Persistent organic pollutants (PCBs and PCDD/Fs), PAHs, and plasticizers in spices, herbs, and tea - A review of chromatographic methods from the last decade (2010-2020).

Edible and highly demanded plant-derived products such as herbs, spices, and tea may be subjected to exogenous contamination of well-known chemical hazards such as persistent organic pollutants (POPs), and emerging ones such as plasticizers, affecting negatively the safety of these food commodities. This fact has led to the increasing analysis of exogenous compounds including priority POPs such as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs), as well as highly persistent polycyclic aromatic hydrocarbons (PAHs). Currently, plasticizer residues are also considered an emerging issue because of the extensive use in food packaging and potential migration into foodstuffs. In this review, the studies published from 2010 to 2020 were discussed, including the main extraction methods applied for these contaminants from herbs, spices, and tea, and it was revealed the trend toward the use of less solvent-consuming and time-effective methods. Chromatographic methods were also described, which were mainly combined with detection techniques such as classical or mass spectrometry (MS) detection. Finally, a comprehensive overview of the occurrence of these selected exogenous compounds was presented in the studied matrices, showing that their monitoring should be further investigated to ensure food safety of highly consumed condiments and tea.

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.

Applicability of high-resolution NMR in combination with chemometrics for the compositional analysis and quality control of spices and plant-derived condiments.

Over the last years, the consumption of spices and plant-derived condiments has increased considerably, owing to new culinary trends. Unfortunately, the current marketing channels make them highly vulnerable to adulteration and food fraud. High-resolution nuclear magnetic resonance (NMR) is a powerful tool for the compositional study of spices and plant-derived condiments. It allows the chemical characterization of a wide range of polar and non-polar metabolites, and provides unique structural information not available by other techniques. The chemometric-based analysis of NMR 'fingerprints' has been used to discriminate samples according to species and geographical origin and to detect adulterations, among other applications. The comprehensive identification and quantification of marker compounds can be achieved even in complex mixtures, demonstrating a great potential for high-throughtput quality control applications. © 2020 Society of Chemical Industry.

Fast analysis of glufosinate, glyphosate and its main metabolite, aminomethylphosphonic acid, in edible oils, by liquid chromatographycoupled with electrospray tandem mass spectrometry.

A method has been developed for the rapid, specific, accurate, precise and sensitive determination of glufosinate, glyphosate and its major metabolite, aminomethylphosphonic acid, in edible oils, by liquid chromatography coupled to tandem mass spectrometry. Oils were extracted with acidified water (1% formic acid), and the extracts were directly injected into an LC using a Hypercarb column as the stationary phase. The analytes were eluted by a mobile phase of methanol and water containing 1% acetic acid, and they were ionised by electrospray ionisation in negative ion mode. The method was validated and limits of quantification ranged from 5 µg kg-1 (aminomethylphosphonic acid) to 10 µg kg-1 (glyphosate and glufosinate). Three concentrations (10, 50 and 100 µg kg-1) were selected to perform recovery studies. Mean recoveries ranged from 81.4% to 119.4%. Intra and inter-day precision were lower than 19%. Different edible oils were analysed, and no residues of the studied herbicides were detected above limits of quantification.

Degradation of tropane alkaloids in baked bread samples contaminated with Solanaceae seeds.

Solanaceae plant seeds, which contain high concentrations of tropane alkaloids, have not been studied in real conditions of proofing and baking processes. In this work both lab vial trials and buckwheat and millet flour samples, contaminated with two species of Solanaceae plants, Datura stramonium and Brugmansia arborea, were undergone to proofing (37 °C) and baking (190 °C) processes. For the determination of tropane alkaloids, a simple solid-liquid extraction with methanol:water 2:1 (v/v) containing 0.5% acetic acid was used to extract the targeted compounds, whereas a chromatographic method employing a Zorbax C18 column coupled to an Exactive-Orbitrap analyser was used for their determination. The results indicate that concentrations of tropane alkaloids decrease under proofing conditions (degradation between 13 and 95%), while they are almost disappeared under baking conditions (degradation between 94 and 100%). Some degradation pathways have been clarified, showing that most of the compounds degrade into tropane and tropine, and into tropine and tropinone under proofing and baking conditions respectively.

