Development of CO<Subscript>2</Subscript>-Mediated Switchable Hydrophilicity Solvent-Based Microextraction Combined with HPLC-UV for the Determination of Bisphenols in Foods and Drinks

In traditional dispersive liquid-liquid microextraction procedures, both extraction and dispersive solvents are required, and thus, it increases the consumption of organic solvent. Herein, we reported a CO₂-mediated switchable hydrophilicity solvent-based microextraction (SHS-BME) for the determination of bisphenol compounds (BPCs) in complex milk and drink samples. N,N-Dimethylcyclohexylamine was used as a switchable hydrophilicity solvent; it can switch reversibly between one form that is miscible with water and another that forms a biphasic mixture with water, and thus allow extraction of the analytes in a homogeneous phase without dispersive solvent. Several important parameters were screened and optimized by single factor experiments and central composite design as follows: 782 μL of switchable solvent, 375 μL of NaOH solvent, and 1.1:1 switchable solvent/water (v/v). Under the optimized SHS-BME conditions, the limit of detections (LODs) for BPCs in milk, orange juice, and energy drink samples were in the range of 0.27–0.40 μg L^?1 for BPE, 0.17–0.30 μg L^?1 for BPA, and 0.50–0.67 μg L^?1 for BPB, respectively, and the extraction recoveries for BPCs were in the range of 79.5–103.4% in milk, of 84.5–97.5% in orange juice, and of 91.9–101.2% in energy drinks. The precision of the method, based on relative standard deviations (RSDs), ranged from 1.7 to 4.8% and from 2.1 to 5.7% for intra-day and inter-day comparisons, respectively. In total, this SHS-BME method possesses many advantages, such as high extraction recovery and high detection sensitivity (low LODs and RSDs), no requirement of dispersive solvent, simple operational procedure, reducing the pretreatment time and workload, and so on. Therefore, it has a great potential application value for detection of trace BPCs in routine food tests.     

Development of an ELISA and Immunochromatographic Assay for Tetracycline,Oxytetracycline, and Chlortetracycline Residues in Milk and Honey Based on the Class-Specific Monoclonal Antibody

A sensitive class-specific monoclonal antibody against tetracyclines (TCs) was generated and used to develop an enzyme-linked immunosorbent assay (ELISA) and an immunochromatographic assay for TC, oxytetracycline (OTC), and chlortetracycline (CTC) detection in milk and honey samples. The dynamic range of detection for TC in ELISA was 0.26–2.00 μg L^?1 with an IC₅₀ of 0.72 μg L^?1. The IC₅₀ value of OTC and CTC was 3.2 and 6.4 μg L^?1, respectively. The recovery of TC, OTC, and CTC in milk samples was 82–102, 91–105, and 90–101 %, respectively, and 88–101, 89–101, and 89–95 % in honey samples, respectively. In the immunochromatographic assay, the cutoff values for TC, OTC, and CTC were 15, 15, and 50 μg L^?1 in milk, respectively, and 40, 40, and 40 μg L^?1 in honey, respectively. The results revealed that ELISA and the immunochromatographic assay can be applied for the rapid and sensitive detection of TC, OTC, and CTC in milk and honey samples.     

Graphene Reinforced Hollow Fiber Liquid Phase Microextraction for the Enrichment of some Phenylurea Residues in Milk Sample

Graphene, as a kind of novel and interesting carbon material, has gained much attention in recent years. In this paper, a new sample preparation technique, graphene reinforced hollow fiber liquid phase microextraction (G-HF-LPME), was developed and used to pre-concentrate some phenylurea herbicides (chlortoluron, isoproturon, diuron, monolinuron, and buturon) in milk sample prior to high-performance liquid chromatography–ultraviolet detection. Different parameters influencing the extraction efficiency of the G-HF-LPME were investigated and optimized. Under the optimized conditions, a good linearity was observed in the range between 10.0 and 400.0 μg L^?1 with the correlation coefficients ranging from 0.9911 to 0.9987. The limit of detection (S/N?=?3) of the method was lower than 2.0 μg L^?1. The developed method is simple, efficient, and has been successfully applied to the determination of the phenylureas in milk samples.     

