Simultaneous spectrophotometric calibration of wavelength and absorbance in an interlaboratory survey using holmium oxide (Ho2O3) in perchloric acid as reference, compared with p-nitrophenol and cobaltous sulphate solutions (1978-1984).

The wavelength accuracy of ten different types of spectrophotometer was tested with holmium perchlorate solutions. It was found to be good, with mean deviations from the literature values of maximally 0.3 nm. Standard deviations over the entire spectral range were within 0.75 nm. The absorbance accuracy for different types of instruments was generally within 5%, except in the 287 nm range where higher deviations were found. The sharpness of the holmium peaks, in combination with band width and sensitivity of the instruments, troubled the majority of the participants. 150 spectrophotometers were involved in the surveys. Linearity of the spectrophotometers was tested with p-nitrophenol and cobaltous sulphate and found to be satisfactory.

A multi-wavelength spectrophotometric method for the simultaneous determination of five haemoglobin derivatives.

A method is described by which the concentration of deoxyhaemoglobin, oxyhaemoglobin, carboxyhaemoglobin, haemoglobin and sulfhaemoglobin in a human blood sample is determined by passing the haemolysate without air contact through a coarse filter and subsequently measuring the absorbance at lambda = 500, 569, 577, 620 and 760 nm. The ensuing set of equations is solved by matrix calculation with the aid of a simple computer program. The method has been tested by comparing it with conventional methods for the determination of the various haemoglobin derivatives separately.