AJP - Renal Physiology, Vol 234, Issue 3 255-F259, Copyright © 1978 by American Physiological Society
Techniques for microdrop analysis of fluids (sweat, saliva, urine) with an energy-dispersive X-ray spectrometer on a scanning electron microscope
P. M. Quinton
Volumes of 10(-10) liter of sweat, saliva, and urine were analyzed with an
energy-dispersive spectrometer (EDS) X-ray analyzer on a standard scanning
electron microscope (SEM). Results of the EDS analysis of diluted and
undiluted samples were verified by comparison with results of analyses of
the same sample prepared by conventional quantitative methods. Except for
Cl in concentrated urines and Mg in low concentrations, good agreement was
found between the methods. The analysis provides quantitation of most
elements of biological interest present in concentrations of about 1 mM,
while it demonstrates good linearity (r greater than 0.99) throughout a
wide range of commonly encountered biological concentrations.
Reproducibility of the analysis is on the order of 2% and the minimal
determinable concentration is generally between 0.5 and 1.0 mM for S, P, K,
and Ca and slightly more than 1.0 mM for Mg.
