IN THIS WORK, WE INTRODUCE A SIMPLE, SELECTIVE, SENSITIVE AND LOW COST PROCEDURE FOR DETERMINATION OF ACIDITY CONSTANTS OF CINNAMIC ACID AND CINNAMIC ACID DERIVATIES IN BINARY MIXTURES OF SOLVENT-WATER AT 25°C BY APPLYING RAFA AND TRAFA METHODS TO PH GRADUAL CHANGE-UV-VIS SPECTRAL DATA. ...

RANK ANNIHILATION FACTOR ANALYSIS (RAFA) IS AN EFFICIENT CHEMOMETRICS TECHNIQUE BASED ON RANK ANALYSIS FOR TWO-WAY SPECTRUM DATA AND CAN BE EMPLOYED TO QUANTITATIVELY ANALYZE THE GRAY SYSTEM WITH UNKNOWN BACKGROUND. IN THIS WORK, RANK ANNIHILATION FACTOR ANALYSIS METHOD WAS PROPOSED FOR DETERMINATION OF THE ACIDITY CONSTANTS OF DIPROTIC ACID OF 4- (2-THIAZOLYLAZO) -RESORCINOL (TAR). AFTER RECORDING THE ELECTRONIC ABSORBANCE SPECTRA OF THE ACIDS AT DIFFERENT PH, THE CONTRIBUTIONS OF BOTH H2A AND A2- WERE ANNIHILATED FROM THE ABSORBANCE DATA, WHICH MADE FEASIBLE THE DETERMINATION OF TWO SUCCESSIVE ACIDITY CONSTANTS. EXTRA TITRATION OF STANDARD AND AUGMENTATION WITH SAMPLE MATRIX AND ALSO THE MATRIX EFFECTS ARE AVOIDED IN THE PROPOSED METHOD. IN THIS ARTICLE, WE WILL SHOW THAT THE DETERMINATION OF THE SUCCESSIVE ACID DISSOCIATION CONSTANTS OF DIPROTIC ACIDS CAN BE FEASIBLE BY RAFA IF THE CONTRIBUTIONS OF BOTH ACIDIC AND BASIC FORMS ARE ANNIHILATED FROM THE ORIGINAL DATA [1-4].

ANNIHILATION OF THE CONTRIBUTION OF ONE CHEMICAL COMPONENT FROM THE ORIGINAL DATA MATRIX IS A GENERAL METHOD IN RANK ANNIHILATION FACTOR ANALYSIS (RAFA). IN THIS WORK, A RANK ANNIHILATION FACTOR ANALYSIS (RAFA) METHOD WAS PROPOSED FOR DETERMINATION OF THE ACIDITY CONSTANTS OF DIPROTIC ACIDS. AFTER RECORDING THE ELECTRONIC ABSORBANCE SPECTRA OF THE ACIDS AT DIFFERENT PH, THE CONTRIBUTIONS OF BOTH H2A AND A2􀃭 WERE ANNIHILATED FROM THE ABSORBANCE DATA, WHICH MADE FEASIBLE THE DETERMINATION OF TWO SUCCESSIVE ACIDITY CONSTANTS. THE METHOD WAS VALIDATED BY ANALYSIS OF SIMULATED DATA AND ITS APPLICATION TO THE DETERMINATION OF THE ACIDITY CONSTANTS OF CAFFEIC ACID, AS A REFERENCE COMPOUND. A CLOSE AGREEMENT WAS OBTAINED BETWEEN THE RESULTED VALUES BY RAFA AND THE DECLARED VALUES. INDEED, THE METHOD WAS USED FOR DETERMINATION OF THE ACIDITY CONSTANTS OF CAFFEIC ACID IN BINARY SOLVENTS MIXTURES OF ETHANOL AND WATER. THE ACIDITY CONSTANTS OF ORGANIC REAGENTS PLAY A VERY FUNDAMENTAL ROLE IN MANY ANALYTICAL PROCEDURES SUCH AS ACID–BASE TITRATION, SOLVENT EXTRACTION AND COMPLEX FORMATION, AND ALSO TRANSPORT BEHAVIOR, BINDING TO RECEPTORS AND MECHANISM OF ACTION OF CERTAIN PHARMACEUTICAL PREPARATION.

A SIGNIFICANT PARAMETER FOR UNDERSTANDING AND QUANTIFYING CHEMICAL PHENOMENA REACTION RATES, BIOLOGICAL ACTIVITY, BIOLOGICAL UPTAKE, BIOLOGICAL TRANSPORT AND ENVIRONMENTAL FATE [1] CAN BE DISSOCIATION CONSTANTS. IN ORDER TO THE DETERMINATION OF DISSOCIATION CONSTANTS, SEVERAL PROCEDURES SUCH AS POTENTIOMETRIC TITRATION, SPECTROPHOTOMETRIC DETERMINATION AND CONDUCTOMETRY, HAVE BEEN REPORTED [2, 3]. ...

RANK ANNIHILATION FACTOR ANALYSIS (RAFA) WAS A MEANS EMPLOYED IN ORDER TO DETERMINE SPECTROPHOTOMETRICALLY THE ACIDITY CONSTANT OF CINNAMIC ACID IN WATER AT 25°C AND AN IONIC STRENGTH OF 0.1 M. A GENERAL METHOD IN RANK ANNIHILATION FACTOR ANALYSIS (RAFA) IS ANNIHILATION OF THE CONTRIBUTION OF ONE CHEMICAL COMPONENT FROM THE ORIGINAL DATA MATRIX. ...

