Gas Chromatography With An Electron Capture Detector Research Articles

DETECTION OF SOME ORGANOCHLORINE PESTICIDES IN LARGE AFRICAN SNAILS FROM OJE MARKET, IBADAN, NIGERIA

Snails (Mollusca: Achatinadae) are crucial fauna species on earth that serve the functions of food and biological indicators of environmental pollution. Numerous chemical discharges from agricultural applications of pesticides and industrial outlets could destroy human body parts and deplete the environment. This study assessed the occurrence of some organochlorine pesticides in giant African snails from Oje Market, Ibadan, Nigeria. Aldrin, dichlorodiphenyltrichloroethane (DDT), and heptachlor epoxide levels were measured in snails taken at random from thirty (30) sample points in the Oje market in Ibadan. Snails were weighed, labeled, and then divided into three groups of ten (10). The forte extraction method was used, and gas chromatography with an electron capture detector (GC/ECD) was used to analyze the various pesticide types in the snail sample. The mean concentration of heptachlor epoxide is 41.65 mg/kg, higher than aldrin and dichlorodiphenyltrichloroethane (9.44 mg/kg and 4.17 mg/kg, respectively). The concentrations of pesticides range from 4.27 mg/kg - 21.77 mg/kg for aldrin, 2.80 mg/kg to 6.92 mg/kg for dichlorodiphenyltrichloroethane, and 22.87 mg/kg to 75.15 mg/kg for heptachlor epoxide. The Pearson correlation coefficient between Aldrin and DDT is 0.939, while that of Aldrin and Heptachlor epoxide is 0.945, and that of Heptachlor epoxide and dichlorodiphenyltrichloroethane is 0.981. The analysis revealed a solid positive correlation between the concentration of pesticides. The pesticide levels observed in the snail samples exceeded those of the World Health Organization and the Food and Agriculture Organization. Therefore, snails' consumption should be monitored to avoid toxicity in humans.

Evaluation of the degree of contamination of breast milk by organochlorine pesticides in the Lower Amazon region: a preliminary study

The main source of human exposure to organochlorines is through food, especially food with a high fat content, such as breast milk, which is critical for child hood development. Therefore, it is important to analyze milk and other biological matrices for organochlorine pesticides (OCPs), and then determine the source of the OCP contamination. The objective of this study was to evaluate the degree of contamination by OCP residues and their metabolites in breast milk samples from the municipalities of Mojuí dos Campos and Belterra-Pará, Brazil. The OCPs analyzed were dichlorodiphenyltrichloroethane (DDT) and its metabolites (o,p'-DDT, p,p'-DDT, o,p'-DDE, p,p'-DDE, o,p'-DDD, and p,p'-DDD), aldrin, endrin, dieldrin, hexachlorocyclohexanes (α-HCH, β-HCH, lindane (γ-HCH), and δ-HCH­­), endosulfan α and β, endosulfan sulfate, heptachlor, and heptachlor epoxide. These substances were analyzed in 22 breast milk samples using gas chromatography with an electron capture detector (GC-ECD). Seven were contaminated with p,p'-DDT and/or p,p'-DDE. The mean p,p'-DDT and p,p’-DDE content in the contaminated samples was 0.0022 and 0.0152 mg·kg-1 of milk, respectively. This contamination may have been due to the inadequate application of DDT until the end of the 1990s for the control of tropical diseases, including malaria. Despite being a preliminary study, the number of contaminated samples was significant, which suggests the need to expand this study to other environmental and biological matrices.

Magnetic dispersive micro solid phase extraction method by Fe3O4/Ni/NixB magnetic nanoparticles for determination of endocrine disruptor pesticides

In this this work, magnetic adsorbent Fe3O4/Ni/NixB nanocomposite was synthesized and used first time for the extraction of pesticides. A magnetic dispersive micro solid phase extraction (MD-µ-SPE) procedure was developed using this nanocomposite. The synthesized magnetic nanoparticles were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET) measurements was also done for taking information on the nanocomposite material’s surface area, pore size, and adsorption properties. Statistical the parameters related to the extraction efficiency were screened by statistical experimental design methods including Plackett Burmann and Box-Behnken for optimization purposes. The extraction performance of Lambda-Cyhalothrin (LMD) and Bromopropylate (BRP) pesticides in well water samples was tested using gas chromatography with an electron capture detector (GC-ECD). Under the optimized conditions, linear calibration plots were obtained by the regression coefficients (>0.99), and the linear range was found to be between 0.1 and 5 ng mL−1. The detection limits and recovery values for LMD and BRP were calculated as 0.03–0.02 ng mL−1 and 90–89% respectively. The enrichment factors were calculated as 30.3 for BRP and 393 for LMD. This work shows the potential of the magnetic adsorbent Fe3O4/Ni/NixB nanocomposite as an alternative sorbent for the MD-µ-SPE extraction procedure.

