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.     

Determination of Eugenol in Aquatic Products by Dispersive Solid-Phase Extraction and Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

A novel procedure, dispersive solid-phase extraction coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), was developed for the determination of eugenol in aquatic products (shrimp, crab, and carp). Aquatic products were extracted with acetonitrile and primarily purified by dispersive solid-phase extraction with graphitized carbon black as absorbent. The pretreated acetonitrile extract was detected by UHPLC-MS/MS. UHPLC was carried out on Dikma Endeavorsil C₁₈ (30 mm × 2.1 mm, 1.8 μm) column eluted by methanol and water (80:20 v/v) at a rate of 0.30 mL min^?1. Tandem mass spectrometry was performed by electrospray ionization in negative ion mode to identify and quantify eugenol during multiple reaction monitoring. Under optimized analytical conditions, the matrix-matched spiked calibration sample demonstrates good linearity between 5.0 and 500.0 μg kg^?1 with a linear regression coefficient of 0.9996. The average recovery of eugenol from aquatic products is 95.3–103.4% at spiked levels between 5 and 50 μg kg^?1 with a relative standard deviation (n = 6) less than 5.4%. The limits of detection and quantification for eugenol were calculated to be 1.47 and 4.91 μg kg^?1, respectively. In comparison with those reported, the proposed method has advantages in low detection limit, high recovery, and short analysis time, meeting the requirements for the determination of trace eugenol residue in aquatic products.     

Simultaneous Determination of Multiclass Pesticides and Antibiotics in Honey Samples Based on Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

A simple, fast, and efficient method was developed for simultaneous determination of 79 pesticides and 13 antibiotics compounds of different chemical classes of pesticides and antibiotics in honey samples by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). The sample preparation procedure includes homogenization with McIlvaine buffer 0.1 mol L^?1 (pH 4), followed by extraction with acetonitrile and cleanup with florisil, using dispersive solid phase extraction (d-SPE). The proposed method was validated with good results, such as linearity (r ²?>?0.9901), normality, and independence of the evaluated data, as well as recoveries between 70 and 120 % with relative standard deviation (RSD) <20 % for most of the compounds spiked from 0.1 to 200 μg kg^?1. The experimental method limits of detection and quantification were from 0.03 to 1.51 μg kg^?1 and from 0.1 to 5 μg kg^?1, respectively, for the pesticides. For the antibiotics, the decision limits (0.1 to 2 μg g^?1) and the detection capacity (0.12 to 2.81 μg g^?1) were below the maximum residue limits (MRLs) established for honey by the Brazilian and European legislation. The method was successfully applied to real samples from different botanical and geographic origins. From them, 44 % presented residues from 0.12 to 10 μg kg^?1 of one or more analytes. The proposed method combines the advantages of a quick sample preparation step with the selectivity and sensitivity of the UHPLC-MS/MS and proved to be suitable for routine analyses.     

Gas Purge Microsyringe Extraction Coupled with Dispersive Liquid-Liquid Microextraction for the Determination of Acidic Compounds in Food Packaging Materials

A green, simple and sensitive method was developed for the analysis of volatile carboxylic acids (VFAs) and perfluorocarboxylic acids (PFCAs) in food packaging materials. The acidic compounds in food packaging materials were first extracted by gas purge microsyringe extraction (GP–MSE) with 1.0 mL 0.1 mol·L^?1 NaOH solution, then the analytes were dispersive liquid-liquid microextracted (DLLME) by 50 μL chloroform as extraction solvent and 200 μL acetonitrile as dispersive solvent. The 2-(5-Benzoacridine) ethyl-p-toluenesulfonate (BAETS) with excellent fluorescence property was applied to enhance the high performance liquid chromatography (HPLC) sensitivity. The obtained recoveries for the VFAs ranged from 92.0 to 101 %. The method LODs calculated at a signal-to-noise ratio (S/N) of 3 were in the range of 0.80–3.40 μg·kg^?1, while the LOQs calculated at S/N of 10 were in the range of 2.5–10.2 μg·kg^?1. All compounds were in good linearity with concentration coefficients of higher than 0.997. Perfluorooctanoic acid (PFOA) was found in all of the 15 kinds of samples analyzed with concentrations ranging from 4.86–7.56 μg·kg^?1. Acetic acid, butyric acid, and caprylic acid were found in half of the samples analyzed. The other analytes were also found in more than 30 % samples with concentrations varied between 3.96 and 293 μg·kg^?1.     

