Fig. 2
Effect of a pH and b types of buffer and buffer concentrations of the eluting solvent on the extraction of spiked urine sample at 1000 ng mL−1 RAC and 1000 ng mL−1 CLEN. Conditioning solvent, 300 μL MeOH and 50 μL water; washing solvent, 800 μL 10:90 (v/v) ACN:water; sample loading, 2.00 mL; eluting solvent, 150 μL 30:70 (v/v) ACN:buffer solution. HPLC-UV condition: column C8, mobile phase 25:75 (v/v) ACN:20 mM acetate buffer pH 4.0 containing 2 mM triethylamine, injection volume of 20 μL, flow rate of 0.7 mL min−1, and detection at 210 nm