274 NICKEL 



Chemistry. A typical analytical method employing dimethylglyoxime 

 is described as follows (Ni-3, Ni-4): The organic material is destroyed by 

 dry-ashing, provided the ash can be brought into HCl solution, or alter- 

 natively by acid digestion with HNO:, and H2SO4. The acid ash solution 

 is treated with sodium citrate, excess ammonia, and dimethylglyoxime 

 and is then extracted with chloroform for treatment with bromine water 

 and colorimetric evaluation. In another procedure (Ni-1) the sample is 

 ashed in a muffle furnace, the ash is dissolved in HCl, and the solution is 

 neutralized and then made slightly acid for separation of heavy metals by 

 H2S. The filtrate is treated with bromine water to oxidize iron, which is 

 then removed as phosphate. The remaining solution is treated with 

 potassium dithiooxalate for colorimetric evaluation. 



Typical Methods. In a study with mice, l/zc Ni^^CU (102 ^g) dissolved 

 in physiological saline was administered intraperitoneally (Ni-5). The 

 tissues were digested with HNO3 and HCIO4, and the digests taken to 

 dryness four to five times ; the residues were further treated with HCIO4 

 until a pure white inorganic residue was obtained. The final residue was 

 dissolved in dilute acid, and 0.5 mg of stable Ni (as NiCl2) was added to 

 an aliquot as a carrier. The solution was treated with 10 ml of 0.75 71/ 

 (NH4)2S04 in 7.5 M NH4OH, and the nickel electroplated onto a copper 

 planchet at 5 volts and 40 ma current. The plated samples were assayed 

 in a gas-flow detector. 



Ni-1. Monier-Williams, G. W.: "Trace Elements in Food," John Wiley & Sons, Inc., 



New York, 1950. 

 Ni-2. Kiihn, U. S. G., Ill and H. Helms: Unpublished results. 

 Ni-3. Scott, W. W.: "Standard Methods of Chemical Analysis," 5th ed., vols. I and 



II, D. Van Nostrand Company, Inc., New York, 1939. 

 Ni-4. Sandell, E. B.: "Colorimetric Determination of Traces of Metals," 2d ed., 



Interscience Publishers, Inc., New York, 1950. 

 Ni-5. Wase, Arthur W., Donald M. Goss, and M. John Boyd: The Metabolism of 



Nickel. I. Spatial and Temporal Distribution of Ni''^ in the Mouse, Arch. 



Biochem. and Biophys., 51: 1-4 (1954). 



