Chromatography-ion Trap Tandem Mass Research Articles

Determination of 16 polycyclic aromatic hydrocarbons (PAHs) in surface and groundwater in North Lebanon by using SPME followed by GC–ITMS/MS

This paper discusses the development of a gas chromatography–ion trap tandem mass spectrometry (GC–ITMS/MS) coupled to solid phase micro-extraction for the quantitative determination of 16 polycyclic aromatic hydrocarbons (PAHs) in water samples. In this study, the factors influencing the GC–ITMS/MS method were investigated and optimized, and then a calibrating program was developed for the quantification of the PAHs under study. The method showed linear calibration curves for the 16 studied PAHs in the range of 0.1–100 ng mL−1 with the correlation coefficient (r2) between 0.92 and 0.999. The precisions (relative standard deviation, RSD) were below 15% and recoveries were between 76 and 105%. The limits of detection and limits of quantification were in the low ng mL−1 level. Therefore, these limits correlated with the standard method 8270D set by the United States Environmental Protection Agency. The optimized method was then effectively applied for the analysis of the 16 PAHs in surface and groundwater samples collected from 30 locations along the Basin of Abou Ali River in Lebanon. So far, no or very low PAHs concentrations were found in groundwater sampling locations while considerable concentrations (ranging from 0 to 28.72 ng mL−1) were detected in surface water of some locations. Consequently, the method was demonstrated to be applicable for the analysis of PAHs in the sampled waters.

Online eluent-switching technique coupled anion-exchange liquid chromatography–ion trap tandem mass spectrometry for analysis of non-steroidal anti-inflammatory drugs in pig serum

A novel method for online extraction, pH-gradient separation, and analysis of nine non-steroidal anti-inflammatory drugs (NSAIDs) was developed by coupling online eluent-switching technique to single anion-exchange chromatographic column/ion trap mass spectrometer (MS) and used for monitoring NSAIDs residues in pig serum. A neutral eluent and a pH-gradient eluent were used for extraction and separation of NSAIDs, respectively. Each of nine NSAIDs has an MS precursor ion of either [M−H]− or [M−Na]−. The extracted ion chromatogram for a specific product ion of each NSAID was used for its quantitative analysis. The dynamic linear ranges of calibration curves were all 0–200ngmL−1 (R2>0.9950). The analysis accuracies estimated by spiking standard concentrations at 20, 100, and 200ngmL−1 were 80.5–99.9%. The corresponding intra-day and inter-day precisions (RSD%) were 2.5–14.5% and 2.9–15.2%, respectively. The limit of detection/limit of quantitation of NSAIDs were 1.3/4.3, 0.5/1.6, 0.2/0.5, 2.5/8.2, 1.5/4.9, 0.6/2.1, 0.6/2.0, 0.5/1.7, and 0.6/2.1ngmL−1 for carprofen, diclofenac, flunixin, ibuprofen, ketoprofen, meclofenamic acid sodium, mefenamic acid, niflumic acid, and tolfenamic acid, respectively. After 1h injection of a dose containing 2mgkg−1 weight pig of flunixin and tolfenamic acid to the pigs, a residue amount of 3480±36ngmL−1 and 431±13ngmL−1, respectively, was reached for the incurred pig serum specimens and both residues were reduced to about 20ngmL−1 at the time of 24h.

Occurrence of β-lactam and polyether ionophore antibiotics in surface water, urban wastewater, and sediment