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.     

Determination of glyphosate,AMPA, and glufosinate in honey by online solid-phase extraction-liquid chromatography-tandem mass spectrometry

A simple method was developed for the simultaneous determination of glyphosate, its main degradation product (aminomethylphosphonic acid), and glufosinate in honey. Aqueous honey solutions were derivatised offline prior to direct analysis of the target analytes using online solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry. Using the developed procedure, accuracies ranging from 95.2% to 105.3% were observed for all analytes at fortification levels of 5, 50, and 150 μg kg^?1 with intra-day precisions ranging from 1.6% to 7.2%. The limit of quantitation (LOQ) was 1 μg kg^?1 for each analyte. Two hundred honey samples were analysed for the three analytes with AMPA and glyphosate being most frequently detected (99.0% and 98.5% of samples tested, respectively). The concentrations of glyphosate were found to range from <1 to 49.8 μg kg^?1 while those of its degradation product ranged from <1 to 50.1 μg kg^?1. The ratio of glyphosate to AMPA was found to vary significantly amongst the samples where both analytes were present above the LOQ. Glufosinate was detected in 125 of 200 samples up to a maximum concentration of 33.0 μg kg^?1.     

Simultaneous Determination of Eight Tranquilizers in Pork by Ultra-Performance Liquid Chromatography Coupled with Electrospray Tandem Mass Spectrometry

An ultra-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) method was developed and validated for quantification of eight tranquillizers (chlorpromazine, imipramine hydrochloride, diazepam, nitrazepam, nordazepam, oxazepam, flurazepam, and haloperidol) in pork. Sample pretreatment consisted of extraction by acetonitrile, defatted by n-hexane, and further solid phase extraction by hydrophilic-lipophilic balance (HLB) extraction cartridges. The triple quadrupole mass spectrometer was operated in positive ion mode, and multiple reaction monitoring was used for drug quantification. The method was validated over the concentration ranges of 1.0 ～ 250 μg kg^?1 for the eight tranquillizers. The calibrations were performed in sample matrices, and the interference effect of sample matrices on the ionization was effectively eliminated. Good linear relationship (R ² > 0.99) was observed within the concentration range of 1.0–250 μg kg^?1. The average recoveries of the eight tranquillizers spiked at three levels ranged from 63.7 to103.2 % with the relative standard deviation below 11.8 %. The limits of detection were between 0.06 and 0.30 μg kg^?1, and the limits of quantification were between 0.2 and1.0 μg kg^?1 for all analytes in pork. This validated method has been successfully used to quantify the concentration of the eight tranquillizers in pork samples.     

Determination and surveillance of hydrocortisone and progesterone in livestock products by liquid chromatography-tandem mass spectrometry

A simple analytical method for the determination of hydrocortisone and progesterone in bovine, swine, and chicken muscle and eggs was developed. Hydrocortisone and progesterone were extracted with acetonitrile and subsequently cleaned-up using an Oasis^® HLB mini-cartridge. The method was validated in accordance with Japanese guidelines and exhibited trueness from 86.6% to 104.3% and precision (relative standard deviations (RSDs) of repeatability and within reproducibility were under 8.7% and 11.7%, respectively). The method was applied to 103 bovine muscle, 137 swine muscle, 69 chicken muscle and 52 egg samples that were commercially available in Tokyo, Japan. The hydrocortisone concentration was 0.9–41.2 µg kg^?1 in all bovine muscle samples, with an average of 7.7 µg kg^?1 and a median of 6.2 µg kg^?1. The progesterone concentration in 50 samples exceeded the limit of quantification (LOQ) and reached a maximum of 95.4 µg kg^?1. Hydrocortisone was also detected in all swine muscle samples at concentrations of 2.0–56.0 µg kg^?1. Its average and median concentrations amounted to 13.1 and 11.3 µg kg^?1, respectively. Twenty-three samples contained progesterone levels surpassing the LOQ, with a maximum concentration of 107.0 µg kg^?1. No chicken muscle samples contained any of the analytes. The progesterone concentration was 15.5–200.0 µg kg^?1 in all egg samples, with an average of 95.4 µg kg^?1 and a median of 90.5 µg kg^?1.     

