Determination of Lead

Photometric Routine Estimation of Traces of Lead by Dithizone Application to Materials Used in the Manufacture of Cosmetics

“…This procedure is not intended to replace the more accurate techniques employing dithizone (3,7,8,11), but rather to provide a comparatively simple method for use by the average control laboratory where a precision of 1 or 2 micrograms is adequate. In such a laboratory, speed and simplicity are important factors and the use of only simple, rugged instruments is desirable.…”

“…The method as set forth below is specific for lead, thallium, and bismuth. Bismuth, if present, may be readily removed by extraction with dithizone at pH 2 (11). No sample of any of the materials described in this article has been found to contain bismuth and the authors have accordingly not felt justified in including a separation step in the procedure.…”

A dithizone method for measurement of small amounts of zinc

“…For more precise description of separations see: for silver, Fischer et al (11); mercury, Winkler (19) and Fischer (6); lead, Clifford and Wichmann (3); zinc, Fischer and Leopold! (10): bismuth, Willoughby and associates (18); copper, Fischer and Leopoldi (9); by polarigraph, Heller, Kuhla, and Machek (12); separations in general, Fischer (8), and White (16). The dithizone method for lead has been thoroughly studied in a model way by Clifford and Wichmann (3).…”

Determination of Lead: A Photometric Dithizone Method as Applied to Certain Biological Material

“…The funnel is shaken well and the phases are allowed to separate. If the chloroform, dithizone-containing phase shows no change of color, bismuth is absent (14) and the aqueous phase is readjusted to pH 7.5 by further addition of weak ammonia, one drop of phenol red being used as indicator. Again the funnel and contents are shaken and the phases permitted to separate.…”

“…If bismuth is present it seriously interferes and must be removed. If the amount is less than 0.5 mg. this is easily accomplished, according to Willoughby et al (14), by extracting with dithizone at the point of extraction, when pH 2 is obtained (see first paragraph under Extraction 2). When large amounts of bismuth (greater than 0.5 mg.) are present a fresh aliquot must be taken from the remainder of the prepared sample, which has been freed from bismuth by a method described, earlier (11), which step is necessary for occasional samples of feces.…”