Abstract
The chemical methods available for the quantitative determination of lead in blood, while accurate, require amounts of blood too large for routine clinical work. Spectroscopic methods are more sensitive and allow of the use of smaller amounts of material. They have, however, been employed for qualitative estimations only.∗, 1 , 2 , 3
We have developed a spectroscopic method for determination of lead quantitatively which using a simple procedure can estimate from 0.0005–0.01 mg. of lead with an error of ±50%.
In principle the method consists of comparing either photometrically or visually, the intensity of lead lines from the unknown sample with lines from admixtures of known amount of lead salt and the amount of sodium normally present in the quantity of serum used. The accuracy of the method is ± 50% visually; this accuracy should be increased when using a photometer.
Since lead is a common contaminant, all glassware used was Pyrex which was steamed for 2–3 hours previous to use. The silica crucibles were similarly treated. Only lead-free needles and syringes were employed.
Spectroscope. The instrument used was the Hilger 4 E quartz spectroscope loaded with Eastman 33 plates. The spectrum produced by this instrument gives a long range of wave lengths extending well into the ultraviolet and permits the use of a large number of lines from which to draw conclusions.
Sodium Chloride Solution.—NaCl is recrystallized several times until free of lead. 8388 mg. is made up to 1000 cc. with redistilled water. 1 cc. of this solution contains 3.3 mg. of sodium.
Lead Chloride Solution—PbCl2 is recrystallized several times. 13.4 mg. is dissolved with 1 cc. of lead-free redistilled nitric acid and then made to 1000 cc. 1 cc. of this solution contains 0.01 mg. lead.
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