Simultaneous Determination of Nine Quinolones in Food by Liquid Chromatography with Fluorescence Detection

A confirmatory analytical method for simultaneous determination of nine regulated quinolones (Council Regulation 2377/90/ECC) in six matrices of animal origin is proposed. The sample pretreatment involves double step liquid extraction with acetonitrile and purification by solid-phase extraction on Oasis HLB cartridges. The quinolones were separated by liquid chromatography on C18 Zorbax column with gradient elution program. Aqueous formic acid, methanol, and acetonitrile were used as a mobile phase. A multi-wavelength excitation/emission program was used for sensitive fluorescence detection of quinolones. The proposed sample pretreatment protocol was applied to each of the six studied matrices without any modification. The method was validated according to Commission Decision 2002/657 EC. Residues were quantified down to 15 μg kg^?1 with limits of detection and quantification ranging from 3 to 50 μg kg^?1 and from 7.5 to 100 μg kg^?1, respectively. The recoveries at the maximum residual limits (MRLs) were between 77 and 120 % with RSD values lower than 30 %. For quinolones without established MRL or maximum required performance limit, the accuracy and precision of the method were estimated at concentration levels corresponding to the lowest linear calibration point and recoveries between 70 and 130 % were achieved. Decision limits, detection capability, and linear range in eggs, milk, fish, ovine muscle, chicken muscle, and porcine kidney are also reported.     

Analysis of Multiple β-Agonist and β-Blocker Residues in Porcine Muscle Using Improved QuEChERS Method and UHPLC-LTQ Orbitrap Mass Spectrometry

The objective of the present study is to develop and optimize a simple, high-throughput method for determining 14 β-agonists (i.e., banbuterol, brombuterol, cimaterol, cimbuterol, clenbuterol, clenpeterol, clorpenaline, isoxsuprine, mabuterol, mapenterol, ractopamine, salbutamol, terbutaline, and tulobuterol) and two β-blockers (propranolol and penbutolol) in porcine muscle. The samples were pretreated by a modified quick, easy, cheap, efficient, rugged, and safe (QuEChERS) method, and analysis was carried out in a reversed phase HSS T3 C18 column using gradients of acetonitrile and 5 mmol L^?1 ammonium acetate (0.1 % formic acid) solution for elution. Ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-LTQ Orbitrap MS, resolution 60,000) was used for qualification and quantification of the 16 target compounds. Under optimized conditions, the limits of detection and quantification obtained ranged from 0.17 to 1.67 μg kg^?1 and from 0.56 to 5.00 μg kg^?1, respectively. Recoveries for spiking levels of 5.0, 10.0, and 20.0 μg kg^?1 ranged from 62.4 to 121.9 %, from 60.4 to 104.3 %, and from 66.5 to 121.3 %, respectively. The relative standard deviations obtained were lower than 20 % for all spiking levels assayed. The proposed method was applied successfully in sample analysis, and satisfactory results were obtained.     

Validation of a liquid chromatography-tandem mass spectrometry method for the simultaneous determination of sulfonamides,trimethoprim and dapsone in muscle,egg, milk and honey

A quantitative multi-residue method that includes 13 sulfonamides, trimethoprim and dapsone was developed and validated according to Commission Decision 2002/657/EC for muscle, milk egg and honey samples. For all matrices, the same extraction procedure was used. Samples were extracted with an acetone/dichloromethane mixture and cleaned up on aromatic sulfonic acid (SO₃H) SPE cartridges. After elution and concentration steps, analytes were identified and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Data were acquired according to the multiple reaction-monitoring approach (MRM) and analytes were quantified both by the isotope dilution and the matrix-matched approaches calculating the response factors for the scanned product ions. The developed method shows good linearity, specificity, precision (repeatability and within-laboratory reproducibility), and trueness. Estimated CCβ for sulfonamides ranged between 5.6 and 8.2 µg kg^?1 for eggs, between 11.1 and 69.9 µg kg^?1 for milk, between 64.7 and 87.9 µg kg^?1 for muscle, and between 2.7 and 5.3 µg kg^?1 for honey. CCβ values for dapsone were 3.1, 0.6, 0.7 and 1.5 µg kg^?1 and for trimethoprim were 3.1, 6.7, 81.7 and 3.0 µg kg^?1 calculated for eggs, milk, muscle and honey, respectively. Recovery for all matrices was in the range from 89.1% and 109.7%. In matrix effect testing, no significant deviations were found between different samples of muscle and milk; however, a matrix effect was observed when testing different types of honey. The validation results demonstrate that the method is suitable for routine veterinary drug analysis and confirmation of suspect samples.     

