SupelMIP SPE-NSAIDs molecular imprinted polymer (25 mg,
3 mL), Supelclean ENVI-18 octadecyl silica C18 SPE tubes (500 mg,
3 mL), and VisiprepTM SPE vacuum manifold were obtained from
Supelco (Bellefonte, PA, USA). All solvents used were LC grade or
higher. Methanol and acetonitrile were purchased from Scharlau.
Ultrapure water used in all experiments (with a resistivity higher
than 18.2 M) was obtained from a Milli-Q unit(Millipore, Bedford,
MA). Acetic acid and ammonium formate (96%) were purchased
from Panreac (Barcelona, Spain).