The occurrence and fate of antibiotic compounds in the aquatic environment has been recognized as an emerging area of interest in environmental chemistry. An analytical method was developed and validated for determining β-lactam and polyether ionophore antibiotics in surface water, urban wastewater, and sediment based on solid-phase extraction (SPE) and liquid chromatography–ion trap tandem mass spectrometry (LC-MS-MS). The average recovery of β-lactams and polyether ionophores from all the fortified samples was generally higher than 80% (except for amoxicillin and ampicillin). A total of 400 actual water and sediment samples were analysed using SPE-LC-MS-MS to evaluate the occurrence and fate of these antibiotic compounds in a river and a wastewater treatment plant in northern Colorado. Most samples were found to be negative for β-lactam compounds. In those samples with positive results, β-lactam compounds were found at 15–17 ng/L in influent wastewater samples, 9–11 ng/L in surface water samples, and 0.13–0.36 μg/kg in sediment samples. No β-lactam compounds were detected in any effluent wastewater samples. The β-lactams are expected to be easily eliminated in wastewater treatment plants due to the lability of the β-lactam ring towards chemical and microbial degradation. The average concentration of ionophores ranged 0.03–0.05 μg/L in surface water samples and 0.5–3.1 μg/kg in sediment samples. These results confirm that β-lactam and ionophore antibiotics are adsorbed by sediment.

Determination of Luteoskyrin in Rice Wine by High-Performance Liquid Chromatography–Ion Trap Tandem Mass Spectrometry

A method for luteoskyrin in Chinese rice wine was developed using high-performance liquid chromatography–ion trap tandem mass spectrometry. The detection limit of luteoskyrin was 0.10 µg/kg. The recovery values of luteoskyrin in fortified Chinese rice wine were between 85.7% and 88.9% at levels between 0.5 µg/kg and 100 µg/kg (R > 0.999). The relative standard deviations were in the range of 1.10% to 3.20%. The method achieved rapid and accurate determination of luteoskyrin in Chinese rice wine while meeting minimum residue measurement requirements.

Mass spectrometric determination of prostanoids in rat hypothalamic paraventricular nucleus microdialysates

The hypothalamic paraventricular nucleus (PVN) is one of the most important autonomic control centers in the brain. Several kinds of prostanoids, such as prostaglandin (PG) E2, are considered to act in the PVN as mediators of autonomic responses. In the present study, we used liquid chromatography ion trap tandem mass spectrometry (LC-ITMS(n)) to simultaneously quantify four prostanoids, thromboxane (Tx) B2, PGE2, PGD2 and 15-deoxy-∆(12,14) (15d)-PGJ2 in PVN microdialysates from urethane-anesthetized rats. The quantification limits were estimated to be 0.05ng/mL for TxB2, 0.025ng/mL for PGE2, 0.1ng/mL for PGD2, and 0.5ng/mL for 15d-PGJ2. The RSD% obtained from all prostanoids was <15%, indicating an acceptable level of reproducibility. LC-ITMS(n) analysis of rat PVN microdialysates revealed that TxA2 may play an important role in adrenomedullary outflow evoked by centrally administered N-methyl-d-aspartate, corticotrophin-releasing factor and glucagon-like peptide-1. This is the first study to use LC-ITMS(n) to analyze prostanoid levels in rat PVN microdialysates. This LC-ITMS(n) method will be useful for investigating the potential involvement of prostanoids in brain function.

Methods for simultaneous detection of the cyanotoxins BMAA, DABA, and anatoxin-a in environmental samples

Blue-green algae, also known as cyanobacteria, can produce several different groups of toxins in the environment including hepatotoxins (microcystins), neurotoxic non-protein amino acids β-methylamino-l-alanine (BMAA), and 2,4-diaminobutyric (DABA), as well as the bicyclic amine alkaloid anatoxin-a. Few studies have addressed the methods necessary for an accurate determination of cyanotoxins in environmental samples, and none have been published that can detect these cyanotoxins together in a single sample. Cyanotoxins occur in a wide range of environmental samples including water, fish, and aquatic plant samples. Using polymeric cation exchange solid phase extraction (SPE) coupled with liquid chromatography and fluorescence detection (HPLC/FD), and liquid chromatography ion trap tandem mass spectrometry (LC/MS/MS), these compounds can for the first time be simultaneously quantified in a variety of environmental sample types. The extraction method for biological samples can distinguish bound and free cyanotoxins. Detection limits for water ranged from 5 to 7 μg/L using HPLC/FD, while detection limits for and LC/MS were in the range of 0.8–3.2 μg/L.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in fish, seafood products and fish oil in Spain

