BACKGROUND: IN THIS RESEARCH A POLYPYRROLE MODIFIED ELECTRODE WAS PREPARED AND USED FOR DETERMINATION OF TIN (II) IN REAL SAMPLES. TIN IS KNOWN AS AN ESSENTIAL TRACE ELEMENT IN VARIOUS METABOLIC PROCESSES IN HUMANS, ANIMALS AND PLANTS. IT MAY BE INTRODUCED INTO HUMAN ENVIRONMENT EITHER AS INORGANIC TIN OR AS ORGANOTIN COMPOUNDS, THROUGH THEY ARE USED AS FUNGICIDES IN CROPS, IN FOOD PACKAGING AND IN SOME VETERINARY FORMULATIONS. CANNED FOOD IS KNOWN TO CONTAIN HIGH CONCENTRATIONS OF TIN, SUCH AS CANNED FISH, CANNED CORN AND CANNED TOMATO [1, 2].METHODS: POLYPYRROLE MODIFIED ELECTRODES WERE PREPARED BY ELECTROPOLYMERIZATION OF PYRROLE IN THE PRESENCE OF 5-SULFOSALICYLATE AS THE COUNTER ANION. THE PPY ELECTRODE WAS OXIDIZED BY CYCLIC VOLTAMMETRY AND APPLIED FOR DETERMINATION OF TIN (II) BY PRECONCENTRATION/DIFFERENTIAL PULSE ANODIC STRIPPING VOLTAMMETRY (DPASV).RESULTS: VARIOUS SIGNIFICANT PARAMETERS THAT INFLUENCE THE ANALYTICAL PERFORMANCE OF THIS VOLTAMMETRIC SENSOR, INCLUDING ELECTROPOLYMERIZATION TIME (8 S), THE CONCENTRATION OF DOPING ANION (0.1 M), THE PH OF THE PRECONCENTRATION SOLUTION (1.5) AND ACCUMULATION POTENTIAL (-700 MV) AND TIME (200 S) WERE EVALUATED. THE LINEAR RESPONSE OF THE SENSOR WAS IN THE SN2+ CONCENTRATION RANGE OF 5.0×10-7 TO 1.0×10-3 M, WITH DETECTION LIMIT OF ABOUT 1.0×10-8 M. THE PREPARED SENSOR WAS USED FOR TIN (II) DETERMINATION IN SEVERAL REAL SAMPLES SUCH AS CANNED CORN AND CANNED FISH. THE OBTAINED RESULTS WERE IN GOOD AGREEMENT WITH RESULTS OBTAIND FROM ATOMIC ABSORPTION SPECTROPHOTOMETRY.CONCLUSION: POLYPYRROLE WAS ELECTROPOLYMERIZED ON GLASSY CARBON ELECTRODE AND OVEROXIDIZED. THE OVEROXIDATION PROCEDURE ENHANCED ANALYTICAL PERFORMANCE CHARACTERISTICS OF THIS ELECTROCHEMICAL SENSOR. THIS OVEROXIDIZED ELECTRODE EXHIBITED A GOOD VOLTAMMETRIC SELECTIVITY, SENSITIVITY AND REPEATABILITY AND SHOWED GOOD RESULTS IN REAL SAMPLE ANALYSIS.

A SWITCHABLE-HYDROPHILICITY SOLVENT IN COMBINATION WITH AIR-ASSISTED LIQUID–LIQUID MICROEXTRACTION (AALLME) CALLED AA-SHS-LPME, HAS BEEN APPLIED FOR MICROEXTRACTION PALLADIUM...

OPTODES REPRESENT A GROUP OF INTEGRATED ANALYTICAL SYSTEMS WITH RAPID GROWTH FOR MEASUREMENT OF HEAVY METALS DUE TO THEIR EASY FABRICATION, GOOD SENSITIVITY AND SELECTIVITY AND LOW COST. THE SENSING PHASE CONSISTS OF REAGENT DYES IMMOBILIZED IN ORGANIC OR INORGANIC MATRICES [1, 2]. ZINC, AS THE SECOND MOST ABUNDANT TRANSITION METAL IN THE BODY AND CONTAINING ITS HIGHEST CONCENTRATIONS IN THE BRAIN, PLAYS DIVERSE ROLES IN MANY VITAL BIOLOGICAL PROCESSES AS STRUCTURAL AND CATALYTIC COFACTORS, NEURAL SIGNAL TRANSMITTERS OR MODULATORS, AND REGULATORS OF GENE EXPRESSION AND APOPTOSIS [3].

THE STUDY OF BIOLOGICALLY IMPORTANT CATIONS AND THIOL-CONTAINING AMINO ACIDS HAS DRAWN GREAT ATTENTION IN RECENT YEARS DUE TO THEIR CRUCIAL ROLES IN A WIDE RANGE OF BIOLOGICAL PROCESSES [1]. PROCESSES, BIOLOGICAL AMINO ACIDS PLAY AN IMPORTANT ROLE. ...

DOPAMINE (DA) IS AN IMPORTANT MONOAMINE NEUROTRANSMITTER IN CENTRAL NERVOUS SYSTEM OF MAMMALIANS. LOW LEVELS OF DA ARE RELATED TO NEUROLOGICAL DISORDERS SUCH AS PARKINSON’S DISEASE, SCHIZOPHRENIA AND TO HIV INFECTION [1]. A CARBON PASTE ELECTRODE MODIFIED WITH NANOPARTICLES PDAL2O3 WAS PREPARED FOR DETERMINATION OF DOPAMINE (DA). CYCLIC VOLTAMMETRY, DIFFERENTIAL PULSE VOLTAMMETRY (DPV) TECHNIQUES WERE USED TO INVESTIGATE THE MODIFIED ELECTRODE FOR THE ELECTROCATALYTIC OF DA OXIDATION IN AQUEOUS SOLUTIONS. POTENTIAL OF DA AT 210MV. THE RESULTS REVEALED THAT THE MODIFIED ELECTRODE SHOWS AN ELECTROCATALYTIC ACTIVITY TOWARD THE ANODIC OXIDATION PEAK OF DA BY A MARKED ENHANCEMENT IN THE CURRENT RESPONSE BUFFER SOLUTION AT PH:6.8. LINER ANALYTICAL CURVE WAS ABSEREVED IN THE RANGE OF .08 MM TO 30 MM [R2:9987]. THE DETECTION LIMITS FOR THIS METHOD IS 6×10-8 M. THE CHEMICALLY MODIFIED ELECTRODE WAS SUCCESSFULLY USED FOR THE QUANTIFICATION OF DA IN SERUM SAMPLE. THEREFORE IT IS ESSENTIAL TO DEVELOP SIMPLE AND RAPID METHODS FOR DETERMINATION OF THESE BIOLOGICAL MOLECULES IN ROUTINE ANALYSIS. THE PREPARED MODIFIED ELECTRODE SHOWED SEVERAL ADVANTAGES،SUCH AS ASIMPLE PREPARATION METHOD HIGH SENSITIVITY LOW DETECTION LIMITS AND EXCELLENT REPRODUCIBILITY.