A LC-HRMS After QuEChERS Cleanup Method for the Rapid Determination of Dye Residues in Fish Products

The reliability of a rapid LC-HRMS method was studied in order to find a sensitive and accurate, simple, cheap, and rapid method for screening and quantitative determination of malachite green (MG), leucomalachite green (LMG), brilliant green (BG), crystal violet (CV), and leucocrystal violet (LCV) in fish muscle. All the analytes were extracted using a mixture of acetonitrile and citrate buffer, while the cleanup phase was carried out by Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method. All the data analyzed were acquired using both full MS and dd-MS² modes. Good specificity, precision (relative standard deviation <11% for each sample tested), recovery (10–60%), decision limit (CCα between 0.55 and 0.62 μg kg^?1), detection capabilities (CCβ between 0.65 and 0.78 μg kg^?1), and ruggedness were achieved for the reliability of the method. Satisfactory results were obtained during the linearity test in the range of 0.10–2 ng mL^?1 (r ² > 0.999). Best recoveries were obtained by the QuEChERS cleanup method for all the analytes examined, presenting values between 70 and 104%. The application of 70,000 FWHM mass resolution and narrow mass windows significantly improved the selectivity of the method, leading to simultaneous screening and quantification of dye residues in comparison to other methods proposed in literature. The optimized method proposed in this work enables a simple and fast preparation; it offers exceptional sensitivity and selectivity and maximizes efficiency and reproducibility with a low consumption of reagents. Finally, the present method was successfully employed to detect dye residues in 73 fish samples, as provided for the national residue control plan.     

A Simple and Fast Method for the Determination of 20 Veterinary Drug Residues in Bovine Kidney and Liver by Ultra-High-Performance Liquid Chromatography Tandem Mass Spectrometry

A simple and rapid sample preparation method was developed and validated for multi-class analysis of veterinary drug residues in bovine kidney and liver. Sample preparation procedure was performed using acetonitrile and trichloroacetic acid for protein precipitation followed by ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) analysis. The proposed method was validated according to the criteria of the Commission Decision 2002/657/EC evaluating linearity, selectivity, accuracy and precision, determination limit (CCα), and detection capacity (CCβ). Linearity presented r ² ≥ 0.99 for all the target compounds, and recoveries ranged from 80 to 110 % with RSD ≤17 % for intra- and inter-day assay. Values of CCα and CCβ ranged from 11 to 1096 and from 12 to 1191 μg kg^?1, respectively. The proposed sample preparation followed by UHPLC-MS/MS analysis was suitable for the determination of 20 veterinary drug residues in bovine kidney and liver in routine analysis. Method applicability was evaluated using commercial samples.     

Determination of Antibiotic Residues in Honey by High-Performance Liquid Chromatography with Electronspray Ionization Tandem Mass Spectrometry

The aim of the present study was to develop a rapid and simple method for the detection and quantification of antibiotic and antibacterial residues in honey using liquid chromatography with electronspray ionization tandem mass spectrometry. Two different extraction methods were used. The first method uses water and 1% formic acid in acetonitrile for the determination of sulfonamides while the second uses phosphate buffer, 10% trichloroacetic acid, and acetonitrile as the extracting solvent for the determination of tetracyclines, amphenicols, fluoroquinolones, penicillin g, trimethoprim, and tiamulin. The multi-residue method was validated in a thyme honey matrix. Thirty-six different antibiotics and residues from four different families (sulfonamides, tetracyclines, amphenicols, fluoroquinolones) and some individual antibiotics (penicillin g, trimethoprim, and tiamulin) were tested in 20 honey samples originating from Cyprus and Greece. The decision limits (CCα) were from 0.1 to 9.2 μg kg^?1; the detection capabilities (CCβ) were from 0.3 to 27.6 μg kg^?1 while recoveries were from to be between 65.0 and 116.1%. The method was successfully applied to commercial samples from different types of honey from Greece and Cyprus. Among them, oxolonic acid, sulfathiazole, and sulfadimethoxine were found in three honey samples. Finally, proficiency testing was applied to the proposed method while analysis of certified samples showed good method performance characteristics.     