Pesticide Residues and Effect of Household Processing in Commonly Consumed Vegetables in Jimma Zone, Southwest Ethiopia.

The long-term and indiscriminate use of pesticides has resulted in serious health effects. Aside from that, developing countries do not have any monitoring systems in place to prevent the consumption of high levels of pesticides in foods. Therefore, this study aimed to determine pesticide residues and the effect of processing in commonly consumed vegetables in the southwestern part of Ethiopia. In total, 12 samples of 1 kg of each type of vegetable were collected from selected markets. Moreover, as a solution to pesticide residue problems in vegetables, the effect of different processing methods such as washing, peeling, boiling, and their cumulative effect was studied. In the analytical procedure, the modified Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction with florisil as a cleanup sorbent was used and the identification of pesticides was done by using gas chromatography with an electron capture detector (GC-ECD). The parent p,p'-DDT was detected at a concentration of 0.015 mg/kg in potato samples from the Serbo market and a concentration of 0.516, 0.232, 0.174, and 1.512 mg/kg in Merkato, Kochi, Serbo, and Shebe onion samples, respectively. P`p-DDT is detected at a high concentration compared to its metabolites (p,p'-DDE and p,p'-DDD), which is an indication of recent use. DDT and its metabolites, other organochlorines (lindane, γ-chlordane, dimethachlor, and heptachlor), and pyrethroids (cypermethrin and deltamethrin) exceeded the recommended limits by FAO and WHO in multiple samples of potato, onion, and cabbage. The processing result showed that washing, boiling, and the combination of the two revealed a 100% reduction in o,p'-DDT, and p,p'-DDT pesticides detected in cabbage. In conclusion, multiple residues were detected in the three vegetables studied, indicating that pesticides were applied intensively. Pesticide levels were reduced by home processing procedures, which is important for consumer safety.

Dissipation of fluazinam in citrus groves and a risk assessment for its dietary intake.

Citrus is one of the most important fruit crops worldwide. Fluazinam is a fungicide that is used to control fungal diseases, and its dissipation and residue in citrus fruits should be studied. A Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) procedure combined with gas chromatography with an electron capture detector (GC-ECD) has been developed. The fortified recoveries ranged from 82.1% to 105.9%, with relative standard deviations (RSDs) of less than 5.7%. Fluazinam dissipated relatively quickly following first-order kinetics, with a half-life of 8.5-9.5 days. The experiments on the terminal residue of fluazinam in citrus were conducted at six locations in China, and the risk quotient (RQ) method was applied to citrus fruits for dietary exposure risk assessment based on the terminal residue test. The RQs of fluazinam at three preharvest intervals (PHIs) (21, 28, and 35 days) were all less than 100%, which is an acceptable level for human consumption. The present study provides a reference for the establishment of maximum residue limit (MRL) for fluazinam in citrus. The dissipation and residues of fluazinam in citrus were monitored. The half-life of less than 10 days showed that fluazinam could degrade relatively easily in citrus. The risk assessment also indicated the intake safety of fluazinam in citrus. © 2019 Society of Chemical Industry.

SPME Extraction Methods of Doped Organochlorine Pesticides in Moroccan Water Samples

To investigate Organochlorine (OC) in Moroccan water samples, two different methods of extraction being the solid phase micro extraction (SPME) and the liquid-liquid extraction (LLE) are exploited. The gas chromatography with an electron capture detector (GC-ECD) and the gas chromatography coupled to a mass spectrum (GC-MS) are elaborated. In order to get the best extraction, different process parameters are cheeked and optimized. The relevant results are obtained using a time of unspecific binding properties of 30 minutes’ duration and mode of agitation for 30 min with agitation by a magnetic stirrer and a temperature of 30 °C. In particular, a comparative study between the results of SPME and LLE coupled to (GC-ECD) and (GC-MS), respectively, are given. Concretely, it has been found that the SPME extraction technique is a very useful method to analyze the pesticide residues in water samples controlled by local laboratories.

