Determination of Polycyclic Aromatic Hydrocarbons in Mosses by Ultrasonic-Assisted Extraction and Gas Chromatography–Tandem Mass Spectrometry

A facile method for the determination of polycyclic aromatic hydrocarbons in mosses is reported using ultrasonic-assisted extraction and gas chromatography–tandem mass spectrometry. The efficiency of ultrasonic-assisted extraction and the reagents was optimized. Tandem mass spectrometry with selective reaction monitoring was used to enhance the selectivity to reduce matrix interferences and simplify the purification protocol. The detection limits were from 0.1 to 2.0?ng/mL. The linear calibration range was two orders of magnitude and the coefficients of linear correlation exceeded 0.9992 for all analytes. The relative standard deviations within 1 day and 3 days were less than 9.0%. Recoveries from 56.8 to 109.0% were obtained in fortified mosses. The rapid, low solvent gas chromatography–tandem mass spectrometry method was used to determine polycyclic aromatic hydrocarbons in mosses.     

Determination of Aromatic Hydrocarbons,Phenols, and Polycyclic Aromatic Hydrocarbons in Water by Stir bar Sorptive Extraction and Gas Chromatography–Mass Spectrometry

The paper presents procedures for stir bar sorptive extraction for selected priority substances that include polycyclic aromatic hydrocarbons, phenols, and benzene and its aromatic homologs. Three extraction and instrumental analysis procedures were developed for the determination of 16 compounds. The developed solid-phase extraction methods using a movable element had high recoveries above 70%. Extraction methods were optimized by selecting an appropriate time and temperature of the process, the sample pH, and stirring speed. The detection limits for the polycyclic aromatic hydrocarbons ranged from 0.33?µg/dm³ for naphthalene to 2.22?µg/dm³ for phenanthrene. Slightly higher limits of quantification were obtained for phenols: from 9.21?µg/dm³ for phenol to 0.51?µg/dm³ for 2,4,6-trimethylphenol. The highest limit of quantification for the tested compounds was obtained for benzene, with a value of 36.6?µg/dm³, while for toluene and ethylbenzene, the values did not exceed 2.7?µg/dm³.     

Determination of Polycyclic Aromatic Hydrocarbons in Soils and Bottom Sediments by Gas Chromatography–Mass Spectrometry with QuEChERS Sample Preparation

Journal of Analytical Chemistry - The work is dedicated to the determination of polyaromatic hydrocarbons (PAHs) in soils and bottom sediments by gas chromatography–mass spectrometry using...     

Optimized Ultrasonic Extraction for the Determination of Polyaromatic Hydrocarbons by Gas Chromatography–Mass Spectrometry

The presence of polycyclic aromatic hydrocarbons (PAHs) in soil is an issue of concern due to their harmful effects on human health. The goal of this study was to optimize ultrasonic extraction to establish an efficient, easy, and low-cost method for the determination of 16 priority PAHs in soil. The time of extraction and solvent systems were optimized with the analysis by gas chromatography–mass spectrometry. The method was validated, and the optimum results were obtained using 1:1 cyclohexane:acetone and 1:1 hexane:acetone solvent systems with 30- and 60-min sonication times.     

Determination of Polycyclic Aromatic Hydrocarbons in Tobacco Smoke by Ionic Liquid Enrichment and Gas Chromatography – Mass Spectrometry

A rapid, efficient and environmentally friendly method based on the ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate ([C₆MIM][PF₆]) was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in mainstream tobacco smoke. This technique combined ionic liquid (IL) enrichment with solvent reverse extraction for the replacement of solid phase extraction and rotary evaporation in the traditional method and enriched PAHs in the organic solvent. Several parameters, including the type of ionic liquid, volume of ionic liquid and water, extraction time, vortex time and reverse extraction time, were optimized. After pretreatment, the analytes were analyzed by gas chromatography-mass spectrometry (GC-MS) using selective ion monitoring (SIM). Satisfactory results were achieved when this method was applied to determine PAHs in mainstream tobacco smoke. The calibration curves were linear with correlation coefficients ranging from 0.9955 to 0.9999 at concentration levels of 10–800?µg?L^?1, and the relative standard deviations of the optimized method were between 0.7% and 5.3%. The limits of detection were 0.01–0.6?ng cig^?1, and the recoveries of the compounds were 80.2–118%. A comparison of this protocol with literature methods demonstrated that the proposed procedure provides accurate and reliable sample-treatment for the determination of PAHs in tobacco samples.     

