Determination of 3-monochloropropanediol esters and glycidyl esters in fatty matrices by ultra-high performance liquid chromatography-tandem mass spectrometry.

The development and validation of a method for the analysis of traces of 3-monochloropropanediol (3-MCPD) esters (19) and glycidyl esters (7) of fatty acids in vegetable oils, margarine, biscuits and croissants was performed. An extraction method based on the use of solvents (tert­butyl methyl ether (20% ethyl acetate, v/v)) was carried out and cleaning of the extract with a mixture of sorbents (Si-SAX, PSA and Z-sep+) was optimized for the elimination of fatty interferents. The analysis of the targeted compounds was carried out by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry, using a triple quadrupole analyzer (UHPLC-MS/MS-QqQ). The validation of the method provided trueness values between 72 and 118% and precision lower than 20%. The limits of quantification ranged from 0.01 to 0.1 mg kg-1, which were below the current legal limits. Twenty samples of vegetable oils as well of 4 samples of margarine, biscuits and croissants were analyzed. Six out of the 24 samples (25%) exceeded the limits set by European legislation, and a maximum contamination of 3-MCPD esters at 2.52 mg kg-1 was obtained in a sample of corn oil (being 1-myristoyl-3-MCPD the compound detected at the highest concentration). A maximum concentration of glycidyl esters at 7.84 mg kg-1 was determined in a soybean oil sample (glycidyl linoleate as the main compound). Only one sample of olive oil exceeded the maximum allowable limit for 3-MCPD esters with a value of 1.72 mg kg-1, expressed as 3-MCPD.

Monitoring of polar pesticides and contaminants in edible oils and nuts by liquid chromatography-tandem mass spectrometry.

A single method was developed for the determination of polar pesticides (fosetyl-Al and its metabolite, phosphonic acid, and ethephon) and environmental contaminants (chlorate and perchlorate) in edible oils and nuts. Two extraction methods based on QuPPe-PO approach (Quick Polar Pesticides Method for products of Plant Origin) were optimized. In oils, a single extraction using water acidified with formic acid (1%) was performed, while in nuts, the clean-up step was modified. C18 was used as sorbent and an extra cleaning step with n-hexane was added. The extracts were analysed by liquid chromatography coupled to a triple quadrupole mass analyser (LC-QqQ-MS/MS). The method was validated and the limit of quantification was 0.01 mg kg-1 for all analyte-matrix combination. Recoveries from 70 to 120%, and intra and inter-day precision values ≤20% were obtained. Forty samples of edible oils and nuts were analysed, detecting phosphonic acid in nuts at concentrations up to 4.6 mg kg-1.

A rapid method for the determination of mycotoxins in edible vegetable oils by ultra-high performance liquid chromatography-tandem mass spectrometry.

An analytical method based on a QuEChERS procedure (quick, easy, cheap, effective, rugged and safe) has been developed for the determination of mycotoxins (α-zearalenol and zearalenone, and aflatoxins B1, B2, G1 and G2) in edible oils. The analysis was performed by ultra-high performance liquid chromatography coupled to triple quadrupole analyser (UHPLC-QqQ-MS/MS). The method was fully validated and the quantification limit is 0.5 µg kg-1 for aflatoxins and 1 µg kg-1 for α-zearalenol and zearalenone. Suitable recoveries were obtained at low concentration levels (0.5-25 µg kg-1 for aflatoxins and 1-25 µg kg-1 for α-zearalenol and zearalenone), ranging from 80 to 120%. Intra and inter-day precision values were also evaluated and relative standard deviation was lower than 20%. The expanded uncertainty, U, was also evaluated ant it was below 32% at 25 µg kg-1. The validated method has been applied to monitor the presence of mycotoxins in 194 samples belonging to different types of edible oils (olive oil, sunflower oil, soy oil and corn oil). Zearalenone was detected in 25% of the analysed samples at concentrations up to 25.6 µg kg-1, and aflatoxin G1 and G2 in 3% and 14% of the samples at a maximum concentration of 1.9 and 6.8 µg kg-1 respectively.

Analytical methods, occurrence and trends of tropane alkaloids and calystegines: An update.

In the last years, the interest in secondary metabolites from plants has been growing, and even more if they have or would have medical applications, as it happens with tropane alkaloids and calystegines. Therefore, the number of analytical methods for the analysis of these compounds has been increasing. In this review, the extraction methods as well as the chromatographic separation and detection techniques based on mass spectrometry to determine tropane alkaloids and calystegines in plant raw material and food have been described. Finally, a summary of the natural occurrence of tropane alkaloids and calystegines in the studied matrices, as well as their accidental presence in food, is presented, highlighting current and future determination trends.

