Evaluating Kaolin Clay as a Potential Substance for ISO Sprayer Cleaning System Tests

Highlights Guidelines for measuring ASP® 602 concentrations with a spectrophotometer or turbidimeters were established. Concentration predictions had errors between 0.1% and 24.6% for the range from 0 to 100 ppm with the instruments. Stationary and portable instruments were able to detect ASP® 602 concentrations as low as 2 ppm. Test results from ISO 22368-1 validated that ASP® 602 could be used for inspecting cleanout and agitation systems. Abstract. ASP® 602 (kaolin clay) was evaluated as an alternate material for performing ISO 22368-1 sprayer clean out test standard. Recommendations for sample homogenization, measurement temperature and sample sizes to address potential concerns or technical challenges in assaying ASP® 602 samples were provided under relevant conditions. Linear regression models for predicting ASP® 602 concentrations from 0 to 100 ppm (mg·L-1) in sample mixtures were developed using outputs from a spectrophotometer and two different turbidimeters. Test results showed that the three instruments could measure ASP® 602 concentrations as low as 2 ppm. Validations of the developed models showed approximation errors were 0.9% to 24.6% and 0.1% to 18.4% for the spectrophotometer and the turbidimeters, respectively. However, their maximum absolute errors were less than 3.7 ppm for the spectrophotometer and 2.3 ppm for the turbidimeters within the validation range. Two agitation and cleaning systems of a sprayer were evaluated with ASP® 602 following the ISO 22368-1 clean out procedure. Residue reduction factors from the initial mixture concentration were 163 for one system which did not meet ISO 16119-2 environmental requirement (factor over 400) and 819 for the other system which exceeded the requirement. Analysis results of ASP® 602 samples from ISO 22368-1 clean out tests showed that ASP® 602 could be used as a potential testing substance to evaluate and differentiate the performance of agitation and cleaning systems of sprayers. Keywords: Absorbance, ASP® 602, ISO Standard, Pesticide, Spectrophotometer, Turbidity.