Effect of tea making and boiling processes on the degradation of tropane alkaloids in tea and pasta samples contaminated with Solanaceae seeds and coca leaf.

In this study, the degradation of tropane alkaloids in pasta under boiling (100 °C during 10 min) and tea making (100 °C and let cool 5 min) conditions has been evaluated for the first time. Pasta and green tea were contaminated with Datura Stramonium and Brugmansia Arborea seeds (pasta and green tea), whereas coca leaf tea was directly analysed. The compounds were extracted using solid-liquid extraction coupled to a preconcentration stage (only for the cooking water), and the compounds were analysed by liquid chromatography coupled to mass spectrometry (Exactive-Orbitrap analyser). Degradation studies indicate that concentration of tropane alkaloids decreases, and it depends on the compound, observing the highest degradation for tropinone, tropane, cuscohygrine and tropine, as well as it was observed that compounds migrated to the aqueous phase during cooking step. Finally, post-targeted analysis was performed and other tropane alkaloids were found, as scopine, tigloidine or convolvine, showing a similar behaviour under cooking conditions.

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.

Screening of drugs and homeopathic products from Atropa belladonna seed extracts: Tropane alkaloids determination and untargeted analysis.

Homeopathic products are still a controversial issue in modern medicine, understood as complementary or alternative medicine (CAM). In this particular case, homeopathic products prepared from Atropa belladonna extracts may present specific problems due to the effects derived from its components. This article applies a simple, rapid, reliable method to the analysis of different homeopathic products obtained from Atropa belladonna; drugs containing high concentration of plant extracts; and Atropa belladonna seeds. The method was based on a simple solid-phase preconcentration method followed by ultra-high pressure liquid chromatography (UHPLC) coupled to high resolution mass spectrometry using Exactive-Orbitrap as an analyser. An in-house database was set and atropine and scopolamine were the compounds detected at highest concentrations in homeopathic products from Atropa belladonna extracts (4.57 and 2.56 µg/kg, respectively), in Belladonna ointment (4007 and 1139 µg/kg, respectively) and Belladonna seeds (338 and 32.1 mg/kg, respectively). Other tropane alkaloids such as tropine, apoatropine, aposcopolamine, tropinone, homatropine, and anisodamine were detected at lower concentrations (0.04-1.36 µg/kg). When untargeted analysis was performed, other tropane alkaloids were identified in the tested samples, such as ecgonine (0.003 µg/kg), benzoylecgonine (0.56 µg/kg), calystegines A (19.6 µg/kg), B (33.1 µg/kg), and C (1.01 µg/kg). Finally other compounds present in the homeopathic products, such as sugars (fructose, glucose, and lactose) or amino acids (valine, ornithine, leucine, and phenylalanine), were identified.

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 phenolic compounds in edible wild leafy vegetables by UHPLC/Orbitrap-MS.

BACKGROUND: A recent interest in edible wild leafy vegetables has been documented. Consumers often associate these species with health promotion. In this study, several wild species of the Asteraceae family and Knautia integrifolia (Dipsacaceae) were locally documented for their use in traditional cuisine and sampled from the wild. RESULTS: Phenolic compounds were identified and quantified by ultra-high-performance liquid chromatography coupled to Orbitrap high-resolution mass spectrometry. Hydroxycinnamic acids ranging from 1388 to 53 076 mg kg-1 dry weight (DW) were the most abundant compounds in all species (69-98% of the total phenolic content) except Tragopogon pratensis. Thirty compounds were identified as flavonoids, mostly as glycosidic forms of luteolin, apigenin, kaempferol and quercetin. The sum of flavonoids ranged between 212 and 12 598 mg kg-1 DW; they represented 65% of the total phenolic content for T. pratensis. Three anthocyanins were detected, representing in most cases less than 1% of the total phenolic content (3-627 mg kg-1 DW). Higher anthocyanin contents were observed for Cichorium types. CONCLUSION: Different phenolic profiles were observed between species, especially considering the class of flavonoids. Individual species may be of some interest for their content of specific minor flavonoids. © 2017 Society of Chemical Industry.

