Control of blood haemoglobin determinations by a simple effective method.

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 (mul.) pipette for use in general chemistry if needed.