Correlation between FSSS and SAS
Correlation of results
Direct Comparison of SAS&trade and FSSS results in side-by-side trials have been carried out using both old and new samples, with cooperation from many different and experienced users of the FSSS. Typical results are shown in the graph, where mean particle size data from the two instruments is compared for 11 different powders of different sizes. There is exceptional correlation between the two sets of data.
Another more extensive and independent study by Astrazenca in England, has come to the same conclusion, after using it at various sites and by different individuals. An example of results published by John Sherwood (also of Astrazenca) are shown in graph on the right where a line of best fit has been drawn through the results. For a perfect match, the slope would be 1 the actual slope (0.9935) is within the bound of experimental error.These tests were performed side by side on the two instruments, literally one after the other and using exactly the same mass of sample in each case.
Repetitive testing of the same sample, to give a measure of reproducibility (precision) has also been reported by the same authors, again using the two devices side-by-side to give the specific surface area. For the first sample, the FSSS gave a mean of 1.061 compared with 1.125 by the SAS with standard deviations of 0.022 and 0.060 respectively. A second sample gave a means of 2.718 and 2.750 and standard deviations of 0.054 and 0.021, for the FSSS and SAS respectively. In both cases, 10 measurements were made on each sample with both devices.