluorescence properties were lost at temperatures above 300°C. The inorganic component remained through 900°C. This information can aid in detection of resin in high temperature circumstances.