Precision and accuracy of analysis of air-filled albumin microspheres using Coulter Multisizer Mark II.

The suitability of the electrical sensing zone technique for routine analysis of air-filled albumin microspheres has been thoroughly investigated using three Coulter Multisizer Mark II instruments. The precision of the method, expressed as repeatability relative standard deviation (RSD), was found to be 1-2% for number distribution parameters and 3-4% for volume distribution parameters. Significant instrument-to-instrument variation as high as 11% was, however, also observed. Accuracy was evaluated from analyses of commercially available latex standards and from comparison of results from Coulter analysis with results from the following alternative techniques: light diffraction, optical microscopy and gravimetry. Accuracy, expressed as the difference from either certified values or values obtained with the alternative techniques, was found to be 100-106%.