This publication uses a colorimetric method based on the absorbance spectra of dye solutions to improve on Beer’s law when calculating the dye concentrations of a three-component mixture. The performance of the new method is compared with that of Beer’s law evaluated at three wavelengths, and Beer’s law evaluated at 16 wavelengths. Colorimetric method gives the best prediction of d...

A pseudocholinesterase catalytic activity assay using p-hydroxybenzoylcholine as substrate and measuring the decrease of NADPH at 340 nm was compared with a colorimetric method using acetylthiocholine as substrate. The assay is simple, uses 50 microliters serum and is performed at 37 degrees C. Precision of the UV-340 method was good except at low ranges. The catalytic activity was depressed by...

A comparison of two colorimetric procedures for the determination of serum glutamic oxaloacetic acid (SCOT) showed that both the dinitrophenylhydrazine and diazonium salt colorimetric assay procedures have good precision and reproducibility acceptable to most clinical laboratories. Babson’s diazonium salt procedure (3) definitely shows greater precision in the important borderline range of valu...