Comparative studies on Ophiopogonis and Liriopes based on the determination of 11 bioactive components using LC–MS/MS and Hierarchical clustering analysis

Radix Ophiopogonis and Radix Liriopes are two widely used herbal medicines and functional foods with similar pharmacological activities and clinical efficacies. In order to figure out whether phytoequivalence of species leads to therapeutic equivalence and consistency, in this study, a novel sensitive and selective high performance liquid chromatography-tandem mass spectrometric method (HPLC-MS/MS) has been developed for the simultaneous analysis of 11 bioactive components (6 steroidal saponins and 5 flavonoids) and then was applied for comparing in Radix Ophiopogonis and Radix Liriopes from different habitats. Separation was performed using a C₁₈ analytical column with gradient elution of acetonitrile and 0.3‰ acetic acid (v/v) at a flow rate of 0.8 mL/min. Multiple-reaction monitoring (MRM) scanning was employed with switching electrospray ion source polarity between positive and negative modes in a single run. All calibration curves showed good linearity (r² > 0.9915) within the test ranges. The intra-day and inter-day precision for 11 analytes were less than 3.7% and 4.2%, respectively. The recoveries were between 95.3% and 106.7%. Fifty-three batches of commercial samples from different sources were analyzed using the developed method. Hierarchical clustering analysis (HCA) and content analysis were performed to differentiate and classify the samples. The results demonstrated that steroidal saponins were the major components in both Liriopes species, and a low content of flavonoids could become an important symbol of distinction between Ophiopogonis and Liriopes. The developed method could successfully differentiate between Ophiopogonis and Liriopes.     

The simultaneous determination of the ionophore antibiotics in animal tissues and eggs by tandem electrospray LC–MS–MS

A method has been developed for the simultaneous extraction and determination of the four most currently used Ionophore antibiotics (lasalocid, monensin, narasin and salinomycin) by LC–MS–MS from different animal tissues and eggs. Results show good repeatability, and mean spiked recoveries for lasalocid, monensin, narasin and salinomycin in animal livers are in the average range 93–103, 96–103, 93–102 and 97–106%, respectively, and in eggs the mean spiked recoveries are 101, 103, 98 and 102% for lasalocid, monensin, narasin and salinomycin, respectively. The detection limit is at 1 ng ml⁻¹ for all the named ionophorous compounds. A quantitation level of 50 ng g⁻¹ for lasalocid, monensin at 2.5 ng g⁻¹, and 10 ng g⁻¹ for narasin and salinomycin is achieved which represents half the action limit prescribed by the UK Regulation in compliance with the European Council Directive 96/23/EC. A high throughput of samples is achievable using this method which allows the analysis of 30–40 samples by one analyst in a day.     

Monitoring of the amphetamine-like substances in dietary supplements by LC-PDA and LC–MS/MS

Recently, amphetamine-like substances derived from the β-phenylethylamine core structure have been detected in dietary supplements. Especially, β-methylphenylethylamine (BMPEA), an amphetamine isomer, has been found in dietary supplements labeled as containing Acacia rigidula. The U. S. Food and Drug Administration determined that BMPEA is not naturally present in food and does not meet the statutory definition of a dietary ingredient. In addition, BMPEA has been classified as a psychotropic drug in South Korea and a doping substance by the World Anti-Doping Agency. The aim of this study was to determine whether dietary supplements contained amphetamine and amphetamine-like substance, including β-phenylethylamine (β-PEA) and BMPEA using LC-PDA and LC–MS/MS. In 10 of 110 samples, illegally added compounds were detected in the following ranges; β-PEA 1.4–122.0 mg/g and BMPEA 4.7–37.6 mg/g. This study will contribute to enhancement of food safety in the South Korea.     

Application of GC–MSD and LC–MS/MS for the determination of priority pesticides in baby foods in Serbian market

Babies and small children are especially sensitive population to the exposure to environmental contaminants. Their small mass and developing systems, including brain development may show adverse health effects from even low levels of contamination on a chronic or single dose case. In this paper one extraction method and two chromatographic techniques for the determination of pesticide residues in baby food were evaluated. A liquid chromatography–tandem mass spectrometry technique combined with electrospray ionization (ESI), (LC–MS/MS) and gas chromatography–mass spectrometry detection (GC–MSD) technique were applied in the detection of 50 pesticides in baby food. So-called QuEChERS (quick, easy, cheap, effective, rugged and safe) method was used as a sample preparation procedure. The recoveries were investigated at three levels (5, 10 and 50 μg/kg) and the results obtained showed compliance with the contemporary EU requirements with a few exceptions. LOQs for most of the tested pesticides were below the EU MRLs (10 μg/kg), except deltamethrin, cypermethrin, fenvalerate, phosalone and beta-cyfluthrin (LOQs were 10 μg/kg). Both techniques were applied in the analysis of 50 samples of baby food manufactured in Serbia.     