Analysis of Infant Formula for Steroid Hormones by Gas Chromatography–Tandem Mass Spectrometry Using Microwave-Assisted Extraction and Gel Permeation Chromatography Clean Up

A new method was developed for effective separation and simultaneous determination of estrogens, gestagens, and androgens, including estrone, 17β-estradiol, testosterone, progesterone, and estriol, in infant formula. The samples were enzymatically digested with β-glucuronidase/arylsulfatase prior to microwave-assisted extraction. After the extract was cleaned up by gel permeation chromatography the hormones were derivatived with 50 μL BSTFA containing 1 % TMCS. The derivatived hormones were measured with GC–MS/MS using electron impact ionization source in the positive multi-reaction monitoring mode. The calibration curves showed good linearity with correlation coefficient (r) of >0.999. The limit of quantification of five hormones ranged from 0.094 to 0.265 μg kg^?1, which is below the minimum required performance limits established by the European Community. The intra- and inter-day precision (as RSD) for six determinations of five analytes at 40 μg kg^?1 spiked level was in range of 3.4–5.4 % and 3.5–6.8 %, respectively. The recovery of five analytes was obtained to be 84.5–104 %, with relative standard deviations (RSD, n?=?6) of 1.7–5.5 %. This method has been successfully used for the qualitatively and quantitatively determination of estrone, 17β-estradiol, testosterone, progesterone, and estriol in infant formula.     

Rapid Screening and Determination of the Residues of Hormones and Sedatives in Milk Powder Using the UHPLC-MS/MS and SPE

A method based on the ultra-high-performance liquid chromatography tandem mass spectrometry for determination of the residues of sex hormones, glucocorticoids, and sedatives in milk powder was developed. The sample was extracted with the acetic acid-acetonitrile (1:99, v/v) twice, purified by the PRiME hydrophilic-lipophilic balance (HLB) cartridges and analyzed by the ultra-high-performance liquid chromatography-tandem mass spectrometry. The analytes were separated by the Waters Acquity UPLC? BEH C18 column (50 mm?×?2.1 mm, 1.7 μm) and determined using the electrospray ionization in the positive mode with the multiple reaction monitoring (MRM). The developed method was validated with the specificity, linearity and range, matrix effects, recovery, and precision. The results showed that the analytes were linear with the correlation of determinations (R²) higher than 0.991 in the corresponding ranges. The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.1–1.1 μg kg^?1 and 0.3–3.8 μg kg^?1, respectively. The average recoveries of the analytes ranged from 78.5 to 107.0% with the relative standard deviations lower than 15%. The practical applicability was tested by analyzing real samples and the progesterone was observed in two samples.     

Optimization of QuEChERS Procedure Coupled to GC-ECD for Organochlorine Pesticide Determination in Carrot Samples

An optimised version of the Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method for simultaneous determination of 14 organochlorine pesticides in carrots was developed using gas chromatography coupled with electron-capture detector (GC-ECD) and confirmation by gas chromatography tandem mass spectrometry (GC-MS/MS). A citrate-buffered version of QuEChERS was applied for the extraction of the organochlorine pesticides, and for the extract clean-up, primary secondary amine, octadecyl-bonded silica (C18), magnesium sulphate (MgSO₄) and graphitized carbon black were used as sorbents. The GC-ECD determination of the target compounds was achieved in less than 20 min. The limits of detection were below the EU maximum residue limits (MRLs) for carrots, 10–50 μg kg^?1, while the limit of quantification did exceed 10 μg kg^?1 for hexachlorobenzene (HCB). The introduction of a sonication step was shown to improve the recoveries. The overall average recoveries in carrots, at the four tested levels (60, 80, 100 and 140 μg kg^?1), ranged from 66 to 111 % with relative standard deviations in the range of 2–15 % (n?=?3) for all analytes, with the exception of HCB. The method has been applied to the analysis of 21 carrot samples from different Portuguese regions, and β-HCH was the pesticide most frequently found, with concentrations oscillating between less than the limit of quantification to 14.6 μg kg^?1. Only one sample had a pesticide residue (β-HCH) above the MRL, 14.6 μg kg^?1. This methodology combines the advantages of both QuEChERS and GC-ECD, producing a very rapid, sensitive and reliable procedure which can be applied in routine analytical laboratories.     