A total of 84 samples of wild and farmed fish, cephalopods and fish oils for animal feeding, traded in Spain, were analysed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) in 2009–2012, by gas chromatography–ion trap tandem mass spectrometry (GC-MS-MS). The method was optimised for screening at moderate costs, allowing PCDD/Fs determination at 1 pg World Health Organization–toxic equivalent quantities (WHO-TEQ) g−1 wet weight (w w) and dl-PCBs at 0.02 pg WHO-TEQ g−1 w w. Concentrations in fish and cephalopods ranged from values below the limit of detection to 1.7 pg g−1 WHO-TEQ sum PCDD/Fs and dl-PCBs, considered as safe with regard to EU legislation. Higher levels were found in cod livers (5.4–54.2) and fish oils (3.3–30.7), with one noncompliant sample in each group.

A serially coupled stationary phase method for the determination of urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine by liquid chromatography ion trap tandem mass spectrometry

Oxidative attack to DNA is of particular interest since DNA modifications can lead to heritable mutations. The most studied product of DNA oxidation is 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG). While 8-oxodG determination in blood and tissue cells is prone to artifacts, its measurement in urine employing liquid chromatography tandem mass spectrometry (LC-MS/MS) has gained more and more interest for increased reliability. LC-MS/MS can be affected by matrix effects and this is particularly true when ion trap is used as MS analyzer, due to ion accumulation in the trap and related space charge effect. In the present work, we have developed a LC-MS/MS method where the combination of cation exchange and reverse phase solid phases resulted in LC separation optimization. This together with the employment of an isotopically labeled internal standard, allowed the usage of ion trap LC-MS/MS, typically not employed for quantitative measurement in biological samples, for the measurement of 8-oxodG in urine samples from control populations.Four different urine matrices were employed for method validation. Limit of quantitation was set at least at 0.5ng/ml. While analyzing urine samples from healthy volunteers, 8-oxodG levels reported as ng/ml were statistically different comparing males with females (p<0.05, Mann Whitney test); while comparing results normalized for creatinine no statistical significant difference was found. Mean urinary 8-oxodG level found in healthy volunteers was 1.16±0.46nmol/mmol creatinine.The present method by enhancing at best the chromatographic performances allows the usage of ion trap LC-MS/MS for the measurement of 8-oxodG in urine samples from control populations.

Mass Spectrometry Parameters Optimization for the 46 Multiclass Pesticides Determination in Strawberries with Gas Chromatography Ion-Trap Tandem Mass Spectrometry

Multiclass analysis method was optimized in order to analyze pesticides traces by gas chromatography with ion-trap and tandem mass spectrometry (GC-MS/MS). The influence of some analytical parameters on pesticide signal response was explored. Five ion trap mass spectrometry (IT-MS) operating parameters, including isolation time (IT), excitation voltage (EV), excitation time (ET), maximum excitation energy or "q" value (q), and isolation mass window (IMW) were numerically tested in order to maximize the instrument analytical signal response. For this, multiple linear regression was used in data analysis to evaluate the influence of the five parameters on the analytical response in the ion trap mass spectrometer and to predict its response. The assessment of the five parameters based on the regression equations substantially increased the sensitivity of IT-MS/MS in the MS/MS mode. The results obtained show that for most of the pesticides, these parameters have a strong influence on both signal response and detection limit. Using the optimized method, a multiclass pesticide analysis was performed for 46 pesticides in a strawberry matrix. Levels higher than the limit established for strawberries by the European Union were found in some samples.

