Simultaneous of illegal additives in dietary supplements and traditional medicines by high performance liquid chromatography–electrospray ionization mass spectrometry

A high performance liquid chromatographic method coupling with electrospray ionization mass spectrometry (HPLC/ESI-MS) for simultaneous determination of phenformin, rosiglitazone, glibenclamide and glimepiride in dietary supplements and traditional Chinese medicines for diabetes mellitus was proposed. The separation was achieved on a C₁₈ column with the mobile phase consisted of acetonitrile and water (0.05% formic acid (v/v) and 20 mM ammonium acetate), at a flow rate of 1.0 ml/min with gradient elution. The analytes were identified and quantified by ESI-MS. Sildenafil was selected as internal standard. Full validation of the proposed method was provided (selectivity, linearity, limit of detection, limit of quantification, precision and accuracy). In contrast to existing methods, the proposed method has obvious advantages of simplicity, rapidity, accuracy and good applicability, and it has been applied to analyze illegal additives in nine dietary supplements and eight traditional Chinese medicines successfully.     

Determination of trichothecenes in cereals and cereal-based products by liquid chromatography–tandem mass spectrometry

A sensitive, accurate and precise method for the simultaneous determination of nivalenol (NIV), deoxynivalenol (DON), T-2 toxin (T-2) and HT-2 toxin (HT-2) in different food matrices, including wheat, maize, barley, cereal-based infant foods, snacks, biscuits and wafers, has been developed. The method, using liquid chromatography coupled with atmospheric pressure chemical ionization triple quadrupole mass spectrometry (LC–APCI–MS/MS), allowed unambiguous identification of the selected trichothecenes at low µg per kg levels in such complex food matrices. A clean-up procedure, based on reversed phase SPE Oasis® HLB columns, was used, allowing good recoveries for all studied trichothecenes. In particular, NIV recoveries significantly improved compared to those obtained by using Mycosep® #227 columns for clean-up of the extracts. Limits of detection in the various investigated matrices ranged 2.5–4.0 µg kg^?1 for NIV, 2.8–5.3 µg kg^?1 for DON, 0.4–1.7 µg kg^?1 for HT-2 and 0.4–1.0 µg kg^?1 for T-2. Mean recovery values, obtained from cereals and cereal products spiked with NIV, DON, HT-2 and T-2 toxins at levels from 10 to 1000 µg kg^?1, ranged from 72 to 110% with mean relative standard deviation lower than 10%. A systematic investigation of matrix effects in different cereals and cereal products was also carried out by statistically comparing the slopes of standard calibration curve with matrix-matched calibration curve for each of the four toxins and the eight matrices tested. For seven of the eight matrices tested, statistically significant matrix effects were observed, indicating that, for accurate quantitative analysis, matrix-matched calibration was necessary. The method was applied to the analysis of 57 samples of ground wheat originated from South Italy and nine cereal food samples collected from retail markets.     

Simultaneous determination of 15 components in Radix Glehniae by high performance liquid chromatography–electrospray ionization tandem mass spectrometry

A novel qualitative and quantitative method using high performance liquid chromatography coupled with tandem mass spectrometry was developed for simultaneous analysis of 15 components including 10 coumarins, four phenolic acids and adenosine in Radix Glehniae, an important traditional Chinese medicine. The separation was performed on a C₁₈ column with isocratic elution consisted of 0.1% formic acid and methanol (30:70, v/v). The identification and quantification of the analytes were achieved on a hybrid quadrupole linear ion trap mass spectrometer. Multiple-reaction monitoring (MRM) scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. Full validation of the method was carried out (linearity, precision, accuracy, limit of detection and limit of quantification). The results indicated that the method was simple, rapid, specific and reliable. And we successfully applied it to analyze 20 Radix Glehniae samples from different sources.     

Determination of phenolic profile and antioxidant activity of pistachio hull using high-performance liquid chromatography–diode array detector–electro-spray ionization–mass spectrometry as affected by ultrasound and microwave

The phytochemicals content and radical scavenging activity of pistachio (Pistacia vera L.) hull extract obtained by different solvents (water, ethanol, and butanol) were measured and compared. Water was selected as superior solvent. Ultrasound-assisted aqueous extraction of the hull by power ultrasound (35 kHz) was more efficient in ascending the phytochemicals content than the sonochemical ultrasonication (130 kHz). High-performance liquid chromatography-mass spectrometry showed increased amounts of vanillic acid, p-coumaric acid, naringenin, and catechin in ultrasound-assisted extracts. Post-extraction sonication declined significantly the phenolics amount and antioxidant property of the aqueous extract. Microwave-assisted extraction increased the phenolics and flavonoids content at extract in a power-dependent trend.     

