Programmed Temperature Vaporizer Research Articles

A lab-developed interface for liquid-gas chromatography coupling based on the use of a modified programmed-temperature-vaporizing injector

The main focus of the present research was the on-line coupling of two separation techniques, namely liquid chromatography (LC) and gas chromatography (GC). For such an analytical combination, a dedicated interface is required to remove solvent from the sample, leaving the latter in a sharp band at the head of the GC column. Considering such an objective, a lab-developed LC-GC interface is herein presented, based on the use of a six-port two-position valve and a programmed-temperature-vaporizing (PTV) injector. The PTV injector was derived from a commercial split/splitless injector body, heated using a resistance heating wire, and enabled a satisfactory recovery of low boiling compounds (≤ C13), working in the normal-phase mode. The lab-developed PTV injector allowed the use of a larger-volume liner (compared to the commercial one initially used), it being characterized by dimensions 95 mm length × 5.0 mm O.D. × 3.4 mm I.D. and a volume of 862 µL, thus facilitating the transfer of larger LC fractions. The developed system is fully automatized and controlled without the use of additional software. The interface was evaluated and used for the analysis of mineral oil saturated hydrocarbons in vegetable oils. Detection was carried out by using a flame ionization detector (FID), with quantification performed through external calibration, across the 5–1000 mg kg−1 range. The LC-GC-FID method linearity, limits of detection and quantification, accuracy and precision were measured. The resulting limits of detection and quantification values were 0.4 and 1.3 mg kg−1, respectively. The average accuracy at the 100 mg kg−1 level was 95.5% (ranging between 93.3 and 99.7%). Intra-day repeatability at levels of 5 and 100 mg kg−1 were 2.4% and 3.5%, respectively.

Fully Automated Determination of Trimellitic Anhydride in Saturated Polyester Resins Using Programmed Temperature Vaporization-Large Volume Injection-Gas Chromatography Previous Aqueous Derivatization with Triethyloxonium Tetrafluoroborate

Trimellitic anhydride (TMAn) is an essential starting material of the chemical manufacturing industry; it is widely used in saturated polyester resins (SPR) manufacturing to produce plasticizers for different purposes. TMAn was recently added, as a new substance of very high concern, to the candidate list by the European Chemicals Agency, since it can lead to sensitization, respiratory tract irritation and lung disease. Any substance from the list of candidates if present in manufactured products at concentrations above 0.1% (w/w) obliges the manufacturer to communicate this to customers down the supply chain and to consumers. We propose here a method that allows the fully automated determination of TMAn in SPR samples by using large volume injection (LVI), with programmed temperature vaporization (PTV) injection, in a gas chromatographic (GC) system equipped with ion trap mass spectrometer (IT) operating in tandem mass spectrometry (MS/MS). The method optimization was obtained by a chemometric model, using the experimental design. Introducing the use of short chromatographic column, triethyloxonium tetrafluoroborate (TEO) as derivatization agent and IS granted specificity, sensitivity and robustness. The detection and quantification limits for TMAn were 0.01% and 0.03% w/w, respectively. Trueness (between 94 and 98%) and precision (RSD lower than 10%, n = 6) were also assessed.

PTV In Situ Derivatization of Several Acidic Herbicides Using a Newly Developed GC-MS/MS Method

The uses of herbicides increased during the last decades. Because acid herbicides can be identified in environmental samples, specific analytical methods are required. In this work a new GC-MS/MS method was developed in order to detect some pyridinecarboxylic acids (clopyralid, triclopyr and fluroxypyr) and a methoxybenzoic acid (dicamba) from environmental water samples. Because these polar analytes involve a derivatization step, a Programmed Temperature Vaporizing injector (PTV) was used to shape the derivatization conditions and to minimize the working time. This process is called in port derivatization (IPD), a relative new technique which encourages greener practices in analytical laboratory. MtBSTFA was chosen to be the most suitable silylation agent due to generation of specific derivatized analyte structures, which can be further fragmented in the EI ionization source to produce specific ions for the targeted analytes, easily detectable with high sensitivity.Few studies analyzed the derivatization of above-mentioned herbicides with MtBSTFA, while no other paper work was identified in studying the in port derivatization of these compounds. The results revealed that the developed method is sensitive and robust to obtain quantitation limits below 10 ng/L.

