Methanol, ammonium acetate, acetic acid and ammonium formate were HPLC grade and obtained from Sigma Aldrich. The reference materials R/S(±)-naproxen, R(-)-naproxen, S(+)-naproxen, R/S(±)ibuprofen, R(-)-ibuprofen, S(+)-ibuprofen, R/S(±)-salbutamol, R/S(±)-bisoprolol, R/S(±)-metoprolol, R/S(±)-amphetamine, S(+)-amphetamine, R(-)-amphetamine, R/S(±)-propranolol, R/S(±)-acebutolol, R/S(±)-fluoxetine, R/S(±)-atenolol, R(+)-atenolol, S(-)-atenolol R/S(±)-chlorpheniramine, and R/S(±)citalopram were purchased from Sigma Aldrich (Gillingham, UK) and Toronto Research Chemicals (Toronto, Canada). The corresponding deuterated surrogates were also purchased as racemates: R/S(±)-
atenolol-d7, R/S(±)-chlorpheniramine-d6, and R/S(±)-citalopram-d6. All chemicals were purchased as Methanolic solutions of 0.1 mg mL -1 or 1 mg mL -1 , or as powder. Powders were prepared at an appropriate concentration in Methanol. All solutions were stored in the dark at -20°C. Oasis HLB cartridges (3cc 60mg) were purchased from Waters (Manchester, UK).
atenolol-d7, R/S(±)-chlorpheniramine-d6, and R/S(±)-citalopram-d6. All chemicals were purchased as Methanolic solutions of 0.1 mg mL -1 or 1 mg mL -1 , or as powder. Powders were prepared at an appropriate concentration in Methanol. All solutions were stored in the dark at -20°C. Oasis HLB cartridges (3cc 60mg) were purchased from Waters (Manchester, UK).