Liquid Chromatography-tandem Mass Spectrometric Detection Research Articles

Green construction of magnetic azo porous organic polymer for highly efficient enrichment and detection of phenolic endocrine disruptors

Porous organic polymers (POPs) are prominent sorbents for effective extraction of endocrine disrupting chemicals (EDCs). However, green and sustainable construction of functional POPs is still challenging. Herein, we developed a magnetic azo POP (Mazo-POP) for the first time using hydroxy-rich natural kaempferol and low-toxic basic fuchsin as monomers through a diazo coupling reaction. The Mazo-POP exhibited excellent extraction capabilities for EDCs with a phenolic structure. Consequently, it was used as a magnetic sorbent for extracting phenolic EDCs from water and fish samples, followed by ultrahigh-performance liquid chromatography-tandem mass spectrometric detection. The Mazo-POP based analytical method afforded a good linearity of 0.06–100 ng mL−1 and 0.3–500 ng g−1 for water and fish samples respectively, with detection limits (S/N = 3) of 0.02–0.5 ng mL−1 and 0.1–1.5 ng g−1, respectively. The method recovery was from 85.2% to 109% and relative standard deviation was less 5.3%. Moreover, the effective adsorption was mainly contributed by hydrogen bond, π-π interaction, pore filling and hydrophobic interaction. This work not only provides an efficient method for sensitive determination of phenolic EDCs, but also highlights the significance of green preparation of environmentally friendly sorbents for enriching/adsorbing pollutants.

Risk Assessment of Pesticide Residues by GC-MSMS and UPLC-MSMS in Edible Vegetables.

In recent years, there has been a significant increase related to pesticide residues in foods, which may increase the risks to the consumer of these foods with the different quality and concentrations of pesticide residues. Pesticides are used for controlling pests that reduce yields. On the other hand, it has become a major public health concern due to its toxic properties. Thus, the objective of the current study employed the application of Quick Easy Cheap Effective Rugged Safe (QuEChERS) method, in combination with gas and liquid chromatography-tandem mass spectrometric detection (GCMSMS, LCMSMS) in order to determine 137 pesticide residues (63 insecticides, 41 acaricides, 40 herbicide, 55 fungicide, nematicide, growth regulator, Chitin synthesis inhibitors, and Juvenile hormone mimics), in 801 vegetables such as 139 tomatoes, 185 peppers, 217 squash, 94 eggplants, and 166 cucumbers from different locations in Hail and Riyadh cities. The results showed that the majority of pesticide residues were detected for each of the following pesticides: acetaimpride, metalaxyl, imidaclopride, bifenthrin, pyridaben, difenoconazole, and azoxystrobien, which were repeated in the samples studied 39, 21, 11, 10, 8, 7, and 5, respectively. In addition, results observed that the tomato was the most contaminated with pesticide residues; it was contaminated with 19 compounds and was followed by pepper, cucumber, and squash, and the last commodity in the contaminated ranking was eggplant. The highest calculated estimated daily intakes (EDIs) were recorded for tomatoes which were estimated between 0.013 to 0.516 mg/kg of body weight per day (bw/day) while the lowest EDIs value was between 0.000002 to 0.0005 mg/kg of bw/day for cucumber. Results indicated that the EDIs values were lower than the acceptable daily intake (ADI) values. Results observed that the most of pesticide residues exposure in food consumption in Saudi Arabia were lower than ADIs. In addition, the highest value for health risk index (HRI) was recorded with Ethion residue in tomato, but in sweet pepper, the highest value for HRI was 127.5 in the form of fipronil residue. On the other hand, results found that the highest values of HRI were 1.54, 1.61, and 0.047 for difenoconazole, bifenthrin, and pyridaben residues in squash, eggplant, and cucumber.

Detection of bazedoxifene, a selective estrogen receptor modulator, in human urine by liquid chromatography-tandem mass spectrometry.