Residue and distribution of triforine in different cultivars and fruit periods of watermelon under field conditions

The dissipation of triforine in the immature and mature fruit periods was investigated under field conditions. Residue levels of triforine in watermelon were determined by gas chromatography with an electron capture detector (GC-ECD). The decline curves of triforine residues in the watermelon corresponded with first-order kinetics. The half-lives of triforine in Dark Belle and Shiny Boy were 2.10–2.57 days and 2.31–2.67 days respectively. Meanwhile, the half-lives of triforine in the immature and mature fruit periods were 1.69–2.04 days and 2.89–3.85 days, respectively. In the terminal residue experiment, the terminal residues of triforine in the watermelon flesh and peel were below 0.01 mg/kg to 0.05 mg/kg and 0.03 mg/kg to 0.36 mg/kg, respectively. The dissipation rates of triforine varied in different cultivars of watermelon, and even in the same cultivar, the half-lives of triforine significantly varied in the different fruit periods. Although triforine is a fungicide within the suction, the terminal residues in the peel and flesh were very significant.

Development, validation and matrix effect of a QuEChERS method for the analysis of organochlorine pesticides in fish tissue

ABSTRACTThis study aims to develop and validate a method to determine OCPs in fish tissues, minimizing the consumption of sample and reagents, by using a modified QuEChERS along with ultrasound, d-SPE and gas chromatography with an electron capture detector (GC-ECD), refraining the pooling. Different factorial designs were employed to optimize the sample preparation phase. The validation method presented a recovery of around 77.3% and 110.8%, with RSD lower than 13% and the detection limits were between 0.24 and 2.88 μgkg−1, revealing good sensitiveness and accuracy. The method was satisfactorily applied to the analysis of tissues from different species of fish and OCPs residues were detected. The proposed method was shown effective to determine OCPs low concentrations in fish tissues, using small sample mass (0.5 g), making the sample analyses viable without the need for grouping (pool).

Fabrication of cross-linked hydrazone covalent organic frameworks by click chemistry and application to solid phase microextraction

Covalent organic frameworks (COFs) are an emerging class of porous organic frameworks with diverse promising applications. Herein, we presented the first example of cross-linked hydrazone COFs (cross-linked COFs) coating via thiol-ene click chemistry for solid phase microextraction (SPME). Strong covalent bonds and interlayer of the prepared networks ensured the adsorption capacity and durability of the novel SPME fiber. π-π conjugated structure existed because of abundant phenyl rings and –C=N groups in the cross-lined COFs. A series of characterizations indicated that the cross-linked COFs possessed large surface areas, high porosities and stabilities as well as hydrophobicities. The fiber was applied to SPME of pesticide residues coupled with gas chromatography with an electron capture detector (GC-ECD). Under the optimum experimental conditions, enhancement factors in the range of 2190–10,998 were obtained, illustrating that the cross-linked COFs possessed remarkable preconcentration ability. The low detection limits of 0.0003–0.0023ngkg−1 were achieved with relative standard deviations (RSDs) in the range of 3.4–7.6% (intra-batch) and 5.7–11.6% (inter-batch), respectively. Recovery values in the range of 78.2–107.0% were obtained when the SPME-GC method was applied to the analysis of pesticides in cucumber samples.

Multi-residue analysis of 26 organochlorine pesticides in Alpinia oxyphylla by GC-ECD after solid phase extraction and acid cleanup.

A simple and effective multi-residue method was developed and validated for the analysis of 26 organochlorine pesticide residues in Alpinia oxyphylla by a gas chromatography with an electron capture detector (GC-ECD). The target pesticides were extracted by sonication and cleaned up with florisil solid phase extraction and sulphuric acid. Some crucial parameters, including extraction solvent and time, sorbent type, elute solvent and concentration of sulphuric acid were optimized to improve the performance of sample preparation procedure. The optimized method gave high sensitivity with detection limit ranging from 0.1 to 2.0μg/kg. Matrix-matched calibration was employed for the quantification, and a wide linear range (from 1.0 to 1000μg/kg) with r(2) values ranging from 0.9971 to 0.9998 was obtained. For the majority of the tested pesticides, the average recoveries were in acceptable range (between 70% and 110%) with relative standard deviation values below 15.0%. Matrix effect was evaluated for target compounds through the study of ratio of peak area obtained in the solvent and blank matrix. The proposed method was applied to simultaneously analyze 26 pesticides in 55 batches of Alpinia oxyphylla samples. 3 samples were found to be positive with four pesticides (α-BHC, quintozene, trans-chlordane and op'-DDD), which were confirmed by gas chromatography-mass spectrometry (GC-MS) in selective ion monitoring (SIM) mode.

