scholarly journals Determination of Amphetamine and Methamphetamine by Dispersive Liquid Phase Micro-extraction: A Novel Experimental Approach

2020 ◽  
Vol 14 (4) ◽  
pp. 253-262
Author(s):  
Daruish Badakhshan ◽  
◽  
Majid Ramezani ◽  
Keyword(s):  
Liquid Phase ◽  
High Performance ◽  
Experimental Approach ◽  
Limit Of Detection ◽  
Urine Samples ◽  
Detection Methods ◽  
Extraction Solvent ◽  
Array Detection ◽  
Solvent Volume

Background: A syringe to syringe dispersive liquid phase micro-extraction-floating organic drop was applied and used for the simultaneous extraction and pre-concentration of trace amounts of amphetamine (AMP) and methamphetamine (MAMP) in urine samples. The extracted analytes were determined by high performance liquid chromatography along with diode array detection. Methods: In this study, n-hexane was selected as the extraction solvent without the need to use dispersive solvent. The analytical parameters affecting the micro-extraction efficiency, including pH of sample solution, extraction solvent volume, the cycles of extraction and time of centrifugation were investigated and optimized by screening and optimization experimental design methods.  Results: Underoptimal conditions, the calibration curve had a linear range of 2-100 μg/L with the determination coefficient of R2=99.8 and R2=99.6 for AMP and MAMP, respectively. The limit of detection was 2 μg/L for AMP and MAMP, and the enrichment factor was 75 and 68 for AMP and MAMP, respectively.  Conclusion: This method is very simple, rapid and has been successfully used for pre-concentration and measurement of the analytes in urine samples, which is important to forensic studies.  

Development of Dispersive Liquid-Liquid Microextraction Procedure for Trace Determination of Malathion Pesticide in Urine Samples

2020 ◽  
Author(s):  
Maryam RAMIN ◽  
Monireh KHADEM ◽  
Fariborz OMIDI ◽  
Mehran POURHOSEIN ◽  
Farideh GOLBABAEI ◽  
...  
Keyword(s):  
Enrichment Factor ◽  
Human Urine ◽  
High Performance ◽  
Limit Of Detection ◽  
Urine Samples ◽  
Human Urine Samples ◽  
Extraction Solvent ◽  
Ultraviolet Detector ◽  
Relative Standard

Background: Measurement of pesticides in biological matrices is become a serious challenge for researches because of their very low concentration in different matrices. The aim of this study was to develop a new sample preparation method with high accuracy and validity, simplicity and short retention time for determination of malathion. Methods: Dispersive liquid-liquid micro-extraction (DLLME) technique coupled with high-performance liquid chromatography equipped with ultraviolet detector (HPLC-UV) developed for trace extraction and determination of malathion pesticide in human urine samples. This study was done in 2017 at Tehran University of Medical Sciences, Tehran, Iran. One variable at a time (OVAT) method was used to optimize parameters affecting the malathion extraction. Different parameters such as extraction solvent, disperser solvent, and volume of the extraction solvent, volume of the disperser solvent, centrifugation time and speed, salt addition, and sample pH were studied and optimized. Results: Under the optimized conditions, the limit of detection and enrichment factor of the method were 0.5 µg L-1 and 200, respectively. The calibration curve was linear in the concentration range of 2-250 µg L-1 . The relative standard deviation for six replicate experiments at 200 µg L-1 concentration was less than 3%. The relative recoveries of spiked urine samples were 96.3%, 101.7% and 97.3% at three different concentration levels of 50, 200 and 1000 µg L-1 , respectively. Conclusion: DLLME procedure was successfully developed for the extraction of malathion from human urine samples. Compared to other extraction techniques, the proposed procedure had some advantages such as shorter extraction time, better reproducibility, and higher enrichment factor.  

Sensitive determination of psychotropic drugs in urine samples using continuous liquid-phase microextraction with an extraction solvent lighter than water

2018 ◽  
Vol 42 (6) ◽  
pp. 4450-4456 ◽  
Author(s):  
Lida Haghnazari ◽  
Hamid Nomani ◽  
Nazir Fattahi ◽  
Kiomars Sharafi ◽  
Masoud Moradi
Keyword(s):  
Liquid Phase ◽  
Psychotropic Drugs ◽  
Urine Samples ◽  
Liquid Phase Microextraction ◽  
Extraction Solvent ◽  
Sensitive Determination ◽  
First Time

A novel extraction vessel was employed, for the first time, in continuous liquid-phase microextraction (CLPME) with an extraction solvent lighter than water for the extraction of psychotropic drugs from urine samples.

scholarly journals Determination of Formaldehyde by HPLC with Stable Precolumn Derivatization in Egyptian Dairy Products

