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 Chlorophenols in Wastewater with Methyl Chloroformate Derivatization,Solid Phase Extraction,and Gas Chromatography–Mass Spectrometry

The determination of chlorophenols in wastewater with methyl chloroformate derivatization, solid phase extraction, and gas chromatography–mass spectrometry is reported. In order to employ this combined solid phase derivative extraction method, quantitative extraction was performed by the introduction of 100 mL of sample in 1.0 mol L^?1 sodium hydroxide into a column containing 500 mg of packed resin at a flow rate of 1.0 mL/min. The chlorophenols were retained and derivatized quantitatively in the column by the introduction of 0.25 mL of methyl chloroformate. The derivatized analytes were eluted with 5.0 mL of hexane before the effluent was dried under a stream of nitrogen. The dried solution was diluted to a volume of 50 µL with hexane followed by analysis by gas chromatography–mass spectrometry. The preconcentration parameters were optimized and under these conditions: limits of detection from 0.010 to 0.423 µg L^?1, a preconcentration factor of 2500, and precision values from 4.8 to 7.7% as the relative standard deviation were obtained. The method was employed for the analysis of water samples and the recoveries of the analytes were between 76 and 103%.     

Determination of the Volatile Components of Apple Juice Using Solid Phase Microextraction and Gas Chromatography–Mass Spectrometry

Headspace solid phase microextraction and gas chromatography–mass spectrometry were employed to characterize the volatile organic compounds, responsible for the flavor, in apple juice. The method was applied for commercial and fresh juice. More than seventy volatile organic compounds were determined from different chemical families. The characterization was based on the relative quantities of total terpenes, sesquiterpenes, esters, ketones, and alcohols. A new index was proposed for apple juice assessment and quality evaluation, based on the relative ratios of total sesquiterpenes and total terpenes.     

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.     

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.     

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 Volatile Disinfection Byproducts in Water by Gas Chromatography–Triple Quadrupole Mass Spectrometry

Chlorination disinfection byproducts have drawn significant attention in water quality research during the last decades, due to their adverse effects on public health. A method is reported for the determination of trihalomethanes, haloacetonitriles, haloketones, and chloropicrin based on liquid–liquid extraction and gas chromatography–tandem mass spectrometry. The optimum electron ionization energy was determined and precursor ions and product ions for thirteen volatile disinfection byproducts were identified. The method provides rapid chromatographic analysis (10 minutes) and good separation. The linear dynamic range extended from 0.05 to 100 µg L^?1 (r² = 0.9983 – 0.9997, n=10) and the limits of detection (LODs) were between 0.003 and 0.014 µg L ^?1 . The intra-day (n=5) and inter-day (n=6) relative standard deviations were in the ranges of 2.81–8.22% and 3.48–10.85%, respectively. The method was validated by measurement of the recoveries of fortified surface, ground, and wastewater to be 74.7–115.4%, 86.1–120.6%, and 81.6–126.1%, respectively.     

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 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.     

Determination of Volatiles in Water Lily Flowers Using Gas Chromatography–Mass Spectrometry

Volatile organic compounds in the stamens, petals, and pistils of 56 water lily cultivars were determined by headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry. The stamens released a majority of the volatiles. A total of 117 volatile organic compounds were determined. Alkanes and alkenes were the most abundant, followed by aldehydes and ketones. Cluster analysis was used to divide the cultivars into three subsets characterized by specific aromatic compounds and associated aromas. Discriminant analysis confirmed the results of the cluster analysis. Three tropical water lily cultivars Colorata, 34, and Ai Ji Bai and one hardy water lily cultivar Somptuosa had particularly high aromatic compound concentrations and are recommended to produce fragrant, colorful, and hardy specimens.     

Diesel-Range Organics Extraction and Determination in Environmental Samples by Gas Chromatography‒Mass Spectrometry: Headspace Solid Phase Microextraction vs. Solvent Extraction

An accurate and sensitive analytical method for the determination of diesel-range organics (DRO) is the basis to monitoring and soil remediation studies. In the present work, the determination of DRO in different water and soil samples was optimized. Solvent extraction procedures, i.e. ultrasonic assisted extraction (USAE) (for water samples) and accelerated solvent extraction (ASE) (for soil samples), and a solvent-free procedure, headspace solid phase microextraction (HS-SPME), were optimized to achieve the highest recoveries for the simultaneous determination of all DRO. One hour of USAE for water samples and ASE of soil samples at 100°C, 2000 psi and two extraction cycles lead to analytical recoveries of 70?100%. Using HS-SPME, 30 min of incubation at 90°C were sufficient to achieve analytical recoveries up to 90% for water and soil samples. HS-SPME enables higher preconcentration factors, which makes this method more appropriate for samples with trace DRO concentrations.     

