Photon-counting microcolorimeter with 40-nl cuvette.
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.
Pallone
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Division of Nephrology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
D000818:Animals; D001158:Arteries; D001798:Blood Proteins / Q000032:analysis; D003124:Colorimetry / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D011827:Radiation; D051381:Rats; D012079:Renal Circulation; D012709:Serum Albumin / Q000032:analysis; D013679:Technology, Radiologic / Q000295:instrumentation*
D001798:Blood Proteins; D012709:Serum Albumin