Identification of Volatile Components in Tea Infusions by Headspace–Programmed Temperature Vaporization–Gas Chromatography–Mass Spectrometry (HS–PTV–GC–MS) with Chemometrics

In this work, the two-step headspace (HS) technique was applied to determine the actual volatile compositions of tea infusions. In order to eliminate the influence of water vapor to the gas chromatography-mass spectrometry (GC-MS) analysis and enable the capability to determine the volatile compounds in water base samples, a programed temperature vaporizer (PTV) was employed for the additional pre-concentration of thee analytes. While using the reported method, the volatile compounds were retained by the absorbent packed in the PTV, while the water vapor was directly removed through the purge valve. Then the retained volatile compounds were splitlessly injected into the GC column, which means that very low detection limits were achieved with the newly developed method. The obtained results demonstrated that the reported protocol possessed excellent repeatability and stability for volatile compound determination, and a total of 94 volatile compounds were identified from 28 teas. Multivariate data analysis was performed to obtain insights into the relationship between volatile compounds composition of the teas and their types. The volatiles composition of tea was shown to be closely related to the processing techniques adopted. Furthermore, the characteristic volatile compounds of each tea type were also illustrated. All of the results demonstrated that the presented method is a reliable approach to analyze and discriminate various beverages.

Organophosphate esters by GC-MS: An optimized method for aquatic risk assessment.

Organophosphate esters used as flame retardants and plasticizers are ubiquitous contaminants in surface waters. Many studies indicate that these compounds are neurotoxicants, endocrine disruptors, and may affect reproduction and development of aquatic organisms. Thus, analytical methods that allow accurate quantification of these contaminants at environmentally relevant concentrations are desirable for risk assessment studies. In this study, a method based on solid phase extraction and gas chromatography coupled to mass spectrometry was developed for determination of organophosphate esters in river water extracts. Multivariate optimization was used to determine the best conditions for injection of larger volumes of sample in a Programmable Temperature Vaporization inlet. Furthermore, the matrix effect on the instrumental response was evaluated and compensated by association of extraction-blank-matched calibration and isotopically labeled focus standards. The method quantification limits ranged from 0.009 to 0.11µg/L, staying below the predicted non-effect concentration for the aquatic compartment for all analytes, which is a requisite for using in risk assessment studies. The method was applied to freshwater samples collected in rivers from the Sao Paulo State, Brazil, and eight out of the ten target organophosphate esters were quantified, being tris(2-chloroisopropyl) phosphate and tris(phenyl) phosphate the most frequently detected compounds.

Influence of physical and chemical barrel sanitization treatments on the volatile composition of toasted oak wood

Various chemical and physical barrel sanitization methods were evaluated in terms of their effect on oak volatiles in situ. A gas chromatography–mass spectrometry (GC–MS) method using a programmable temperature vaporizing (PTV) injector in solvent-split mode was developed and validated for the analysis of oak volatiles extracted in aqueous acetone. Results revealed that barrel sanitization methods affected oak volatile compounds and that the degree of modification depended on the type of sanitization method and the duration or concentration of the applied treatment. Sanitization predominantly lowered concentrations of oak volatiles when hot water treatment at 80 °C, steam, ethanol treatment, and a 200 ppm peracetic acid treatment were applied. Gaseous sulphur dioxide, aqueous ozone, and hot water treatment at 60 °C, however, had no significant effect. This work provides the first direct comparison of an array of barrel sanitization methods in relation to their impact on desirable oak volatile compounds.

Optimization of Programmed Temperature Vaporization Injection for Determination of Polycyclic Aromatic Hydrocarbons from Diesel Combustion Process

In this study, programmed temperature vaporization in the solvent vent mode (PTV-SV) of gas chromatography-mass spectrometry was optimized and validated for the analysis of particle-phase and gas-phase polycyclic aromatic hydrocarbons from diesel engine combustion. Because of the large number of experimental and response variables to be studied, central composite inscribed design was used to optimize the PTV-SV injection factors, including initial inlet temperature, vaporization flow and time. The optimized PTV-SV method was validated by linearity, accuracy and sensitivity. For the 16 Polycyclic aromatic hydrocarbons (PAHs) studied, the correlation coefficients for the calibration plots of peak areas versus concentrations (0.5–300 ng mL−1) ranged from 0.9812–0.9998. Limits of detection ranged from 0.016–20,130.375 ng mL−1, and limits of quantification ranged from 0.055–1.25 ng mL−1. The optimized method was used for the analysis of real samples collected from a diesel engine, which included particle-phase and gas-phase PAHs. The results showed that the improved PTV-SV method was satisfying for simultaneously identifying and quantifying PAHs produced during diesel combustion.

