A sensitive spectrophotornetric method was developed for the determination of zirconium in monazite sand. The zirconium ion was previously separated from the ather interfering elements by a 0.5 M rhenoyltrinuoroacetone (TT.4)-xylene extraction, then determined with Arsenazo I11 in 9 h.f HCI medium. Zirconium reacted with Arsenazo 111 to form a n emeraled green coloured complex having maximum absorbance a t 665nm i n 9M HCI medium, The color mas stabte €or a t least 2hours. Effects of time, HCI concentration, gdatine and various ions have been studied. The system confirms the Beer's larv over the concentration range investigated. Optimum condition range for measurement in 1.Ocrn quartz ceIl is 0.1-0.5pg/mI of zirconium. The molar absorptivity is 1.51~10~ liter mole" cm-'. The metal-ligand ratio of 1:4 was confirmed by Job's Continuous Variation method and the conditional stability constant of Zirconium-Arsenazo 111 Complex in 4 M HC1 and 9 M HCl weTe also determined b y this method,

Key Word Index-Differential pulse polarography; 0.5 M CaCL as supporting electrolyte; nitrate analysis in AUT solution.A differential pulse polarographic method for the determination of nitrate ion has been developed, W i t h 0.5 M CaCI, a s supporting electrolyte, NO; is reduced to give a peak with E1/2=--1.836 Volt US. the Ag/AgCl electrode. The differential pulse polarographic peak height is proportional t o the nitrate concentration from 20 to 6 0 p p m . The detection limit for nitrate is 2 p p m in pure aqueous solution. I n the determination of 40 ppm nitrate a relative precision (relative standard

Key Word Index-Sorption properties; amorphous zirconium phosphate.Amorphous zirconium phosphate ion-exchanger has been prepared in our laboratory according to the procedure given by Gal and Gal. The Chemical composition has been determined. Some chemical properties; stabilities and sorption of mono-to hexavalent cations have been studied in detail. It was found that washing the zirconium phosphate ion exchanger with alcohol before drying would increase the exchange capacity of amorphous zirconium phosphate.