Document BVpbBw7bmJJ9mLO2Ykp5L2y8

April 26, 1934 Dr. Howard H. Beard Terrell's Laboratories Medical Arts Building Fort Worth, Texas Dear Doctor Beard: I send you herewith, unfortunately after an undue but unavoidable delay, a reprint of the article referred to in your letter of March 31. In reply to your question on analytical methods, I may say feat if the method referred to (i.e. H25 precipitation, etc.) is employed in all the steps required to separate out lead, specifically, from possible interfering elements in biological materials, it may be expected to yield losses of the order of magnitude of G. 06 to 0. 10 mg. per sample analysed. Therefore, if the sample is large, and its lead content is such that this amount is insignificant as an error, the method can be employed satis factorily. Otherwise it is inadequate, x can see no reason at present for the use of such a method in view of the specificity and sensitivity of suitable modifications of the dithizone method. We abandoned the carbazide method in-1.939 and have not resorted tc it since. The reason lay in the very great superiority of the dithizone and spectrographic methods in dealing with fairly small samples of biological materials. It is necessary, however, to employ one of the very carefully and critically examined versions of the dithizone method in order to obtain uniformly satisfactory results, vv'e do pot use or advocate any of the short cut methods, except in. occasional screening tests which are to be followed up by the more elaborate method. Very truly yours. ?xAK ef Dictated but not read. r~bsnc_ . Robert A. Kehoe, M. D. ^ 0019340 NS OF Al l e r g y Ch e mis t r y TERRELL'S LABORATORIES The North Texas Pasteur Institute T. C. Te r r e l l , M.D.. F.A.C.P., F.C.A.P., d ir e c t o r MEDICAL ARTS BUILDING PHONE FORTUNE 4S61 f o r t w o r t h , Te x a s ABILENE AMARILLO CORPUS CHRIST! FORT WORTH MUSKOGEE arch, 31, 19$k Dr. R.A.Kehoe, Kettering Laboratory of Applied Physiology, university of Cincinnati, Cincinnati, Ohio,, Ky .Dear Dr. Kehoe, I would greatly appreciate a reprint of your article on "Experimental Studies on the Ingestion of Lead Compounds11 19l;0. I -{yonder if you tould be so kind as to give me your idea abort the following: ~'e had two samples of urine from supposedly cases of lead poisoning recently. 1'y assistant ran these using the s-diphenylcarbazide method after precicitation of the samolem-dth HpS0 The case in question showed 0.039mg lead per lOOOcc of urine. The other ran O.lrag/lOOOcc. iiow I maintain that this method vdll not pick up such small amounts of lead and that the dithizone method should be used, vihich is very sensitive to lead, fould you care to comment on this. I vdll greatly appreciate it. Idny thanks, Howard H. Beard, Fn.D Chemist K* 0018841 N19912.01