Finding of pesticides in fashionable fruit juices by LC–MS/MS and GC–MS/MS

Products labelled as containing extracts from two mushrooms (cordyceps plus reishi) and the juices from açaí, goji, mangosteen, noni, pomegranate, and sea buckthorn have been analysed for 174 different pesticides, using the validated QuEChERS method for sample preparation and electrospray LC–MS/MS in the positive ion mode for analysis. Pesticides were found in 10 of the 21 samples analysed. Most pesticides found were below the tolerance levels (1–6 μg/g, depending on the pesticide), but some were not. This included boscalid, dimethomorph, iprovalicarb, pyridaben, pyrimethanil, and imazalil, for which there is no tolerance reported or zero tolerance in any fruit. However, genuine açaí that was harvested in the state of Pará and lyophilised in Rio de Janeiro had no detectable pesticides, when analysed by both LC–MS/MS and GC–MS/MS, which can detect 213 more pesticides and industrial chemicals. Likewise no pesticides were found in one sample each of cordyceps plus reishi, sea buckthorn and noni.     

Optimisation and validation of a specific analytical method for the determination of thiram residues in fruits and vegetables by LC–MS/MS

Thiram is a non-systemic dithiocarbamate fungicide, which is easily degraded during sample preparation since it is affected by pH, matrix components and temperature. In this work, specific methodology for thiram analysis in vegetable (eggplant and lettuce) and fruit (strawberry) samples has been developed based on liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS). Minimising thiram degradation during standards storage and sample preparation was carefully studied. The effect of low temperature (about 5 °C), addition of a dehydrating agent (Na₂SO₄ anhydrous), pH regulator (NaHCO₃), and enzymatic activity reduction (EDTA) during extraction was evaluated. The optimised procedure was validated for eggplants, lettuces, and strawberries. Satisfactory recoveries, between 80% and 106%, and relative standard deviations below 10% were obtained at 0.1 and 0.01 mg/kg fortification levels (n = 5). Limits of detection below 0.0012 mg/kg were achieved. The validated method has been applied to eggplant and lettuce samples collected from different field trials as well as several strawberry and apple samples.     

LC–MS/MS with atmospheric pressure chemical ionisation to study the effect of UV treatment on the formation of vitamin D3 and sterols in plants

Some plant species are known to cause calcium intoxification in grazing animals. This has been attributed to the presence of vitamin D₃-like activity. However, research into the presence of vitamin D₃ in plants has been limited. One reason for this may be limitations in the analytical methods available for unambiguous detection and quantification of vitamin D₃. This paper presents a new method for determining vitamin D₃ and its sterol precursors. The method is based on saponification and extraction followed by solid phase clean-up of the compounds from plant leaves and detection by APCI-MS. Recoveries ranged from 101% to 114% and precision from 3% to 12%. Detection limits were 2–8 ng/g fresh weight for the substances tested. In a pilot study we found that Solanum glaucohyllum Desf. and Solanum lycopersicum L. produced vitamin D₃ after UV-treatment. The preliminary results presented suggest that vitamin D₃ formation in plants is dependent on light exposure.     

Analytical strategy for the determination of non-steroidal anti-inflammatory drugs in plasma and improved analytical strategy for the determination of authorised and non-authorised non-steroidal anti-inflammatory drugs in milk by LC–MS/MS

A sensitive and selective method for the determination of six non-steroidal anti-inflammatory drugs (NSAIDs) in bovine plasma was developed. An improved method for the determination of authorised and non-authorised residues of 10 non-steroidal anti-inflammatory drugs in milk was developed. Analytes were separated and acquired by high performance liquid chromatography coupled with an electrospray ionisation tandem mass spectrometer (ESI–MS/MS). Target compounds were acidified in plasma, and plasma and milk samples were extracted with acetonitrile and both extracts were purified on an improved solid phase extraction procedure utilising Evolute? ABN cartridges. The accuracy of the methods for milk and plasma was between 73 and 109%. The precision of the method for authorised and non-authorised NSAIDs in milk and plasma expressed as % RSD, for the within lab reproducibility was less than 16%. The % RSD for authorised NSAIDs at their associated MRL(s) in milk was less than 10% for meloxicam, flunixin and tolfenamic acid and was less than 25% for hydroxy flunixin. The methods were validated according to Commission Decision 2002 European Commission Decision. 2002. Decision(2002/657/EC) of 12 August 2002 implementing Council Directive 96/23/EC concerning the performance of analytical methods and interpretation of results. Off J Eur Commun, L221: 8–36.  [Google Scholar]/657/EC.     

