SELECTIVE SOLID-PHASE EXTRACTION OF CATECHOLAMINES AND METANEPHRINES FROM SERUM USING A NEW MOLECULARLY IMPRINTED POLYMER

Abstract

A new commercially molecularly imprinted polymer dedicated to the specific solid phase extraction of catecholamines and metanephrines has been tested for the extraction of neurotransmitters in serum samples. A protocol was developed especially for several aminergic neurotransmitters and metabolites (dopamine, 3-methoxytyramine, epinephrine, norepinephrine, normetanephrine, and serotonine). The serum was diluted in water (1/10, v/v), loaded on a cartridge filled with molecularly imprinted polymer and washed successively with water, methanol-water (15/85, v/v), and methanol. Analytes were then eluted with methanol-acetic acid (99/1, v/v). No matrix peak was observed on the chromatograms obtained by high performance liquid chromatography coupled with ultra-violet detection (281 nm). High selectivities were observed between imprinted and nonimprinted polymers. Extraction recoveries ranged from 64–98% (RSD <6%, n = 4) depending on the type of analytes and linearity was assessed in the 0.30–0.90 µM concentration range by least squares regression (r2 > 0.991). Then, large volumes of sample (8–40 mL) were loaded on the cartridge to evaluate the binding capacity of the cartridge. Increasing loaded sample volumes induced a decrease in extraction recovery, particularly for hydrophilic compounds. For a given elution recovery, higher preconcentration factors were achieved (∼55) for less hydrophilic compounds (sample volume of 40 mL).