scholarly journals Multiresidue Method for N-Methyl Carbamates and Metabolite Pesticide Residues at the Parts-per-Billion Level in Selected Representative Commodities of Fruit and Vegetable Crop Groups

2004 ◽  
Vol 87 (5) ◽  
pp. 1237-1251 ◽  
Author(s):  
Lynda V Podhorniak ◽  
Frank J Schenck ◽  
Alexander Krynitsky ◽  
Francis Griffith ◽  
Francis Griffith
Keyword(s):  
Environmental Protection Agency ◽  
Solid Phase ◽  
Reversed Phase ◽  
Mass Spectrometric ◽  
Fruit And Vegetable ◽  
Vegetable Crop ◽  
Additional Material ◽  
Liquid Chromatograph ◽  
Mass Spectrometric Detector

Abstract A reversed-phase liquid chromatographic method with both fluorescence and mass spectrometric detection is presented for the determination of 13 parent N-methyl carbamate pesticides and their metabolites, as well as piperonyl butoxide, for a total of 24 compounds in selected fruits and vegetables. The commodities chosen were of special concern to the U.S. Environmental Protection Agency (EPA) because they had the least amount of monitoring data for dietary exposure estimates used in risk assessment. The method is based on a judicious selection of procedures from U.S. Food and Drug Administration sources such as the Pesticide Analytical Manual (Volume I), and Laboratory Information Bulletins, plus additional material from the chemical literature combined in a manner to recover the N-methyl carbamates and their metabolites at the 1 μg/kg or 1 part-per-billion level. The method uses an acetone extraction, followed by an aminopropyl solid-phase extraction cleanup. Determination of residues is by RP-LC, in which the liquid chromatograph is interfaced with either a fluorescence or a mass spectrometric detector. The method is designed so that a set of 6 samples can be prepared in 1 working day for overnight instrumental analysis. Recovery data are presented from analyses of selected commodities in some of EPA's fruit and vegetable crop groupings. A table listing relative retention times is presented for the N-methyl carbamates and their metabolites.

LC–MS-MS Method for the Determination of Antidepressants and Benzodiazepines in Meconium

2020 ◽  
Vol 44 (6) ◽  
pp. 580-588
Author(s):  
A López-Rabuñal ◽  
E Lendoiro ◽  
M Concheiro ◽  
M López-Rivadulla ◽  
A Cruz ◽  
...  
Keyword(s):  
Extraction Efficiency ◽  
Solid Phase ◽  
Gradient Methods ◽  
Reversed Phase ◽  
Process Efficiency ◽  
Limit Of Quantification ◽  
Mode 2 ◽  
Positive Mode ◽  
Compound Method

Abstract An LC–MS-MS method for the determination of 14 benzodiazepines (BZDs) (alprazolam, α-hydroxyalprazolam, clonazepam, bromazepam, diazepam, nordiazepam, lorazepam, lormetazepam, oxazepam, flunitrazepam, 7-aminoflunitrazepam, triazolam, midazolam and zolpidem) and 15 antidepressants (ADs) (amitriptyline, nortriptyline, imipramine, desipramine, clomipramine, norclomipramine, fluoxetine, norfluoxetine, sertraline, norsertraline, paroxetine, venlafaxine, desmethylvenlafaxine, citalopram and desmethylcitalopram) in meconium was developed and validated. Meconium samples (0.25 ± 0.02 g) were homogenized in methanol and subjected to mixed-mode cation exchange solid-phase extraction. Chromatographic separation was performed in reversed phase, with a gradient of 0.1% formic acid in 2 mM ammonium formate and acetonitrile. Two different chromatographic gradient methods were employed, one for the separation of ADs and another for BZDs. Analytes were monitored by tandem mass spectrometry employing electrospray positive mode in MRM mode (2 transitions per compound). Method validation included: linearity [n = 5, limit of quantification (LOQ) to 400 ng/g], limits of detection (n = 6, 1–20 ng/g), LOQ (n = 9, 5–20 ng/g), selectivity (no endogenous or exogenous interferences), accuracy (n = 15, 90.6–111.5%), imprecision (n = 15, 0–14.6%), matrix effect (n = 10, −73 to 194.9%), extraction efficiency (n = 6, 35.9–91.2%), process efficiency (n = 6, 20.1–188.2%), stability 72 h in the autosampler (n = 3, −8.5 to 9%) and freeze/thaw stability (n = 3, −1.2 to −47%). The method was applied to four meconium specimens, which were analyzed with and without hydrolysis (enzymatic and alkaline). The authentic meconium samples tested positive for alprazolam, α-hydroxyalprazolam, clonazepam, diazepam, nordiazepam, fluoxetine, norfluoxetine, clomipramine and norclomipramine. Therefore, the present LC–MS-MS method allows a high throughput determination of the most common BZDs and ADs in meconium, which could be useful in clinical and forensic settings.

