Application of solidified floating organic drop microextraction method for biomonitoring of chlorpyrifos and its oxon metabolite in urine samples

WOS: 000331674400015PubMed ID: 24487040A simple, efficient and green analytical procedure for monitoring sub ppb amounts of chlorpyrifos (CP) and chlorpyrifos-oxon (CPO) in urine samples was reported. The methodology is based on the solidified floating organic drop microextraction of the analytes with a free microdrop of 2-dodecanol. The parameters those can affect the microextraction efficiency, such as solvent type, extraction solvent volume, extraction time and temperature, salt effect, pH and stirring rate on extraction were optimized. The analytes were extracted from the urine samples by using 10 mu L of 2-dodecanol for 40 min at 70 degrees C and then, the extracts were injected to GC-MS column by applying 100 kPa injection pressure. The regression coefficients relating to linearity were at least 0.99. The accuracy of the developed method was tested upon recovery studies for CP and CPO calculated as 100 +/- 7% and 110 +/- 9% (at 0.1 ng mL(-1) level), respectively. LOD value for CP was found 4.8 ng L-1 and for CPO it was found 3.8 ng L-1. This method can easily be adopted by clinical laboratories for the contribution to policies aiming to reduce exposure of pesticides. (C) 2014 Elsevier B.V. All rights reserved.Ege UniversityEge University; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [212T210]The authors thank to the Ege University and TUBITAK (Project no: 212T210) for financial support

Optimization of Extraction Parameters of Reverse Iontophoretic Determination of Blood Glucose in an Artificial Skin Model

WOS: 000560561900006Background: Reverse Iontophoresis (RI) is one of the promising non-invasive technologies. It relies on the transition of low magnitude current through the skin and thus glucose measurement becomes possible as it is extracted from the surface during this porter current flow. Objective: This paper deals with the development and optimization of an RI determination method for glucose. CE dialysis membrane based artificial skin model was developed and the dependence of RI extraction on various experimental parameters was investigated. Methods: Dependence of RI extraction performance on noble electrodes (platinum, silver, palladium, ruthenium, rhodium) was checked with CA, CV and DPV, in a wide pH and ionic strength range. Optimizations on inter-electrode distance, potential type and magnitude, extraction time, gel type, membrane MWCO, usage frequency, pretreatment, artificial body fluids were performed. Results: According to the optimized results, the inter-electrode distance was 7.0 mm and silver was the optimum noble metal. Optimum pH and ionic strength were achieved with 0.05M PBS at pH 7.4. Higher glucose yields were obtained with DPV, while CA and CV achieved almost the same levels. During CA, +0.5V achieved the highest glucose yield and higher potential even caused a decrease. Glucose levels could be monitored for 24 hours. CMC gel was the optimum collection media. Pretreated CE membrane with 12kD MWCO was the artificial skin model. Pretreatment affected the yields while its condition caused no significant difference. Except PBS solution (simulated as artificial plasma), among the various artificial simulated body fluids, intestinal juice formulation (AI) and urine formulation U2 were the optimum extraction media, respectively. Conclusion: in this study, various experimental parameters (pretereatment procedure, type and MWCO values of membranes, inter-electrode distance, electrode material, extraction medium solvents, ionic strength and pH, collection medium gel type, extraction potential type and magnitude, extraction time and etc) were optimized for the non-invasive RI determination of glucose in a CE dialysis membrane-based artificial skin model and various simulated artificial body fluids.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [SBAG-104S236]; Ege University Department of Scientific Research Projects (BAP)Ege University [16/ECZ/007, 18/ECZ/006, 11/ECZ/030]This study was supported by a series of grants from TUBITAK (SBAG-104S236) and from the Ege University Department of Scientific Research Projects (BAP, Project numbers: 16/ECZ/007, 18/ECZ/006 and 11/ECZ/030)

Determination of Carbidopa, Levodopa, and Droxidopa by High-Performance Liquid Chromatography-Tandem Mass Spectrometry

WOS: 000416519900006Modern treatments of Parkinson's disease include the use of carbidopa and droxidopa along with levodopa that demonstrates the necessity for their binary and simultaneous determination in pharmaceutical tablets and biological matrices. This study presents a rapid, accurate, and precise method for the simultaneous determination of these analytes by liquid chromatography- tandem mass spectrometry method for the first time. Accordingly, performances of two types of analytical columns, namely, octadecylsilane and hydrophilic interaction liquid chromatographic columns, were tested and better resolution was obtained with the former. The pH of aqueous mobile phase (0.5% formic acid) was adjusted to 2.3 to ensure the analytes were in molecular form. Calibration graphs were obtained using multiple reaction mode and detection limits were in the region from 0.002 to 0.007 mu M for both columns. The method developed was applied for quality control samples and tablets and satisfactory recovery values from 100 to 106% were obtained.TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114 Z 153]This project was supported by TUBITAK with project number 114 Z 153