The presence of mercuric chloride affects Bettendorff's test for arsenic. The addition of enough mercuric chloride to make its concentration 0.00001 M., before the addition of stannous chloride: (1) hastens the appearance of the coloration, (2) increases the sensitivity of Bettendorff's test ten-fold to one hundred fold and (3) enables the test to be made in a lower concentration of hydrochloric acid. Mercuric chloride in 0.00001 M. solutions does not produce turbidity when stannous chloride is added. In the presence of mercuric chloride Bettendorff's test will detect a smaller quantity of arsenic than Gutzeit's test or Marsh's test. The rate of formation of the colloidal arsenic is a function of the concentration of mercuric chloride. Because of this unknown, concentrations of mercuric chloride as small as 0.00000002 M. may be determined by comparing the rate of appearance of color in the unknown solutions with the rate of appearance in the presence of known concentrations of mercuric chloride'.
Proceedings of the Iowa Academy of Science
©1933 Iowa Academy of Science, Inc.
King, W. Bernard and Brown, F. E.
"A Modification of Bettendorff's Arsenic Test and a Quantitative Determination from Small Concentrations of Mercury,"
Proceedings of the Iowa Academy of Science, 40(1), 96-97.
Available at: https://scholarworks.uni.edu/pias/vol40/iss1/42