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quadrupole MS stands out as a fast, sensitive, and accurate quantification method for complex systems, such as natural product extracts [ 10 , 11 ]. The goal of the present study was to develop and validate a method coupling HPLC with tandem mass

Open access

A new sensitive and validated liquid chromatography electro spray ion-tandem mass spectrometry (HPLC-ESI-MS/MS) method for the quantification of Vildagliptin (VG) in rat plasma has been developed and validated using repaglinide (RG) as an internal standard (IS). The analytes were extracted by liquid-liquid extraction using ethyl acetate. Elution of the VG and IS was achieved on a reverse phase Betasil (C18 50 mm 4.6 mm ID, 5 μ) column with an isocratic mobile phase composed of acetonitrile: 2 mM ammonium acetate (90:10 v/v). The analytes monitored in the Multiple Reaction Monitoring (MRM) mode were m/z 304.2→154.0 and 453.3→230.3 for VG and RG, respectively. The calibration curve was linear in the range of 1.57–501.21 ng/mL for VG with lower limit of quantification 1.57 ng/mL. The intra run and inter run precision values are within 11.70% for VG at LOQ level.

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The rhizome of Sparganium stoloniferum Buch.-Ham has been used as a traditional Chinese folk medicine for thousands of years. Phenolic compounds are the main bioactive ingredients of the plant. In order to determine the content of phenolic compounds from different major cultivations, a reliable method has been developed using ultra-high performance liquid chromatography coupled with a triple quadrupole electrospray tandem mass spectrometry. Seven compounds, including rutin, kaempferol, p-hydroxybenzaldehyde, formononetin, ferulic acid, vanillic acid, and p-coumaric acid, were simultaneously measured in 10 min. The established approach was fully validated in terms of linearity, sensitivity, precision, repeatability as well as recovery, and successfully applied to determine seven phenolic compounds of Rhizoma Sparganii. This study may be helpful in the quality control of Rhizoma Sparganii and can offer technical support for the pharmacological and clinical study of related drugs.

Open access

A sensitive and effective method based on a modified QuECHERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of polyoxin B in cucumber and soil using liquid chromatography tandem–mass spectrometry (LC–MS/MS) was developed and validated. Samples were extracted using 1% formic acid in ultrapure water and purified via reversed-dispersive solid phase extraction (r-dSPE) using C18. Recovery of polyoxin B ranged from 83.0% to 112.1% with relative standard deviation (RSD) (n = 5) of 3.0–5.2%. The limit of quantification (LOQ) and the limit of detection (LOD) were 0.01 and 0.003 mg/kg for cucumber and soil, respectively. The method was subsequently applied for real sample analysis. The dissipation experiments showed that half-lives of polyoxin B in cucumber and soil were 2.5–5.0 days. The terminal residues of polyoxin B at preharvest intervals (PHIs) of 3 days and 5 days in cucumber were less than 0.05 mg/kg. We therefore suggest that the developed method can be extrapolated to other agricultural crops or food for routine analysis. It also can be used to determine the PHIs. Moreover, these results will aid in establishing the maximum residue limit (MRL) for cucumber in China.

Open access

The analysis of trace levels of explosives in post-blast debris is critical in homeland security, environmental analysis, and crime scene forensic investigations. A fast and a selective determination method with high recovery was developed for the common explosives 2,4,6-trinitrotoluene (TNT), 3,5-trinitro-1,3,5-triazacyclohexane (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in soil, using liquid chromatography—tandem mass spectrometry (LC—MS/MS). An easy and practical sample preparation method was developed using 4.00 mL acidified acetone with 0.25% HCl. After the easy evaporation of acetone extract, 10 min LC—MS/MS analysis provided a clear separation in column. Short duration of the whole procedure allows the use of this method in routine analysis. As a result of the analysis performed in spiked soils in 50.0, 100.0, and 250.0 ng g−1 concentrations, high recoveries such as 100.4 (±8.8)% for RDX, 96.9 (±10.5)% for HMX, and 97.6 (±13.9)% for TNT were obtained. Limit of detection (LOD) and limit of quantification (LOQ) values obtained from the analysis of the spiked soils were 4.3 ng g−1 and 7.00 ng g−1 for RDX, 6.8 ng g−1 and 10.0 ng g−1 for HMX, and 18.9 ng g−1 and 38.0 ng g−1 for TNT, respectively. The Horwitz Ratio (HorRat) calculation was used to evaluate if the inter-day and inter-analyst precisions were in the acceptable limits. The method was successfully applied to three artificial explosion samples for detection of explosives.

