Analysis of Steroid Hormones in Water Using Palmitate-Coated Magnetite Nanoparticles Solid-Phase Extraction and Gas Chromatography–Tandem Mass Spectrometry

A new extractive method based on magnetic solid–phase extraction using palmitate-coated magnetite nanoparticles coupled with gas chromatography-tandem mass spectrometry was developed for the extraction of estrone, androstenedione and progesterone hormones from water. The amount of nanoparticles and extraction time were optimized applying an experimental design to estimate simultaneously their influence on the recoveries. Results showed that the extraction efficiency was highly affected by the addition of salt and acetonitrile was the solvent used to elute the analytes from the nanoparticles. Derivatization via enolization of ketone group was carried out in the extract for the simultaneous derivatization of hydroxyl and ketone groups of steroid hormones previously to their chromatographic analysis. The extraction efficiencies of the nanoparticles were studied spiking at four concentration levels and recoveries from 94.6 to 109.7 % were obtained. The limits of detection ranged from 4 to 8 ng L^?1. The developed method provided a preconcentration factor of 100. The present work shows that palmitate-coated magnetite nanoparticles have good applicability for the extraction of natural estrogenic hormones that could be pollutants in real water samples.     

Analysis of Steroid Hormones in Water Using Palmitate-Coated Magnetite Nanoparticles Solid-Phase Extraction and Gas Chromatography–Tandem Mass Spectrometry

A new extractive method based on magnetic solid–phase extraction using palmitate-coated magnetite nanoparticles coupled with gas chromatography-tandem mass spectrometry was developed for the extraction of estrone, androstenedione and progesterone hormones from water. The amount of nanoparticles and extraction time were optimized applying an experimental design to estimate simultaneously their influence on the recoveries. Results showed that the extraction efficiency was highly affected by the addition of salt and acetonitrile was the solvent used to elute the analytes from the nanoparticles. Derivatization via enolization of ketone group was carried out in the extract for the simultaneous derivatization of hydroxyl and ketone groups of steroid hormones previously to their chromatographic analysis. The extraction efficiencies of the nanoparticles were studied spiking at four concentration levels and recoveries from 94.6 to 109.7 % were obtained. The limits of detection ranged from 4 to 8 ng L⁻¹. The developed method provided a preconcentration factor of 100. The present work shows that palmitate-coated magnetite nanoparticles have good applicability for the extraction of natural estrogenic hormones that could be pollutants in real water samples.

     

Determination of β2-Agonists in Porcine Urine by Molecularly Imprinted Solid Phase Extraction Followed Ultra-Performance Liquid Chromatography–Tandem Mass Spectrometry Detection

A novel, sensitive, and robust method has been developed to detect 9 β₂-agonists in porcine urine to monitor illegal use of β₂-agonists in swine rearing. The method based on the molecular imprinted polymer (MIP) rapid extraction followed ultra-performance liquid chromatography coupled tandem mass spectrometry (UPLC-MS/MS) detection. The cleaning efficiency of MIP cartridges was demonstrated by comparing with common ion exchange solid phase extraction. The presented method was validated in accordance with the European Commission Decision 2002/657/EC. The linearity, decision limit (CCα), detection capability (CCβ), recovery, precision, robustness, and stability were studied in detail. CCα and CCβ values were from 0.006 ng/mL to 0.03 ng/mL and from 0.02 ng/mL to 0.08 ng/mL, respectively. The mean recoveries and repeatability varied from 68.8% to 94.2% and from 2.8% to 10.1%. The proposed method was applied to test 170 porcine urine samples from the Shaanxi province in China and two urine samples were confirmed as clenbuterol positive and the concentrations of clenbuterol in positive urine samples were about 0.08 ng/mL and 0.1 ng/mL, respectively. The developed method was demonstrated to be more sensitive and robust for the determination of 9 β₂-agonists in porcine urine. The method was proven to be simple and easy in operation with high selectivity and good reproducibility.     

Determination of Pesticides in the Respirable Fraction of Airborne Particulate Matter by High-performance Liquid Chromatography–Tandem Mass Spectrometry

Potential harmful effects of pesticides include risks to human health of workers involved in the wet spray application in cultivated areas. Inhalation exposure depends on several factors including pesticide concentrations in the respirable fraction of airborne particulate matter (PM₄). To ensure a high level of protection, the use of tractors with cabins provides protection against dust, aerosols, and vapors. Since tractors not providing maximum protection are still in use, PM₄ was sampled during spreading operations in agricultural fields inside and outside tractor cabins. Sample preparation technique based on accelerated solvent extraction and solid-phase extraction cleanup was optimized before analysis of nine pesticides in PM₄. Meptyldinocap, deltamethrin, myclobutanil, fluopyram, methoxyfenozide, dimethomorph, fluopicolide, cyflufenamid, and metrafenone were simultaneously determined by high-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (HPLC–ESI–MS–MS). The results demonstrated the efficacy of the tractor cabs used in the sampling sites.     