Validation of Two Variations of the QuEChERS Method for the Determination of Multiclass Pesticide Residues in Cereal-Based Infant Foods by LC–MS/MS

Over the past years to ensure food safety and particular for food that intend to be consumed by infants and young children, the European Union has adopted specific legislation concerning the control of pesticide residue levels in that kind of food. In this paper, a liquid chromatography tandem quadrupole mass spectrometry (LC–MS/MS) multiresidue method for the simultaneous analysis of 23 pesticides and metabolites chosen according to the Commission Directives 2006/141/EC, 2006/125/EC, and 96 multiclass pesticides and metabolites chosen according to their physicochemical properties is presented and validated. The extraction procedure is based on three modifications of the quick, easy, cheap, effective, rugged, and safe method according to the analyte. The analytical performance was demonstrated by the analysis of extracts from cereal-based infant foods, spiked at two concentration levels for each pesticide or metabolite. Good sensitivity and selectivity of the method were obtained with limits of quantification at 10 or 3 μg/kg, depending on the analyte. All pesticides and metabolites, except six cases, gave recoveries in the range of 60.4–125.4%, with relative standard deviations less than 29.7%, for both validation levels.     

Analysis of seven folates in food by LC–MS/MS to improve accuracy of total folate data

An LC–MS/MS method for analyzing seven folates in food was developed and validated. 5-Methyltetrahydrofolate, 5-formyltetrahydrofolate, 10-formylfolic acid, tetrahydrofolate and folic acid were quantified using a stable isotope dilution assay (SIDA) with deuterated analogues as internal standards. Additionally, 10-formyldihydrofolate and 5,10-methenyltetrahydrofolate were quantified using deuterated internal standards different in structure. Due to interconversion of 5,10-methenyltetrahydrofolate to 5-formyltetrahydrofolate and 10-formyldihydrofolate to 10-formylfolic acid during sample preparation, a SIDA was not considered because of a resulting double calculation of the amounts interconverting. [²H₄]-5-methyltetrahydrofolate was used as internal standard for 5,10-methenyltetrahydrofolate, due to a similar retention time, and [²H₄]-10-formylfolic acid as well as [²H₄]-5-methyltetrahydrofolate was used for 10-formyldihydrofolate, because no internal standards co-elute. To confirm that no matrix effects affect the quantitation of 5,10-methenyltetrahydrofolate and 10-formyldihydrofolate, postcolumn infusion experiments were performed. Validation of the assay was accomplished by determining linearity, precision, recovery, limit of detection and limit of quantitation. The latter parameters were partly obtained by application of a dual-isotope label design including [¹³C₅]-labeled folates. The amounts of 5,10-methenyltetrahydrofolate in the purified extracts of different food samples ranged between 0.3 and 1.3 % and for 10-HCO-H₂folate between 0.05 and 8 % of the total folate amount. Correction for incomplete recovery of the latter folate during cleanup indicates even higher contents. Therefore, especially 10-formyldihydrofolate should not be neglected to obtain accurate results for folates.     

Arsenic speciation in white wine by LC–ICP–MS

This study deals with As speciation in white wine. Arsenic species were selectively determined by liquid chromatography–inductively coupled plasma–mass spectrometry (LC–ICP–MS). Separation of As species was performed using an anion exchange column with ammonium phosphate solution (pH 6.00) as mobile phase. Samples of 14 white wine produced in South America were analysed. They were 10-fold diluted in the mobile phase prior to analysis by LC–ICP–MS. Accuracy was evaluated by recovery tests, whereas As species recovery ranged from 95% to 106%. Additionally, the sum of arsenic species concentration found by LC–ICP–MS was in agreement with the total arsenic concentration determined by ICP–MS after sample digestion. Arsenic species detected were arsenite [As(III)], arsenate [As(V)] and dimethylarsinic acid (DMA). As(III) and As(V) were detected in all analysed wine samples and DMA was detected only in wines produced in Argentina. Results for As determination in samples were from 2.9 to 10.3, 8.6 to 17.8, and <0.45 to 1.07 μg L⁻¹ for As(III), As(V) and DMA, respectively.     