Bazedoxifene, a selective estrogen receptor modulator, has been explicitly included in the prohibited list issued by the World Anti-Doping Agency (WADA) since January 2020. A high-resolution liquid chromatography-tandem mass spectrometric detection method was developed to identify bazedoxifene and its metabolites in human urine and to quantify bazedoxifene (free plus glucuronide) for doping control purposes. Bazedoxifene acetate (20 mg) was orally administered to seven male volunteers, and the urine samples collected were analyzed using the developed method. The linearity ranged from 0.5 to 200 ng/ml, and the limit of detection was <0.2 ng/ml. The interday precision (2.2% to 3.6%) and the interday accuracy (-10.0% to 1.9%) were adequate. Bazedoxifene, bazedoxifene-N-oxide, and bazedoxifene glucoconjugates were identified in the urine samples. The profiles of the urinary excretion indicated the presence of small amounts of free bazedoxifene and bazedoxifene-N-oxide, whereas bazedoxifene glucuronide was the predominant metabolite. The cumulative excretion amount of bazedoxifene (free form plus glucuronide conjugate) within 78 h after the administration was 0.7% to 1.3% of the total dose. In all subjects, bazedoxifene (free plus glucuronide) could be detected in urine up to 78 h after administration.

Determination of heterocyclic aromatic amines in airborne particulate matter (PM2.5 and PM10) from different emission sources by ultra-high performance liquid chromatography-tandem mass spectrometry

A novel ultrasound assisted extraction procedure was developed prior to the determination of heterocyclic aromatic amines by ultra-high performance liquid chromatography-tandem mass spectrometric detection. Airborne particulate matter PM2.5 and PM10 samples (n=34) were collected during the spring season from urban residential emission sites, as well as from biomass burning. The organic compounds were extracted from the quartz fiber filter by a quick ultrasound assisted methanol-based extraction. Linearity of the method was in the range 0.58ngg−1 to 50ngg−1 with correlation coefficients (R2) from 0.993 to 0.999. The limits of detection resulted to be between 0.19ngg−1 and 3.27ngg−1. The relative standard deviations varied from 5.4 to 8.5 (n=3). The recoveries ranged from 83% to 109% for all of the analytes. Concentrations of the analytes in PM2.5 were between 4.1ngm−3 (2.07ngg−1) and 240.9ngm−3 (120.5ngg−1), meanwhile in PM10, were from 23.0ngm−3 (11.4ngg−1) to 355.1ngm−3 (176.2ngg−1). The proposed methodology resulted simple, rapid and accurate for its application to the determination of heterocyclic aromatic amines in airborne particulate matter from different emission sources.

Dissipation rate study and pre-harvest intervals calculation of imidacloprid and oxamyl in exported Egyptian green beans and chili peppers after pestigation treatment

Two QuEChERS-based methods were developed and validated, using liquid chromatography–tandem mass spectrometric detection, in order to accurately determine residues of imidacloprid and oxamyl in green beans and chili peppers after treatment via irrigation system under field conditions in Egyptian farms. The validation included experiments for specificity, linearity, trueness, precision, matrix effect and limits of detection and quantification according to European Commission standards. The dissipation rates of both pesticides in green beans and chili peppers were studied and the pre-harvest intervals (PHIs) were calculated. The LOQ values of imidacloprid were 0.47 and 2.6μg/kg in green beans and chili peppers, respectively, while for oxamyl the LOQs were 2.9 and 0.67μg/kg, respectively. No PHI of imidacloprid is required, while for oxamyl it was found that still after 21days, its residues’ concentration on both crops was significantly higher than the maximum residue limit.

Detection of the tremorgenic mycotoxin paxilline and its desoxy analog in ergot of rye and barley: a new class of mycotoxins added to an old problem

A newly developed enzyme immunoassay (EIA) for the detection of the tremorgenic indole-diterpene alkaloid paxilline (PAX) and closely related analogs was used to analyze ergot sclerotia collected from rye and barley fields. The mean EIA standard curve detection limit was 0.47±0.14ng/mL; relative cross-reactivity of toxin standard solutions was found for 11-hydroxy-paspaline (terpendole E, 1.1%) but not for lolitrem B or ergot alkaloids. Sclerotia from all fields were positive in the PAX-EIA at concentration levels of 620±200 and 160±37μg/kg in ergot of rye and 130±47μg/kg in ergot of barley. Confirmatory analyses of sclerotia by liquid chromatography-tandem mass spectrometric detection identified PAX and its analog 13-desoxypaxilline. To the best of our knowledge, this is the first report on the natural occurrence of tremorgenic indole-diterpene alkaloid mycotoxins in ergot sclerotia from rye and barley. Along with details on the analytical methodology developed in this study, particularly PAX-antibody production, the relevance and implications of these findings for food and feed safety are discussed. Presence or absence of elevated levels of tremorgenic mycotoxins, along with the ergot alkaloids, would help in explaining the difference between the two distinct manifestations of historic ergotism, the convulsive and the gangrenous form. Further method development for paxilline and other tremorgenic mycotoxins in cereals used for food and feed is a prerequisite for a comprehensive risk assessment, which seems to be necessary in light of the findings reported here. Paxilline in ergot of rye.