Using Hypercrosslinked Polystyrene for the Multicomponent Solid-Phase Extraction of Residues of 63 Veterinary Preparations in Their Determination in Chicken Meat by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

Journal of Analytical Chemistry - Hypercrosslinked polystyrene is proposed for the multicomponent solid-phase extraction of residues of 63 veterinary preparations from various classes...     

Determination of Aflatoxins in Rice and Maize by Ultra-High Performance Liquid Chromatography–Tandem Mass Spectrometry with Accelerated Solvent Extraction and Solid-Phase Extraction

A fast and reliable ultra-high performance liquid chromatography–tandem mass spectrometry method was developed for the determination of aflatoxins B₁, B₂, G₁, and G₂ in cereal. The analytes were extracted by accelerated solvent extraction with methanol/water (80:20). A polymeric solid-phase extraction column was used for sample preparation. Under optimum conditions, the analyte recoveries for samples spiked at different concentration levels in rice and maize ranged from 71.2 to 94.0%, with relative standard deviations less than 16.4%. Limits of detection (signal-to-noise ratio, 3:1) for the aflatoxins ranged from 0.25 to 0.93 ng/g. The developed method was applied to the determination of aflatoxins in ten rice and maize samples. One maize sample tested positive with an aflatoxin B₁ concentration of 2.7 ng/g.     

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 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.     

Determination of Flavonoids in Stellaria by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

The genus Stellaria (Caryophyllaceae) presents widely distributed plants often used in traditional medicine. Flavonoids are highly active plant secondary metabolites that may be involved in some of the effects of Stellaria plants. In this study, two new high-performance liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC–ESI-MS-MS) methods were developed for the determination of flavonoids and isoflavonoids in plant material. The separations were performed on a reverse-phase C₁₈ column with gradient elution using methanol and water with 0.5% acetic acid as the mobile phase. Multiple reaction monitoring was used for the tandem mass spectrometry detection and the two most intensive transitions were chosen for the identification of each analyte. The limits of detection and the limits of quantification were between 0.2 and 15.0 ng/mL and 0.6 and 50.0 ng/mL. The developed methods were successfully used for the analyses of four representatives of the genus Stellaria. All the studied herbs contained luteolin and its 7-O-glycosides, naringenin, kaempferol, quercetin, its glycoside rutin, apigenin, and its 7-O-glycoside. One coumarin, scopoletin, was also found. Isoflavones were primarily represented by genistein, genistin, and ononin. Some of the analytes were detected for the first time in Stellaria sp. The findings support that these methods are suitable for analyses of plant material.     

Analysis of Chloramphenicol Residues in Honey by Liquid Chromatography–Tandem Mass Spectrometry

Antibiotics are often used in bee-keeping to control European and American foulbrood. The broad spectrum antibiotic chloramphenicol (CAP) was used for curative purposes in veterinary medicine, but is now forbidden in numerous countries, although still used in south-east Asia. A liquid-chromatographic method with tandem mass spectrometric detection (LC–MS–MS) has been developed for analysis of sub-g kg^–1 residues of chloramphenicol in honey. Results from full validation of the procedure and analysis of 75 honey samples obtained commercially in Switzerland are presented. These show the method is satisfactory and useful for monitoring chloramphenicol residues in honey.     

A Novel Method for the Determination of Fungicide Residues in Tobacco by Ultra-performance Liquid Chromatography–Tandem Mass Spectrometry Combined with Pass-Through Solid-Phase Extraction

Chromatographia - A novel method for the rapid simultaneous determination of multiple fungicide residues in tobacco was established using ultra-performance liquid chromatography–tandem mass...     

Determination of Microcystins in Cyanobacteria by Supercritical Fluid Extraction and Liquid Chromatography‐Tandem Mass Spectrometry

Abstract

A method for the detection of microcystins (microcystin LR, RR, and YR) in cyanobacteria by supercritical fluid extraction (SFE) and liquid chromatography‐mass spectrometry (LC/MS) has been developed. Supercritical fluids for the analytical extraction of nonvolatile, higher molecular weight compound, and microcystins from cyanobacteria were investigated. The microcystins included in this study are sparsely soluble in neat supercritical fluid CO₂. However, the microcystins was successfully extracted with a ternary mixture (90% CO₂, 9.5% methanol, 0.5% water) at 40°C and 250 atm. The polar carbon dioxide‐aqueous methanol fluid system gave high extraction efficiency for the extraction of the polar microcystins from cyanobacteria. The microcystins were determined by liquid chromatography‐tandem mass spectrometry (LC/MS/MS).     