Open access

Summary

Coccidiostats are a group of drugs used for the treatment of coccidiosis. This disease is common among animals for slaughter. Residues of the mentioned drugs can be potentially harmful for human health, so there is a constant need for cheap and quick method for their determination. A novel sample preparation technique, solvent front position extraction (SFPE), for liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for such a purpose. In the SFPE procedure, the adsorbent layer of a chromatographic plate is used for purification and separation of substances of interest from matrix components. After applying the SFPE technique, solutes and the internal standard are not only separated from unwanted components, but also focused and evenly distributed in the zone located at the solvent front position. From such a zone, the substances can be directly transferred from thin-layer chromatography (TLC) plate to LC-MS instrument using the TLC-MS Interface. Focusing the substances of interest in a narrow zone improves the sensitivity of an assay, while the homogeneity of these zones guarantees their accurate quantification, even if only a part of the substance zone undergoes extraction using a TLC-MS Interface. The SFPE procedure is especially recommended for samples with high viscosity or/and with large amounts of contaminants and enables cleaning a final sample solution from matrix components, showing lower and stronger retention than the solutes of interest. In this work, the application of SFPE procedure for separation of the substances of interest from two biological matrices (bovine serum and animal feed) is presented. The results are promising and allow their application for further research of these compounds.

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In this study, thin-layer chromatography—direct bioautography (TLC—DB) was used for guiding the isolation and identification of antibacterial constituents of Thymus vulgaris L. ethanol extract. This TLC—bioassay method enables the separation and detection of active components directly on the surface of chromatographic plates. They can be identified by comparison with reference substances or using physicochemical methods, preferably spectroscopic ones (liquid chromatography—tandem mass spectrometry [LC—MS/MS], in the presented paper). The described method belongs to the effect-directed analyses (EDA). Seven bacterial strains were used as test organisms, both pathogenic and nonpathogenic, including methicillin-resistant Staphylococcus aureus as well as luminescent bacteria like Aliivibrio fischeri. Five fractions with the widest antimicrobial spectra were detected using TLC—DB, isolated by semi-preparative TLC and subjected to LC—MS/MS analyses. Finally, two bioactive components were tentatively identified, basing on their fragmentation pattern, as eriodictyol and 4,4′-dihydroxy-5,5′-diisopropyl-2,2′-dimethyl-3,6-bifenylodion.

Open access

Thin-layer chromatography—direct bioautography (TLC—DB) followed by liquid chromatography—tandem mass spectrometry (LC—MS/MS) was used for screening and tentative identification of the antibacterial constituents of Salvia officinalis L. ethanol extract. Seven bacterial strains were used as test organisms, both pathogenic and nonpathogenic, that is, Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Staphylococcus epidermidis, Micrococcus luteus, Bacillus subtilis, luminescence gene-tagged Pseudomonas syringae pv. maculicola, and naturally luminescent marine bacterium Aliivibrio fischeri. Eight fractions with the widest antimicrobial spectrum were detected using TLC—DB, isolated by semi-preparative TLC, and subjected to LC—MS/MS analyses. Finally, five bioactive components were tentatively identified, based on their fragmentation pattern, such as salvigenin, cirsimaritin, rosmanol, carnosic acid, and 12-O-methyl carnosic acid.

Open access

Shenqi Fuzheng Injection (SFI) is a traditional Chinese medicine injection, widely used to enhance immune function of clinical cancer patients undergoing chemotherapy. In this study, a high-performance liquid chromatography-diode array detection-evaporative light scattering detection (HPLC-DAD-ELSD) method was established for quality control of SFI, which could simultaneously semiquantitatively reflect the constituents displayed in the chromatographic profile of SFI. The relative retention time and relative peak areas of the 21 common peaks related to the reference peak were calculated. The validity and advantage of this method were validated by systematically comparing chromatograms of 10 batches of SFI samples with the analytical methods of principal component analysis and angle cosine method recommended by the State Food and Drug Administration of China. Moreover, a total of 21 constituents of SFI were identified or tentatively characterized in the fingerprint via ultrafast liquid chromatography-diode array detection-quadrupole time-of-flight (UFLC-DAD-Q-TOF) tandem mass spectrometry technique on the basis of the retention time, ultraviolet spectra, fragmentation patterns, and reported literatures. All the results proved that the technique was useful in comprehensive quality evaluation of SFI and further study.

Open access

Abstract

This study focused on developing an effective and environmentally friendly method to measure ligustrazine in rat serum by using polymer monolith micro-extraction (PMME) technique. A poly (methacrylic acid-ethylene glycol dimethacrylate) material was used to extract ligustrazine through hydrophobic and ion-exchange interaction. Qualitative and quantitative analysis was performed by a liquid chromatography and tandem mass spectrometry. After optimization of several PMME conditions, the developed method exhibited excellent extraction performance to the ligustrazine. Good linearity was acquired ranging from 10 to 2,000 ng mL−1, and the limit of detection of the proposed method was 0.14 ng mL−1. The recoveries measured by spiking three different concentrations in rat serum ranged from 82.6 to 95.3%, and excellent precision was found with relative standard deviations (RSDs) less than 8.3% for intra-day and 9.7% for inter-day, respectively. At last, the applicability of the method was further confirmed through continuous monitoring of ligustrazine in rat serum after dosing of ligustrazine tablets to rats.

Open access