A Rapid Quantification of β-Carotene in Fruits and Vegetables by Dispersive Liquid–Liquid Microextraction Coupled with UV–Vis Spectrophotometry: Optimized by Response Surface Methodology

A simple, fast, and efficient method consisted of optimized dispersive liquid–liquid microextraction (DLLME) followed by UV–vis spectrophotometry was developed for determination of β-carotene in fruits and vegetables. Chloroform and methanol were chosen as extraction and disperser solvents, respectively. The extraction process was optimized using a central composite design (CCD) with the optimum points of 115 μL for volume of extraction solvent and 6.5 % (w/v) for salt concentration. Under the optimal conditions, the relative standard deviation (RSD, C?=?500 μg L^?1, n?=?5), limit of detection (LOD), linear dynamic range (LDR), and coefficient of determination (R²) were 1.08 %, 2 μg L^?1, 50–1,500 μg L^?1, and 0.991, respectively. The present method consisted of a simple and fast sample preparation procedure without any antioxidant addition, saponification, and purification was used.     

Novel Binary Solvents-Dispersive Liquid—Liquid Microextraction (BS-DLLME) Method for Determination of Patulin in Apple Juice Using High-Performance Liquid Chromatography

A simple and rapid binary solvents-based dispersive liquid–liquid microextraction (BS-DLLME) method has been developed for determination of patulin (PAT) in apple juice followed by high-performance liquid chromatography. This method involves the use of an appropriate mixture of miscible binary extraction solvents and disperser solvent to form fine droplets of extractant in a sample solution. Parameters affecting extraction efficiency such as the type and volume of high-density extraction solvent, the volume of ethyl acetate, the kind and volume of disperser solvent, and salt addition were investigated and optimized. The detection and quantification limits were 2.0 and 10.0 μg L^?1, respectively. The relative standard deviation for five measurements of 25 μg L^?1 of PAT was 3.8 %. The relative recoveries of PAT from apple juice samples at spiking levels of 25, 50, and 75 ng mL^?1 were in the range of 91.3–95.2 %.     

Rapid Determination of Trace Sulfonamides in Milk by Graphene Oxide-Based Magnetic Solid Phase Extraction Coupled with HPLC–MS/MS

A simple and rapid method based on magnetic solid-phase extraction (MSPE) combined with high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC–MS/MS) was used for the determination of 15 sulfonamides from milk samples. The extraction and cleanup used a graphene oxide-based magnetic nanocomposite (Fe₃O₄@GO) as an adsorbent. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe₃O₄@GO, the extraction time, the ionic strength of sample solution, and the type of eluent, were investigated. Under optimized experimental conditions, good linearity was observed in the range of 2.0 to 100.0 μg L^?1 for all of the analytes, with correlation coefficients (R²) ranging from 0.994 to 0.999. The limits of detection for the method ranged between 0.02 and 0.13 μg L^?1. Mean values of the relative standard deviation of intraday and interday precision ranging from 1.0 to 7.3 % and from 1.7 to 8.1 % were obtained, respectively. The average recoveries were between 73.4 and 97.4 % at three different spiked levels. It was confirmed that the Fe₃O₄@GO nanocomposite was an effective MSPE material for use in sulfonamide analyses in milk samples.     

Ionic Liquid-Based Dispersive Liquid–Liquid Microextraction Following High-Performance Liquid Chromatography for the Determination of Fungicides in Fruit Juices

This paper described an ionic liquid-based dispersive liquid–liquid microextraction (IL-DLLME) combined with high-performance liquid chromatography (HPLC) method to determine fungicides in fruit juices. In this method, 1-hexyl-3-methyli-midazolium hexafluorophosphate (HMIMPF₆) was used as extraction solvent, which dispersed into the fruit juices under vigorously shaking with the vortex. The effects of experimental parameters, such as extraction solvent volume, disperser solvent and its volume, vortex time, centrifugation time, sample pH, on the extraction efficiency were investigated. Under the optimum conditions, the linear correlation coefficients ranged from 0.9902 to 0.9979 for concentration levels of 0.02–2 mg l^?1, the extraction recoveries were ranged 66.2–92.9 % except pyrimethanil (39.5–44.6 %), The relative standard deviations (RSDs; n?=?6) ranged from 2.2 % to 11.6 %, and the limits of detection (LODs) for the fungicides were between 3.1 and 10.2 μg l^?1. Two real samples including apple and grape juices, spiked at two concentration levels were analyzed and yielded recoveries ranging from 71.3–93.1 % and 65.4–87.7 %, respectively.     

