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  A suitable 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.