BACKGROUND: COPPER (II) CAN ALSO BE AN ECOLOGICAL POLLUTANT AND POTENTIALLY TOXIC TO LIVING CELLS IF PRESENT IN SLIGHTLY LARGE CONCENTRATIONS [1]. DUE TO ITS ROLE AND EFFECTS IN METABOLIC PATHWAYS, A SIMPLE, SELECTIVE AND SENSITIVE METHOD IS ESSENTIALLY REQUIRED FOR THE QUANTIFICATION AND DETECTION OF COPPER (II) IN DRINKING WATER, INDUSTRIAL, ENVIRONMENTAL, AND FOOD SAMPLES [2]. THUS, THE DEVELOPMENT OF COLORIMETRIC RECEPTORS FOR COPPER (II) HAS EMERGED AS A MOUNTING AREA OF SIGNIFICANT IMPORTANCE [3].METHODS: A NEW REAGENT 2-AMINO-3- [(2-HYDROXY-BENZYLIDENE) -AMINO] -BUT-2-ENEDINITRILE HAS BEEN PREPARED AND USED FOR DEVELOPING A SIMPLE SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF COPPER WHICH IS BASED ON A 1: 1 COMPLEX FORMATION BETWEEN COPPER (II) AND REAGENT IN AQUEOUS SOLUTION. UPON ADDITION OF COPPER (II) A NEW STRONG ABSORPTION BAND CENTERED AT 455 NM WAS FORMED. THE OBVIOUS COLOR CHANGE FROM PALE YELLOW TO A GREENISH-YELLOW THE ADDITION OF COPPER (II) COULD MAKE IT A SUITABLE „NAKED-EYE‟ INDICATOR FOR COPPER (II (.HOWEVER, IN THE PRESENCE OF OTHER METAL IONS INCLUDING HG2+, AG+, PB2+, CD2+, NI2+, CO2+, FE3+, MG2+, K+ AND NA+, THE ABSORPTION SPECTRA OF REAGENT SOLUTION DID NOT SHOW ANY OBVIOUS CHANGE.RESULTS: THE METHOD IS OPTIMIZED IN TERMS OF PH, AMOUNT OF REAGENT REQUIRED, SENSITIVITY, AND LINEARITY AND TOLERANCE LIMITS OF VARIOUS FOREIGN IONS. UNDER THE OPTIMUM CONDITIONS, THE CALIBRATION GRAPH WERE LINEAR OVER OF 10-6-2×10-5MOL.L-1 WITH LIMIT OF DETECTION OF 9.5×10-9 MOL.L-1. RELATIVE STANDARD DEVIATION FOR FIVE REPLICATE DETERMINATION OF 10-5 M CONCENTRATION LEVEL WAS CALCULATED TO BE 2%.CONCLUSION: THE CU2+ RECOGNITION PROCESS IS HARDLY INTERFERED BY OTHER COEXISTING METAL IONS. THE EXCELLENT SELECTIVITY AND SENSITIVITY OF REAGENT TO CU2+ MAKE IT A PROMISING SENSOR FOR CU2+ DETECTION IN ENVIRONMENTAL AND BIOLOGICAL SAMPLE.

IN THIS PAPER, A SIMPLE AND A SELECTIVE COLORIMETRIC METHOD FOR THE NAKED-EYE DETECTION ANDDETERMINATION OF HISTIDINE (HIS) IN BIOLOGICAL FLUIDS USING MUREXIDE AS AN INDICATOR AND CU2+ A RECEPTORCHEMOSENSOR IS DESCRIBED. ...

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. ...

