Abstract
The turbidimetric assay method established previously was studied to apply for determination of nitrofuran compounds in the body fluids.
The slope of th growth curve was not affected by adding 10 per cent of rabbit serum to the medium. As a result, it has been found that serum concentration of about 0.5 mcg/ml of furazolidone could be measured by using thsi standard curve. About 70 per cent of furazolidone added to rabbit blood was recovered by this assay method.
There were some rabbits of which sera showed antagonistic action to the drug. This action was removed by inactivation of their sera, but in the rabbit of which serum had no antagonistic action, the slope of standard curve became slower on using the inactivated serum than on using the intact serum. This phenomenon is disadvantageous for microdetermination and, therefore, it would be better in this experiment not to use the rabbit of which serum shows an antagonistic action.
As the standard growth curve was greatly affected by adding more than 5 per cent of rabbit urine to the medium, it was necessary to make urine concentration in the medium less than 2 per cent. In this condition, urine concentration of more than 2.5 mcg/ml of furazolidone was determinable. And by this method 100 per cent of furazolidone added to rabbit urine was recovered.
The activity of furazolidone was considerably affected by adding the gastrointestinal saline suspensions. When the concentration of gastrointestinal samples in the medium was 0.025 per cent, the minimum determinable concentration of the drug was about 100mcg/gm in the stomach and small intestine and about 200mcg/gm in the large intestine. The recovery rates of added furazolidone from the gastrointestinal organs were roughly 30-90 per cent, varing according to the organs.