Determination of Gibberellin A3 residue in fruit samples by liquid chromatography–tandem mass spectrometry

A fast, simple, low cost, and high throughput method has been developed for the determination of Gibberellin A3 residue in fruit samples (apple, orange, peach, pear and grape). Analysis is performed by LC–MS/MS operated in the multiple reaction monitoring (MRM) mode, acquiring two specific precursor-product ion transitions per target compound. The method has been validated showing good linearity and selectivity. Limits of quantification (LOQs) were 10 μg kg⁻¹ for apple, orange, peach, pear and grape samples. The average recoveries, measured at three concentration levels (10, 20 and 200 μg kg⁻¹) were in the range 77.8–96.2% for the compound tested with relative standard deviations below 13.7%. The proposed method is rapid, simple and could be utilised for the routine analysis of Gibberellin A3 in fruit samples.     

Determination of selected pesticides in fruit juices by matrix solid-phase dispersion and liquid chromatography–tandem mass spectrometry

A rapid and sensitive liquid chromatography–tandem mass spectrometry method has been developed for the analysis of acephate, monocrotophos, carbendazim, acetamiprid, dimethoate, simazine, carbofuran, atrazine, diuron, DNOC (4,6-dinitro-o-cresol), malathion and tebufenozide in fruit juices. Extracts were obtained by matrix solid-phase dispersion using diatomaceous earth as dispersant and dichloromethane as eluent. Significant matrix effects observed for most of the pesticides tested were eliminated using matrix-matched standards. The quantification of the analytes was carried out using the most sensitive transition. The confirmation of residues detected in real samples was performed by repeated injection and acquiring additional transitions to that used for quantification. Recoveries were in the range 71–118%. Repeatability of the method, expressed as the relative standard deviation, was in general between 5–15%. Low limits of detection (0.01–0.94 ng ml⁻¹) and quantification (0.03–3.12 ng ml⁻¹) were readily achieved with this method for all tested pesticides.     

Rapid determination of lycopene and β-carotene in tomato by liquid chromatography/electrospray tandem mass spectrometry

BACKGROUND: The tomato fruit is a dietary source of carotenoids, bioactive antioxidant compounds that play an important role in the prevention of degenerative diseases. Several extraction and detection techniques regarding carotenoids in tomatoes can be found in the literature, mainly based on high‐performance liquid chromatography separation and ultraviolet‐visible detection. RESULTS: The best extraction conditions and tandem mass spectrometry (MS) analysis were evaluated: lycopene and β‐carotene were extracted in a cyclohexane/ethyl acetate mixture without the addition of antioxidants, next separated by liquid chromatography on a C₁₈ column and then determined through electrospray tandem MS. Ionic suppression by the matrix in negative ionisation mode did not allow the analysis of extracts, hence the positive ionisation mode was chosen. Validation parameters demonstrated the suitability for purpose of the analytical method: accuracy, precision, linearity and detection limits were adequate. The method was finally applied to different tomato samples, and differences could be easily highlighted. CONCLUSION: The method was simple, fast and appropriate for the purpose of analysing lycopene and β‐carotene in tomatoes. Copyright © 2011 Society of Chemical Industry     

Determination of sulbactam in raw bovine milk by isotope dilution–ultra-high-performance liquid chromatography–tandem mass spectrometry

We developed a sensitive and selective isotope dilution ultra-high-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) method for the determination of sulbactam residue in raw bovine milk. Sulbactam and internal standard, sulbactam-d₅, were extracted from raw bovine milk via liquid-liquid extraction and enriched with strong anion exchange solid-phase extraction cartridges and finally analyzed by using UPLC-MS/MS with multiple reaction monitoring mode. The method was validated according to European regulations. The calibration curve showed good linearity, with a correlation coefficient of 0.9998. Decision limit and detection capability of sulbactam were determined by matrix calibration curve and were 0.0445 and 0.0517 μg/L, respectively. The recoveries of sulbactam in fortified raw bovine milk ranged from 72.1 to 91.5%, with the intra- and interday relative standard deviations ranging from 3.0 to 18.9%. Furthermore, the developed method was applied to analyzing real raw bovine milk samples collected from dairy farms in Beijing, China. Sulbactam was not determined in all samples. The proposed method could ultimately serve as a methodological foundation for the determination of sulbactam in different types of raw milk and dairy products.     

