Document KG4767yG1eXNKX90zoErM1ap0

December 13# 1952 Dr. E l 3 ton L. Belknap 231 T`-r Wisconsin Avenue Milwaukee, Wisconsin Dear Doctor Belknap I have looked into the Lederer method for lead determinations referred to in jour letter of November 20th and in my opinion and in that of m y assistant Mr. Thamann, it is hardly sensitive enough to employ in the case o f the urine. Since in my opinion the urinary findings are commonly more important than the results in the faeces, it would seem to mo that this method could not be used satisfactorily. According to Mr. Thamann, quantities as high as .2 of a milligram might bo lost entirely, while with the use of the H2S generator described, the samples would almost certainly be contaminatod with iron in variable amounts. Such iron precipitated as FeS would be estimated a.s lead. Since the l&ii hare v/ould be inconstant, th method could hardly he regarded as satisfactory. I see no reason why we can not cooperate with your laboratory by giving your technician such assistance a3 you suggest. If you will let me know what you wish to do, weTshall he pleased to make it possible for her to work with U3 for a time. Cordially yours, RAKjIS KE 0019889