Studies on Chromium: I. The Quantitative Determination of Chromium in Human Tumors

Abstract

A preliminary note with regard to our finding of chromium in certain human tumors was published in 1932 (1) and a detailed description of the new technic for the determination of transmittancy was given in a recent communication (2). The present paper deals with the application of this method to the quantitative determination of chromium in certain human tumors. In the above mentioned note it was pointed out that chromium could be determined in the presence of iron from transmission values at wavelengths between 5040 A and 5800 A. In order to choose the most suitable spectrum lines for use in determining transmission values in this region, microphotometer (Moll type A) record was made of a tungsten spark spectrogram. The air lines 5045 A and 5710.7 A gave records that were sharp and sufficiently distant from neighboring lines to be satisfactory for this purpose. A series of spectrograms was made using various slit widths. An investigation of the microphotometer records of the lines mentioned led to the choice of 0.05 mm. slit width as being the most desirable. The length of exposure time was determined from the characteristic curve to the Wratten M plates used. Fifteen seconds was found to be the longest exposure time that produced density values falling on the straight line portion of the curve, and this was accordingly chosen as the standard time.