Multiple headspace sampling coupled to a programmed temperature vaporizer to improve sensitivity in headspace-gas chromatography. Determination of aldehydes

The improvement of sensitivity in headspace (HS) sampling of not very volatile analytes constitutes a challenge that has usually been approached through coupling with additional techniques. Here we propose a new methodology for increasing sensitivity through a multistep approach. This proof of concept is based on direct coupling of a headspace sampler with a programmed temperature vaporizer (PTV) and a gas chromatograph (GC), with mass spectrometry (MS) detection. Analytes are extracted from the same vial in a stepwise procedure, splitting the headspace generation time of conventional HS into four periods and using the PTV to cryogenically trap the analytes during the successive HS samplings. Solvent vent mode is mandatory in order to retain the analytes, purging the gas solvent at an adequate initial low temperature and flash-heating the PTV liner in a quick ramp (720 °C/min), once the HS samplings are finished. Linear aldehydes, from pentanal to decanal, possible biomarkers of several diseases have been selected as model compounds. This multiple HS method has been compared with conventional HS, and it has been validated in terms of linearity, limits of detection, repeatability, reproducibility and accuracy. The limits of detection (LOD) ranged from 0.004 to 0.159 µg/L. Enrichment factors (EF) in relation to the conventional HS method ranged from 3.0 to 6.7, except for pentanal (EF: 0.8), which is too volatile and polar to be trapped in the PTV with the multiple HS methodology. Similar enrichment factors were obtained in a urine sample.

A sensitive and automatic method based on microextraction by packed sorbents for the determination of polycyclic aromatic hydrocarbons in saliva samples

A sensitive method for the quantification of polycyclic aromatic hydrocarbons (PAHs) in saliva samples is proposed. The method is based on the use of microextraction by packed sorbents (MEPS), injection with programmed temperature vaporizer (PTV), gas chromatography (GC) and mass spectrometry with a single quadrupole (MS). As far as we know, the MEPS technique has not been used to date for the analysis of PAHs in saliva samples.Sample treatment carried out only involves centrifugation and filtration of the saliva sample, which is subjected to the MEPS process without dilution. Standard addition was used as a calibration strategy, due to the matrix effect found using ultrapure water and among the different saliva samples. Nine saliva samples were analysed and phenanthrene was found (15 ± 6 ng L−1) in one of them.To confirm the accuracy of the method, the concentrations added in the standard additions were compared with the value predicted by the calibration model. The values ranged between 78 and 123%. The limits of detection (LOD) found in the saliva samples ranged between 4.6 and 79 ng L−1 and the repeatability and reproducibility were always equal to or lower than 10 and 17%, respectively.The main advantage of the proposed methodology over the existing ones is the complete automation of the analysis process (extraction, separation and detection). Once the saliva sample is placed in the vial, the entire process occurs on-line.

Determination of polyamines and related compounds in saliva via in situ derivatization and microextraction by packed sorbents coupled to GC-MS

Here we show the determination of different polyamines (putrescine, cadaverine, spermidine) and related compounds (gamma-aminobutyric acid and l-ornithine) in saliva samples. These compounds are known to be biomarkers for several diseases. We have optimised an in situ derivatization process using ethyl chloroformate, an automated microextraction by packed sorbent and the determination of the corresponding products using a programmed temperature vaporizer coupled to a gas chromatograph – mass spectrometer. After finding that saliva matrix has an effect on the analysis, quantitation was performed using the one-point standard additions method and normalization to IS. This allows the detection of the analytes in the range of µg/L within a matrix obtained by a non-invasive procedure. The method has been successfully validated and it has been used in the determination of these compounds in six saliva samples finding that putrescine and cadaverine present the highest concentrations in the subject diagnosed with rheumatoid arthritis. For ornithine and spermidine, the highest concentrations were found for male subjects, especially heavy smokers. All concentrations found for the compounds were in good agreement with data found in bibliography.

