MICROTRAC PARTICLE-SIZE ANALYZER

The Microtrac method is particularly well suited to particle-size analysis of suspended sediment samples having low concentrations and limited quantities, because quantities of 0.01 g may be routinely analyzed. Major advantages of the Microtrac method are the speed and ease with which the measurements are performed and the speed with which the results, in a usable form, are presented. We compared the sieve-pipette and Microtrac methods of particle-size analysis for 10 soils representing the common range of size distribution found in soils and sediment. The effect of organic constituents on the comparison of laser and pipette analyses was investigated by removal of organic matter from replicate samples. Regression analysis may be used to convert Microtrac results to those of the sievepipette method with an acceptable degree of accuracy; however, this is best achieved when done by particle-size ranges. The agreement between the two methods was highest for the two size ranges from 62 to 31 μm, and 31 to 16 μm, with a correlation of 0.92 for both. The agreement for all size ranges improved when sieve data from 62 to 176 μm were removed from the comparison.