Persistent organochlorine contaminants in hair samples of Northern Poland population, 1968–2009

The concentrations of persistent chlorinated organic pollutants were determined in hair samples (n=40) collected from inhabitants of Northern Poland in 1968, 1989 and 2009 using gas chromatography ion-trap tandem mass spectrometry (GC–MS/MS). Among the analytes were β- and γ-isomers of hexachlorocyclohexane (β- and γ-HCH), dichlorodiphenyltrichloroethane (p,p′-DDT) and its metabolites (p,p′-DDE, o,p′-DDD, o,p′-DDT and p,p′-DDD) and 6 polychlorinated biphenyl (PCB) congeners (IUPAC Nos. 28, 52, 101, 138, 153 and 180). The following: p,p′-DDE, o,p′-DDT, p,p′-DDT and PCB congeners: 28, 52 and 101 could be quantified in all samples. Overall total organochlorines level was found to decrease in that order: 1968>1989>2009. The most significant time-dependent decrease was noticed for sum of mean values, ∑DDTs (1658, 143.9 and 36.5ngg−1) and ∑PCBs (42.2, 29.4 and 14.9ngg−1) while ∑HCHs (β-HCH and γ-HCH) were present at comparable levels (22.2, 9.8 and 12.6ngg−1) in 1968, 1989 and 2009 respectively. The highest concentrations of DDTs were found in samples from 1968. Despite the long storage time of samples, metabolites either parent compound p,p′-DDT are still present in those samples at very high concentrations. p,p′-DDE as the predominant and stable metabolite of DDT was detected in every sample in the highest concentration. A significant, continuous decrease of total concentration of all studied PCB congeners was observed over the studied period of time. Current results confirm previous reports of other authors upon the utility of hair as an alternative matrix for evaluation of human exposure to persistent organic pollutants.

Determination of fungicide residues in baby food by liquid chromatography–ion trap tandem mass spectrometry

Current European Commission Directives on foods for infants and young children places emphasis on the control of pesticide residues at levels below 10 μg kg(-1). In the present work, a liquid chromatography electrospray ionisation ion trap tandem mass spectrometry (LC-Ion Trap-MS/MS) has been developed for the multiresidue of 10 multiclass fungicides (carbendazim, thiabendazole, imazalil, tridemorph, triadimefon, bitertanol, prochloraz, flutriafol, myclobutanil and diphenylamine) in fruit-based baby food. The developed method is based on a simple sample treatment (QuEChERS), which consists of a liquid-liquid extraction using acetonitrile, followed by a clean-up step based on dispersive solid-phase extraction with primary secondary amine (PSA). Subsequent identification and quantitation was accomplished by liquid chromatography/electrospray tandem mass spectrometry using an ion-trap mass spectrometer in the product ion scan MS/MS mode. Matrix effects were evaluated in LC-MS and LC-MS/MS mode experiments, obtaining a reduction of these effects when working in MS/MS mode for most of the analytes. Limits of detection (LOD) were between 0.5 and 3.0 μg kg(-1) depending on the pesticide studied, all being within European Union regulations for baby food. Finally, the proposed method was applied to 25 baby food samples obtained from local supermarkets. Imazalil, thiabendazole and carbendazim were detected in the studied samples. However, none of the samples tested were found to be upper the EU standard.

Quantification of carbamazepine and its active metabolite by direct injection of human milk serum using liquid chromatography tandem ion trap mass spectrometry

This work reports the use of a liquid chromatography ion trap tandem mass spectrometry (LC–IT-MS/MS) system for quantification in human milk samples of both carbamazepine (CBZ) and its active metabolite, carbamazepine 10,11-epoxide (CBZE). An octadecyl restricted-access media bovine serum albumin column (RAM-BSA C18) was used in single-column mode. Selectivity, extraction efficiency, accuracy and precision were achieved employing 100μL of the sample, without preparation, with detection limits of 20.0ng/mL for CBZ and 40.0ng/mL for CBZE. The matrix effect was investigated for the compounds by post-column infusion (qualitative) and by on-line extraction (quantitative). It was observed suppression effect for CBZ and CBZE by post-column infusion, ion suppression of 0.80 for CBZ, and enhancement of 1.28 for CBZE by on-line extraction. The developed method was validated and applied to analyze breast milk samples from one nursing mother. CBZ and CBZE were quantified in the concentrations of 2.26μg/mL and 1.54μg/mL, respectively. To our knowledge, this is the first report on the simultaneous determination of CBZ and its active metabolite by direct injection of human milk serum.