THE USE OF RANK ANNIHILATION FACTOR ANALYSIS (RAFA) FOR SPECTROPHOTOMETRIC STUDIES OF ELECTRON DONOR–ACCEPTOR COMPLEX FORMATION EQUILIBRIA BETWEEN LIDOCAINE AND 2,3-DICHLORO-5,6-DICYANO- 1,4-BENZOQUINONE(DDQ) IN CHLOROFORM, DICHLOROMETHANE (DCM) AND 1,2-DICHLOROETHANE (DCE) SOLUTIONS AT 25 ◦C HAS BEEN REPORTED. RAFA IS PROPOSED AS AN EFFICIENT CHEMOMETRIC ALGORITHM FOR COMPLETELY ANALYSIS OF EQUILIBRIUM SYSTEMS BY SPECTROPHOTOMETRIC MOLE RATIO METHOD. THE RAFA IS BASED ON THE PRINCIPLE THAT THE RANK OF TWO-WAY BILINEAR MATRIX OF PURE COMPOUND IS ONE. THE PROPOSED METHOD MAKES IT POSSIBLE TO OBTAIN THE STABILITY EQUILIBRIUM CONSTANTS, PURE ABSORPTION SPECTRA AND SPECIES CONCENTRATION PROFILES IN SEVERAL ELECTRON DONOR–ACCEPTOR COMPLEX FORMATION SYSTEMS WITH SEVER SPECTRAL OVERLAPPING. THE STOICHIOMETRY OF THE COMPLEX WAS FOUND TO BE 1:1 BY JOB‘S METHOD OF CONTINUOS VARIATION. RAFA METHOD WAS USED FOR COMPLETE RESOLUTION OF THE MEASURED SPECTROPHOTOMETRIC DATA. STABILITY OF THE RESULTING COMPLEX IN THE THREE SOLVENTS WAS ALSO FOUND TO VARY IN THE ORDER OF 1,2-DCE >DCM> CHCL3.

CHEMICAL KINETICS HAS BEEN WIDELY ACKNOWLEDGED AS A FUNDAMENTAL THEORY IN ANALYSIS OF CHEMICAL PROCESSES AND THE CORRESPONDING REACTION OUTPUTS AND RATES. THE STUDY AND APPLICATION OF CHEMICAL KINETICS THUS PROVIDE A SIMULATION TOOL TO PREDICT MANY CHARACTERISTICS A CHEMICAL PROCESS...

SPECTROPHOTOMETRIC DETERMINATION OF PARA AMINO BENZOIC ACID (PABA) WAS FULFILLED BY APPLYING RANK ANNIHILATION FACTOR ANALYSIS (RAFA) ON VARIATION MATRIX BASED ON PH GRADUAL CHANGE-UV SPECTRAL DATA (PH-SPECTRA) [1].SINCE IN REAL SAMPLES ABSORPTION SPECTRA OF VARIOUS FORMS OF PABA OVERLAP WITH OTHER COMPONENTS, PABA CANNOT BE DIRECTLY DETERMINED BY SPECTROPHOTOMETRIC METHOD [2].HENCE RANK ANNIHILATION FACTOR ANALYSIS BASED METHOD WAS DEVELOPED FOR SPECTROPHOTOMETRY. IN THE PROPOSED METHOD, THE SPECTRA OF THE SAMPLE SOLUTIONS AT DIFFERENT PH DATA POINTS WERE RECORDED AND THE PH-SPECTRA BILINEAR DATA MATRIX WAS GENERATED. FRIST LINE OF THIS MATRIX IS SUBTRACTED FROM ALL LINES AND THEN VARIATION MATRIX IS CREATED [3]. THE RANK OF VARIATION MATRIX IS EQUAL TO CHEMICAL COMPONENTS EXIST IN SOLUTION AND THEREFORE DATA ANALYSIS RESULTS ARE MORE ROBUST [4].BASED ON THESE VARIATION MATRIX DATA, THE RAFA WAS THEN APPLIED TO CALCULATE THE CONCENTRATION OF PABA IN REAL AND SYNTHETIC SAMPLES. THE DETERMINATION OF PABA CARRIED OUT IN MIXTURES BY RECORDING THE ABSORPTION SPECTRUM BETWEEN 200 AND 350 NM. AT THE OPTIMUM CONDITIONS, DYNAMIC RANGES WERE 10-5, 2*10-5, 4*10-5, 8*10-5 MOL L-1FOR PABA. THE SYNTHETIC SAMPLES CONCENTRATIONS WERE PREPARED IN THE DYNAMIC RANGES. THE PARAMETERS OF CHEMOMETRICS PROCEDURE FOR THE DETERMINATION OF PABA WERE OPTIMIZED AND THE PROPOSED METHOD WAS VALIDATED BY STANDARD ADDITION SET. FINALLY THE PROCEDURE WAS SUCCESSFULLY APPLIED TO DETERMINATION OF PABA IN SYNTHETIC MIXTURES AND A PHARMACEUTICAL TABLET.