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1.
Talanta ; 119: 467-72, 2014 Feb.
Article in English | MEDLINE | ID: mdl-24401442

ABSTRACT

Sensitive disposable potentiometric sensors for determination of the organophosphorus pesticide (OPs), ethion and its degradation residues have been constructed. The fabricated screen printed sensors are based on multi-walled carbon nanotube-polyvinyl chloride (MWNT-PVC) composite incorporated with α-cyclodextrin (α-CD) ionophore for butyrylcholine (BuCh) determination. Butyrylcholinesterase (BuChE) activity was measured through monitoring the BuCh hydrolysis using the fabricated sensors. The electrode potential changes linearly with BuChE concentration over the range from 0.04 to 0.4 U in phosphate buffer solution. This approach can also be used to analyze ethion and its degradation products in the concentration range from 0 to 330 ng mL(-1) by measuring the relative inhibition percentage of BuChE. From different ethion degradation products, inhibition by dioxon and monooxon were more potent than the parent pesticide. The proposed method was applied for determination of ethion in different samples with good accuracy and precision. The relative simple fabrication protocol of biosensor, high sensitivity and stability represents a promising approach for determination of environmental pollutants in field conditions.


Subject(s)
Biosensing Techniques , Organothiophosphorus Compounds/analysis
2.
Talanta ; 83(2): 357-63, 2010 Dec 15.
Article in English | MEDLINE | ID: mdl-21111146

ABSTRACT

A highly sensitive disposable screen-printed butyrylcholine (BuCh) potentiometric sensor, based on heptakis (2,3,6-tri-o-methyl)-ß-cyclodextrin (ß-CD) as ionophore, was developed for butyrylcholinesterase (BuChE) activity monitoring. The proposed sensors have been characterized and optimized according to the constituents of homemade printing carbon ink including ß-CD, anionic sites, and plasticizer. The fabricated sensor showed Nernstian responses from 10(-6) to 10(-2)mol L(-1) with detection limit of 8 × 10(-7)mol L(-1), fast response time (1.6s) and adequate shelf-life (6 months). Improved selectivity towards BuCh with minimal interference from choline (Ch) was achieved and the sensor was used for determination of 0.06-1.25 U mL(-1) BuChE. The developed disposable sensors have been successfully applied for real-time intoxication monitoring through assaying cholinesterases (ChEs) activity in human serum. Determination of organophosphate pesticide was conducted by measuring their inhibition of BuChE with successful assaying of malathion in insecticide samples with high accuracy and precision.


Subject(s)
Biosensing Techniques , Butyrylcholinesterase/analysis , Cholinesterases/analysis , Potentiometry/methods , Butyrylcholinesterase/blood , Calibration , Carbon/chemistry , Choline/analogs & derivatives , Choline/analysis , Cholinesterases/blood , Electrodes , Humans , Hydrogen-Ion Concentration , Ionophores , Malathion/analysis , Organophosphates/chemistry , Pesticides/pharmacology , Reproducibility of Results , beta-Cyclodextrins/analysis
3.
Drug Test Anal ; 2(9): 424-9, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20839365

ABSTRACT

A simple, rapid, reliable, and reproducible method for mass production of disposable sensors using screen-printing technology is described. Homemade printing has been characterized and optimized on the basis of effects of the modifier and plasticizers. The fabricated bi-electrode potentiometric strip containing both working and reference electrode was used as dextromethorphan (DXM) sensor. The proposed sensors worked satisfactorily in the concentration range from 10⁻5 to 10⁻² mol L⁻¹ with detection limit reaching 6 × 10⁻6 mol L⁻¹ and adequate shelf life of 8 months. DXM was determined in pharmaceutical formulations under batch and flow injection analysis (FIA) conditions with sampling output 120 h⁻¹.


Subject(s)
Dextromethorphan/analysis , Potentiometry/methods , Electrodes , Flow Injection Analysis , Pharmaceutical Preparations/analysis , Quality Control
4.
Talanta ; 81(1-2): 510-5, 2010 Apr 15.
Article in English | MEDLINE | ID: mdl-20188955

ABSTRACT

The construction and performance characteristics of dextromethorphan (DXM) carbon paste (CPEs) and polyvinyl chloride (PVC) electrodes are described. Different modes for electrode modification, including incorporation of ion pairs (IPs), ion pairing agent or soaking the plain electrode in IPs suspension, have been used. Matrices compositions were optimized referring to the effect of modifier and plasticizer. The fabricated electrodes work satisfactorily in the concentration range from 10(-5) to 10(-2) mol L(-1) with fast response time (1.6s) and long operational lifetime (2 months). The developed electrodes have been successfully applied for the potentiometric determination of DXM in pharmaceutical formulation under batch and flow injection analysis (FIA) conditions. Under FIA conditions, the proposed electrodes allow the analysis of 90 samples h(-1) and offer the advantage of simplicity, accuracy and automation feasibility. The solubility products of various DXM-IPs were determined conductometrically.


Subject(s)
Carbon/chemistry , Dextromethorphan/analysis , Polyvinyl Chloride/chemistry , Potentiometry/methods , Dextromethorphan/chemistry , Dosage Forms , Electrodes , Flow Injection Analysis , Ointments , Time Factors
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