A rapid analytical method for cholecalciferol (vitamin D3) in fortified infant formula, milk and milk powder using Diels–Alder derivatisation and liquid chromatography–tandem mass spectrometric detection

A method for analysing vitamin D(3) (VD3, cholecalciferol) has been established and validated. This method is rapid and cost effective and is intended for use in quality control in the manufacture of fortified infant formulae and milk powders. Milk or reconstituted milk powder was solubilised in methanol and extracted in one step into isooctane, which was separated by centrifugation. A portion of the isooctane layer was then transferred, and an aliquot of 4-phenyl-1,2,4-triazoline-3,5-dione was added to derivatise VD3. The analyte was then re-extracted into a small volume of acetonitrile and analysed by reverse-phase chromatography. Detection was by triple quadrupole mass spectrometer using a selective transition, m/z 560 → 298. An internal standard, deuterium-labelled VD3, was used to correct for losses in extraction and any variation in derivatisation and ionisation efficiencies. The method has been subjected to a single-laboratory validation and has been found to be linear, highly selective and accurate with respect to National Institute of Standards and Technology Standard Reference Material 1849, analyte spiking experiments and comparison with an LC-UV-based method. The repeatability standard deviation was 4.23 %. Significantly for routine laboratories, the method returns results within 2 h, generates minimal waste and minimises health and safety concerns to the analyst.

Development and validation of a liquid chromatography method with electrospray ionization tandem mass spectrometry for the determination of brotizolam residues in beef and commercial whole milk

In this work, a liquid chromatography-tandem mass spectrometric detection technique was developed and validated for the determination of brotizolam residues in beef muscle and commercial whole milk. This procedure involves the extraction of the analyte from the samples via liquid-solid extraction, and caffeine was used as an internal standard. The analyte was successfully separated on an XTerra-C(18) column, with a mobile phase composed of 0.01% formic acid in acetonitrile and 1 mm ammonium formate-0.01% formic acid in water. The one-step extraction method evidenced good selectivity, precision (RSD = 9.87-26.47%), and the recovery of the extractable analyte was 92.61-115.98% in the matrices. The limits of quantification ranged between 0.4 and 0.5 µg/kg. The developed method is simple since it requires no additional cleanup procedures.

Quantification of 3-deazaneplanocin A, a novel epigenetic anticancer agent, in rat biosamples by hydrophilic interaction liquid chromatography–tandem mass spectrometric detection

A sensitive and selective LC–MS/MS based bioanalytical method was developed and validated for the quantification of 3-deazaneplanocin A (DZNep), a novel epigenetic anti-tumor drug candidate, in Sprague–Dawley (SD) rat biosamples (plasma, urine, feces and tissue samples). The method comprises a phenylboronic acid (PBA)-containing solid phase extraction procedure, serving for binding and clean-up of DZNep in rat biosamples spiked with tubercidin (as internal standard). The analytes were separated on an Agilent hydrophilic interaction chromatography (HILIC) column. LC–MS/MS in positive ion mode was used to perform multiple reaction monitoring at m/z of 263/135 and 267/135 for DZNep and tubercidin, respectively. The limit of quantification (LOQ) of DZNep in rat biosamples was 20 ng/mL. The data of intra-day and inter-day accuracy were within 15% of nominal concentration while the precision (relative standard deviation) less than 10% for all biosamples. The extraction recoveries for DZNep and tubercidin were consistent and reproducible (around 80%) and the matrix effects were negligible (around 10% suppression) in all biosamples. This method was demonstrated to be applicable for pharmacokinetic studies of DZNep in SD rats.