Identification of new stilbenoids–formaldehyde adducts by isotope labeling and electrospray ionization mass spectrometry

Excessive endogenous formaldehyde in cardiovascular tissue is considered to be a harmful factor associated with atherosclerosis, diabetes, Alzheimer’s disease, and et al. It will be helpful to relieve cardiovascular diseases by removing excess endogenous formaldehyde. Stilbenoids are nutrient substances of many natural food, and they exhibit noticeable cardiovascular beneficial effects. Trans-2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside (trans-TSG), one of widely investigated stilbenoids, has been widely reported to have cardiovascular beneficial effect, prevalent theory accounts for its pharmacological activity to antioxidant mechanism, it was rarely reported trans-TSG can also exert such beneficial effect by formaldehyde scavenger mechanism. In the present paper, we will show that trans-TSG has reactivity with formaldehyde in vitro; moreover, the three new adducts of trans-TSG with formaldehyde were identified by isotope labeling and electrospray ionization mass spectrometry. The result will give some hint of another explanation of stilbenoids’ cardiovascular beneficial effect.     

Determination of aflatoxins in edible oil from markets in Hebei Province of China by liquid chromatography–tandem mass spectrometry

Analysis of aflatoxin B₁ (AFB₁), B₂ (AFB₂), G₁ (AFG₁) and G₂ (AFG₂) in 76 edible oil samples (peanut oil, soybean oil, corn embryo oil and blended oil) was performed by liquid chromatography–tandem mass spectrometry (LC–MS/MS). The oils were sampled from three areas (Shijiazhuang, Baoding and Tangshan) of Hebei Province of China. AFB₁ was detected in 22 samples representing 28.9%, followed by AFB₂ (7.89%) and AFG₁ (3.95%), while no AFG₂ contamination was detected in any samples. AFB₁ levels in oil samples ranged 0.14–2.72?µg?kg^?1 and AFB₂ ranged 0.15–0.36?µg?kg^?1, while lower levels of 0.01–0.02?µg?kg^?1 for AFG₁ were recorded. The paper is part of an on-going investigation of aflatoxin contamination in Chinese edible oils.     

Liquid chromatography–electrospray ionization–tandem mass spectrometry method for determination of twenty multi-class pesticide residues in cashew

This paper describes an analytical methodology employing the extraction QuEChERS (Quick, Easy, Cheap, Effective, Robust and Safe) method and liquid chromatography coupled to mass spectrometry using electrospray ionization source (LC–ESI–MS/MS). The methodology was validated for the determination of twenty multiclass pesticides in cashew. It was evaluated for selectivity, linearity, limits of detection (LOD) and quantification (LOQ), matrix effect, as well as the precision and accuracy in terms of percentage of recovery. Analyses were performed by selected reaction monitoring (SRM) using two transitions (precursor ion → ion product). All pesticides studied showed good linearity with correlation coefficient greater than 0.99. LODs and LOQs ranged from 0.10 to 0.25 ng g⁻¹ and 0.30 to 0.75 ng g⁻¹, respectively. Due to the complexity of the sample, study the effect matrix was performed. Cashew apples samples spiked (5, 50 and 100 ng g⁻¹) showed recovery results ranging from 66 to 119 g/100 g, and RSD ≤ 12%, which is in accordance with standard recommended by Brazilian rules (ABNT NBR 14029/2005), except simazine. The validated method was applied to commercial samples obtained in Fortaleza-CE, Brazil, but no contamination of pesticides residues was observed.     

Determination of alkylphenol residues in breast and commercial milk by solid-phase extraction and gas chromatography–mass spectrometry

This study presents a feasible and sensitive method to determine alkylphenol residues (i.e., 4-t-octylphenol (4-t-OP) and the isomers of 4-nonylphenols (4-NPs)) in breast milk samples and commercial cow milk products. The matrix interference associated with the constituents in the milk was reduced by extraction with n-hexane and dilution with 50% methanolic solution (v/v, methanol/water), then followed by the Oasis-HLB SPE extraction. The analytes were determined by a GC–MS system in full-scan and selected ion monitoring modes simultaneously. Limit of quantitation was less than 0.05 ng/g in a 20 g (wet weight) milk sample. The 4-NPs were detected in 19 of the 20 breast milk samples at concentrations ranging from 1.7 to 11.6 ng/g, while 4-t-OP was detected in 8 samples at concentrations ranging from 0.4 to 1.1 ng/g. The 4-NPs were detected in all the testing commercial cow milk products at concentrations ranging from 2.9 to 8.8 ng/g.     

