Enhancement of sensitivity of ion-exchanger absorptiometry by using a thick ion-exchanger layer

Enhancement of the sensitivity of ion-exchanger absorptiometry by the use of much thicker ion-exchanger layers than those previously employed has been investigated. Because the background attenuance due to light-scattering from the solid particle layer increases only moderately, whereas the net absorbance of the sorbed sample species increases greatly when the cell length is increased, a cell with at least 10-mm path-length may be effectively used without difficulty in most commercial spectrophotometers, giving at least ten times the sensitivity obtainable with a 1-mm cell. Since the background attenuance depends on the optical geometry, it can be lowered to some extent by using a particular type of spectrophotometer, and by placing a cylindrical mirror between the cell and the light-detector window or by setting the cell as close as possible to the window. The use of such long cells has been found to improve the sensitivity in the chromium-diphenylcarbazide, iron-1,10-phenanthroline, nickel-PAN, cadmium-PAR, bismuth-chloride and uranium-thiocyanate systems. Other methods may be similarly improved.