Non-separative method based on a single quadrupole mass spectrometer for the semi-quantitative determination of amino acids in saliva samples. A preliminary study

Amino acids have been of great interest in clinical studies since variation in their concentration may provide information about different disorders. For the first time, a non-separative method based on single quadrupole mass spectrometry (qMS) for the simultaneous semiquantitative determination of sixteen amino acids in saliva samples has been developed. The method includes derivatisation of amino acids with ethyl chloroformate-pyridine-ethanol to obtain volatile products, liquid-liquid extraction (LLE) and further analysis using a programmed temperature vaporizer (PTV) coupled to qMS. This method could be applied to the analysis of a great number of saliva samples, limiting the use of separative methods only when abnormal concentrations of amino acids were found, reducing analysis time and cost. The results obtained in the determination of amino acids using the non-separative method were compared to those obtained when a separative method based on gas chromatography (GC) was used, providing values of average relative predictive error (E %) ranging between 2 and 48%. Repeatability and reproducibility were tested, obtaining relative standard deviation (RSD) values equal to or lower than 11% and 16%, respectively. Detection limits were in the range of 0.076–8.747 mg L−1 for the non-separative method.

A Method for Controlled Odor Delivery in Olfactory Field-Testing.

A widely recognized limitation in mammalian olfactory research is the lack of current methods for measuring odor availability (i.e., the quantifiable amount of odor presented and thus available for olfaction) of training or testing materials during behavioral or operational testing. This research utilized an existing technology known as Controlled Odor Mimic Permeation Systems (COMPS) to produce a reproducible, field-appropriate odor delivery method that can be analytically validated and quantified, akin to laboratory-based research methods, such as permeation devices that deliver a stable concentration of a specific chemical vapor for instrumental testing purposes. COMPS were created for 12 compounds across a range of carbon chain lengths and functional groups in such a way to produce similar permeation rates for all compounds. Using detection canines as a model, field-testing was performed to assess the efficacy of the method. Additionally headspace concentrations over time were measured as confirmation of odor availability using either externally sampled internal standard-solid phase microextraction-gas chromatography-mass spectrometry (ESIS-SPME-GC-MS) or collection onto a programmable temperature vaporizing (PTV) GC inlet with MS detection. Finally, lifetime usage was considered. An efficient method for producing and measuring reliable odor availabilities across various chemical functional groups was developed, addressing a noted gap in existing literature that will advance canine and other nonhuman mammal research testing.

Part per quadrillion quantitation of pentaerythritol tetranitrate vapor using online sampling gas chromatography–mass spectrometry

The development of an online sampling method using programmable temperature vaporization gas chromatography with a mass spectrometer detector (PTV-GC/MS) for the analysis of trace pentaerythritol tetranitrate (PETN) vapor is presented. PETN degradation was minimized by optimizing the temperature and flow rates of the vapor sampling infrastructure. Validation of the online method was done using a previously published technique, vapor sampling with Tenax-TA thermal desorption tubes followed by analysis with a thermal desorption system coupled to a programmable temperature vaporization gas chromatograph with a micro-electron capture detector (TDS-PTV-GC/μECD). Trace PETN vapor was generated using state-of-the-art instrumentation known as the TESTbed, located at the US Naval Research Laboratory. For PETN vapor concentrations in the parts per trillionvolume (pptv) range, quantitative results from the TDS-PTV-GC/μECD consistently showed concentrations approximately double that measured by the online PTV-GC/MS method, indicating that sample loss due to additional exposure to the vapor sampling infrastructure occurs when using online sampling. Further utilization of the online PTV-GC/MS system allowed for the quantitation/semi-quantitation of PETN vapor concentrations as low as 260 parts per quadrillionvolume (ppqv) with only 10 min of sampling time.

Simultaneous analysis of volatile and semi-volatile components in a topical formulation by gas chromatography using a programmed temperature vaporization inlet and flame ionization detection

Topical formulations are medications applied locally on the skin to treat ailment. They are made up of complex mixtures of active ingredients and excipients. Till date, no analytical method has been found in literature that is able to simultaneously analyze volatile and semi-volatile actives present in topical formulations. In this work, an analytical procedure by gas chromatography equipped with a programmed temperature vaporizing (PTV) inlet and a flame ionization detector was developed and validated for the simultaneous quantitative determination of volatile and semi-volatile actives such as camphor, L-menthol, methyl salicylate, ethyl salicylate, salicylic acid, glycol monosalicylate and capsaicin in a topical formulation. Liquid-liquid extraction was used to isolate the components of interest prior to injection into the gas chromatographic system. All target analytes were completely separated from each other and a linear calibration curve was achieved for all analytes with a determination coefficient > 0.995. 2-phenoxyethanol was used as internal standard for quantitation. Good repeatability and recovery values were achieved and reported. This method reports for the first time, the simultaneous quantitative analysis of volatile and semi-volatile active pharmaceutical ingredients in a single measurement. The developed method was successfully applied to the analysis of real pharmaceutical samples and the described analytical protocols can be recommended for routine analysis of both volatile and semi-volatile actives in the topical formulation.

