SULFUR 307 



injected into rats (S-3). Aciuoou.s homogenates of or<^ans and feces were 

 prepared by grinding a 1-g sample in a ground-glass blender and diluting 

 to 15 ml. One-milliliter ali(|Uots were added to cupped planchets and 

 dried under infrared for counting with a 1.7-mg/cm- end-window tube. 

 Standards were prepared by addition of known amounts of activity to 

 corresponding amounts of nonradioactive tissue samples. In a study 

 with rats, 2-p-toluenesulfonamidofluorene-S^^, a carcinogen, was orally 

 administered (S-4). The tissues, feces, and intestinal contents were 

 dried, ground in a mortar, and then suspended in 1 per cent XaOH plus 

 a wetting agent by mixing in a Waring Blendor. A few drops of capryl 

 alcohol was used to prevent foaming. After standing for 24 hr at 5°C, the 

 mixture was brought to room temperature and agitated in the Blendor, 

 and a 1-ml aliquot dried on an aluminum planchet for measurement with 

 an internal counter. One-milliliter portions of urine, plasma, and blood- 

 cell samples were placed directly in the planchet. Standards were pre- 

 pared to contain the same mass as the sample. 



Alkaline Peroxide Digestion. Methionine labeled with 91 Mc/g of S^^ 

 was fed to rats and dogs in amounts of 1 and 3.7 g, respectively (S-5). 

 Some of the tissues were refluxed for 24 hr with concentrated HNO3 and 

 made to volume, and 0.5-ml aliquots dried on w^atch crystals under infra- 

 red for counting. It was claimed that there were some losses within the 

 expected limits of error. Other workers, however, have claimed quantita- 

 tive results by this method (S-2) . Other samples w^ere treated by alkaline 

 digestion as follows: The tissue was dried at 105°C, and 500 mg weighed 

 into an iron crucible for a 6- to 8-hr hydrolysis with 10 ml of 10 per cent 

 NaOH on a steam bath. The hydrolysate was concentrated to about 

 1 ml, 4g anhydrous XaoCOs added, the mixture dried at 105°C, 4 g Xa202 

 added, and the mixture slowly fused to a cherry-red color. The melt was 

 made to a known volume with IICl to give pH 3, and an aliquot trans- 

 ferred to a centrifuge tube with a removable bottom. Carrier sulfate 

 was added, the solution warmed, and 10 ml of 10 per cent BaCl-i added 

 dropwise. The sample was centrifuged, washed twice with distilled 

 water, collected, and dried for counting with a 2.6-mg/cm^ end- window 

 tube. 



Magnesium Nitrate Digestion. Laying hens were given orally or 

 intramuscularly about 3 X 10" counts/min of carrier-free S^^ in the form 

 of H2S'^^04 (S-6). Egg samples were digested according to the standard 

 magnesium nitrate procedure (S-7), except that to the ashing mixture was 

 added 5 ml of a 50 per cent solution of copper nitrate per 100 ml magne- 

 sium nitrate solution (150 g MgO dissolved in 1:1 IIXOs and made to 

 1 liter). At least 12 ml of ashing mixture was used per gram of dried 

 sample. The general method is to use a porcelain crucible and heat the 

 sample plus ashing mixture at 180°C on a hot plate and then to muffle at 



