Spectrophotometric study of total protein-albumin methods applied to cerebrospinal fluid.

A spectrophotometric study was carried out for three proteins assays when modification of their serum procedures using bromcresol green, bromcresol purple and biuret reagents were applied to the determinations of total proteins and albumin in cerebrospinal fluids. A novel concentration device wherein the sample itself was used as the primary diluent for the three reagents concentrated to contain the proper amounts of chemicals in smaller volumes than suggested in their serum procedures allowed reasonable absorbance signals to be obtained. Low molecular weight molecules were separated from the albumin and globulins of the fluids by centrifugal ultrafiltration using a 25K cutoff and spectra were obtained for both high and low molecular weight fractions. Some materials were obtained in the separated ultrafiltrates which gave reactions with all three reagents, reactions which either overlapped the spectra of the albumin reactions or superimposed the spectra obtained with the total protein reaction. A screening procedure for cerebrospinal fluid total proteins or centrifugally ultrafiltered albumin appears reasonable as an inference from studies made, although further elucidation of the low molecular weight fractions in needed as a confirmation device.