Simple and fast spectrophotometric determination of low levels of thiabendazole residues in fruit and vegetables after pre-concentration with ionic liquid phase microextraction

There is a great importance of monitoring thiabendazole (TBZ) residues in fruits and vegetables to ensure food safety. Therefore, a new ionic liquid (IL) phase microextraction method using IL, 1-butyl-3-methylimidazoliumhexafluorophosphate [C₄mim][PF₆], as extracting solvent is proposed for simple and fast determination of low levels of TBZ in fruits and vegetables by spectrophotometry. The method is based on selective complex formation of TBZ with Cu(II) ions in presence of PF₆^– as counter ion at pH 5.5, and then microextraction of the complex into the fine micro-drops of IL phase. After optimisation of variables affecting microextraction efficiency, the analytical parameters of the method were determined by calibration curves. The method exhibits a linear relationship (0.3–280 μg L^?1), low detection limit (0.1 μg L^?1), good intra- and inter-day precision (2.4–4.5% as RSD_r%, 2.1–5.6% as RSD_R%), good recovery (≥95.1–98.2%) and high sensitivity enhancement factor (150) by solvent-based calibration curve. It allows a detection limit of 0.24 μg L^?1 and a range of 0.8–250 μg L^?1 by the matrix-matched calibration curve. After validation, the method was successfully applied to the determination of TBZ residues with method quantification limits in fruit and vegetables of 2.0 and 2.5 µg kg^?1 with and without adding polyvinylpyrrolidone (PVP-15) solution. Recoveries range from 85.5% to 98.2% after spiking (10, 50 and 100 µg kg^?1, n: 3).     

Dual-Label Chemiluminescence Strategy for Multiplexed Immunoassay of 20 Fluoroquinolones, 15 β-Lactams, 15 Sulfonamides,and CAP in Milk

In this paper, a novel dual-label time-resolved chemiluminescent multiplexed immunoassay (DLTRC-MIA) based on the distinction of the kinetic characteristics of horseradish peroxidase (HRP) and alkaline phosphatase (ALP) with approximate estimation approach for simultaneous determination of 20 fluoroquinolones (FQs), 15 β-lactams, 15 sulfonamides (SAs), and chloramphenicol (CAP) in milk was developed. The strategy integrated a single-chain variable fragment–alkaline phosphatase fusion protein (scFv-ALP), a recombinant penicillin-binding protein (PBP) 2×*, a monoclonal antibody (MAb), and a polyclonal antibody (PAb) in one immunoassay and in a single well together to fulfill the simultaneous detection of 51 low-molecular weight contaminants (20 FQs, 15 β-lactams, 15 SAs, and CAP). The limits of detection for FQs, β-lactams, SAs, and CAP range from 0.29 μg L^?1 for ciprofloxacin (CIP) to 81.6 μg L^?1 for trovafloxacin (TRO), 0.27 μg L^?1 for ceftiofur (CEF) to 44.1 μg L^?1 for cephalexin (CEL), 0.089 μg L^?1 for sulfadimethoxine (SDM) to 2.7 μg L^?1 for sulfadiazine (SDZ), and 0.028 μg L^?1 for CAP, respectively. The results demonstrated that the detection limits of DLTRC-MIA meet the requirement of detection levels for 51 drug residues in milk, suitable for high-throughput screening of low-molecular weight contaminants.     

Determination of Hormones Residues in Milk by Gas Chromatography-Mass Spectrometry

The article presents the use of gas chromatography-mass spectrometry (GC-MS) technique in a method for the determination of 18 anabolic hormones from synthetic stilbenes, steroids and resorcylic acid lactones (RALs) groups in raw milk and milk powder. Sample preparation consisted of liquid-liquid extraction with diethyl ether and purification by solid phase extraction (SPE). Prior to instrumental analysis, the reaction of derivatisation with the heptafluorobutyric anhydride or N-methyl-N-trimethylsilyltrifluoroacetamide was performed. Method validation was carried out according to the required performance criteria of the Commission Decision 2002/657/EC. The apparent recovery of all analytes at 1 μg L^?1 (kg^?1) level was ranged between 70.4 and 119.4 % with the coefficients of variation values less than 30 %. The decision limits (CCα) and the detection capabilities (CCβ) were in the range of from 0.11 to 0.44 μg L^?1 (kg^?1) and from 0.19 to 0.75 μg L^?1 (kg^?1), respectively. The procedure has been accredited and successfully applied as a screening method for the presence of hormone residues in the study of commercial samples of milk.     

