1  Suitable standards are available from NIST(Gaithersburg,MD),Beckman Instruments (Fullerton,CA),Sigma Chemical (St.Louis,MO),Pierce (Rockford,IL),or Hewlett-Packard.

2  Asuitable grade is available commercially as “Palladium Catalyst,Type I(5%Palladium on Calcium Carbonate),”from Engelhard Industries,Inc.,fax number (864)885-1375.

3  Dye purity is important in the reagent preparation.It is intended to propose a reagent footnote to indicate that Serva Blue G(Crescent Chemical Company,Hauppauge,NY)is an acceptable grade.