I currently have a method for atomic absorption, wherein the resin is dissolved in toluene. A linear three-point calibration (0, 0.5 ppm, and 1 ppm) curve is used; however, there are issues of reproducibility between runs and overrange values for the verification with a 0.5 ppm standard after calibration. I believe all issues point to toluene. Does anyone have any suggestions for alternative solvents to use (safety being the primary concern).