Abstract
Lead was suggested as an etiological factor in multiple sclerosis by Putnam. 1 Cone, et al., 2 examined a series of 40 spinal fluids for lead, using the qualitative hexanitrite test of Fairhall. 3 In their series were 8 patients with multiple sclerosis. In 6 of these the tests for lead were positive. Rabinowitch, et al., 4 about the same time reported the results of tests of 50 spinal fluids, including those from 27 cases of multiple sclerosis. These authors used the Fairhall hexanitrite method and checked their results by spectographic determinations. These authors found positive tests for lead in only 2 of their 27 cases of multiple sclerosis; in 2 additional cases they obtained positive tests after administering ammonium chloride to their patients. Boshes 5 tested 28 specimens of spinal fluid for lead, by the same method. Sixteen of his patients had multiple sclerosis; in only one of these did the spinal fluid yield a positive test for lead. All the above authors found occasional positive tests for lead among their control cases.
Because the above findings depended on a qualitative test that is difficult to control, we believed it would be worth while to investigate the lead content of a series of spinal fluids, using a precise quantitative micro-chemical method. Such a method has been devised by Wilkins, et al. 6 This method involves the titrimetric extraction of lead with a standard solution of diphenylthiocarbazone in the presence of ammoniacal cyanide. The original method was designed for use with blood; we have adapted it to spinal fluids in the manner described below.
Lumbar puncture was done with a dry, sterilized needle, and the fluid allowed to drop directly into a lead-free Pyrex flask. A measured volume of fluid, varying from 25–50 cc. was transferred to a Pyrex evaporating dish, and evaporated to dryness on a steam bath. The Pyrex dish was then transferred to an electric muffle furnace and ashed for 16 hours at 450°C. The ashed sample was dissolved in warm 5% nitric acid and transferred to a Pyrex separatory funnel, in which the titrimetric extraction was carried out. Simultaneous blanks were run with each set of determinations.
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