Gowda, H. Sanke

Keshavan, B.

English

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16. BENT, E. E. & FRENCH, C. L., ]. Am. chem, Soc., 63(1941), 569.17. YOE, J. H. & JONES, A. L., Ind. engng Chern; Anal. Edn,16 (1944), 111-18. HARVEY (Jr), A. E. & MANNING, D. L., J. Am. chem,Soc., 72 (1950), 4488.19. RINGBOM, A., Z. analyt. cu-«, 115 (1939), 332.20. SANDELL, E. B., Colorimetric determination of traces ofmetals (Interscience, New York), 1959, 83.21. STEELE, E. L. & YOE, J. H., Analytica cbim. Acta, 20(1959), 211; Analyt. Chem .• 29 (1957). 1623.22. LATIMER. W. H., The oxidation states of the elements andtheir potentials in aqueous solutions (Prentice-Hall,New York), 1952,232.23. DESHMUKH. G. S. & TATWAWADl, S. V., Ann. Chim. Roma,50 (11i60). 428.24. WILSON, A. M. & MEFARLAND, O. K., Analyt. cu«,35 (1963). 302.25. GOTSCHALK. G., Z., analyt. Chem., 187 (1962), 164.Promethazine Hydrochloride as a NewReagent for SpectrophotometricDetermination of Pd(II)H. SANKE GOWDA & B. KESHA VANPostgraduate Department of ChemistryUniversity of Mysore, MysoreReceived 2 April 1975; accepted 20 May 1975Promethazine hydrochloride (PH) forms a red-colour-ed 1: 1 (metal: Ilgand) complex instantaneously withPd(II) at a pH 1·3-4,0. The sensitivity of the reactionis 0·027 11~/cma and the molar absorptivity is 3·86 x 103litre mote'? em'? at 470 nrn, Beer's law is valid overthe concentration range 0·4-20'0 ppm. However, theoptimum range for the effective colorimetric determi-nation is 2·0-19·0 ppm. The stability constant of thecomplex at 27° and pH 3·0±0·1 is found to be 5·1.CAVATORTAl studied the reaction of PdCl2 withpromethazine hydrochloride (PH) and usedit for the colorimetric determination of the latter.Sanke Gowda and Ramappa" studied the complexformation of Pd(II) with diethazine hydrochloride.The present paper describes PH as a sensitive re-agent for the spectrophotometric determination ofPd(II).The stock solution of Pd(II) was prepared bydissolving raci, (0·9886 g) of Johnson M~tthey gr~dein dil. HCI (Analar) and diluted to 1 htr~ to gIVe0·1 M with respect to HCI. The solution wasstandardized gravimetrically using dimethyl gly-oxime. It was further diluted to give a standardsolution containing 30 ~ Pd(II)/mI. The stocksolution of PH (May & Baker g:ade) was pr~p~redby dissolving a known amount in doubly dlst~lledwater and stored in an amber-coloured bottle m arefrigerator. . .Walpole buffers" in the PH range 0·65-5·20 wereprepared using sodium a~etate .(lM) and.HCI (1M)solutions. Solutions of diverse IOns of SUItable con-centrations were prepared using AR grade rea%ents.Procedure - To an aliquot of Pd(II) solution (10to 500 (Jog)in a 25 ml volumetric flask were added5 ml of Walpole buffer (PH 2·6) and 3 ml of PH,solution (0·2%) and the volume made up to ~hemark with doubly distilled water. The solutionNOTESwas mixed well and the absorbance measured at470 nm against a solution containing all-the reagentsexcept Pd. The amount of Pd was read froma standard calibration curve.PH forms ared-coloured complex with Pd at PH1·3-4·0. If the PH of the medium is >4, theabsorbance readings are not constant and above 7a white precipitate is formed. A maximum colouris produced when the mixture contains a thirteen-fold [reagent] with respect to (metal ion). The redcomplex exhibits Amax at 466-476 nm. The reagentunder similar conditions does not absorb at thiswavelength. The absorbance values remain con .•stant for 24 hr and at 5-97°C. Beer's law is validover the (Pd) range 0·4-20·0 ppm. However, theoptimum concentration range evaluated by Ring-born's method+s is 2·0-19·0 ppm. The Sandell'ssensitivity, as calculated from Beer's law data, is0·027 {Jog/cm2and the molar absorptivity is 3·86x103 litre mole'< vcrrr+, There is no appreciablechange in the absorbance or in colour intensity ofthe complex if the order of addition of reactants .arechanged.Job's method of continuous variations-? ([1. = O·lMNaNOs; PH 3·0±0·1; temperature 27°±1°C; Amax470 nm) and the mole ratio method indicate theformation of 1:1 complex between the metal andreagent. The observations recorded at 450 and 500nm also confirm the existence of only one complex.The apparent stability constants of the complexcalculated from the absorbance data by (a) methodof Foley and Anderson? modified by Mukherji andDey-" and (b) mole ratio methods are 5·05 ± 0·1 and5·15 ± 0·1 respectively. .The following amounts ({Jog/ml)of foreign .ions arefound to cause error <2% in the determinationof 10 (Jogof Pd(II) per ml: Os(VIII), 40; Pt (IV) ,12; Ir(III), 12; Rh(III), 9; Ru(III), 0·6; Ni(II), 575;Cu(II), 500; Co(II) , 96; Fe (III) , 4; C1-,7500; NOa,2850,F-, 1500; S024, 1000; acetate, 600; POi-,550; Br-,180 and 1-, 0·8. The present spectrophotometricmethod for the determination of Pd(II) using PHhas the following advantages over that usingdiethazine hydrochlorides: (a) Pd(II) may be deter-mined in a wider range of concentration, (b) longerstability of colour (24 hr in contrast to 4 hr withdiethazine hydrochloride), (c) insensitivity towardstemperature (5-97°C), and (d) lower amount ofreagent used.References1. CAVATORTA, L., J. Pharm, Pharmacol., 11 (1959).49.2. SANKE GOWDA, H. & RAMAPPA, P. G., Indian J. Chem.,1975, (in press).3. BRITTON, H. T. S., Hydrogen ions (Chapman & Hall,London), 1955, 353.4. RINGBOM, A., Z. Analyt; cu«; 115 (1938), 332.5. AYRES, G. H., Analyt. Chem., 21 (1949), 652. .6. JOB, P., Ann. cu«, 9 (1928), 113.7. IRVING, H. & PIERCE, T. B., J. chem. Soa., (1959),2565. - .8. YOE, J. H. & JONES, A. L., Ind. Engng Chem., 16 (1944).III.9. FOLEY, R. T. & ANDERSON, R. C., J. Am. chem. ss«, 7(}(1948), 1195; 71 (1949), 909. .10. MUKHER]I, A. K. & DEY, A: K., Analyt; chim,Acta, 18 (1958), 324; J. inorg. nuct: Chern." 6(1958). 314. '293'

Promethazine Hydrochloride as a New Reagent for Spectrophotometric Determination of Pd(II)

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Promethazine Hydrochloride as a New Reagent for Spectrophotometric Determination of Pd(II)

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