Abstract

Thawed, frozen `mixed oxalated' blood for haematology or citrated blood from the blood bank may be used as a precision control, maintaining reliability and accuracy, for periods of one to two years from a single batch of control material. Blood haemoglobin determinations using the cyanmethaemoglobin method and the Coleman Jr. spectrophotometer can be done routinely with a day-to-day variability of ±0·3 to 0·5 g./100 ml. (or ±2 to 3%) as demonstrated in the range of 11 to 15 g./100 ml. A by-product of this precision is that it effectively checks the calibration of the 20 lambda (μl.) pipette for use in general chemistry if needed.