Simultaneous determination of atropine and scopolamine in buckwheat and related products using modified QuEChERS and liquid chromatography tandem mass spectrometry.

A method was developed for the determination of atropine and scopolamine in buckwheat and related products. A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction procedure was evaluated. Dispersive solid phase extraction (d-SPE) was studied as clean-up step, using graphitized black carbon (GBC) and primary secondary amine (PSA). The extract was diluted with water (50:50, v/v) prior to chromatographic analysis. The method was validated and recoveries (except chia samples spiked at 10µg/kg) ranged from 75% to 92%. Intra and inter-day precision was lower than or equal to 17%. The limit of quantification of atropine and scopolamine was 0.4 and 2µg/kg, respectively. Eight types of samples (buckwheat, wheat, soy, buckwheat flour, buckwheat noodle, amaranth grain, chia seeds and peeled millet) were analyzed. Target compounds were not found above the detection limits of the method, but three transformation products of scopolamine (norscopine, hydroscopolamine and dihydroxyscopolamine) were putative identified in the tested samples using high resolution mass spectrometry (Exactive-Orbitrap).

Enantiomeric determination and evaluation of the racemization process of atropine in Solanaceae seeds and contaminated samples by high performance liquid chromatography-tandem mass spectrometry.

A new method has been developed for the enantioselective separation of (-) and (+) hyoscyamine in Solanaceaes seeds and contaminated buckwheat. Chromatographic separation was optimized, evaluating two chiral columns, Chirobiotic V and Chiralpal-AY3. Better resolution was obtained using a Chiralpak-AY3 column, utilizing as mobile phase ethanol (0.1% diethanolamine). An extraction procedure based on a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) was applied, using water and acetonitrile containing 1% of acetic acid, and a clean-up step utilizing primary secondary amine (PSA) and graphitized carbon black (GCB) as sorbents. The extract was diluted with ethanol (50/:50, v/v) prior to chromatographic analysis, and the separation was carried out avoiding the racemization during this stage. Enantiomerization process of atropine was studied in samples at different conditions such as temperature (30, 50 and 80°C) and pH (3, 5, 7 and 9), observing that racemization occurs at high pH (9) and temperature (80°C). Stramonium and Brugmansia seeds were analyzed and the concentration of (-)-hyoscyamine was 1500mg/kg and 320mg/kg respectively. Contaminated buckwheat was also determined and (-)-hyoscyamine was detected at 170µg/kg.

Fast determination of four polar contaminants in soy nutraceutical products by liquid chromatography coupled to tandem mass spectrometry.

An analytical method based on a modified QuPPe (quick polar pesticide) extraction procedure coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was evaluated for the determination of four polar compounds (chlorate, fosetyl-Al, maleic hydrazide, and perchlorate) in nutraceutical products obtained from soy. Experimental conditions including extraction such as solvent, acidification, time, and clean-up sorbents were varied. Acidified acetonitrile (1 % formic acid, v/v) was used as extraction solvent instead of methanol (conventional QuPPe), which provides a doughy mixture which cannot be injected into the LC. Clean-up or derivatization steps were avoided. For analysis, several stationary phases were evaluated and Hypercarb (porous graphitic carbon) provided the best results. The optimized method was validated and recoveries ranged between 46 and 119 %, and correction factors can be used for quantification purposes bearing in mind that inter-day precision was equal to or lower than 17 %. Limits of quantification (LOQs) ranged from 4 to 100 µg kg-1. Soy-based nutraceutical products were analyzed and chlorate was detected in five samples at concentrations between 63 and 1642 µg kg-1. Graphical Abstract Analysis of polar compounds in soy-based nutraceutical products.

