Forensic discrimination of photocopy and printer toners I. The development of an infrared spectral library

Microscopical reflection-absorption by infrared spectroscopy (R-A IR) was shown as a viable technique for analyzing the polymer resins contained in dry, black photocopy and printer toners. The sampling technique involves a heat transfer of the toner from a document to the reflective surface of aluminum foil followed by analysis by R-A IR. The technique is simple, fast, and readily available to most forensic laboratories. A searchable spectral library was created that contains 807 toner samples analyzed by R-A IR. Ninety-eight groups were established based on spectral characteristics, and a flowchart was developed to assist with group assignments. A blind study was conducted to compare twenty photocopied documents each paired to a test document to determine if the pair could have been produced from the same copier. The analyst obtained 100% correct results in this study. Tests on thirty samples with the spectral library produced 90% first hits for the correct group. The three remaining samples were correctly determined by visual comparison of spectra for the top three hits. An actual case study was conducted where the investigation was narrowed from 400 possible machines to eight based on a comparative study of the photocopy toners.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00216-003-2073-0This is publication number 03-02 of the Laboratory Division of the Federal Bureau of Investigation. Names of commercial manufacturers are provided for identification only and inclusion does not imply endorsement by the Federal Bureau of Investigation. This paper was presented in part as a poster at the International Symposium on the Forensic Examination of Trace Evidence in Transition, San Antonio, Texas, 24–28 June 1996.     

Forensic discrimination of photocopy and printer toners II. Discriminant analysis applied to infrared reflection-absorption spectroscopy

Copy toner samples were analyzed using reflection-absorption infrared microscopy (R-A IR). The grouping of copy toners into distinguishable classes achieved by visual comparison and computer-assisted spectral matching was compared to that achieved by multivariate discriminant analysis. For a data set containing spectra of 430 copy toners, 90% (388/430) of the spectra were initially correctly grouped into the classifications previously established by spectral matching. Three groups of samples that did not classify well contained too few samples to allow reliable classification. Samples from two other pairs of groups were similar and often misclassified. Closer examination of spectra from these groups revealed discriminating features that could be used in separate discriminant analyses to improve classification. For one pair of groups, the classification accuracy improved to 91% (81/89) and 97% (28/29), for the two groups, respectively. The other pair of groups were completely distinguishable from one another. With these additional tests, multivariate discriminant analysis correctly classified 96% of the 430 R-A IR toner spectra into the toner groups found previously by spectral matching.This is publication number 03–03 of the Laboratory Division of the Federal Bureau of Investigation. Names of commercial manufacturers are provided for identification only, and inclusion does not imply endorsement by the Federal Bureau of Investigation.     

Direct exposure electron ionization mass spectrometry and gas chromatography/mass spectrometry techniques to study organic coatings on archaeological amphorae

Two different analytical approaches, direct exposure electron ionization mass spectrometry (DE-MS) and gas chromatography/mass spectrometry (GC/MS), were compared in a study of archaeological resinous materials. DE-MS was found to be an efficient fingerprinting tool for the fast screening of organic archaeological samples and for providing information on the major components. GC/MS appeared to be more efficient in unravelling the sample composition at a molecular level, despite the long analysis time and the need for a wet chemical pretreatment. Both procedures were applied to characterize the organic material present as coatings in Roman and Egyptian amphorae. DE-MS successfully identified abietanic compounds, hence a diterpenic resinous material could be identified and its degree of oxidation assessed. GC/MS enabled us to identify dehydroabietic acid, 7-oxodehydroabietic acid, 15-hydroxy-7-oxodehydroabietic acid, 15-hydroxydehydroabietic acid, retene, tetrahydroretene, norabietatriene, norabietatetraene and methyl dehydroabietate. These oxidized and aromatized abietanes provided evidence that the amphorae examined were waterproofed with a pitch produced from resinous wood of plants from the Pinaceae family. The chemometric evaluation of the GC/MS data highlighted significant chemical differences between the pitches found in the two archaeological sites, basically related to differences in the production techniques of the materials and in their degradation pathways.     

