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).

Keywords:

• catecholamine
• metanephrine
• molecularly imprinted polymer
• preconcentration factor
• serum
• solid phase extraction

ACKNOWLEDGMENT

The authors would like to thank POLYINTELL (Voie de l'Innovation – PHARMAPARC II, 27100 Val-de-Reuil, France) for the gift of “AFFINIMIP® Catecholamine & Metanephrine'’ SPE cartridges.

Notes

Standard Solutions: NA, A, NMN, DA, 3-MT, and 5-HT (0.30–0.90 µM) dissolved in bovine serum diluted in water (1/10, v/v). Experimental conditions relative to the SPE protocol B are provided in the Sample Preparation section.

Sample: NA, A, NMN, DA, 3-MT, and 5-HT (0.5 µM) dissolved in the high-salt matrix aqueous solution (ionic strength of 151.5 mM). Experimental conditions relative to the SPE protocol B are provided in the Sample Preparation section.