Multi-class methodology to determine pesticides and mycotoxins in green tea and royal jelly supplements by liquid chromatography coupled to Orbitrap high resolution mass spectrometry.

A multi-class methodology was developed to determine pesticides and mycotoxins in food supplements. The extraction was performed using acetonitrile acidified with formic acid (1%, v/v). Different clean-up sorbents were tested, and the best results were obtained using C18 and zirconium oxide for green tea and royal jelly, respectively. The compounds were determined using ultra high performance liquid chromatography (UHPLC) coupled to Exactive-Orbitrap high resolution mass spectrometry (HRMS). The recovery rates obtained were between 70% and 120% for most of the compounds studied with a relative standard deviation <25%, at three different concentration levels. The calculated limits of quantification (LOQ) were <10 µg/kg. The method was applied to green tea (10) and royal jelly (8) samples. Nine (eight of green tea and one of royal jelly) samples were found to be positive for pesticides at concentrations ranging from 10.6 (cinosulfuron) to 47.9 µg/kg (paclobutrazol). The aflatoxin B1 (5.4 µg/kg) was also found in one of the green tea samples.

Occurrence of pesticide residues and transformation products in different types of dietary supplements.

The purpose of this study was to evaluate the presence of pesticide residues and transformation products in dietary supplement products. Thirty-two samples were analysed to determine 177 pesticides by gas chromatography-tandem mass spectrometry (GC-MS/MS) and 333 pesticides by liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Pesticides were extracted from different kinds of dietary supplements by the use of a modified QuEChERS extraction method. Six samples contained pesticide residues at concentration up to 92.7 µg kg(-1), but only butralin exceeded the maximum residue limits set for raw material. In addition to target compounds, LC-HRMS enables the simultaneous detection of non-target pesticides. In this case, transformation products of pesticides were detected in the analysed samples using HRMS analyser (Exactive-Orbitrap). These compounds were not included in the original method, and they were monitored as post-target compounds, knowing their molecular formula and exact mass. Mass accuracy was always < 2 ppm, corresponding to a maximum mass error. The positive findings endorse the idea that a deeper and continuous investigation of pesticide residues and transformation products in dietary supplement products is necessary in order to guaranty consumer's safety.

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).

Determination of multi-class pesticide residue in dietary supplements from grape seed extracts by ultra-high-performance liquid chromatography coupled to triple quadrupole mass spectrometry.

A new method was developed and validated for the determination of multi-class pesticide residues in nutraceutical products obtained from grape seed extracts. The extraction procedure was based on QuEChERS methodology using ethyl acetate as solvent and a dispersive solid-phase extraction (dSPE) clean-up stage with C18 was included to minimise matrix effects. Pesticides determination was achieved using ultra-high-performance liquid chromatography coupled to triple quadrupole mass spectrometry (UHPLC-QqQ-MS/MS); total running time was 11 min. Pesticides were quantified using matrix-matched calibration. The developed method was validated in terms of matrix effect, linearity, selectivity, limits of detection and quantification, trueness, repeatability and inter-day precision at three concentration levels (10, 50, 100 µg kg(-1)). Suitable recovery values were obtained for 76% of analysed pesticides at the lowest concentration (10 µg kg(-1)). For most of the compounds, relative standard deviation values were lower than 20% and 25% for intra- and inter-day precision, respectively. Finally, 106 pesticides were determined, and the method was applied to seven dietary supplements from grape seed extract, obtaining various positive results for piperonyl butoxide, cyromazine and diniconazole at concentrations ranging from 2.0 to 13.4 µg 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.