Determination of 3-MCPD in grilled meat using pressurized liquid extraction and gas chromatography–high resolution mass spectrometry

An analytical method for the determination of free 3-monochloropropane-1,2-diol (3-MCPD) in grilled meat using pressurized liquid extraction, derivatisation using phenylboronic acid, and gas chromatography/high resolution mass spectrometry was developed. The limit of quantification was 1???g/kg. Using this method, the contents of 3-MCPD in grilled steaks (collar) were analysed for different grilling conditions. Charcoal, an electric grill, and a gas grill were used for grilling collars. Further parameters investigated were the pre-treatment of meat (untreated, salted, marinated with oil or emulsion marinade), the use of aluminium grill trays, and a lid. For grilled steaks, contents of 3-MCPD in the range of <1 to 365???g/kg (median 16???g/kg) were detected. The highest contamination was found for a steak pre-treated with an oily marinade grilled on a charcoal grill with a closed lid. Consuming such a steak will exhaust the tolerable daily intake of 2???g/kg body weight for 3-MCPD to about 26?%.     

Folate composition of 10 types of mushrooms determined by liquid chromatography–mass spectrometry

White button, crimini, shiitake, maitake, enoki, oyster, chanterelle, morel, portabella, and uv-treated portabella mushrooms were sampled from U.S. retail outlets and major producers. Folate [5-methyltetrahydrofolate (5-CH₃-H₄folate), 10-formyl folate (10-HCO-folate), 5-formyltetrahydrofolate (5-HCO-H₄folate)] was analysed using a validated LC–MS method in four composites of each product, including an in-house mushroom control composite and a reference material (BCR 485 Lyophilised Mixed Vegetables). Chanterelle and morel had the lowest total folate (2–6 μg/100 g), oyster had the highest (mean, 44.2 μg/100 g); other types contained 12.4 μg/100 g (shiitake) to 29.8 μg/100 g (vitamin D-enhanced portabella). Enoki and oyster had almost exclusively 5-CH₃-H₄folate. Morel and chanterelle contained predominately formyl folates. Other species had similar amounts of 5-CH₃-H₄folate and formyl folates. Enoki, oyster, and shiitake, unlike all others, had low to non-detectable 10-HCO-folate (<1 μg/100 g). These precise data on the composition of folate vitamers in different types of mushrooms will facilitate assessment of the dietary contribution of naturally occurring folate.     

Determination of phthalate esters in wine using solid-phase extraction and gas chromatography–mass spectrometry

A method for the determination of six phthalate esters in wine samples has been developed. The phthalates were extracted from wine samples with an optimised solid-phase extraction method on C18 column and quantification was achieved via gas chromatography coupled with a mass spectrometer. The method was linear between 0.015 and 5.000 μg mL⁻¹ for DMP, DEP and DEHP and between 0.018 and 5.000 μg mL⁻¹ for iBP, DBP and BBP. The LOQs of DMP, DEP and DEH were 0.024 μg mL⁻¹ while those of iBP, DBP and BBP were 0.029 μg mL⁻¹. The intra-day method repeatability was between 10% and 15% RSD, whereas the inter-day method repeatability was between 13% and 21% RSD. A survey was performed on white and red wines (n = 62) from the market, winemakers and an experimental pilot plant. All the analysed samples were phthalate contaminated. Commercial wine showed higher detection frequency and level of total phthalate, DBP and BBP than those produced in a pilot plant. iBP and DEHP concentrations were similar in all the groups of samples. iBP concentration was higher in red wines than in white ones.     

Determination of polybromodiphenyl ethers (PBDEs) in milk cream by gas chromatography–mass spectrometry

An analytical method for polybromodiphenyl ethers (PBDEs) in milk cream has been optimized. The six PBDEs targeted were chosen on criteria of toxicity and occurrence in environmental matrices. Three methods of extraction were tested and compared in terms of lipid recovery yields and repeatability. The sample preparation process includes two steps: extraction by accelerated solvent extraction (ASE) and purification by solid phase extraction (SPE). The preferred method of extraction used a hexane/methylene chloride/methanol (5 : 2 : 1, v/v) solvent mixture. Three extraction cycles were carried out per sample at a temperature of 80°C and a pressure of 1500 psi. The method was validated on milk cream samples spiked with the specified PBDEs. Recoveries for the whole sample preparation process (extraction and cleanup) for cream samples spiked at 10 and 100 ng g^?1 were greater than 80% (ranging from 81 to 106%) at both concentrations for BDE-99, -100, -153 and 154. Recoveries were lower (ranging from 65 to 75%) for BDE-28 and BDE-47. PBDEs were quantified by GC/MS detection with selected ion monitoring (SIM) using three ions formed by electron capture. The method was successfully tested on real samples.