Simultaneous analysis of tropane alkaloids in teas and herbal teas by liquid chromatography coupled to high-resolution mass spectrometry (Orbitrap).

A new method has been developed for the simultaneous determination of 13 tropane alkaloids in tea and herbal teas using high-performance liquid chromatography coupled to an Exactive-Orbitrap analyzer. A mixture of methanol, water, and formic acid was used for the extraction of the target compounds followed by a solid-phase extraction step. The validated method provided recoveries from 75 to 128% with intra- and interday precision lower than or equal to 24% (except for apoatropine). Limits of quantification ranged from 5 to 20 µg/kg. Eleven tea and herbal tea samples and two contaminated samples with Datura stramonium seeds were analyzed. Tropane alkaloids were detected in six samples with concentrations from 5 (apoatropine) to 4340 µg/kg (sum of physoperuvine, pseudotropine, and tropine), whereas concentrations from 5 (apoatropine) to 1725 µg/kg (sum of physoperuvine, pseudotropine, and tropine) were found in the contaminated samples.

Identification and quantification of phytochemicals in nutraceutical products from green tea by UHPLC-Orbitrap-MS.

A method has been developed and validated for the simultaneous detection and quantification of phytochemicals in nutraceutical products obtained from green tea. For that purpose, ultra-high performance liquid chromatography coupled to single-stage Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-MS) has been used. A database containing 37 compounds has been used for the detection and identification of the target compounds. The developed methodology was based on solid-liquid extraction, using a mixture of methanol:H2O (80:20, v/v, pH 4), followed by dilution (10 times) with a mixture of ammonium acetate:methanol (50:50, v/v). Chromatographic conditions were optimised and full scan accurate mass data acquisition using electrospray ionisation in positive and negative ion mode was used. Moreover, all-ion fragmentation mode was used to get information of fragment ions, and they were used for identification purposes. The developed method was validated, obtaining repeatability (intra-day) and inter-day precision values (expressed as relative standard deviation, RSD) lower than 16% and 20%, respectively. Lower limits were also evaluated and limits of detection (LODs) ranged from 1 to 50 µg L(-1), while limits of quantification (LOQs) ranged from 2 to 150 µg L(-1). Recovery was performed at five levels and it ranged from 70% to 109%. Finally, this method was used to evaluate the phytochemical content in 10 samples (tablets or capsules), showing concentrations of (+)-catechin, (-)-epicatechin, gallic acid, (-)-gallocatechin and quercetin-3-O-rutinoside, ranging from 258 (C6) to 10,729 (C6) mg kg(-1).

Identification and quantification of the main isoflavones and other phytochemicals in soy based nutraceutical products by liquid chromatography-orbitrap high resolution mass spectrometry.

The specific phytochemicals composition of soy nutritional supplements is usually not labelled. Hence, 12 dietary supplements were analyzed in order to detect and identify the main phytochemicals present in these samples, using a database containing 60 compounds. Ultra-high performance liquid chromatography coupled to single-stage Orbitrap high resolution mass spectrometry (UHPLC-Orbitrap-MS) has been used. Two consecutive extractions, using as extraction solvent a mixture of methanol:water (80:20, v/v), were employed, followed by two dilutions (10 or 100 times depending on the concentration of the components in the sample) with a mixture of an aqueous solution of ammonium acetate 30mM:methanol (50:50, v/v). The method was validated, obtaining adequate recovery and precision values. Limits of detection (LODs) and quantification (LOQs) were calculated, ranging from 2 to 150µgL(-1). Isoflavones were the predominant components present in the analyzed supplements with values higher than 93% of the total amount of phytochemicals in all cases. The aglycones (genistein, daidzein, glycitein and biochanin A) as well as their three conjugated forms, ß-glucosides (genistin, daizin and glycitin) were detected and quantified, being daidzein the isoflavone detected at higher concentration in 8 out of 12 samples reported, with values ranging from 684 to 35,970mgkg(-1), whereas biochanin A was detected at very low concentrations, ranging from 18 to 50mgkg(-1). Moreover, other phytochemicals as flavones, flavonols, flavanones and phenolic acids were also detected and quantified.

Analysis of phenolic compounds in olive oil by solid-phase extraction and ultra high performance liquid chromatography-tandem mass spectrometry.