Screening of 23 β-lactams in foodstuffs by LC–MS/MS using an alkaline QuEChERS-like extraction

A fast and robust high performance LC–MS/MS screening method was developed for the analysis of β-lactam antibiotics in foods of animal origin: eggs, raw milk, processed dairy ingredients, infant formula, and meat- and fish-based products including baby foods. QuEChERS extraction with some adaptations enabled 23 drugs to be simultaneously monitored. Screening target concentrations were set at levels adequate to ensure compliance with current European, Chinese, US and Canadian regulations. The method was fully validated according to the European Community Reference Laboratories Residues Guidelines using 93 food samples of different composition. False-negative and false-positive rates were below 5% for all analytes. The method is adequate for use in high-routine laboratories. A 1-year study was additionally conducted to assess the stability of the 23 analytes in the working standard solution.     

Development of multiresidue DLLME and QuEChERS based LC–MS/MS method for determination of selected neonicotinoid insecticides in honey liqueur

Honey liqueur is an alcoholic drink derived from honey and strong fruit brandy of suitable type, traditionally made in Serbia and other Balkan countries. Although European Union has regulated the levels of neonicotinoid insecticides in honey and pollen, there is an increased risk of the presence of these compounds in traditional products made from honey. The objective of this study was to develop an optimized LC–MS/MS analytical method with dispersive liquid–liquid microextraction (DLLME) and QuEChERS sample preparation procedures for analysis of seven neonicotinoids (dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid and thiacloprid) in honey liqueur. The LC–MS/MS conditions were optimized to unequivocally provide good chromatographic separation, selectivity and specificity of developed method. The method was validated to fulfill the requirements of SANCO/12495/2011 for both sample pretreatment procedures providing results for accuracy (R, 69.2–113.4% for DLLME; 71.8–94.9% for QuEChERS), precision (RSD expressed in terms of repeatability (3.21–10.20% for DLLME; 4.19–12.81% for QuEChERS) and within-laboratory reproducibility (9.11–16.63% for DLLME; 11.32–16.40% for QuEChERS)), limits of detection (LOD, 0.5–1.5 μg L^− 1 for DLLME; 1.0–2.5 μg L^− 1 for QuEChERS) and quantification (LOQ, 1.0–5.0 μg L^− 1 for DLLME; 2.5–10.0 μg L^− 1 for QuEChERS). Matrix effects were compensated by the use of matrix-matched calibration. Analysis of real honey liqueur samples obtained from local markets showed the presence of clothianidin or thiacloprid in four of the analyzed samples, therefore implicating the necessity of ongoing control of this type of traditional product.     

LC/ESI–MS/MS method for the identification and quantification of spinosad residues in olive oils

This paper reports the use of liquid chromatography/electrospray ionisation tandem mass spectrometry (LC/ESI-MS/MS) method for the identification and quantification of residues of the natural insect control agent Spinosad in olive oils. The method determines the active ingredients Spinosyns A and D and two minor metabolites Spinosyns B and K without laborious sample treatment. All four analytes are determined simultaneously in a single injection using positive electrospray ionisation LC–MS with multiple reaction monitoring (MRM). For the quantitative analysis of samples an external calibration curve was built. The calibration curves for each analyte were linear in the concentration range 20–500 ng/mL with a correlation coefficient ranging between 0.995 and 0.999. Results from spike and recovery experiments at levels of 100 and 200 ng/mL gave mean recoveries ranging from 87–116% with satisfactory precision (relative standard deviation (RSD) from 1–8%). The excellent selectivity and sensitivity allows quantification and identification of low levels of Spinosad in olive oils (limits of quantification (LOQs) 0.004–0.073).     

Survey on acrylamide in roasted coffee and barley and in potato crisps sold in Italy by a LC–MS/MS method

ABSTRACT

A survey on the occurrence of acrylamide (AA) in roasted coffee, barley, and potato crisps was carried out using an intra-lab validated liquid chromatography (LC)–MS (mass spectrometry)/MS method. Over the years 2015–2016, 66 samples of coffee, 22 of roasted barley, and 22 of potato crisps were collected from retail outlets in Italy. AA was detected in almost all samples. In roasted coffee, the level exceeded 450 µg kg^?1, the limit recommended by the European Commission (EC), in 36.4% of the samples. In roasted barley, mean contamination was slightly lower than in coffee and no sample exceeded the EC limit of 2000 µg kg^?1. The AA contamination in potato crisps was remarkable. A percentage of 36.4 (n = 8) showed a value higher than the EC limit of 1000 µg kg^?1. Considering the average consumption of coffee and potato crisps by Italian people, AA exposure is significant and should be decreased.     