Preconcentration and Simultaneous Determination of Heterocyclic Aromatic Amines in Grilled Pork Samples by Ion-Pair-Based Surfactant-Assisted Dispersive Liquid-Liquid Microextraction and High-Performance Liquid Chromatography

An effective ion-pair-based surfactant-assisted dispersive liquid-liquid microextraction combined with high-performance liquid chromatography (HPLC) has been evaluated for the extraction and preconcentration of four heterocyclic aromatic amines (i.e., 2-amino-3,4-dimethyl-3H-imidazo[4,5-f]quinoline (MeIQ); 2-amino-3,4,8-trimethyl-3H-imidazo[4,5-f]quinoxaline (4,8-DiMeIQx); 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP); and 1-methyl-9H-pyrido[3,4-B]indole (Harmane)). In the extraction method, sodium dodecyl sulfate (SDS) was used as both ion-pairing and disperser agent and 1-octanol was selected as extraction solvent. The effects of various parameters on the extraction efficiency such as kind and concentration of surfactant, kind and volume of extraction, salt addition, vortex extraction, and centrifugation time were investigated. Under the selected condition, the method provided high enrichment factor in the ranged of 124–145. Good linearity was 0.01–1000 μg kg^?1 with the correlation coefficient (R ²)?>?0.999. The limit of detection was 0.01 μg kg^?1 for all compounds. The matrix match calibration was used for quantitation of the target analytes in grilled pork samples. The proposed method was successfully applied to analysis of heterocyclic aromatic amines in grilled pork samples where good recoveries were obtained in the range of 90 and 106 %.     

Application and Optimization of Microwave-Assisted Extraction and Dispersive Liquid–Liquid Microextraction Followed by High-Performance Liquid Chromatography for the Determination of Oleuropein and Hydroxytyrosol in Olive Pomace

In the present study, a new method based on microwave-assisted extraction and dispersive liquid–liquid microextraction (MAE–DLLME) followed by high-performance liquid chromatography (HPLC) was proposed for the separation and determination of oleuropein (Ole) and hydroxytyrosol (HyT) from olive pomace samples. The effective factors in the MAE–DLLME process such as microwave power, extraction time, the type and volume of extraction, and dispersive solvents were studied and optimized with the aid of response surface methodology (RSM) based on a central composite design (CCD) to obtain the best condition for Ole and HyT extraction. At the optimized conditions, parameter values were 220 W microwave power, 12 min extraction time, 60 μL extracting solvent, and 500 μL dispersive solvent. The calibration graphs of the proposed method were linear in the range of 10–500,000 μg L^?1, with the coefficient of determination (R²) higher than 0.99 for Ole and HyT. Repeatability of the method, described as the relative standard deviation (RSD), was 4.12–5.63% (n?=?6). The limits of detection were 35 and 20 μg L^?1 for Ole and HyT, respectively. The recoveries of these compounds in the spiked olive pomace sample were from 93 to 98%. The proposed method, MAE–DLLME–HPLC–UV, was an accurate, rapid, and reliable method when compared with previous methods.     

Extraction and Preconcentration of Some Triazole Pesticides in Grape Juice by Salting Out Homogeneous Liquid–Liquid Extraction in a Narrow-Bore Tube Prior to Their Determination by Gas Chromatography–Flame Ionization Detection

A fast and simple extraction and preconcentration method for some triazole pesticides has been developed using a homogeneous liquid–liquid extraction method performed in a narrow-bore tube. The extraction is based on phase separation of a water-miscible organic solvent from aqueous solution in the presence of a salting out agent. In this work, the homogeneous solution of water and acetonitrile (water-soluble extraction solvent) was broken by addition of 30 %, w/v, sodium chloride (salting out agent). After sonication, a small volume of acetonitrile was collected on top of the tube and the extracted analytes in the collected phase were determined by gas chromatography–flame ionization detection. The effect of various experimental parameters including kind and volume of the water-soluble organic solvent, amount of salt, length and diameter of tube, and pH of sample solution was investigated. Under the optimum conditions, calibration graphs were linear over the range of 3–5,000 μg L^?1. Relative standard deviations were less than 5.4 % for six repeated determinations (C?=?100 μg L^?1). Furthermore, the limits of detection (S/N?=?3) and quantification (S/N?=?10) were obtained in the ranges of 0.60–4.8 and 1.9–16 μg L^?1, respectively. This method is very simple and rapid, requiring less than 10 min for sample preparation. It has been successfully utilized for the analysis of triazole pesticides in the grape juice samples.     