Combination of liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry for the detection of 21 anabolic steroid residues in bovine urine

For the detection of anabolic steroid residues in bovine urine, a highly sensitive liquid chromatographic/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method was developed using both positive and negative ionization. For four compounds the ESI mode was not sensitive enough and gas chromatographic/mass spectrometric GC/MS detection was therefore still necessary as a complementary method. The sample clean-up consisted of solid-phase extraction (SPE) on a C(18) column followed by enzymatic hydrolysis and a second solid-phase extraction on a combination of a C(18) and a NH(2) column. After this last SPE clean-up, the eluate was split into two equal aliquots. One aliquot was further purified and after derivatization used for GC/MS analysis. The other aliquot was analyzed with LC/MS/MS in both ESI+ and ESI- modes. The method was validated according to the European Commission Decision 2002/657/EC. Decision limits (CCalpha) were between 0.16 and 1 ng ml(-1) for the compounds detected with the LC/MS/MS method. The developed method is used in routine analysis in our laboratory.     

气质联用法测定医用橡皮塞中防老剂BHT

橡胶具有高弹性,可获得良好的密封性能和再密封性能。通常在橡胶中加入少量的防老剂如2,6-二叔丁基对甲酚(BHT)来延缓其氧化过程,延长使用寿命。目前,化妆品、食品、塑料等制品中BHT的含量已受到严格的控制。在注射药剂的过程中,医用橡皮塞中的BHT会随着药液直接流人人体静脉,过量的BHT会给人体健康带来隐患。本文采用气质联用法测定了医用橡皮塞中的BHT。含量,采用总离子流图给出的质谱图进行定性,以m／z205作为选择离子,选择离子法(SIS)定量。     

气相色谱/质谱法测定大鼠脑中5-羟色胺的含量

采用气相色谱／质谱法（ＧＣ／ＭＳ）测定了正常大鼠和服药大鼠脑组织中５－羟色胺（５－ＨＴ）的浓度。大鼠脑组织制成匀浆后,先将５－ＨＴ酰化,酰化物经乙酸乙酯提取后,再经七氟丁酸酐衍生化,用ＧＣ／ＭＳ测定。ＭＳ采用电子捕获负离子化学电离（ＥＣＮＩＣＩ）模式。方法的线性范围为０．５０～５０．０μｇ／Ｌ,回归方程为Ｙ＝０．１３４８Ｘ－０．０７９９５（ｒ＝０．９９９６）;平均回收率为９８．２％±３．８％（ｎ＝１０）;检测限为０．５μｇ／Ｌ;相对标准偏差小于１０％。     

Capillary gas chromatography/mass spectrometry of aza-arenes isolated from crude coal tar

Summary The basic fraction of crude coal tar was isolated in a two-step partition process. Its constituents, mostly azaarenes up to four-ring structures, were resolved on a Superox-coated glass capillary column and tentatively identified by combined gas chromatography/mass spectrometry.     

捕集阱顶空气相色谱/质谱法测定水中的二氯一溴甲烷

建立了捕集阱顶空气相色谱/质谱测定水中二氯一溴甲烷的方法。采用正交实验设计对平衡温度、平衡时间、循环次数3个参数进行了优化,在平衡温度70 ℃、平衡时间20 min、循环次数2次的优化条件下,对水中的二氯一溴甲烷进行测定。结果显示,在0.1～10.0 μg/L范围内,二氯一溴甲烷的质量浓度和峰面积呈良好的线性关系,相关系数为0.9991。方法的检出限(S/N=3)为0.03 μg/L,定量限(S/N=10)为0.1 μg/L,回收率为83.1%～111.3%,相对标准偏差为1.7%～5.2%(n=6)。将该方法应用于水中二氯一溴甲烷的定性定量分析,效果良好。     

