above, and after all traces of copper were removed, the 

 solution was diluted to 1 liter. 



Perchloric Acid 70-72% - Reagent grade Baker analyzed 

 //9652. 



Standard Solution - 113.36 mg of fine granular copper 

 metal (Mallinkrodt Analytical Reagent) was dissolved 

 in 6 ml of a nitric-sulfuric acid mixture (1+1). 

 The solution was heated to dense fumes of sulfuric acid, 

 cooled and diluted to 1 liter. This solution contained 

 113.36 pg/ml. A substandard solution was prepared by 

 diluting 1 ml of the stock solution to 1 liter. This 

 solution contained 0.113 yg Cu/ml. The standard curve 

 was prepared by taking suitable subsamples of the 

 dilute solution to cover the working range (zero to 

 50 ijg/liter was sufficient for most seawater samples). 



Procedures : 



Water Samples : Digestion - add 3 ml perchloric acid 

 to 25 ml of sample and cover with watch glass. Place 

 on hot plate and boil slowly until almost dry. Add 

 25 ml distilled deionized water and dissolve precipi- 

 tate completely. 



Add reagents in the following order: 



a. 2 ml hydroxylamine hydrochloride 



b. 5 ml neocuproine solution 



c. 10 ml sodium acetate solution 



Swirl sample between each addition. Allow fifteen minutes 

 for color development. 



Optical density was measured at 454 mu in a Beckman 

 DU spectrophotometer with 10 cm cells. 



Sed iment Samples : 200 mg of dried sediment was 

 pulverized with mortar and pestle and digested as 

 above with 3 ml of perchloric acid. Analysis then 

 proceeded as with water samples. 



Tissue Samples : The tissue was macerated and an 

 aliquot selected and dried to obtain the dry versus 

 wet weight. 3 ml of perchloric acid was added to 

 a wet aliquot and the samples were treated as 

 described for water samples. 



150 