Determination of Pyrethroids in Dendrobium officinale by Ultrasound/Microwave-Assisted Solid–Liquid–Solid Dispersive Extraction,Gas Chromatography,and Triple-Quadrupole Mass Spectrometry

An ultrasound/microwave-assisted solid–liquid–solid dispersive extraction method was developed for the determination of 16 pyrethroid insecticides in Dendrobium officinale. The extraction and purification were performed in one step. The pyrethroids were extracted with 8:2 acetone:hexane and purified with a mixture of primary secondary amine, Florisil, C18, and graphitized carbon black. The extraction temperature, extraction time, and ultrasound power were optimized. Trans-cyfluthrin-d₆ was used as the internal standard to improve the accuracy. Under the optimized conditions, the recoveries of the pyrethroids were from 72.2 to 113.9% with the limits of detection between 0.29 and 9.38?µg?kg^?1. The optimized method was successfully used for the determination of pyrethroids in commercial D. officinale samples and may allow monitoring pyrethroids in herbal products.     

Determination of Chlorophenols in Sewage Sludge and Soil by High-Performance Liquid Chromatography–Tandem Mass Spectrometry with Ultrasonic-Assisted and Solid-Phase Extraction

Chlorophenols are a category of toxic pollutants that are ubiquitously present in the environment. This paper presents a reliable and feasible method for the determination of five chlorophenols in sewage sludge and soil using liquid chromatography–tandem mass spectrometry (LC-MS/MS). The pretreatment involved ultrasonic-assisted extraction and solid-phase extraction purification with hydrophilic–lipophilic balance cartridges. LC-MS/MS equipped with an electrospray ionization source operated in negative mode was used for detection, and multitude reaction monitoring mode was applied for data acquisition. The pretreatment and working conditions of LC-MS/MS were optimized to achieve satisfactory results. The intra-batch accuracies were 100.5–113.4% with relative standard deviations?≤?15.6% for the chlorophenols in sewage sludge and 71.3–102.7% with relative standard deviations?≤?14.0% for those in soil. The inter-batch accuracies were 86.1–100.5% (relative standard deviations?≤?33.6%) for sewage sludge samples and 70.5–112.5% (relative standard deviations?≤?28.2%) for soil samples, respectively. This method has been applied to the determination of chlorophenols in sewage sludge of wastewater treatment plants and soil collected from Guangzhou, China. Parachlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol were detected in some sewage sludge samples, with concentrations from 0.51 to 13.20?ng/g. In addition, parachlorophenol, 2,3,4,6-tetrachlorophenol, and pentachlorophenol were found in all the soil samples with concentrations from 0.33 to 5.21?ng/g. The chromatographic behavior, on-filter adsorption behavior, and the relationship between optimal collision energies and degree of chlorination of the chlorophenols was investigated. This method will be conducive to environmental research focusing on pollution investigation of chlorophenols in the environment.     

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 δ-Hexadecanesultone in Anionic Surfactants and Detergents by Gas Chromatography–Mass Spectrometry

Journal of Analytical Chemistry - A method is proposed for the determination of sultones in the anionic surfactant sodium α-olefin sulfonate (AOS Na) and products based on this surfactant. The...     

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.     

Preconcentration and Determination of 2,6-Dichlorobenzamide in Water by Stir Bar Extraction and High-Performance Liquid Chromatography–Tandem Mass Spectrometry

Polyacrylate stir bar sorptive extraction (SBSE) of 2,6-dichlorobenzamide followed by liquid desorption and analysis by liquid chromatography–tandem mass spectrometry using electrospray ionization is presented. The parameters influencing the methods were optimized and included a stirring speed of 500 revolutions per minute, an extraction time of two hours, a sample volume of 15 milliliters, 30 percent NaCl, and liquid desorption using acetonitrile under ultrasonication for fifteen minutes. A reverse phase C₁₈ column was used with isocratic elution (50 percent acetonitrile and 50 percent 5 millimoles per liter aqueous ammonium acetate buffer at pH 2.4), a flow rate of 0.4 milliliter per minute, and an injection volume of 10 microliters. Quantitative analysis was carried out by multiple reaction monitoring using positive polarity. The developed method required low sample volume (15 milliliters) and provided satisfactory figures of merit with a limit of detection of 0.002 microgram per liter, a limit of quantification of 0.006 microgram per liter, and good precision (inter-day relative standard deviation below 10 percent). The polyacrylate Twister was employed for up to twenty-five extraction and liquid desorption cycles. The applicability of the method was assessed by analyzing ground water collected at five sites in North Italy. The concentrations of 2,6-dichlorobenzamide were between 0.070 and 0.282 microgram per liter. Preliminary results on the use of polar stir bars for the determination of other polar pesticides in water are also provided.     

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.