A total of 105 CECs were investigated in this study, these were split into two groups: A) general pharmaceutical, including personal care products B) AAs, spanning a broad range of classes (table ). Methods used in this study were previously developed and established as discussed in Petrie et al. and Holton et al. . CEC analytes and internal standards (IS) were ordered from Sigma-Aldrich, LGC standards, TRC or MCE. All standards were purchased as 1.0 or 0.1 mg mL -1 solutions or in powdered forms, those in powdered forms were prepared at concentrations of 1 mg mL -1 in the appropriate solvents. All standards were stored in the dark at -20 °C. Methanol (MeOH) was purchased from Sigma-Aldrich and was HPLC grade, the water was of 18.2 MΩ quality.