Novel Sorbent and Solvent Combination for QuEChERS Soil Sample Preparation for the Determination of Polycyclic Aromatic Hydrocarbons by Gas Chromatography–Mass Spectrometry

Polycyclic aromatic hydrocarbons (PAHs) represent priority contaminants, and the development of fast, reliable and accurate methods for their determination is of essential importance. The soil is a part of the environment which easily accumulates PAHs, making them available for transport to the air and water over long time periods and by plants through the food chain to humans. The aim of present study was to introduce a novel sorbent to the quick, easy, cheap, effective, rugged, and safe technique for soil sample preparation for the determination of 16 European Union priority PAHs by gas chromatography–mass spectrometry. Two solvent systems, 2:1 (v/v) hexane:acetone and ethyl acetate, were investigated in combination with five clean-up sorbents [Primary secondary amine (PSA), C18, florisil, clinoptilolite, and diatomaceous earth] in this study. The highest overall recovery of the method was achieved by the combination of hexane:acetone with clinoptilolite (recoveries of 70–110%) with limits of detection in the range of 0.60–1.53?µg?kg^?1. The analysis of 20 soil samples from Ni?, Serbia resulted in the identification of 11 samples with concentration greater than the values prescribed by law. The ratios of phenanthrene/anthracene and fluoranthene/pyrene were used to elucidate the origin of the PAHs as pyrolytic.     

Multidimensional Gas Chromatography–Mass Spectrometry Method for Fingerprinting Polycyclic Aromatic Hydrocarbons and Their Alkyl-Homologs in Crude Oil

The composition of polycyclic aromatic hydrocarbons in crude oil is usually too complex to use standard capillary gas chromatography to separate all of the components. In this study, a multidimensional gas chromatography–mass spectrometry (GC-MS) technique was used to analyze polycyclic aromatic hydrocarbon fractions of crude oil collected from the Dongying oil field in the Bohai Sea. A DB-17MS column (30?m?×?0.25?mm?×?0.25?µm) was used as a prefractionating column and only selected heart-cuts were transferred to the second chromatographic dimension (HP-5MS, 15?m?×?0.25?mm?×?0.25?µm) by a pressure-adjusted continual flow-type switching device for quantification of the polycyclic aromatic hydrocarbons. The chromatographic elements and parameters, such as detector selection and column combinations, were optimized. Naphthalene, phenanthrene, fluorene, dibenzothiophene, chrysene, and their C₁–C₄ alkyl homologs were identified. The profile of the polycyclic aromatic hydrocarbons obtained using the multidimensional GC-MS method was compared with the results obtained by traditional one-dimensional GC-MS.     

Determination of Herbicides in Corn Flour by Novel Extraction and Gas Chromatography–Mass Spectrometry

A simple and efficient procedure was developed to determine eight herbicides in corn flour by gas chromatography–mass spectrometry in selected ion-monitoring mode. Samples were prepared with a modified, quick, easy, rapid, effective, rugged, and safe procedure. The type and volume of extraction solvent, type and amount of adsorbent, and time of sonication were optimized. The protocol method was rigorously verified. The mean recoveries were from 85 to 108% at various fortification levels with relative standard deviations below 15% and limits of quantification from 4 to 48?ng g^?1. The method was used to determine herbicides in corn flour.     

Characterization of Oil by Micro-Solid-Phase Extraction and Gas Chromatography–Mass Spectrometry

Micro-solid-phase extraction is reported for the preparation of Bohai crude oil for the determination of hydrocarbons by gas chromatography-mass spectrometry. The operational parameters were optimized. Micro-solid-phase extraction provided higher quantities of low-molecular weight components than conventional liquid chromatography. The concentrations of high-molecular weight n-alkanes, polycyclic aromatic hydrocarbons, and their alkylated homologs obtained were comparable by micro-solid-phase extraction and liquid chromatography. The diagnostic ratios also indicated that there were no significant differences between these methods. Therefore, micro-solid-phase extraction with gas chromatography–mass spectrometry is recommended for the characterization of spilled oil.     

Determination of Aromatic Microbial Metabolites in Blood Serum by Gas Chromatography–Mass Spectrometry

We present the results of the determination of eight aromatic microbial metabolites, phenylcarboxylic acids (PhCAs), by gas chromatography–mass spectrometry after their liquid–liquid extraction from serum samples and derivatization. The analytical range for the analytes is 0.5–40 μM. The concentration of phenylcarboxylic acids in the serum of healthy donors (n = 40) and the time profile of the concentration of different PhCAs in serum samples of four patients from the intensive care unit (ICU) are studied. The results correlated with the severity of the clinical state of patients.     

