The standard solution was prepared by weighing approximately
5 mg of the standard into a 10 mL volumetric flask, adding
10 mL of diluent, mixing the solution and vialing for analysis. The
green coffee extract samples were prepared by weighing approximately
250 mg of sample into a 50 mL volumetric flask and
adding 40 mL of diluent. The solutions were sonicated for 10 min,
cooled to room temperature, brought to volume with Milli-Q
water and mixed well. Aliquots of the solutions were filtered using
0.45 mm PTFE syringe filters and the filtrates were collected in
HPLC vials for analysis.