Determination of Eupatilin in Human Plasma by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric method (LC-MS-MS) for the determination of eupatilin in human plasma has been developed. Eupatilin and an internal standard; (S)-N-(3-{3-fluoro-4-[6-(1-methyl-1H-tetrazol-5-yl)-pyridine-3-yl]-phenyl}-2-oxo-oxazolidin-5-ylmethyl)-acetamide (DA-7867) were extracted from human plasma by liquid-liquid extractionand analyzed on a phenyl-hexyl column using the mobile phase: acetonitrile-ammonium formate (10 mM, pH 3.0) (60:40, /). Analytes were detected using electrospray ionization-tandem mass spectrometry in multiple-reaction monitoring mode. The calibration curve was linear (r = 0.999) over the concentration range: 1.00–500 ng mL^–1 with a lower limit of quantification of 1.0 ng mL^–1 using a 100 L plasma sample. The precision (CV%) of this assay ranged: 2.4–7.0%, relative error: –7.0 to +2.0%. Recoveries of eupatilin ranged: 64.3–65.0%, with that of DA-7867 (internal standard) being 87.0 ± 5.3%.     

Analysis of the Heterocyclic Aromatic Amines in Cigarette Smoke by Liquid Chromatography–Tandem Mass Spectrometry

In this paper, a sensitive accurate method for the determination of heterocyclic aromatic amines (HAAs) in cigarette smoke has been developed and validated using solid-phase extraction coupled with liquid chromatography–tandem mass spectrometry. A calibration curve was obtained with representative cigarette smoke using the standard addition method to compensate for matrix effects because the smoke of different cigarettes shows similar matrix effects. With this method, the accuracy of the method can be improved using a common analog of HAAs, which will greatly reduce the expense of using an isotope-labeled internal standard. Validation results showed that the method has high sensitivity (quantification limits of 0.08–0.56 ng cig⁻¹), good reproducibility (RSD 6.37–9.31 %) and satisfactory recoveries (81.0–111 %). With this method, the emissions of HAAs in 30 commercial cigarette samples were analyzed and compared.

     

Analysis of the Heterocyclic Aromatic Amines in Cigarette Smoke by Liquid Chromatography–Tandem Mass Spectrometry

In this paper, a sensitive accurate method for the determination of heterocyclic aromatic amines (HAAs) in cigarette smoke has been developed and validated using solid-phase extraction coupled with liquid chromatography–tandem mass spectrometry. A calibration curve was obtained with representative cigarette smoke using the standard addition method to compensate for matrix effects because the smoke of different cigarettes shows similar matrix effects. With this method, the accuracy of the method can be improved using a common analog of HAAs, which will greatly reduce the expense of using an isotope-labeled internal standard. Validation results showed that the method has high sensitivity (quantification limits of 0.08–0.56 ng cig^?1), good reproducibility (RSD 6.37–9.31 %) and satisfactory recoveries (81.0–111 %). With this method, the emissions of HAAs in 30 commercial cigarette samples were analyzed and compared.     

Determination of Nitrofurans in Chicken Feed by High-Performance Liquid Chromatography–Tandem Mass Spectrometry

Liquid chromatography with tandem mass spectrometry was used for the determination of nitrofurantoin, nitrofurazone, furazolidone, and furaltadone in chicken feed. The nitrofurans were extracted with phosphate buffer (pH 7) and sodium chloride. Proteins and lipids were removed with acetonitrile and hexane before purification with ethyl acetate, dilution in 1:1 acetonitrile-5 millimolar ammonium acetate at pH 7.3, and filtration prior to analysis. The limits of detection were 1.69, 1.74, 2.01, and 1.45 microgram per kilogram for nitrofurantoin, nitrofurazone, furazolidone, and furaltadone, respectively. The mean recoveries were between 84.6 and 110.6 percent. The method was employed to determine nitrofurans in chicken feed.     

Determination of 16 Mycotoxins in Maize by Ultrahigh-Performance Liquid Chromatography–Tandem Mass Spectrometry

An ultrahigh-performance liquid chromatography–tandem mass spectrometry method was developed and validated for the simultaneous determination of sterigmatocystin, verruculogen, enniatin A, fusarenon-X, fumonisins B1, B2, B3, aflatoxins B1, B2, G1, G2, ochratoxin A, deoxynivalenol, 3-acetyldeoxynivalenol, 5-acetyldeoxynivalenol, and zearalenone. The mycotoxins were extracted and cleaned up using a multitoxin column, separated on a C18 column, and then detected on a triple-quadrupole mass spectrometer. The limits of detection and quantification ranged within 0.2–2?µg/kg and 1–10?µg/kg, respectively. The recoveries ranged from 70.8 to 118.4%, with relative standard deviations below 15%. The method was used to analyze 80 samples obtained from Shandong Province in China. Fifty-eight samples were contaminated with 10 mycotoxins at concentrations ranging from 1.4 to 6566.1?µg/kg. Some samples exceeded the maximum limits in China and in European regulations for mycotoxins in unprocessed maize.     

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.     

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.