scholarly journals Accurate Determination, Matrix Effect Estimation, and Uncertainty Evaluation of Three Sulfonamides in Milk by Isotope Dilution Liquid Chromatography-Tandem Mass Spectrometry

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Chaonan Han ◽  
Xiuqin Li ◽  
Hui Jiao ◽  
Yan Gao ◽  
Qinghe Zhang
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Matrix Effect ◽  
Mobile Phase ◽  
Accurate Determination ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
The Matrix ◽  
Liquid Chromatography Tandem Mass

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the most commonly used method for sulfonamide determination. Its accuracy, however, can be affected by many factors. In this study, sulfadiazine (SDZ), sulfadimidine (SMZ), and sulfadimethoxine (SDM) in milk were selected to investigate an accurate determination method and the potential influencing factors in the use of ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Milk samples were extracted by 25 mL perchloric acid solution (pH = 2) and cleaned up using HLB solid-phase extraction (SPE) cartridges. Four kinds of filters, including PTFE, GHP, nylon, and glass fiber, were compared, and PTFE was selected since it had the best recoveries of target sulfonamides (SAs). Three quantitative methods, including external standard (ES), matrix matching (MM), and isotope dilution mass spectrometry (IDMS), were compared, among which IDMS exhibited the best accuracy. The matrix effect under different mobile phase compositions and of different sample matrices were evaluated and discussed. Ion suppression effects were observed during the determination of all SAs, which got stronger with the increase of the methanol composition percent in the mobile phase. After correction by IDMS, the matrix effect could be neglected. Matrix spiked recoveries at three spiked levels (1 μg/kg, 10 μg/kg, and 20 μg/kg) ranged from 96.8% to 103.8% by IDMS. The expanded relative uncertainties were in the range of 2.02% to 5.75%. The method exhibited wide application range, high accuracy, good stability, and high sensitivity.

scholarly journals A Simple Ultraperformance Liquid Chromatography-Tandem Mass Spectrometry Method for Measurement of Cortisol Level in Human Saliva

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Syed N. Alvi ◽  
Muhammad M. Hammami
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Cortisol Level ◽  
Mobile Phase ◽  
Room Temperature ◽  
Human Saliva ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

A simple ultraperformance liquid chromatography-tandem mass spectrometry assay for measurement of cortisol level in human saliva was developed and validated. Saliva samples containing cortisol were spiked with tolperisone as internal standard (IS) and extracted with a mixture of methyl tert-butyl ether and hexane (8:2, v:v). After solvent evaporation, residue was reconstituted in 100 μl mobile phase. Analysis was performed on Atlantis dC18 column (2.1 × 100 mm, 3 μm particle size) with a mobile phase composed of acetonitrile and 2 mM ammonium acetate (50:50, v:v) and delivered at a flow rate of 0.3 ml/minute. Mass spectrometry acquisition was performed with multiple reaction monitoring in positive-ion mode for cortisol and IS (m/z: 363.1 → 121.0 and 246.0 → 97.9, respectively). Retention times of cortisol and IS were about 1.35 and 2.45 minutes, respectively. The relationship between cortisol level and peak area ratio of cortisol to IS was linear in the range of 0.5-100 ng/ml. Intra- and interday coefficient of variation and bias were ≤ 9.0% and ≤12.0%, respectively. Mean extraction recoveries of cortisol and IS from saliva samples were 92% and 94%, respectively. Using the method, cortisol was found to be ≥ 86% stable in processed (24 hours at room temperature or 48 hours at -20°C) and ≥ 91% stable in unprocessed (24 hours at room temperature or 20 weeks at -20°C) saliva samples. Further, the method was successfully applied to determine daily cortisol profile in saliva samples of a healthy volunteer.

Method Validation for Quantitative Analysis of Metribuzin in Wheat by Liquid Chromatography–Tandem Mass Spectrometry

2020 ◽  
Vol 59 (1) ◽  
pp. 47-54
Author(s):  
Dipak Kumar Hazra ◽  
Aloke Purkait ◽  
Durgesh Raghuwanshi ◽  
K Sri Rama Murthy
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Sample Preparation ◽  
Tandem Mass Spectrometry ◽  
Accurate Determination ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Limit Of Quantitation ◽  
Liquid Chromatography Tandem Mass

Abstract A high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the accurate determination of metribuzin levels in wheat. The widespread use of this herbicide in the production of wheat is of concern and could follow as well as the need for methodology, which required simple sample preparation being needed. Validation of method was done as per single laboratory validation approach. Samples were extracted through a modified quick, cheap, effective, rugged and safe technique. Sample preparation includes extraction by acetonitrile solvent and cleans up by C18, primary secondary amine and anhydrous MgSO4 for dispersive solid-phase extraction. LC–MS/MS was calibrated at 5 calibration levels with high correlation coefficients (r2) >0.995. Limit of detection and limit of quantitation of metribuzin were 0.01 and 0.03 μg/g, respectively. The mean recovery percentages lie in the range of 87–97 with standard deviation for repeatability (RSDa) <10% at three spiking levels (0.03, 0.15 and 0.30 μg/g). Combined uncertainty (U = 0.0017) and expanded uncertainty (2U = 0.0033) were fairly consequential. The method may successfully be applied to other cereals samples for determination of metribuzin.

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