Validation of a Gas Chromatography–Ion Trap-Tandem Mass Spectrometry Assay for the Simultaneous Quantification of Cocaine, Benzoylecgonine, Cocaethylene, Morphine, Codeine, and 6-Acetylmorphine in Aqueous Solution, Blood, and Skeletal Muscle Tissue

A gas chromatography-ion trap-tandem mass spectrometry method was developed and validated for the simultaneous solid-phase extraction and quantification of cocaine, benzoylecgonine, cocaethylene, morphine, codeine, and 6-monoacteylmorphine in blood, muscle tissue, and water. An assay for total morphine in blood and muscle was also validated. The limit of quantification was ≤ 0.01 mg/kg in muscle and ≤ 0.005 mg/L in blood and water. Good linearity was observed over the concentration ranges studied (r ≥ 0.99). The repeatability (% RSD) at the three concentration levels was typically ≤ 15% and never exceeded 17%. Intermediate precision of ≤ 16% was obtained for all matrices. Deviation < 20% of the nominal concentration was obtained in all repeatability and intermediate precision experiments. Extraction recoveries for cocaine and metabolites ranged from 91% to 110% in water, 81% to 110% in blood, and 61% to 75% in muscle. Recoveries for opiates ranged from 59% to 104% in water, 50% to 95% in blood, and 41% to 79% in muscle. The hydrolysis efficiency for the total morphine assay in blood and muscle ranged from 91% to 99% with within-day and intermediate precisions of ≤ 14% and ≤ 12%, respectively.

On-line Solid-Phase Extraction Coupled to Liquid Chromatography–Ion Trap Tandem Mass Spectrometry for Determination of Penicillins in Catfish

A highly selective method was developed for the simultaneous determination of eight penicillins in catfish using automated on-line solid-phase extraction coupled to liquid chromatography–tandem mass spectrometry (XLC–MS/MS). The type of cartridge, equilibration sample volume, volume of solvent to carry the sample into the cartridge, and elution times were studied in order to optimize the XLC operating conditions. MS/MS conditions were also adjusted for better peak resolution. The present method was validated in agreement with the criteria of Commission Decision 2002/657/EC, showing a linear range from 2 to 350 μg kg−1 and regression coefficient higher than 0.995 for the studied penicillins. Decision limits, calculated in the case of substances with no permitted limit, were lower than 0.6 μg kg−1, and detection capability values were lower than 2.0 μg kg−1. Samples spiked at 2.0, 10.0, and 50.0 μg kg−1 showed high recovery (72–92%) and precision values lower than 20% except for amoxicillin. The present method was also applied for the analysis of penicillins in 30 catfish samples bought in local markets.

Simultaneous analysis of select pharmaceuticals and personal care products in fish tissue using pressurized liquid extraction combined with silica gel cleanup