Tandem solid phase extraction coupled to LC–ESI–MS/MS for the accurate simultaneous determination of five heterocyclic aromatic amines in processed meat products

Carcinogenic heterocyclic aromatic amines are difficult to measure since only trace levels are present in processed meat products. In this study, typical heterocyclic aromatic amines, including 2-amino-3-methylimidazo [4,5-f] quinoline (IQ), 2-amino-3,4-dimethylimidazo [4,5-f] quinoline (MeIQ), 2-amino-3,8-dimethyli-midazo [4,5-f] quinoxaline (MeIQx), 2-amino-3,4,8-trimethylimi-dazo [4,5-f] quinoxaline (4,8-DiMeIQx), 2-amino-1-methyl-6-ph-enylimidazo [4,5-b]pyridine (PhIP), were studied to develop a sensitive and accurate method for their rapid quantification in animal-derived products, with 2-Amino-3,4,7,8-dimethylimidazo [4,5-f] quinoxalline (TriMeIQx) as an internal standard. Liquid chromatography–electrospray-tandem mass spectrometry conditions were analyzed to enhance detection sensitivity. Diatomaceous earth was employed to extract heterocyclic aromatic amines from meat samples, and the analytes were purified and enriched using tandem solid phase extraction, with siliprep propylsulfonic acid coupled to a C₁₈ cartridge. A number of parameters, including pH, eluent and volume, were carefully optimized to improve the extraction and purification efficiency. Under the optimal experimental conditions, the limits of detection for each analyte within the meat matrix were 0.5 pg (injected). The established method was applied to evaluate commercial meat products. At three spiked levels of 0.2, 1 and 4 μg kg⁻¹, the recoveries and relative standard deviations were measured as 76.4–122.2 and 0.9–23.4%, respectively, suggesting the developed method is promising for the accurate quantification of heterocyclic aromatic amines at trace levels in processed meats.     

Quantification of folpet and phthalimide in tea and herbal infusions by LC– high-resolution MS and GC–MS/MS

Two methods based on a modified QuEChERS sample preparation and either LC coupled to atmospheric pressure ionisation and high-resolution MS or GC coupled to electron ionisation and tripled quadrupole MS have been assessed for the quantification of folpet and phthalimide in tea and other dry herbal infusions. Both methods have been fully validated in green tea and further checked in black tea, verbena and rooibos, and they performed according to the SANTE/11813/2017 criteria at the target LOQ concentration level (50 µg/kg). These methods allow the accurate quantification of folpet in the selected matrices according to the new EU residue definition, which includes phthalimide. Phthalimide is the main metabolite and degradation product of folpet, although according to recent studies, it could be generated from different sources than folpet breakdown, such as food processing or analysis by GC.     

Determination of brominated flame retardants in food by LC–MS/MS: diastereoisomer-specific hexabromocyclododecane and tetrabromobisphenol A

The levels of the brominated flame retardants (BFRs) hexabromocyclododecane (α, β and γHBCD diastereoisomers) and tetrabromobisphenol A (TBBPA) have been determined in two studies using LC–MS/MS. The methodology developed was validated in-house and used to analyse UK 2004 Total Diet Study (TDS) samples and shellfish (oysters, mussels and scallops) collected from Scotland. HBCD was detected in most samples; in both studies the αHBCD diastereoisomer was generally the most abundant as opposed to the γ diastereoisomer that tends to dominate in environmental samples and manufactured products. It is reported that selective metabolism or biotransformation of the β and γ diastereoisomers may be taking place. TBBPA was not detected in any samples above the limit of detection, which was as low as 0.05 µg kg^–1. This may be because TBBPA, unlike HBCD, is chemically bound to the polymer matrix during manufacture and not readily leached. The UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) concluded that the concentrations of HBCD and TBBPA detected in the TDS study did not raise toxicological concerns and, as levels in the shellfish samples were in a similar concentration range, it was concluded that exposure to the BFRs measured is not significant when compared to exposure from the rest of the diet.