Pyrolysis–gas chromatography/mass spectrometry of peroxynitrite-treated melanins

Peroxynitrite—a strong oxidizing and nitrating agent—is thought to be a mediator of the cytotoxic action of nitric oxide in biological systems. There is some evidence that peroxynitrite-dependent processes may be involved in the pathomechanism of Parkinson's disease. Recently, it has been suggested that neuromelanin, present in the cytoplasm of nigrostriatal neurons, can act as natural scavenger of peroxynitrite. In this study the effect of peroxynitrite on the structure of synthetic models of human neuromelanin was investigated. Model neuromelanins, obtained from dopamine (DA) and/or 5-S-cysteinyldopamine (5-S-CysDA), were pyrolyzed at 770 °C before and after treatment with peroxynitrite and the thermal degradation products separated by gas chromatography were identified by mass spectrometry. After exposure to peroxynitrite, reduced content of the typical pyrolysis products accompanied by elevated levels of low molecular weight gases in the pyrolysates were observed. The changes in pyrolytic patterns were dependent on melanin type and peroxynitrite concentration. It was concluded that interaction with peroxynitrite causes extensive oxidative degradation of the analyzed pigments. This may be of great biological importance with regard to depigmentation of nigrostriatal neurons demonstrated in Parkinson's disease.     

Optimization of congener-specific analysis of 40 polybrominated diphenyl ethers by gas chromatography/mass spectrometry

The analysis by gas chromatography coupled with mass spectrometry (GC/MS) of 40 different congeners of polybrominated diphenyl ethers (PBDEs) containing 1-7 bromine atoms is described. Two different MS approaches were used, negative chemical ionization (NCI-MS) and electron ionization (EI-MS). Operating parameters such as electron energy and source temperature were optimized in order to obtain the maximum sensitivity in the EI-MS study. For NCI-MS analyses, the effects of the moderating gas (methane or ammonia), source temperature and system pressure were studied. The quality parameters of the two approaches tested were compared. NCI-MS gave detection limits between 30 fg and 1.72 pg, whereas EI-MS gave detection limits between 0.53 and 32.09 pg. The main advantage of EI-MS is that it provides better structural information. Moreover, the use of EI-MS allowed the use of an isotope dilution method for quantification, making the analysis more reliable at trace levels.     

Towards identification of traditional European and indigenous Australian paint binders using pyrolysis gas chromatography mass spectrometry

We report a pyrolysis GC–MS method capable of analysing Indigenous Australian and European binders typically used in the manufacture of culturally important painted works. Eleven different traditional European binders and ten different Indigenous Australian binders were examined. The method allows discrimination between highly complex and impure lipid, resin, polysaccharide, wax, and protein-based binders. Each was found to have characteristic pyrolysis products that were unique to the binder material, demonstrating the potential for differentiation of these binders on Australian Aboriginal artworks towards identification and conservation of cultural heritage.     

Rapid quality checking of polyethylene water/gas-pipelines: a model based on pyrolysis-gas chromatography/mass spectrometry and discriminant analysis

Eighty-five samples taken from polyethylene (PE) water/gas-ducts were pyrolyzed (from triplicate to 9-fold analyses) at 700 °C for 20 s in an N₂ atmosphere using a platinum coil pyrolyzer and a tube cooled in liquid nitrogen. The pyrolyzed products were identified and quantified by gas chromatography/mass spectrometry (GC/MS), and subjected to discriminant analysis. The samples included intact materials and sections fractured both in-field and following laboratory tests. Statistical data treatment allowed the samples to be subdivided into three groups. These groups were consistent with a pattern that fits well with sample rating after a modified stress-cracking test based on pipe resistance to increasing internal pressure. Such results can be explained through the relationship between pyrolysis (PY) fingerprint and polymer structure, which is in turn known to be related to the lifetime of the material. Compared with semi-empirical mechanical tests which are seldom used by water companies because of their lengthy duration, the PY and GC/MS approach is faster, simpler, cost effective, and provides molecular data on the original samples. The statistical models based on PY and GC/MS can be a valuable tool for water/gas companies that need to check the quality of PE pipes and predict their lifetime prior to purchase and installation, thus, helping companies set appropriate quality standards to reduce the occurrence of failures along operating pipelines.     