Analysis of pesticide residue in fruits and vegetables using analytical protocol based on application of the QuEChERS technique and GC-ECD system

The QuEChERS sample preparation method was used for the determination of ten pesticides and their metabolites in fruits (apples, grapes) and vegetables (tomatoes, peppers), coupled to gas chromatography with an electron capture detector (GC-ECD). The experimental parameters including the amount of the sample, types of solvents, extraction time and types of sorbents at the purification stage were optimised. The GC-ECD method was validated in terms of its linearity, selectivity and recovery. The limits of detection for all investigated analytes ranged from 0.003 to 0.011 mg kg−1 and limits of quantification ranged from 0.009 to 0.03 mg kg−1. The mean recoveries from four matrices for development method ranged from 70 to 120%, with relative standard deviations in the range of 3.9 to 7.2% for all ten test compounds. The method has been demonstrated to be convenient and reliable for routine monitoring of pesticides and their metabolites in fruits and vegetables. The QuEChERS approach takes advantages of the wide analytical scope and high degree of selectivity and sensitivity, It is simple, rapid and requires low solvent consumption, which, in the era of green chemistry, represents a significant advantage. Therefore, this technology is of great interest because of its favourable toxicological, environment and economic aspects.

Contamination of fish in important fishing grounds of the Czech Republic

The aim of this study was to compare the contamination levels of certain important fishing grounds in the Czech Republic and to assess the health risk of consuming the fish from these localities. The assessment was performed from 2006 to 2010 in 27 fishing grounds. Within this project, 707 fish from 14 different species were sampled. The concentration of selected toxic metals (Hg, Pb, Cd) and persistent organic pollutants (POPs), such as non-dioxin-like polychlorinated biphenyls (NDL-PCBs), hexachlorocyclohexane (HCH) isomers, dichlorodiphenyltrichloroethane (DDT) and its metabolites (o,p´-DDE; p,p´-DDE; o,p´-DDD; p,p´-DDD; o,p´-DDT; p,p´-DDT) and hexachlorobenzene (HCB), were analysed in the muscle tissue of the sampled fish. Atomic absorption spectrometry (AAS) was used for the analysis of toxic metals. All of the POPs were analysed using gas chromatography with an electron capture detector (GC/ECD). Common bream (Abramis brama) was chosen as a reference fish species for the comparison of fishing grounds. Mercury was found as a major pollutant in fish flesh at all of the sampling sites. Concentrations in excess of the maximum level (ML) of mercury in the muscle tissue of fish (0.5mgkg−1) were registered in 32 samples. Concentrations of other monitored toxic metals in fish muscle were low, typically below the limit of quantification (LOQ). From the tested POPs, DDTs and NDL-PCBs were found as major pollutants. ML for NDL-PCBs (ICES-6) in muscle tissue of fish (0.125mgkg−1) was exceeded in 7 samples. In case of tested pesticides, concentrations in excess of the MRL were not registered.

Biomarker Measurements of Prenatal Exposure to Polychlorinated Biphenyls (Pcb) in Umbilical Cord Blood from Postpartum Hispanic Women in Brownsville, Texas

Biomarkers of polychlorinated biphenyls (PCB) were measured in both maternal and umbilical cord blood from 35 pregnant Hispanic women living in Brownsville, TX. Gas chromatography with an electron capture detector (GC/ECD) was used to analyze for 22 PCB analytes. Results indicated that both pregnant mothers and their fetuses were exposed to a variety of PCB at relatively low levels (≤0.2 ng/ml), and that concentrations in maternal and cord blood were similar. Concentrations of total PCB (sum or all PCB congeners) averaged more than 2.5 ng/ml, with highest values exceeding 3 ng/ml. Although health implications are uncertain, reports in the literature of PCB-related health effects raise concerns about possible future health consequences, especially obesity and diabetes, in this potentially vulnerable population.

Optimization of HS-SPME analytical conditions using factorial design for trihalomethanes determination in swimming pool water samples

Trihalomethanes (THMs) are widely referred and studied as disinfection by-products (DBPs). The THMs that are most commonly detected are chloroform (TCM), bromodichloromethane (BDCM), chlorodibromomethane (CDBM), and bromoform (TBM). Several studies regarding the determination of THMs in swimming pool water and air samples have been published. This paper reviews the most recent work in this field, with a special focus on water and air sampling, sample preparation and analytical determination methods.An experimental study has been developed in order to optimize the headspace solid-phase microextraction (HS-SPME) conditions of TCM, BDCM, CDBM and TBM from water samples using a 23 factorial design. An extraction temperature of 45°C, for 25min, and a desorption time of 5min were found to be the best conditions. Analysis was performed by gas chromatography with an electron capture detector (GC-ECD).The method was successfully applied to a set of 27 swimming pool water samples collected in the Oporto area (Portugal). TCM was the only THM detected with levels between 4.5 and 406.5μgL−1. Four of the samples exceeded the guideline value for total THMs in swimming pool water (100μgL−1) indicated by the Portuguese Health Authority.