Determination of Phthalate Esters in Textiles by Solid Phase Extraction and Gas Chromatography–Mass Spectrometry

A sensitive and rapid method was developed for the determination of seven phthalate esters in baby waterproof fabrics, decorated waterproof tarpaulins, and printed textiles by solid phase extraction followed by gas chromatography–mass spectrometry. The method showed good linearity with correlation coefficients between 0.9958 and 0.9999 and limits of quantification and detection from 23 to 274 micrograms per liter and 7 to 82 micrograms per liter, respectively. The maximum recoveries were between 96.2 and 100.9 percent with relative standard deviations from 1.06 to 6.87 percent. The protocol was applied to the determination of phthalate esters in textiles: the samples contained more than 0.1 percent phthalate esters, which exceed relevant standards.     

Determination of Pesticides in Carrots by Gas Chromatography–Mass Spectrometry

ABSTRACT

A sensitive and selective method was developed to determine pesticides in carrots by gas chromatography–mass spectrometry following the development of an optimized extraction procedure. The method was validated for 30 organochlorine pesticides for gas chromatography with electron capture detection obtaining limit of detection from 0.18 to 0.92?µg/kg except for cis- and trans-permenthrin. Twenty-six carrot samples were analyzed and six pesticides were detected. The results compared with the accepted maximum residue levels in correlation to crop origin.     

Microwave-Assisted Solvent Extraction of Melamine from Seafood and Determination by Gas Chromatography–Mass Spectrometry: Optimization by Factorial Design

Melamine attracts considerable attention because of its toxicity. The determination of melamine in seafood was performed by gas-chromatography–mass spectrometry, using an optimized version of a method adopted by the U.S. Food and Drug Administration. The melamine was extracted by closed-vessel microwave-assisted solvent extraction (MAE), as a valid alternative in sample preparation, to reduce analysis time and provide less ambiguous data. The procedure was optimized by means of experimental factorial design considering the three main variables that affect this process: microwave oven power, the maximum temperature inside the extraction tube, and the hold time. The recovery of melamine in spiked samples was used as the elemental response value of the design. Temperature and hold time had a more positive effect on the response than the microwave power. A significant positive interaction was observed between oven power and hold time. A temperature of 70°C and a hold time of 1 min gave a recovery of 92 ± 5% for a microwave power of 600 W. Under these conditions, the total microwave extraction time was approximately 2 minutes, a much shorter time compared to the ultrasonic bath, which required a total time of 40 min. The repeatability of the method was approximately 3%. The limits of quantification were 0.55 mg kg^?1 for MAE and 1.9 mg kg^?1 for the ultrasonic bath; the linearity was confirmed up to 10 mg kg^?1. In conclusion, the MAE procedure was shown to be an excellent alternative to the official method.     

Determination of Preservatives in Water-Based Adhesives by Gas Chromatography–Mass Spectrometry

This study establishes an analytical method for the determination of eighteen preservatives in water-based adhesives. The method was based on liquid–liquid extraction by methyl tertiary-butyl ether and subsequent determination by gas chromatography–mass spectrometry. Experimental conditions (instrumental parameters, extraction solvent, extraction mode, dispersant volume, and extraction time) were optimized and validated. When the method was applied to water-based adhesives, the limits of detection and recovery were 2.29–17.59 milligrams per kilogram and 85.7 ? 93.9 percent, respectively, and the repeatability was below 5 percent for all analytes. None of the analytes were found in five cigarette adhesives.     

Analytical Method Validation and Determination of Iron and Phosphorus in Vegetable Oil by Inductively Coupled Plasma–Mass Spectrometry with Microwave Assisted Digestion

Inductively coupled plasma–mass spectrometric determination of iron and phosphorus in three vegetable oils (soybean, coconut, and sunflower) was validated for the intermediate precision, trueness, linearity, and quantitation limit. The overall precision (n?=?5) for the analytes, which were above the method’s practical limit of quantification, were less than 2% relative standard deviation and the same as the laboratory control, NIST-SRM-1849a. Trueness was demonstrated with spike recoveries of the analytes in all vegetable oils at limit of quantification-level spiking. Although good linearity (regression coefficient greater than 0.9990) obtained, the recovery of phosphorus (156–189%) was high, possibly due to oil matrix enhancement, compared to the recovery of iron (91–106%). For soybean oil, sunflower oil, coconut oil, and medium chain triglycerides, the concentrations (mg/kg) of iron were in the range of 0.10–1.47, 0.09–1.51, 0.20–0.35, and 0.09–0.13, respectively. Similarly, phosphorus concentrations (mg/kg) were in the range of 0.77–124.56, 0.49–125.57, 0.52–9.72, and 0.85–11.90, respectively. The study achieved considerably low instrument-based practical limits of quantification for iron (0.005?mg/kg) and phosphorus (0.05?mg/kg), which are fivefold lower than the AOAC Official Method 2015.06. The high instrument sensitivity and selectivity of the method allow the determination of trace levels of iron and phosphorus in vegetable oils with good precision and trueness.     