A simple; efficient and environmentally friendly method for the extraction of pesticides from onion by matrix solid-phase dispersion with liquid chromatography–tandem mass spectrometric detection

An evaluation of the extraction of pesticides from onion by matrix solid-phase dispersion (MSPD) with the determination by liquid chromatography tandem mass spectrometry using electrospray as the ionization source (LC-ESI-MS/MS) was carried out. The performance of different sorbents, including reused C18 bonded silica, was evaluated. Different parameters affecting the extraction efficiency were evaluated, such as the type and amount of sorbent, the time of interaction after the fortification step, the time of sample dispersion and the elution solvent. The matrix effect regarding the recovery of the pesticides by MSPD was also investigated. The best results were obtained using 0.5 g of sample, 1.0 g reused C18, interaction time of 1 h, dispersion time of 5 min, and acetonitrile as the elution solvent. The method was validated by the fortification of the onion sample, free of pesticides, at different concentration levels (0.01, 0.1 and 1.0 mg kg −1). Average recoveries ranged from 78.3 to 120.4% and relative standard deviation below 20% was obtained. Detection and quantification limits ranged from 0.003 to 0.03 mg kg −1 and from 0.01 to 0.1 mg kg −1, respectively.

Quantification of CLR1401, a novel alkylphosphocholine anticancer agent, in rat plasma by hydrophilic interaction liquid chromatography–tandem mass spectrometric detection

A rapid and specific LC–MS/MS based bioanalytical method was developed and validated for the determination of 18-( p-iodophenyl)octadecyl phosphocholine (CLR1401), a novel phosphocholine drug candidate, in rat plasma. The optimal chromatographic behavior of CLR1401 was achieved on a Kromasil silica column (50 mm × 3 mm, 5 μm) under hydrophilic interaction chromatography. The total LC analysis time per injection was 2.8 min with a flow rate of 1.5 mL/min under gradient elution. Liquid–liquid extraction in a 96-well format using ethyl acetate was developed and applied for method validation and sample analysis. The method validation was conducted over the curve range of 2.00–1000 ng/mL using 0.0500 mL of plasma sample. The intra- and inter-day precision and accuracy of the quality control samples at low, medium, and high concentration levels showed ≤ 5.9% relative standard deviation (RSD) and −10.8 to −1.4% relative error (RE). The method was successfully applied to determine the toxicokinetics of CLR1401 in rats from three dose groups of 0.4, 4.0, and 10.0 mg/kg/day via intravenous administration.

Validation of method for determination of different classes of pesticides in aqueous samples by dispersive liquid–liquid microextraction with liquid chromatography–tandem mass spectrometric detection

In this study, a simple, rapid and efficient method has been developed for the extraction and preconcentration of different classes of pesticides, carbofuran (insecticide), clomazone (herbicide) and tebuconazole (fungicide) in aqueous samples by dispersive liquid–liquid microextraction (DLLME) coupled with liquid chromatography–tandem mass spectrometric detection. Some experimental parameters that influence the extraction efficiency, such as the type and volume of the disperser solvents and extraction solvents, extraction time, speed of centrifugation, pH and addition of salt were examined and optimized. Under the optimum conditions, the recoveries of pesticides in water at spiking levels between 0.02 and 2.0 μg L −1 ranged from 62.7% to 120.0%. The relative standard deviations varied between 1.9% and 9.1% ( n = 3). The limits of quantification of the method considering a 50-fold preconcentration step were 0.02 μg L −1. The linearity of the method ranged from 1.0 to 1000 μg L −1 for all compounds, with correlation coefficients varying from 0.9982 to 0.9992. Results show that the method we propose can meet the requirements for the determination of pesticides in water samples. The comparison of this method with solid-phase extraction indicates that DLLME is a simple, fast, and low-cost method for the determination of pesticides in natural waters.

Unauthorised antibiotic treatments in beekeeping: Development and validation of a method to quantify and confirm tylosin residues in honey using liquid chromatography–tandem mass spectrometric detection

A liquid chromatographic–tandem mass spectrometric (HPLC-MS/MS) method is proposed for the identification and quantification of tylosin in honey. Sample treatment involves an extraction in a Tris buffer at pH 10.5, followed by a solid-phase clean up step on an Oasis HLB column. Roxithromycin was used as the internal standard. Chromatographic separation of tylosin and roxithromycin was performed on an XTerra MS C 18 column (100 mm × 2.1 mm i.d., 5 μm) using a gradient of aqueous 0.01 M ammonium acetate pH 3.5 and acetonitrile as the mobile phase, at a flow rate of 0.25 ml min −1. The method was validated according to the guidelines laid down by the Commission Decision 2002/657/EC. Tylosin residues were confirmed by MS/MS experiments considering the appropriate identification points. All validation parameters such as Ccα (lower than 3 ng g −1), Ccβ (lower than 5 ng g −1), recovery and precision were assessed on the basis of the “critical ion” (less intense ion permitting unambiguous identification of the analyte).