Analytical improvements were developed and validated for measuring select personal care products (PCPs) and two pharmaceuticals in fish tissue. The method was validated using fortified fillet tissue for twelve PCPs including fragrance materials, alkylphenols, photo initiators, and triclosan as well as two pharmaceuticals including carbamazepine (anti-seizure) and diazepam (anti-convulsant). The analytical method utilized pressurized liquid extraction (PLE) combined with silica gel cleanup, gel permeation chromatography, and gas chromatography ion-trap tandem mass spectrometry. Silica gel cleanup was combined with the PLE to produce one automated extraction/cleanup technique. This analytical improvement served to reduce the incurred cost, time, and loss of potential target analytes associated with independent cleanup steps. The combined extraction/cleanup technique resulted in an average increase of 10% in analyte recoveries. Average triplicate recoveries and relative standard deviations for the entire method, using 2.5 g of fish fillet tissue, were 92 ± 9% (recoveries ranged from 64 to 131%). The sensitivity of the analytical methods was improved by optimizing the resonant collision induced dissociation energy to the hundredths place (0.01 V). Improvements in ion production range from 24 to 122% for six of the 12 PCPs. Statistically derived method detection limits (MDLs) were also lowered on average by a factor of 8 and ranged from 1.2 to 38 ng/g wet weight. MDLs for carbamazepine and diazepam were 18 and 3.7 ng/g wet weight, respectively. Galaxolide and tonalide were measured in an environmental sample at concentrations of 81 and 5.5 ng/g wet weight, respectively.

Automated on‐fiber derivatization with headspace SPME‐GC‐MS‐MS for the determination of primary amines in sewage sludge using pressurized hot water extraction

An automated, environmentally friendly, simple, selective, and sensitive method was developed for the determination of ten primary aliphatic amines in sewage sludge at μg/kg dry weight (d.w.). The procedure involves a pressurized hot water extraction (PHWE) of the analytes from the solid matrix, followed by a fully automated on-fiber derivatization with 2,3,4,5-pentafluorobenzaldehyde (PFBAY) and headspace solid-phase microextraction (HS-SPME) and subsequent gas chromatography ion-trap tandem mass spectrometry (GC-IT-MS-MS) analysis. The limits of detection (LODs) of the method were between 0.5 and 45 μg/kg (d.w.) for all compounds except for ethyl-, isopropyl-, and amylamine, whose LODs were 70, 109, and 116 μg/kg (d.w.), respectively. The limits of quantification (LOQs) were between 10 and 350 μg/kg (d.w.). Repeatability and intermediate precision, expressed as RSD(%) (n=3), were lower than 18 and 21%, respectively. The method developed enabled to determine primary aliphatic amines in sludge from various urban and industrial sewage treatment plants as well as from a potable treatment plant. Most of the primary aliphatic amines were found in the sewage sludge samples analyzed corresponding to the maximum concentrations to the samples from the urban plant: for instance, isobutylamine and methylamine were found at 7728 and 12 536 μg/kg (d.w.), respectively. Amylamine was detected only in few samples but always at concentrations lower than its LOQ.

On-line two-dimensional liquid chromatography–tandem mass spectrometric determination of estrogens in sediments

The development of an on-line system for the simultaneous determination of α-estradiol, β-estradiol, estrone and 17α-ethynylestradiol in river sediments is described. The analytes were extracted from sediments by microwave-assisted extraction. A crude extract was directly analysed by a heart-cutting two dimensional high-performance liquid chromatography–ion trap-tandem mass spectrometry with an atmospheric pressure photoionization source operating in the positive mode. The method shows excellent performance in terms of accuracy, precision, and sensitivity. The accuracy of each estrogen was in the range of 98.8–107.1%. Intra-batch and inter-batch precisions were in the range of 6.2–7.0% and 8.3–9.5%, respectively. The limits of detection ranged from 90 to 250 pg g −1. A significant reduction in the total analysis time and a reduction in sample manipulation are the main advantages of the proposed method. Finally, the method was applied on real sediment samples.

Suitability of selective pressurized liquid extraction combined with gas chromatography–ion-trap tandem mass spectrometry for the analysis of polybrominated diphenyl ethers