Determination of three volatile N-nitrosamine in drinking water by solid phase extraction and gas chromatography-triple quadrupole mass spectrometry with programmable temperature vaporizer-based large volume injection

A method had been developed for the determination of three N-nitrosamines, namely, N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), and N-nitrosodiethylamine (NDEA) in drinking water by solid phase extraction (SPE) and gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS) with programmable temperature vaporizer (PTV)-based large volume injection (LVI). The N-nitrosamine compounds were extracted from the water sample using a solid phase extraction (SPE) cartridge filled with coconut charcoal, and then eluted with 10 mL methylene chloride. The eluate was dried by anhydrous sodium sulfate and 10 μL was injected into the GC-MS/MS by PTV-LVI. The target compounds were detected by the multi-reaction monitoring (MRM) mode, and quantified with the external standard method. The results showed that the three compounds had good linearities in the range of 1-50 ng/L with correlation coefficients (r2) higher than 0.999. Drinking water samples were spiked with the target compounds at three concentration levels (10, 20, and 50 ng/L), and satisfactory recoveries (between 94.8% and 109%) and good reproductivities (relative standard deviation RSD<10%) were achieved. The limits of quantitation (LOQs) of the three N-nitrosamines were found to be in the range of 0.08-0.7 ng/L. The developed method was sensitive, accurate, convenient, and reliable for the determination of the three trace level N-nitrosamines in drinking water.

An environmentally friendly method for the determination of polycyclic aromatic hydrocarbons in different soil typologies

Environmental contextPolycyclic aromatic hydrocarbons (PAHs) are widespread organic pollutants that tend to accumulate in soil. We developed an environmentally friendly analytical method for PAHs to evaluate human health risks associated with their presence in soils. The method is feasible for the analysis of soils with widely varying PAH contamination levels, and is well suited to environmental monitoring studies of relevance to human health. AbstractA microwave-assisted extraction, with a dispersive solid-phase purification step followed by programmed temperature vaporisation–gas chromatography–tandem mass spectrometry, is proposed as an environmentally friendly, simple and cheap analytical method for polycyclic aromatic hydrocarbons (PAHs) in soil. Different extraction and clean-up operating variables were tested to achieve satisfactory analytical performances: trueness from 92 to 114%, limit of quantification (LOQ) from 0.4 to 2µgkg−1 for most PAHs and intermediate precision, calculated as relative standard deviation (RSD), below 10%. The method was validated using both Certified Reference Material and real soil samples collected at sites subjected to different human activities. PAH contents ranged from 0.11 (in holm oak forest soil) to 1mgkg−1 d.w. (in an industrial soil) according to the anthropic gradient. The soil PAH contents measured were used to estimate the risk to human health, which suggested the exposure to the PAHs in soil as a potential risk for human health, especially at the industrial site. The feasibility of the method for soils with different PAH contamination degrees makes it relevant in monitoring programs.

Simultaneous high-temperature gas chromatography with flame ionization and mass spectrometric analysis of monocarboxylic acids and acylglycerols in biofuels and biofuel intermediate products

Triacyl-, diacyl- and monoacylglycerols (TAGs, DAGs, MAGs) along with monocarboxylic acids (MCAs) are intermediate products in many triacylglycerol oil-to-biofuel conversion pathways. Accumulation of these compounds leads to poor biofuel characteristics and may result in fuel system damage. We developed a method for simultaneous identification and quantification of a wide range of MCAs (C4-C18), MAGs, DAGs, and TAGs. The method is based on trimethylsilylation followed by high temperature GC with programmed temperature vaporizer (PTV) injection coupled to parallel FID and MS detectors (HTGC-FID/MS).To minimize the discrimination of both low and high molecular weight species typically occurring on the injector, we optimized injection conditions using a central composite design. The critical variables were the time at initial temperature (40 °C), splitless time, and the interaction between these two parameters. Among three tested electron ionization source/quadrupole analyzer temperatures, a 350/200 °C setting provided the highest response and signal-to-noise ratio for TAGs and did not have an effect on MAGs and DAGs.Similar results were obtained when quantifying target analytes in intermediate products of soybean oil cracking with FID and MS (using specific acylglycerol fragmentation ions). The instrumental FID limits of detection (LODs) were 0.07–0.27 ng for most of the target analytes. Selected ion monitoring (SIM) LODs were 0.01–0.05 ng for MCAs and 0.03–0.14 ng for acylglycerols. For the total ion current (TIC), LODs observed increased with acyl chain length and degree of unsaturation, resulting in an increase from 0.05 to 0.18 ng for MCAs (C5 to C18) and from 0.03 to 1.8 ng for acylglycerols (TAGs C8 to C22). Deviations in the repeatability of sample preparation, intra- and inter-day analyses, including sample stability over an eight-day time period, did not exceed 10% variance. These results demonstrate that the developed method is accurate and robust for the determination of acylglycerols and MCAs produced during the processing of TAGs into biofuels.