气相色谱/质谱法分析孔石莼中的脂肪酸

建立了孔石莼脂肪酸的气相色谱/质谱(GC/MS)测定方法。使用Folch法提取了孔石莼中的总脂,经过2 mol/L HCl-甲醇溶液的甲酯化处理后,采用GC/MS法对其脂肪酸组成进行了分离分析,同时结合有机质谱学规律,分别对饱和脂肪酸甲酯、单不饱和脂肪酸甲酯和多不饱和脂肪酸甲酯的裂解规律和质谱特征进行了分析归纳。通过质谱数据库检索和标准品对照,鉴定出孔石莼中的24种脂肪酸,其中9,12,15-十八碳三烯酸、4,7,10,13-十六碳四烯酸和6,9,2,15-十八碳四烯酸3种主要多不饱和脂肪酸占总脂肪酸含量的45.14%。通过对孔石莼中脂肪酸的分析,表明特征离子在脂肪酸甲酯尤其是多不饱和脂肪酸甲酯的定性方面具有很好的应用价值。     

Lignans in resin of Araucaria angustifolia by gas chromatography/mass spectrometry

Total extract of resin from Araucaria angustifolia was analyzed by gas chromatography/mass spectrometry and 32 lignans were identified. Lignan acetates are present in the resin and consist of four secoisolariciresinol acetates, six lariciresinol acetates, two 7'-hydroxylariciresinol acetates and an isolariciresinol acetate, which have hitherto not been reported in the plant kingdom. Shonanin and 7'-hydroxylariciresinol type lignans are also present in A. angustifolia resin. Lignans containing syringyl moieties, characteristic for angiosperms, occur in the resin and consist of 5-methoxylariciresinol-9-acetate, 5'-methoxylariciresinol-9-acetate, 5-methoxypinoresinol dimethyl ether and 5-methoxypinoresinol. This is noteworthy because syringyl moieties have only been reported for Thuja species (Cupressaceae) among the gymnosperms. The mass spectra of the various lignan trimethylsilyl derivatives are discussed with the interpretations of the fragmentation patterns.     

固相萃取-气相色谱-质谱联用法测定水中的硝基苯类有机污染物的分析方法研究

建立了固相萃取、毛细柱气相色谱-质谱、内标标准曲线法使用选择离子(SIM)监测采集数据定量分析水中硝基苯类有机化合物的分析方法.通过对固相萃取柱的选择、固相萃取条件(样品溶液的pH、上样速率、上样体积、洗脱液选择及配比)的优化,得出了最佳实验条件.始漏体积达1.5 L.回收率大于80%.检出限为0.015～0.045 μg/L.RSD在1.1%～5.9%之间.     

Quantitative analysis of memantine in human plasma by gas chromatography/negative ion chemical ionization/mass spectrometry

A sensitive and specific method for the determination of memantine in human plasma is presented. Memantine was extracted from plasma and derivatized to the pentafluorobenzoyl derivative in a one-step procedure avoiding any sample concentration steps. Amantadine was used as an internal standard. The compounds were measured by gas chromatography/negative ion chemical ionization mass spectrometry without any further processing. Using this detection mode, the fragment ions at m/z 353 and 325 were obtained at high relative abundance. Calibration graphs were linear over the range 0.117-30 ng ml(-1). At the limit of quantification (LOQ), the inter-assay precision was 2.00% and the intra-assay variability was 3.22%. The accuracy at the LOQ showed deviations of -1.42% (intra-assay) and -2.47% (inter-assay). The method is rugged, rapid and robust and was applied to the batch determination of memantine during pharmacokinetic profiling of the drug.     

Validated toxicological determination of 30 drugs of abuse as optimized derivatives in oral fluid by long column fast gas chromatography/electron impact mass spectrometry

An analytical procedure was developed for the simultaneous sensitive identification, screening and quantitation of 30 drugs of abuse using 250 microl of human oral fluid. The method employs sequential mixed-mode solid-phase extraction (SPE), optimized derivative formation and long-column fast gas chromatography/electron impact mass spectrometry (GC/EI-MS). After sequential SPE elution, the most sensitive and stable derivatives were formed by taking careful account of the characteristics of the active functional groups and possible steric hindrances affecting derivatization chemistry. Amphetamine-type stimulant drugs were acylated with heptafluorobutyric anhydride, benzodiazepines and Delta(9)-tetrahydrocannabinol were silylated with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide and benzoylecgonine, codeine, ethylmorphine, 6-monoacetylmorphine, morphine, pholcodine, buprenorphine and norbuprenorphine with N-methyl-N-(trimethylsilyl)trifluoroacetamide. In addition, the following analytes were included: methadone, cocaine, alprazolam, midazolam, fentanyl and zolpidem. In GC separation, fast temperature ramping and high carrier gas flow-rate combined with long 30 m columns of i.d. 0.32 mm offered a reduction in analysis time and sharp peak shapes while still maintaining sufficient resolution and high sample capacity. Validated parameters including selectivity, linearity, accuracy, intra- and inter-day precision, extraction efficiency and limit of quantitation were all within required limits. In contrast to previously published methods, this single procedure is suitable for the simultaneous toxicological determination of the most common illicit drugs and benzodiazepines, and also zolpidem, in a small amount of oral fluid.     