Liquid Chromatography-Tandem Mass Spectrometry Determination and Depletion Profile of Chlortetracycline,Doxycycline, and Oxytetracycline in Broiler Chicken Muscle After Oral Administration

A simple and fast method based on liquid chromatography–electrospray ionization-tandem mass spectrometry (LC–ESI-MS/MS) was developed and validated for determination of tetracyclines in broiler chicken muscle. Sample preparation was performed using extraction with acetonitrile, followed by low-temperature purification (at ??20 °C) and further concentration. The chromatographic analysis was carried out using a Zorbax SB-C18 column with gradient elution using water and methanol both acidified with 0.025 M of formic acid. Mass spectrometry with electrospray ionization was operated in positive polarity using selected reaction monitoring (SRM) analysis mode, achieving the requirements of four identification points for each compound. Demeclocycline was used as internal standard. The method validation was done according to the criteria of Commission Decision 2002/657/EC. Parameters such as recovery, matrix effects, selectivity/specificity, linearity, precision (intra- and inter-day precision), accuracy, limits of detection (LOD) and quantification (LOQ), decision limit (CCα), detection capability (CCβ), and robustness were determined. Intra-day precision values were within the range 2.2–5.8% and inter-day precision was less than 10% for all analytes. Accuracy ranged from 98.2 to 103.2%. The method was successfully applied for depletion studies of chlortetracycline, doxycycline, and oxytetracycline in broiler chicken tissues after multiple oral administrations. After the depletion studies, the present study support more prudent use of CTC, DOX, and OTC for treatment of chickens and suggest a dose of 60 mg kg^?1 body weight for CTC and OTC and 20 mg kg^?1 body weight for DOX, orally administrated for five consecutive days.     

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.     

Simultaneous Determination of Seven Adulterants in Slimming Functional Foods by HPLC�CESI�CMS/MS

A high-performance liquid chromatography?Celectrospray ionization?Ctandem mass spectrometric method for simultaneous determination of seven adulterants including pseudoephedrine, norpseudoephedrine, caffeine, strychnine, fenfluramine, sildenafil, and amfepramone in slimming functional foods was established. For tablet formulation, the target chemicals were extracted with ammoniated methanol, while for liquid samples, plant powder, or capsules formulations, these chemicals were extracted with a mixture solution of ammoniated methanol-diethyl ether (2:1 v/v). After anhydrous sodium sulfate being added, the extracts were centrifuged and then the supernatant was evaporated to dryness under condition of a nitrogen gas flow. The residue was reconstituted with acetonitrile?Cwater (1:9 v/v) to produce a test solution. Chromatographic separation was accomplished using a RP-C18 column with a gradient elution procedure using 0.03% formic acid in acetonitrile and 0.01% formic acid solution. Seven chemicals were separated and detected in 10 min. Clenbuterol was used as an internal standard. The recoveries of seven targeted chemicals in different formulations are from 81.2% to 110.3%. Limits of detection of the method are from 4.2 to 16.7 ??g kg^?1 with relative standard deviations of 1.1?C8.4%. The linearity of the method ranges from 2.0 to 500 ng mL^?1 for all chemicals, with linear correlation coefficients varying from 0.9982 to 0.9992. The method has been used for determining the target chemicals in nine slimming functional foods, and satisfactory results are achieved. Among these tested samples, norpseudoephedrine and fenfluramine were not detected for all samples. Some other components, such as pseudoephedrine, amfepramone, strychnine, and sildenafil were detected in one or more samples, while caffeine was detected in almost all of these tested samples.