GC-ECD와 GC-MSD를 이용한 유니코나졸 잔류실태조사

본 연구에서는 2012년 1월부터 8월까지 농산물 중 엽채류에 대하여 GC-ECD 및 GC-MSD를 이용하여 uniconazole의 잔류실태조사를 실시하였다. 겨자채에 표준용액을 0.05, 0.5 mg/kg 농도로 하여 회수율을 측정한 결과 98.9%에서 109.4%까지 양호한 결과를 나타내었다. 2012년 1월부터 8월까지 서울지역에 유통되고 있는 농산물 중 엽채류 3,632건에 대하여 모니터링을 실시한 결과 14건에서 uniconazole이 검출되었다. Uniconazole의 검출양은 0.098 mg/kg에서 2.2 mg/kg로 나타났다. 본 연구를 통하여 동시분석법으로 보다 효율적인 검사가 가능할 것으로 기대된다. We evaluated the presence of uniconazole residual pesticide in agricultural products by using multiclass pesticide multiresidue methods. Samples were collected from January to August, 2012. The pesticide was detected in 14 samples among the 3,632 samples tested. Amount of the uniconazole pesticide ranged from 0.098 to 2.2 mg/kg in the 14 samples. This method was described for the simultaneous determination of uniconazole by using gas chromatography with an electron capture detector (GC-ECD) and mass spectrometry (MS). For evaluating the GC-ECD method, uniconazole was spiked into gyeojachae at a level of 0.05, 0.5 mg/kg. The recoveries of uniconazole with the GC-ECD method ranged from 98.9-109.4%. The results indicate that our method of simultaneous analysis is applicable to uniconazole analysis.

Comparative study of different clean-up techniques for the determination of λ-cyhalothrin and cypermethrin in palm oil matrices by gas chromatography with electron capture detection

Solid phase extraction (SPE) and dispersive solid-phase extraction (d-SPE) were compared and evaluated for the determination of λ-cyhalothrin and cypermethrin in palm oil matrices by gas chromatography with an electron capture detector (GC-ECD). Several SPE sorbents such as graphitised carbon black (GCB), primary secondary amine (PSA), C(18), silica, and florisil were tested in order to minimise fat residues. The results show that mixed sorbents using GCB and PSA obtained cleaner extracts than a single GCB and PSA sorbents. The average recoveries obtained for each pesticide ranged between 81% and 114% at five fortification levels with the relative standard deviation of less than 7% in all cases. The limits of detection for these pesticides were ranged between 0.025 and 0.05 μg/g. The proposed method was applied successfully for the residue determination of both λ-cyhalothrin and cypermethrin in crude palm oil samples obtained from local mills throughout Malaysia.

PCBs in wild mussels (Mytilus galloprovincialis) from the N–NW Spanish coast: Current levels and long-term trends during the period 1991–2009

Concentrations of polychlorinated biphenyls (PCBs) were determined in wild mussels (Mytilus galloprovincialis) from seven areas of the N–NW Spanish coast, during the period 1991–2009. The studied area is comprised of highly productive ecosystems which support important commercial fishing and shellfishing activities. The seven PCBs indicator congeners recommended by ICES (IUPAC nos. 28, 52, 101, 118, 138, 153 and 180), were analysed by gas chromatography with an electron capture detector (GC-ECD). Lowest average concentrations of PCBs were recorded in Arousa (1.04μgkg−1 wet weight), a low populated area with no industry; while the highest levels were found in areas near cities and/or showing a high industrial activity such as: Bilbao Ziérbena (139μgkg−1ww) or A Coruña (55μgkg−1ww). The hexachlorinated congeners CB153 and CB138 dominated the profiles in all wild mussel populations, although a geographical pattern was found in which the relative contributions of the lower chlorinated congeners were higher in the west coast (Rías of Vigo, Pontevedra and Arousa), which may reflect the occurrence of recent inputs of those compounds in the area. Finally, the application of the Mann–Kendall’s test demonstrate the existence of a significant decrease in PCBs levels since 1991 up to 1996 in the studied area, whereas either a slow decrease or stable concentrations were registered over the past decade.