三重串联四级杆气质联用法测定化妆品中的三种邻苯二甲酸酯类增塑剂

建立了一种快速、灵敏、准确的三重串联四级杆气质联用(GC-MS/MS)法,将其用于同时检测化妆品中的三种邻苯二甲酸酯(邻苯二甲酸二丁酯、邻苯二甲酸丁基苄基酯、邻苯二甲酸二乙基己酯)增塑剂.化妆品经甲醇提取,HP-5MS柱分离,采用GC-MS/MS的多反应监测模式,以保留时间和离子对(母离子和子离子)信息比较定性,以母离子和响应值高的子离子进行定量.结果表明,该方法的检出限为12～28ng/g,相对标准偏差为1.6%～7.54%,目标物的加标回收率为86.4%～121.1%;该方法可用于检测日常化妆品中邻苯二甲酸酯的含量.     

溶剂转移-气相色谱-质谱法和选择洗脱-气相色谱法测定大蒜中289种农药多残留

以溶剂转移净化为核心步骤,建立了一种适用于大蒜样品中农药多残留分析的前处理方法(方法I),配以一个辅助方法(方法II),构成大蒜中常见289种农药多残留的分析体系(方法I283种,方法II6种)。方法I中,样品用乙腈-水溶液提取,盐析分配,溶剂转移和固相萃取(SPE)净化后进行气相色谱-质谱(GC-MS)分析;方法II中,样品用无水Na2SO4配合乙酸乙酯均质研磨,超声波辅助提取,提取液经Primary Secondary Amine (PSA)粉末分散固相萃取和LC-Si柱选择洗脱净化后进行GC分析。GC-MS采用选择离子监测(SIM)方式,GC采用火焰光度检测器(FPD)检测,外标法定量。方法简便、快速,通过优化前处理和上机条件,在最优条件下进行测试,方法的定量限(S/N≥10)为0.01～0.05 mg/kg。方法I中,在加标水平为0.02、0.20 mg/kg时,回收率为52%～163%,其中回收率在70%～120%之间的占88%,相对标准偏差为2.4%～18%;方法II中,在加标水平为0.01、0.02、0.10、0.20 mg/kg时,回收率为70%～111%,相对标准偏差为3.2%～9.3%。详细描述了实验模型的构建,并对GC-MS灵敏度的提高提出了新的见解。该方法准确、灵敏、快速,可满足大蒜中多种农药残留的检测要求。     

Determination of breath gas composition of lung cancer patients using gas chromatography/mass spectrometry with monolithic material sorptive extraction

A gas chromatographic–mass spectrometric method with monolithic material sorptive extraction (MMSE) pretreatment was developed to determine the breath gas composition in lung cancer patients. MonoTrap silica monolithic and hybrid adsorbent was selected as the extraction medium during MMSE, given its strong capacity to extract volatile organic compounds (VOC) from exhaled gas. Under the appropriate conditions, high extraction efficiency was achieved. Using the selected ion‐monitoring mode, the limit of detection (signal‐to‐noise ratio 3) for the benzene series was 0.012–2.172 ng L^?1. The limit of quantitation (signal‐to‐noise ratio, 10) was 0.042–7.24 ng L^?1. The linearity range of the method was 4–400 ng L^?1. Average recovery of the benzene series at lower concentrations was 65–74% (20 ng L^?1). The relative standard deviation of benzene series contents determined within the linear range of detection was <10% of the mean level determined. Our proposed method is simple, rapid and sensitive, and can be competently applied to determine the breath gas composition of lung cancer patients. Copyright © 2014 John Wiley & Sons, Ltd.