Abstract
The study on pretreatment in analysis of guanidinocompounds resulted in the following knowledges.
1) Ultrafiltration of acidified sample solution served for highest recovery.
2) Taking into accont rapidity of the measurement, it seems reasonable that the time taken to ultrafilter is about one hour.
3) It is assumed that the dilution of sample solution affect the concentration of free-guan-idino-compounds unbound to protein in plasma, and that this procedure change the permiability of guanidino-compounds through membrane.