BACKGROUND: GLUTATHIONE (GSH) IS A PHYSIOLOGICALLY IMPORTANT TRIPEPTIDE (CONSISTING OF GLUTAMATE, CYSTEINE AND GLYCINE) [1]. ABERRANT LEVELS OF GSH HAVE BEEN ASSOCIATED WITH A NUMBER OF DISEASES, INCLUDING CANCER, AIDS, ALZHEIMER‟S AND CARDIOVAS [2]. A SIMPLE AND EFFICIENT COLORIMETRIC METHOD FOR THE NAKED-EYE DETECTION AND QUANTIFICATION OF GSH IN BIOLOGICAL FLUIDS WAS DEVELOPED [3]. THIS ABSTRACT FOCUSES ON THE COLORIMETRIC SENSORS FOR GSH ACCORDING TO INTRAMOLECULAR CHARGE TRANSFER (ICT) MECHANISMS BETWEEN SENSORS AND GSH. WE USED SOLOCHOROM DARK BLUE (CALCON) FOR THIS SENSOR AS AN ELECTRON DONOR–ACCEPTOR COMPOUND. THIS COMPOUND WITH STRONG ICT CHARACTER WAS DESIGNED AS A COLORIMETRIC SENSOR FOR DETECTION GSH.METHODS: IN THIS RESEARCH, CATIONIC DYE CALCON WAS ADDED TO BORATE BUFFER IN OPTIMAL CONDITIONS (PH=9, CONCENTRATION DYE= 0.001).THEN DIFFERENT AMINO ACID SOLUTIONS WITH CONCENTRATION OF 0.001M ADDED. ABSORPTION SPECTRUM OF SOLUTIONS WAS MEASURED. CHANGING IN ABSORPTION SPECTRUM WITH ADDED GSH SOLUTION CHANGES SOLUTION COLOR FROM BLUE TO VIOLET.RESULTS: COLOR OF CHEMOSENSOR CHANGES FROM BLUE TO VIOLET WITHIN ABSORPTION SPECTRUM WAVELENGTH FROM 576 NM TO 650 NM. LINEAR RANGE AND LOW DETECTION LIMIT WERE CALCULATED FOR THIS CHEMOSENSOR WHICH RESPECTIVELY ARE 4.62×10-6- 4.867×10-5 M AND 3.591×10-7 M.CONCLUSION: IN THIS INVESTIGATION, WE HAVE DEVELOPED A COLORIMETRIC CHEMOSENSOR CALCON WITH AMINO ACID GSH IN AQUEOUS ENVIRONMENT. WE REPORTED A SIMPLE AND EASY WAY TO MAKE RECEPTOR (CALCON) THAT RESPOND EFFICIENTLY IN THE ICT MECHANISM FOR NACKED-EYE DETECTION OF GSH AMONG OTHER KIND OF AMINO ACIDS.

DEVELOPMENT OF NEW SYNTHETIC RECEPTORS FOR THE DETECTION OF PHYSIOLOGICALLY IMPORTANT CATIONS AND ANIONS IS OF CONSIDERABLE IMPORTANCE [1]. HIGH SENSITIVITY AND EASY OPERATIONAL USE HAVE ENCOURAGED THE RECENT INTEREST IN UV–VIS AND FLUORESCENCE SPECTROSCOPY- BASED ANALYTICAL TECHNIQUES. ...

BACKGROUND: MOLYBDENUM IS AN ESSENTIAL TRACE ELEMENT FOR BOTH PLANTS AND ANIMALS, INCLUDING HUMANS, FIRST OF ALL BECAUSE IT PLAYS AN IMPORTANT ROLE IN ENZYMATIC REDOX REACTIONS. NEVERTHELESS, IT IS HARMFUL AT HIGHER CONTENTS, SO MONITORING THE MOLYBDENUM CONTENT IN ENVIRONMENTAL SAMPLES IS DESIRABLE AND HIGHLY RECOMMENDED [1]. CARBONATE COMPOUNDS ARE USED EXTENSIVELY IN THE MANUFACTURING OF GLASS, PAPER, RAYON, SOAPS, DETERGENTS AND FOR DYING PROCESSES IN TEXTILE INDUSTRIES. CARBONATE IS ONLY SLIGHTLY TOXIC, BUT LARGE DOSES ARE CORROSIVE TO THE GASTRO-INTESTINAL TRACT WHERE SYMPTOMS MAY INCLUDE SEVERE ABDOMINAL PAIN, VOMITING, DIARRHEA, COLLAPSE AND DEATH [2]. A NUMBER OF METHODS SUCH AS FOURIER TRANSFORM INFRARED SPECTROSCOPY, PASSIVE ACOUSTIC EMISSION, GAS CHROMATOGRAPHY AND ACOUSTIC WAVE IMPEDANCE SENSOR HAVE BEEN DEVELOPED FOR THE QUANTIFICATION OF CARBONATE [3]. HOWEVER, MAINTENANCE AND OPERATIONAL COST OF THESE TECHNIQUES ARE HIGH AND REQUIRE ADEQUATE EXPERTISE. THEREFORE, THE ANALYSIS IS MOSTLY LIMITED TO LABORATORY LEVEL ONLY.METHODS: IN THIS CONTEXT WE HAVE SHOWN THAT THE BROMO PYROGALLOL RED (BPR) IS HIGHLY SELECTIVE AND SENSITIVE CHEMOSENSOR FOR MO (VI) ION IRRESPECTIVE OF OTHER METAL IONS AS DETECTED BY ‘NAKED-EYE’ COLOR CHANGE AND UV-VIS SPECTRAL CHANGES. WE HAVE ALSO REPORTED THE CARBONATE IONS EFFECT IN ‘NAKED-EYE’ COLOR CHANGE AS WELL AS IN UV-VIS SPECTRAL CHANGES.RESULTS: NEW SIMPLE COLORIMETRIC CHEMOSENSORS, (BPR AND BPR-MO COMPLEX) HAVE BEEN CHARACTERIZED BY SPECTROSCOPIC TECHNIQUES. CATION AND ANION BINDING STUDIES CARRIED OUT USING UV-VISIBLE SPECTROPHOTOMETRIC TITRATIONS REVEALED THAT THESE RECEPTORS EXHIBIT SELECTIVE RECOGNITION TOWARDS MO6+ AND CO32- OVER OTHER IONS IN DMSO/H2O (50: 50 V/V) MEDIA.CONCLUSION: A RELIABLE, LOW COST, QUICK AND PORTABLE ANALYTICAL TECHNIQUE IS THE NEED OF THE DAY, ESPECIALLY FOR THE ANALYSIS OF LARGE NUMBER OF SAMPLES IN THE FIELD AND SUCH REQUIREMENTS ARE GREATLY MET WITH ION SENSORS. TAKING THIS DILEMMA INTO CONSIDERATION RECENTLY, WE HAVE UNDERTAKEN AN EXTENSIVE RESEARCH PROGRAM TO EXPLORE EASILY AVAILABLE DYES DEMONSTRATED A HIGH CHROMOGENIC RECEPTOR FOR CATIONS AND ANIONS [4]. BPR HAS BEEN IDENTIFIED AS HIGHLY SENSITIVE PROBE FOR MO6+WHICH RESPONDS AT 0.05 M MOL L-1 CONCENTRATION LEVELS. THE COMPLEX OF MO6+ WITH BPR ALSO DISPLAYED ABILITY TO DETECT UP TO 0.15 MMOL L-1 CO32-. AMONG OTHER COMPETING ANIONS THROUGH A FAST RESPONSE TIME OF LESS THAN 40 S WHICH IS MUCH LOWER THAN MOST RECENTLY REPORTED CHROMOGENIC PROBES. THIS METHOD COULD HAVE POTENTIAL APPLICATION IN A VARIETY OF CASES REQUIRING RAPID AND ACCURATE ANALYSIS OF MO6+ AND CO32- FOR REAL SAMPLES.