Estrogens determination exploiting a SIA-LOV system prior in-port derivatization-large volume injection-programmable temperature vaporization-gas chromatography

In this work, we present a method for the clean-up, preconcentration and quantification of the four most widely found estrogens (estrone E1, estradiol E2, estriol E3 and ethynyl estradiol EE2) in seawater samples. A sequential injection analysis-lab on valve system (SIA-LOV) has been developed to perform the microsolid phase extraction (µSPE) of the analytes in a fully automated way. After testing different resins and solvents, C18 resin with acetonitrile (ACN) as eluent have been chosen as they provided the best results. Several parameters affecting the extraction have been studied and optimized. Besides, extraction column lifetime has also been checked as it is indicative of the number of consecutive analysis that the column is able to perform before replacing it. Results showed that the same column can be used up to 50 times. Then, the derivatization of the extracts has been performed unattended by exploiting an in-port derivatization of the analytes with N-methyltrimethylsilyltrifluoroacetamide (BSTFA) prior their quantification using large volume injection with programmable temperature vaporization gas chromatography (LVI-PTV-GC-MS).

Assessment of heavy metals, fungicide quintozene and its hazardous impurity residues in medical Panax notoginseng (Burk) F.H.Chen root.

A quick, easy, cheap, effective, rugged, and safe extraction approach and gas chromatography/tandem mass spectrometry with programmed temperature vaporization sampling technology were used to determine fungicide quintozene and its hazardous impurity hexachlorobenzene (HCB) in Panax notoginseng root, which is commonly used as a rare traditional Chinese medicine worldwide. The mean recoveries were in the ranges of 94-125 and 84-119% for quintozene and HCB with relative standard deviations of 6.2-16.1% at three concentrations: 0.01, 0.1 and 1 mg kg-1 . Heavy metals arsenic, cadmium, copper and lead were simultaneously detected by an inductively coupled plasma-mass spectrometry approach after digestion with nitric acid. The above methods were used to analyze 50 samples of P. notoginseng roots collected at markets and planting bases from the special local producing areas, namely, Honghe, Kunming and Wenshan in Yunnan province, China. Quintozene and HCB in root samples were determined at <0.0015-1.50 and <0.0015-0.125 mg kg-1 . In the 50 samples, 60, 16, 56, 2 and 6% exceeded the maximum permissible levels in medicinal plants (WM/T2-2004) for quintozene, arsenic, cadmium, lead and copper. The results showed that the method is robust and suitable for measuring quintozene, its hazardous impurity and heavy metals in P. notoginseng roots.

Simultaneous determination of drugs and pesticides in postmortem blood using dispersive solid-phase extraction and large volume injection-programmed temperature vaporization-gas chromatography–mass spectrometry

A d-SPE protocol followed by gas chromatography–mass spectrometry (GC–MS) analysis using large volume injection–programmed temperature vaporization (LVI–PTV) was optimized for simultaneous quantification of 14 pesticides, drugs of abuse, prescription drugs and metabolites in human postmortem blood without derivatization. The validated method showed good repeatability, linearity, intermediate precision, and recovery. LOQs were 0.02 or 0.03μg/mL. The method showed to be fast and easy-to-implement in a forensic laboratory and was satisfactorily applied for the analysis of 10 postmortem blood real samples. Six samples contained cocaine (0.04–3.13μg/mL), two 3,4-methylenedioxymethamphetamine hydrochloride (MDMA, 0.04–0.09μg/mL) and two carbamazepine (0.08–0.98μg/mL). Other analytes found were carbofuran (27.3μg/mL), the metabolite 7-aminoflunitrazepam (1.12μg/mL), amitriptyline (0.21μg/mL) and diazepam (0.03μg/mL).