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Ahmed Salem Sebaei ◽  
Ahmed M. Gomaa ◽  
A. A. El-Zwahry ◽  
E. A. Emara
Keyword(s):  
Dairy Products ◽  
High Performance ◽  
Limit Of Detection ◽  
Precolumn Derivatization ◽  
Limit Of Quantification ◽  
Chromatography Method ◽  
Derivatizing Agent ◽  
Array Detection ◽  
Liquid Chromatography Method

Formaldehyde is one of the most dangerous chemical compounds affecting the human health; exposure to it from food may occur naturally or by intentional addition. In this study a high performance liquid chromatography method for determination of formaldehyde in dairy products was described. The dairy samples were reacted and extracted with a warmed organic solvent in the presence of derivatizing agent 2,4-dinitrophenylhydrazine (DNPH) and formaldehyde; the mixture was centrifuged and followed by diode array detection. The method is validated and gives average recovery of formaldehyde at the three different levels 0.1, 5.0, and 10.0 mg/kg varied between 89% and 96%. The method is linear from the limit of quantification 0.1 mg/kg up to 10 mg/kg levels. This method is intended for formaldehyde analyses in dairy products simply with stable derivatization, minimum residue loss, excellent recovery, and accurate results with a sensitive limit of detection 0.01 mg/kg. 90 dairy samples from milk, cheese, and yogurt were investigated from seven Egyptian governorates and all samples were free from formaldehyde.

scholarly journals Determination of Nicotine in Libyan Smokers' Urine Compared with that of Nonsmokers using Reversed Phase – High Performance Liquid Chromatog-raphy (RP-HPLC)

2019 ◽  
Vol 34 (3) ◽  
pp. 172-180
Author(s):  
Galal Elmanfe ◽  
Suad K. Omar ◽  
Noreldin S.Y. Abdolla ◽  
Amna M. Hassan
Keyword(s):  
High Performance ◽  
Limit Of Detection ◽  
Cost Effective ◽  
High Performance Liquid Chromatog ◽  
Reversed Phase ◽  
Urine Samples ◽  
Average Value ◽  
Limit Of Quantitation ◽  
One Step

The aim of the present study was to evaluate the levels of nicotine in twenty urine samples taken from ten smokers and ten non-smokers in Libya. Each volunteer was required to complete a questionnaire before providing the urine sample. The evaluation of the nicotine concentrations was carried out by means of a simple, rapid, cost effective but reliable, one-step extraction technique-reversed-phase high-performance liquid chromatography which was developed and validated for this purpose. The criteria and factors taken into consideration for this evaluation and validation include the linearity, precision, accuracy, limit of detection, and limit of quantitation. The urine samples from the smokers presented nicotine concentrations in the range of 0.037-1.979 µg/ml, with an average of 0.663 µg/ml. The range of the nicotine concentrations in non-smokers, on the other hand, was from 0.017-1.331 g/ml, where 0.273 µg/ml is the average value. Statistical analyses show that the nicotine concentrations were very significant in the smoker samples in contrast with the nonsmoker samples

Optimum HPLC Conditions for Determination of Dibucaine HCL, Fluocortolone Pivalate and Fluocortolone Caproate by Using Experimental Design

2018 ◽  
Vol 15 (1) ◽  
pp. 32-38 ◽  
Author(s):  
Bürge Aşçı ◽  
Mesut Koç
Keyword(s):  
Experimental Design ◽  
Flow Rate ◽  
Mobile Phase ◽  
High Performance ◽  
Limit Of Detection ◽  
Pharmaceutical Preparations ◽  
Acid Mixture ◽  
Solution Stability ◽  
Uv Detector

Introduction:This paper presents the development and validation of a novel, fast, sensitive and accurate high performance liquid chromatography (HPLC) method for the simultaneous quantitative determination of dibucaine HCl, fluocortolone pivalate and fluocortolone caproate in pharmaceutical preparations.Experiment:Development of the chromatographic method was based on an experimental design approach. A five-level-three-factor central composite design requiring 20 experiments in this optimization study was performed in order to evaluate the effects of three independent variances including mobile phase ratio, flow rate and amount of acid in the mobile phase.Conclusion:The optimum composition for mobile phase was found as a methanol:water:acetic acid mixture at 71.6 : 26.4 : 2 (v/v/v) ratio and optimum separation was acquired by isocratic elution with a flow rate of 1.3 mL/min. The analytes were detected using a UV detector at 240 nm. The developed method was validated in terms of linearity, precision, accuracy, limit of detection/quantitation and solution stability and successfully applied to the determination of dibucaine HCl, fluocortolone pivalate and fluocortolone caproate in pharmaceutical topical formulations such as suppositories and ointments.

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