Determination of Chlorophenols and Alkylphenols in Water and Juice by Solid Phase Derivative Extraction and Gas Chromatography–Mass Spectrometry

A solid phase derivative extraction method using acetic anhydride was developed for the determination of chlorophenols and alkylphenols in water and fruit juice by gas chromatography–mass spectrometry (GC–MS). The quantitative extraction was performed by passing 100 mL of sample prepared in 0.1 mol L^?1 sodium hydroxide through a column packed with 500 mg of a strong anion-exchange resin at a flow rate of 0.75 mL min^?1. The retained phenols were quantitatively derivatized in the column by the introduction of 0.25 mL of acetic anhydride. The derivatized phenols were eluted with 3.0 mL of hexane and the effluent was dried under nitrogen. The final volume was diluted to fifty microliters with hexane and analyzed by GC–MS. Under the optimum conditions, preconcentration factors of 2000, limits of detection between 0.005 and 1.796 µg L^?1, and relative standard deviations of 2.1% to 6.7% were obtained. The method was successfully applied to wastewater and fruit juice and the recoveries of phenols were between 76% and 111%.     

Gas Chromatography–Mass Spectrometry Determination of Pregabalin in Human Plasma Using Derivatization Method

A gas chromatography–mass spectrometry method for the determination of pregabalin in human plasma is described. The procedure involves precipitation of protein, liquid–liquid extraction with ethylene glycol monomethyl ether, and derivatization with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide in the presence of N-hydroxysuccinimide as additive. Separation was attained on HP column (30 m × 0. 25 mm ID, 0.25 μm) coupled with mass spectrometric detector using electron impact selected ion monitoring. The assay showed an excellent linearity in the concentration range of 0.36–10 μg mL^?1 with correlation coefficient (r²) values of 0.999. The intra- and inter-day assay variations for three different concentration levels were less than 10%. The limit of quantification was detected at 0.36 μg mL^?1. The method is highly specific, precise, accurate, and reproducible and could also be applied for the determination of pregabalin in human plasma.     

Novel Sampling for the Determination of Naphthalene in Air by Gas Chromatography–Mass Spectrometry

Here are reported two new sampling method approaches for the determination of naphthalene in ambient air for concentrations from 0.25 to 18.7?µg/L. The first method used for gas phase naphthalene analysis produced an average recovery of 88.8% and the second method using headspace sampling produced an average recovery of 93.8%. The second method showed better recovery than the former, so it was used for subsequent comparative gas-phase determination of naphthalene. The second method was validated at various naphthalene concentrations and humidity using a naphthalene gas generator to produce various naphthalene standards and a naphthalene-monitoring instrument. The naphthalene concentrations generated using the gas generator and determined second sampling method with gas chromatography–mass spectrometry (GC–MS) were compared to the sensor measurements and were in good agreement. In summary, the sampling methods presented provided reliable gas-phase naphthalene determination when coupled with GC–MS.     

Determination of Toluene and Ethanol in Urine by Headspace and Cryotrapping Gas Chromatography–Mass Spectrometry

Toluene is the major volatile organic compound found in glue and is often used as a hallucinogenic for abusers. Use with alcohol increases the risk of adverse effects from toluene exposure. In this study, a headspace and cryotrapping gas chromatography–mass spectrometry method was developed and validated for the determination of toluene and ethanol in urine. Experimental and instrumental variables were investigated to optimize the method for sensitivity. Excess sodium sulfate was used as the salting-out reagent before the headspace protocol. Linear least squares regression with a 1/x weighting factor was used to construct calibration curves from 0.002 to 0.4?µg?mL^?1 for toluene and 10 to 2000?µg?mL^?1 for ethanol. The correlation coefficients exceeded 0.9993. The limits of detection were 0.0005?µg?mL^?1 for toluene and 0.21?µg?mL^?1 for ethanol. Intraday and interday precisions were within 5.4 and 11.5%, while intraday and interday accuracies were between ?11.3 to ?4.0% and ?11.0 to 1.2%, respectively. The method validation results for selectivity and stability were satisfactory. The validation results were used to estimate the expanded uncertainty and the contribution of individual steps in the method for the quantification of toluene and ethanol. The relative expanded uncertainties were 14.1% for toluene and 4.6% for ethanol.