AJP - Renal Physiology, Vol 261, Issue 1 203-F206, Copyright © 1991 by American Physiological Society
Photon-counting microcolorimeter with 40-nl cuvette
T. L. Pallone
Division of Nephrology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
A colorimeter with a 40-nl cuvette has been constructed. The wall of
standard capillary glass was perforated to produce a sample injection port.
A section of the capillary glass was drawn to a length of 1/2 cm and 80
microns ID by heating on a microforge. This produced a cuvette volume of
approximately 40 nl. Two fiber-optic filaments, 80 microns in diameter,
were fixed into the cuvette to transmit and receive light from the sample.
The output of the colorimeter was measured with a microscope
photon-counting detection assembly. It has been shown that the colorimeter
enables a reduction of the plasma volume requirements of the Lowry
microprotein assay from several nanoliters to 60 pl. The linearity and
reproducibility of the microcolorimeter when used with the Lowry assay has
been verified. The colorimeter output is several orders of magnitude above
the lower limit of detection of the photon counter.