Determination of Sulfonylurea Herbicides in Food Crops by Matrix Solid-Phase Dispersion Extraction Coupled with High-Performance Liquid Chromatography

A simple and sensitive method was developed for the determination of four sulfonylurea herbicides (metsulfuron-methyl, chlorsulfuron, chlorotoluron, and bensulfuron-methyl) using matrix solid-phase dispersion (MSPD) extraction followed by high-performance liquid chromatography. The experimental conditions for the MSPD extraction, such as type and amount of dispersant, the ratio of dispersant to sample, type and volume of washing and elution solvent were evaluated and optimized. Under the optimal conditions, the calibration curves for the sulfonylurea herbicides had good linear relationships (r?>?0.997) in the concentration range of 0.2–10 μg g^?1, and the limits of detection were in the range of 0.02–0.07 μg g^?1. The recoveries of the sulfonylurea herbicides at two fortification levels were between 62.0 and 102.6 % with the relative standard deviations less than 6.92 %. The methodology was successfully applied to the analysis of four sulfonylurea herbicides in food crops.     

Ultrasound-Assisted Emulsification-Microextraction/Ion Mobility Spectrometry Combination: Application for Analysis of Organophosphorus Pesticide Residues in Rice Samples

The present paper describes the validation of ultrasound-assisted emulsification-microextraction method followed by ion mobility spectrometry (IMS) detection for simultaneous determination of two organophosphorus pesticides, diazinon and chlorpyrifos. Ultrasound radiation was applied for accelerating the emulsification of microliter organic solvent in aqueous solutions and enhancing the microextraction efficiency. This preconcentration step combined with IMS detection provided a precise and accurate method for determination of trace amounts of diazinon and chlorpyrifos pesticides. The effect of parameters influencing the extraction efficiency such as sonication time, type of extraction solvent, extraction solvent volume, and salt concentration were investigated and discussed. The enrichment factors found, under optimum conditions, were 230 and 300 for diazinon and chlorpyrifos, respectively, with corresponding LOD of 2.1 and 3.2 μg L^?1. The presented method can be applied for the determination of diazinon and chlorpyrifos in the range 6.0–700 and 8.9–750 μg L^?1, respectively, with correlation coefficients (R ²)?>?0.99. The applicability of the proposed method was evaluated by determination of the residues of the investigated pesticides in rice paddy water gathered from four stations during 60 days after spraying (June 2014), and in storage rice samples in Mazandaran province, Iran.     

Determination of Benzalkonium Homologues and Didecyldimethylammonium in Powdered and Liquid Milk for Infants by Hydrophilic Interaction Liquid Chromatography–Mass Spectrometry

In this study, a hydrophilic interaction liquid chromatography–mass spectrometry (HILIC-MS/MS) method for the determination of benzalkonium (BAC) homologues and didecyldimethylammonium (DDAC) was developed. A satisfactory chromatographic separation of BAC homologues and DDAC was achieved using, as mobile phase, acetonitrile–aqueous 50 mM ammonium formate (pH 3.2) (93?+?7 v/v) at 0.3 mL min^?1. The elution order of BAC homologues was from benzyldimethylhexadecylammonium chloride (C₁₆-BAC) to benzyldimethyldecylammonium chloride (C₁₀-BAC), the exact opposite with respect to separation using reversed liquid chromatography. The instrumental method was successfully applied to powdered and liquid milk for infants (about 50 samples). From powdered milk samples, BAC and DDAC were extracted using 5 % formic acid in methanol for 60 min at 60 °C in an ultrasonic bath; after dilution with water and 5 % NH₄OH solution, a purification step using a weak cationic exchange column was performed. Satisfactory limit of detections (LODs) were achieved, below 1.0 μg kg^?1 and 0.05 μg L^?1 for powdered and liquid milk for infants, respectively. No sample was free of BAC homologues and DDAC, and in one powdered milk sample, the contamination level exceeded 500 μg kg^?1, the maximum level recommended by the Standing Committee on the Food Chain and Animal Health for food and feed.     