Dissipation and residue of dimethomorph in pepper and soil under field conditions

The dissipation and residual levels of dimethomorph in pepper and soil under field conditions were determined by gas chromatography with an electron capture detector (GC-ECD). The dissipation rates of dimethomorph were described using first-order kinetics and its half-life ranged from 1.7 to 3.8 days in pepper and 11.5–18.5 days in soil. At harvest time, the terminal residues of dimethomorph were below the EU's maximum residue limit (MRL, 0.5 mg kg −1) in pepper when measured 7 days after the final application, which suggested that the use of this fungicide was safe for humans. The collected field samples were stable for up to two months when refrigerated at −20 °C. The residues persistence varied among three geographically separated experimental fields, suggesting that it might be affected by climatic, soil properties and local microorganisms. These results will be helpful in setting MRL guidance for dimethomorph in pepper in China.

Determination of persistent cyclic organochlorine residues in sediment slurry by microporous membrane liquid-liquid extraction and gas chromatography-mass spectrometry

A method, using microporous membrane liquid-liquid extraction technique (MMLLE) and gas chromatography with an electron capture detector (GC-ECD) and gas chromatograph coupled to a mass spectrometer, was developed for the analysis of cyclic organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in sediment slurry. The MMLLE extraction employed isooctane as the organic liquid that was immobilised in the hollow fibre pores and in the lumen, at optimal sample pH value of 2.0 for OCPs and 7 for PCBs. The effect of triton x-100, in enhancing the dissolution of the compounds from sediment, was found to be optimal at a value of 0.15%, while the ionic strength was optimal at a value of 0.01 M. Samples from coastlines along the Indian Ocean in the southern parts of South Africa were found to be contaminated with cis and trans chlordane at concentrations of up to 0.003 mg/kg, while samples from northern parts were contaminated with 2,2’,4’,4-tetrachloro-1,1’biphenyl at concentrations of up to 0.02 mg/kg.Keywords: Organochlorine pesticides, polychlorinated biphenyls, hollow fibre liquid phase micro-extraction, high performance liquid chromatography, mass spectrometry

Explosive Contamination from Substrate Surfaces: Differences and Similarities in Contamination Techniques Using RDX and C-4

Explosive trace detection equipment has been deployed to airports for more than a decade. During this time, the need for standardized procedures and calibrated trace amounts for ensuring that the systems are operating properly and detecting the correct explosive has been apparent but a standard representative of a fingerprint has been elusive. Standards are also necessary to evaluate instrumentation in the laboratories during development and prior to deployment to determine sample throughput, probability of detection, false positive/negative rates, ease of use by operator, mechanical and/or software problems that may be encountered, and other pertinent parameters that would result in the equipment being unusable during field operations. Since many laboratories do not have access to nor are allowed to handle explosives, the equipment is tested using techniques aimed at simulating the actual explosives fingerprint. This laboratory study focused on examining the similarities and differences in three different surface contamination techniques that are used to performance test explosive trace detection equipment in an attempt to determine how effective the techniques are at replicating actual field samples and to offer scenarios where each contamination technique is applicable. The three techniques used were dry transfer deposition of standard solutions using the Transportation Security Laboratory’s (TSL) patented dry transfer techniques (US patent 6470730), direct deposition of explosive standards onto substrates, and fingerprinting of actual explosives onto substrates. RDX was deposited on the surface of one of five substrates using one of the three different deposition techniques. The process was repeated for each substrate type using each contamination technique. The substrate types used were: 50% cotton/50% polyester as found in T-shirts, 100% cotton with a smooth surface such as that found in a cotton dress shirt, 100% cotton on a rough surface such as that found on canvas or denim, suede leather such as might be found on jackets, purses, or shoes, and painted metal obtained from a car hood at a junk yard. The samples were not pre-cleaned prior to testing and contained sizing agents, and in the case of the metal, oil and dirt. The substrates were photographed using a Zeiss Discover V12 stereoscope with Axiocam ICc1 3 megapixel digital camera to determine the difference in the crystalline structure and surface contamination in an attempt to determine differences and similarities associated with current contamination deposition techniques. Some samples were analyzed using scanning electron microscopy (SEM) and some were extracted and analyzed with high performance liquid chromatography (HPLC) or gas chromatography with an electron capture detector (GC-ECD) to quantify the data.