In this study a simultaneous determination of several classes of polyphenolic compounds (benzoic acid derivates, cinnamic acid derivates, phenyl ethyl alcohols, flavones and other phenolic acids) in feed oils has been carried out by ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). Solid-phase extraction (SPE) with Diol and C(18) cartridges were compared in terms of recovery and number of extracted compounds, obtaining better results when Diol cartridges were used. The analytical procedure was validated, obtaining recoveries ranging from 70% (vanillic acid) to 111% (gallic acid) with repeatability values (expressed as relative standard deviations, RSDs) lower than 20% at two concentration levels (500 and 1000 µg/kg). Limits of quantification (LOQs) were always equal or lower than 50 µg/kg except for gentisic acid (100 µg/kg). Finally the method was applied to different types of feed oils, and it can be observed that higher concentrations of polyphenols were found in olive oil, whereas pomace olive oil and sunflower oil had the lowest level of these compounds.

Compensation for matrix effects in gas chromatography-tandem mass spectrometry using a single point standard addition.

One of the major problems in quantitative analysis of pesticide residues in food samples by gas chromatography-tandem mass spectrometry (GC-MS/MS) is the enhancement or the suppression, of the target analyte signals in matrix extracts. Potentially positive samples, which had previously been identified by a rapid screening method, were quantified using standard addition to compensate matrix effects. As example we performed a systematic study on the application of the standard addition calibration (SAC) method for the determination of 12 pesticides (acephate, bromopropylate, chlorpyrifos, cypermethrin, diazinon, etrimfos, heptenophos, iprodione, methamidophos, procymidone, tetradifon, and triadimefon) in two matrices (cucumber and orange) in the range of initial concentrations of 10-200 microg kg(-1). The influence of some factors, such as the minimum number of standard additions used (single, two, three or four points calibration), as well as the known amount of analyte added to the sample, is evaluated in order to obtain reliable results. Accurate quantification is achieved when a single point SAC at 200 microg kg(-1) was used, obtaining for all the cases recoveries between 70 and 120%. The proposed analytical approach only needs two injections per sample (blank and spiked extracted sample) to determine the final concentration of pesticide in positive samples.

One-year routine application of a new and rapid method based on ultra performance liquid chromatography-tandem mass spectrometry to the analysis of selected pesticides in citrus fruits.

A rapid method has been developed for monitoring five multiclass pesticides commonly used in citrus fruits. The determination is performed by ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS), after extraction with a mixture of ethyl acetate and sodium sulfate. The method has been validated for orange matrix. Mean recoveries obtained were between 74-110% with a repeatability precision of < 7%, intermediate precision of < 10% and reproducibility precision of < 17%. Linearity over the range 0.010-0.150 mg/kg was demonstrated (r(2) > or = 0.99) with limits of quantification (LOQs) of < or = 0.01 mg/kg. Also, an analytical study focused on the stability of pesticide residues in orange extracts under storage was performed. The method has been applied to the analysis of 365 samples from the agricultural area of the Valencian Community (Spain). Of 103 samples that contained pesticide residues, only abamectin in 2 samples and carbendazim in 5 samples slightly exceeded the European maximum residue limits (MRLs).

Application of gas chromatography coupled to triple quadrupole mass spectrometry for the multiresidue analysis of pesticides in olive oil.

A new multiresidue method has been developed and validated for the simultaneous determination of 100 pesticide residues in olive oil. The determination of pesticide residues was carried out in only 19 min by gas chromatography coupled to tandem mass spectrometry using a triple quadrupole mass analyzer. The mass spectrometer was operated in electron ionization and the selection reaction monitoring mode was used, acquiring two or three fragmentation reactions per compound. Two extraction processes were studied, and an evaluation of the stability and sensitivity of the chromatographic system has been performed for the tested extraction procedures. The final proposed methodology was based on a liquid-liquid partition with an n-hexane/acetonitrile mixture followed by a gel permeation chromatography cleanup step. An adequate lineal relation was obtained in the studied concentration range (10-200 microg kg (-1)); the recovery values were in the range 70-110% for the two levels of concentration studied: 12 and 50 microg kg (-1). Precision values, expressed as relative standard deviation, were lower than 18% at the aforementioned spiking levels; detection limits, confirmation limits, and quantitation limits were below or equal to 1.9, 2.6, and 3.6 microg kg (-1), respectively. The developed methodology was applied to the analysis of pesticide residues in real samples of olive oil from the south of Spain.