A one-step extraction and clean-up method using pressurized liquid extraction (PLE) (selective PLE) combined with gas chromatography–ion-trap tandem mass spectrometry (GC–ITMS–MS) was evaluated for the analysis of polybrominated diphenyl ethers (from tri- to hepta-PBDEs) at low concentrations in fish and shellfish samples. To this end, the performance of an on-line PLE extraction/clean-up method and of a classical Soxhlet extraction and clean-up method using a multi-layer modified silica column were compared. The two sample treatment methods provided similar results, although an important reduction in the sample treatment time (40 min per sample) was achieved using the selective PLE method. In addition, the suitability of the PLE combined with GC–ITMS–MS method was evaluated by comparing the results obtained in the analysis of fish samples with those obtained by gas chromatography–high resolution mass spectrometry (GC–HRMS). Good agreement between both techniques was obtained with differences between the mean values of less than 16%. The selective PLE method coupled to GC–ITMS–MS produced accurate results for PBDE determination with low limits of detection (1.0–16.8 pg g −1 wet weight) and quantification (3.1–51 pg g −1 wet weight) as well as good precision (RSD < 16%). This method has been applied to the analysis of PBDEs in fish and shellfish samples collected at fish markets in Catalonia (NE Spain).

Gas chromatography–ion trap tandem mass spectrometry method for the analysis of methoxylated polybrominated diphenyl ethers in fish

Gas chromatography coupled to ion trap tandem mass spectrometry (GC–ITMS-MS) is proposed for the analysis of methoxylated polybrominated diphenyl ethers (MeO-PBDEs) in fish and shellfish. MS–MS operating parameters related to the isolation and fragmentation of the precursor ions were optimized to achieve maximum sensitivity and selectivity. This new method allows the determination of both MeO-PBDEs and PBDEs in a single run. Low limits of detection (0.4–2.5 pg injected) and high precision (RSD < 13%) were achieved. A sample treatment based on a selective pressurized liquid extraction (PLE) using Florisil as fat retainer was applied for the analysis of these compounds in fish samples. Method limits of quantification ranged from 0.11 to 0.95 ng g −1 lipid weight for MeO-PBDEs and between 0.18 and 0.50 ng g −1 lipid weight for PBDEs. In addition, good repeatability of the whole method was achieved (RSD < 15%). The suitability of the method was evaluated by analyzing a certified reference material (SRM 1945, whale blubber) with satisfactory results. The developed method was applied to the simultaneous analysis of MeO-PBDEs and PBDEs in fish and shellfish samples from the Mediterranean Sea.

Validation of an analytical method for analysis of cannabinoids in hair by headspace solid-phase microextraction and gas chromatography–ion trap tandem mass spectrometry

The development of an analytical method for the determination of Δ 9-tetrahydrocannabinol (THC), cannabidiol (CBD) and cannabinol (CBN) in samples of human hair is described. Samples were subjected to a procedure based on the combination of headspace solid-phase microextraction (HS-SPME) with gas chromatography linked with mass spectrometry operating in tandem mode (GC–MS/MS). A 10 mg aliquot of sample was firstly decontaminated using petroleum ether, deionized water and dichloromethane (2 mL of each solvent), for 10 min under sonication, and then digested in alkaline solution (1 mol L −1 NaOH). The method variables evaluated were pH, mass of hair, fiber type, extraction temperature, desorption time, ionic strength, pre-equilibrium time and extraction time. Parameters concerning operation of the tandem mode MS/MS were also assessed and optimized. Validation of the method demonstrated excellent linearity in the range 0.1–8.0 ng mg −1, with regression coefficients better than 0.994. Precision was determined using two different concentrations (upper and lower limits of the linear range), and RSD values were between 6.6 and 16.4%. Absolute recoveries (measured in triplicate) were in the range 1.1–8.7%, and limits of detection and quantification were 0.007–0.031 ng mg −1 and 0.012–0.062 ng mg −1, respectively. The LOQ for THC (0.062 ng mg −1) was below the cut-off value (LOQ ≤ 0.1 ng mg −1) established by the Society of Hair Testing (SOHT), the Society of Toxicological and Forensic Chemistry (STFCh) and the Société Française de Toxicologie Analytique (SFTA). The optimized SPME method was applied in analysis of hair samples from Cannabis drug users, showing that CBN and CBD were present in all samples analyzed.