Simultaneous pre-concentration of Pb and Sn in food samples and determination by atomic absorption spectrometry

A cloud point extraction (CPE) method has been developed for the pre-concentration and simultaneous determination of lead [Pb(II)] and tin [Sn(II)] using Acridine Orange as complexing reagent and mediated by nonionic surfactant (Triton X-114) by flame atomic absorption spectrometry (FAAS). The main factors affecting analytical performance of CPE have been investigated in detail. The extracted surfactant-rich phase was diluted with (1.0 mol L^?1) nitric acid in methanol, prior to subjecting FAAS. The calibration graphs obtained from Pb(II) and Sn(II) were linear in the concentration ranges of 5–1,000 and 10–5,000 μg L^?1 with detection limits of 1.40 and 2.86 μg L^?1, respectively. The relative standard deviations for 10 replicates containing 25 μg L^?1 of Pb(II) and Sn(II) were 2.15 and 2.50 %, respectively. The analytical procedure was verified by the analysis of the standard reference materials NWTMDA-61.2 (water-trace elements) and NIST SRM 1548a (typical diet). The developed method has been applied to the simultaneous determination of total Pb and Sn in canned food samples including juices, tomato paste, corn, and green pea.     

Determination of benzo[α]pyrene in edible oil using tetraoxocalix[2]arene[2]triazine bonded silica SPE sorbent

Benzo[α]pyrene (BaP) is a well-known carcinogen in edible oil. In this study, a method combined solid-phase extraction (SPE) with fluorescent detection was developed using tetraoxocalix[2]arene[2]triazine sorbent (SiO₂-OCA) for the clean-up and enrichment of BaP. The interaction between SiO₂-OCA and BaP involves a donor–acceptor complex mechanism. The experimental procedure was as follows: BaP was extracted from edible oil with DMF/H₂O (9:1, v/v). Then, the ratio of DMF/H₂O was adjusted to 1:2 prior to SPE. The final concentrate was analysed using a fluorescence detector at excitation and emission wavelengths of 255 and 420 nm. The method was fully validated. The linearity was in the range of 0.1–100 μg kg^?1 with a coefficient of 0.999. The limits of detection and quantification were 0.03 and 0.1 μg kg^?1, respectively. The average recoveries were in the range of 88.0 ? 122.3%. The intraday and interday precisions were 6.8% and 9.2%, respectively. Compared with other methods, the method reported in this article shows a good detection limit, high reproducibility and recovery and linearity over a broad concentration range. This established method was also applied to evaluate real samples. The concentration of six tested samples was below 5 μg kg^?1.     

Hollow Fiber Liquid Phase Microextraction Method Combined with High-Performance Liquid Chromatography for Simultaneous Separation and Determination of Ultra-Trace Amounts of Naproxen and Nabumetone in Cow Milk,Water, and Biological Samples

A simple and highly sensitive method based on hollow fiber liquid phase microextraction combined with high-performance liquid chromatography and fluorescence detection has been developed for simultaneous separation, preconcentration, and determination of naproxen and nabumetone from water, wastewater, milk, and biological samples. Parameters affecting the microextraction efficiency were evaluated and optimized. Under optimum conditions (extractant (14 μL of 1-undecanol), sample pH (3.0), extraction time (20 min), stirring rate (600 rpm), temperature (45 °C), potassium chloride concentration (4.0 %) and sample volume (9 mL)), the limits of detection based on (S/N?=?3) were 1.3 ng L^?1 for naproxen and 2.9 ng L^?1 for nabumetone. The intra- and inter-assay relative standard deviations for naproxen and nabumetone were in the ranges of 3.2–6.1 % and 6.5–9.5 %, respectively. The calibration curves were linear in concentration ranges of 4.0–300.0 ng L^?1 and 9.0–300.0 ng L^?1 for naproxen and nabumetone, respectively, with good coefficient of determination (r ²?>?0.999). The method was successfully applied to the determination of naproxen and nabumetone in cow milk, water, wastewater, human plasma, and urine samples.     

Determination of Trichothecenes in Cereal Matrices Using Subcritical Water Extraction Followed by Solid-Phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry

Subcritical water extraction followed by solid-phase extraction and ultra-high performance liquid chromatography coupled with tandem mass spectrometry detection is reported for the first time for the determination of 6 trichothecenes (deoxynivalenol, deoxynivalenol-3-glucoside, 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, HT-2 toxin, and T-2 toxin) from different cereals. Water with 1% formic acid was used as the extraction solvent followed by a solid-phase extraction clean-up, achieving good performance with acceptable extraction recoveries, method detection limits between 0.05 μg kg^?1 and 4.0 μg kg^?1, and method quantification limits between 0.4 μg kg^?1 and 20 μg kg^?1. The use of water as the extraction solvent allowed a selective extraction affording low matrix effect levels and the detection and quantification of natural target trichothecenes at very low concentration levels. This extraction method was applied to different cereals, a pseudocereal and an oilseed sample, of which maize, millet, and oat were contaminated by at least one trichothecene.