Comparison of New Methods of Laser Particle Analysis for the Range 0.0005 μm to 700 μm

Abstract

Particulate size and distribution measurements in the sub-micron region by light scattering have been advanced by implementation of unique concepts expressed in a design named the MICROTRAC ULTRAFINE PARTICLE ANALYZER (UPA). Whereas only a distribution of intensity of signals was previously available, the advanced mathematical treatment allows presentation of data as a volume distribution (range 0.005 to 3uM). Computation of volume distributions by the UPA permits comparison to other light scattering particle size methods such as the MICROTRAC Small Particle Analyzer (range.12 to 60uM) and MICROTRAC Full Range Analyzer (range 0.1 to 700uM). Each instrument type operates under different physical or optical concepts in conjunction with mathematical concepts specific to each instrument type. A discussion of the importance of array design including other design concepts is included. Differences and refinements of algorithms used in the new MICROTRAC models as compared to older models may preclude agreement. Additionally the highly visible application of pigment, dye and colorants particle size measurement is discussed within the context of the effect of color on light scattering data. Many materials such as dyes, pigments and lattices are manufactured to exhibit particular color properties which can be affected by particle size. This paper attempts to examine the effect of color on reported particle size while showing comparisons of data among the three MICROTRAC models using a variety of commercial pigments. As an aside, a comment is added concerning potential errors associated with data presentation and interpretation.