INFLUENCE OF SOLID LIQUID RATIO ON THE EXPERIMENTAL ERROR OF SORPTION COEFFICIENTS IN PESTICIDE SOIL SYSTEMS

The influence of the solid/liquid ratio on the experimental error in the sorption coefficient in pesticide/soil systems was assessed by theoretical analysis. It was assumed that the sorption coefficient is derived from the measured decrease in concentration in the liquid phase of a soil suspension. A first analysis based on systematic errors in the concentration in the liquid phase showed that the relative error in the sorption coefficient is controlled by the product of the solid/liquid ratio and the sorption coefficient (a dimensionless quantity). If this quantity tends to zero, the relative error tends to infinity. A second analysis, based on random errors in the concentration in the liquid phase, gave a similar result. To minimize experimental errors the solid/liquid ratio should be taken as large as possible unless the equilibrium concentration becomes too low to be measured accurately. Copyright © 1990 John Wiley & Sons, Ltd