Determination of uric acid in grain using HPLC

2021 ◽  
pp. 74-77
Author(s):  
Артём Валерьевич Яицких ◽  
Геннадий Алексеевич Закладной ◽  
Дмитрий Сергеевич Степаненко
Keyword(s):  
Uric Acid ◽  
Extraction Method ◽  
High Performance ◽  
Reversed Phase ◽  
Calibration Graph ◽  
Improved Method ◽  
Liquid Chromatograph ◽  
Yield Time ◽  
Grain Contamination

В данной статье показана возможность улучшения определения мочевой кислоты методом высокоэффективной жидкостной хроматографии (ВЭЖХ), с помощью увеличения растворимости ее в 1 %-ном растворе ацетата натрия, повышения удержания мочевой кислоты и тем самым изменения времени выхода, что позволяет повысить точность анализа. Проведено сравнение градуировочных растворов и опытных образцов зерна зараженных вредителями хлебных запасов. В процессе исследования был опробован метод для определения и идентификации мочевой кислоты как одного из загрязняющих зерно веществ с помощью ВЭЖХ в обращенной фазе. Экспериментально опробована и усовершенствована методика анализа мочевой кислоты в зерне с использованием жидкостного хроматографа «Стайер». Описаны оборудование и материалы для ВЭЖХ, условия хроматографического разделения и детектирования, построения калибровочного графика, экстракции, включая методику экстракции, сходимости результатов при экстракции и введении экстракта в хроматограф, а также порядок и расчет измерений. Экспериментально показано, что усовершенствованная методика с применением ВЭЖХ позволяет использовать ее для проведения дальнейших исследований зависимости содержания мочевой кислоты от величины загрязнения зерна насекомыми. This article shows the possibility of improving the determination of uric acid by high-performance liquid chromatography (HPLC), by increasing its solubility in a 1 % solution of sodium acetate, increasing the retention of uric acid, and thereby changing the yield time, which allow to improve the accuracy of the analysis, a comparison of calibration solutions and experimental grain samples of pest-infected bread stocks have been carried out. During the research course a method for the determination and identification of uric acid has been tested as one of the grain polluting substance using HPLC in the reversed phase. The method of uric acid in grain analysis using a liquid chromatograph «Stayer» has been experimentally tested and improved. The equipment and materials for HPLC, the conditions of chromatographic separation and detection, the construction of a calibration graph, extraction, including the extraction method, the convergence of the results during extraction and the introduction of the extract into the chromatograph, as well as the course and calculation of measurements have been described. It has been experimentally shown that the improved method with HPLC allows to use it for further research of the uric acid content dependence on the amount of grain contamination by insects.

scholarly journals Determination of Flumorph Residues in Vegetables, Soil, and Natural Water by Solid-Phase Extraction Cleanup and High-Performance Liquid Chromatography with UV Detection

2008 ◽  
Vol 91 (6) ◽  
pp. 1459-1466 ◽  
Author(s):  
Ji-Ye Hu ◽  
Yu-Chao Zhang ◽  
Hai Yan
Keyword(s):  
Solid Phase Extraction ◽  
Natural Water ◽  
High Performance ◽  
Solid Phase ◽  
Residue Analysis ◽  
Reversed Phase ◽  
Uv Detection ◽  
Phase Extraction ◽  
Limit Of Quantification

Abstract A method for high-performance liquid chromatographic (HPLC) determination of flumorph residues in cucumber, tomato, soil, and natural water was developed and validated. Primary secondary amine or octadecylsilyl (C18) solid-phase extraction cartridges were used for sample preparation. Reversed-phase HPLC with UV detection was used for separation and quantification of the pesticide. The combined cleanup and chromatographic method steps were sensitive and reliable for simultaneous determination of residues of the 2 isomers of flumorph in the studied samples. This method is characterized by recovery >97.9, coefficient of variation <6.2, and limit of quantification of 0.01 mg/kg, in agreement with directives for method validation in residue analysis. Flumorph residues in the samples were further confirmed by HPLC/mass spectrometry. The proposed method is fast, easy to perform, and could be used for monitoring of pesticide residues.

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