DEVELOPMENT OF NEW SYNTHETIC RECEPTORS FOR THE DETECTION OF PHYSIOLOGICALLY IMPORTANT CATIONS AND ANIONS IS OF CONSIDERABLE IMPORTANCE [1]. FEW RECEPTORS HAVE BEEN DESIGNED BASED ON THE CONCEPT OF ‗SINGLE SENSOR FOR MULTIPLE ANALYTES‘, THAT IS, ANALYSIS OF MORE THAN ONE ANALYTE BY ONE RECEPTOR USING A SINGLE DETECTION METHOD, OR ALTERNATIVELY, AN ARRAY OF DETECTION METHODS [2].CURRENTLY, MOLECULAR DIAGNOSTICS IS MOVING TOWARDS THE DEVELOPMENT OF TESTS THAT ARE CAPABLE OF DETECTING DIFFERENT ANALYTES SIMULTANEOUSLY [3]. THESE ANION RECEPTORS ARE RATHER DIFFICULT TO SYNTHESIZE OR ARE EXPENSIVE INSTRUMENTS FOR DETECTIONS. TAKING THIS DILEMMA INTO CONSIDERATION RECENTLY, WE HAVE UNDERTAKEN AN EXTENSIVE RESEARCH PROGRAM TO EXPLORE AVAILABLE DYE DEMONSTRATED A HIGH CHROMOGENIC RECEPTOR FOR CATIONS AND ANIONS [4, 5]. WE HAVE DEMONSTRATED THE USE OF READILY ACCESSIBLE DYE (ERIOCHROME BLACK T (EBT)), FOR HIGHLY SELECTIVE AND SENSITIVE COLORIMETRIC SENSING OF SN2+ IN AQUEOUS MEDIUM. THE PROCESS IS FREE FROM INTERFERENCE BY COMPETITIVE TRANSITION METAL IONS SUCH AS CO2+, CU2+ AND ZN2+ IN ADDITION TO ALKALI AND ALKALINE EARTH METALS. THE RESULTING COMPLEX SN+2 WITH EBT FORMED IN SITU CAN BE USED TO DETECT THE CNˉ AND CIT−3 WITH TWO MECHANISM,AMONG OTHER INORGANIC ANIONS AND DETECTION CAN BE TREATED AS AN ALTERNATIVE APPROACH FOR THE ‘NAKED-EYE’ COLORIMETRIC SENSING OF CNˉ AND CIT−3 IN AQUEOUS MEDIUM THROUGH A FAST RESPONSE TIME OF LESS THAN 30 S. THE RESULTS HAVE PROVIDED A NEW OPPORTUNITY TO DETECT CNˉ AND CIT−3 THROUGH THE USE OF A CATIONCHEMOSENSOR (FIG.1).