In many chemical processes there is a need to quickly identify unexpected precipitates in a solution. If x-ray fluorescence equipment is available, the precipitates can be collected by a Millipore filter and easily analyzed qualitatively. When an x-ray fluorescence spectrometer is not available, or the suspected elements are not amenable to the technique, the methods described here are helpful
M. S. Wang, "Qualitative Analysis of Precipitates by Graphite Filter Methods," Appl. Spectrosc. 24, 613-614 (1970)
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