Mixed-mode monolithic pipette-tip micro-solid-phase extraction coupled with HPLC–UV for rapid determination of urinary serotonin

Information from the abstract

Serotonin (5-hydroxytryptamine, 5-HT) is an important neurotransmitter and a potential biomarker for neurological and psychiatric disorders, necessitating sensitive and reliable analytical methods for its determination in biological samples. Herein, a mixed-mode monolithic pipette-tip micro-solid-phase extraction (PT µ-SPE) platform coupled with HPLC–UV was developed for the rapid determination of urinary serotonin. A poly(methacrylic acid- co -ethylene dimethacrylate) monolith was synthesized in situ within a surface-modified polypropylene pipette tip by UV-initiated polymerization, providing synergistic cation-exchange and hydrophobic interactions for selective serotonin extraction. Under optimized conditions, the proposed PT µ-SPE achieved a 12-fold pre-concentration factor with an extraction efficiency of 91%. The mixed-mode monolith exhibited a dynamic breakthrough capacity approximately 200-fold higher than that of a hydrophobic monolith and substantially higher than those of commercial C18 SPE sorbents, enabling highly efficient single-pass extraction. The PT µ-SPE–HPLC–UV method demonstrated excellent analytical performance, with limits of detection and quantification of 1.70 and 5.67 ng mL⁻ 1 , respectively, recoveries of 95–104%, and good repeatability (RSD < 3.42%). Under the selected conditions (2 mL sample volume and 150 µL elution volume), the complete PT µ-SPE–HPLC–UV workflow required approximately 10 min, comprising 5 min for extraction and 5 min for analysis. The method was successfully applied to the determination of urinary serotonin in healthy volunteers. The proposed mixed-mode PT µ-SPE platform provides a simple, rapid, and cost-effective sample preparation strategy using conventional HPLC–UV instrumentation and demonstrates the potential of mixed-mode monolithic sorbents for the routine laboratory analysis of polar basic compounds in complex biological matrices.

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Related topics: Analytical chemistry methods development · Microfluidic and Capillary Electrophoresis Applications · Analytical Methods in Pharmaceuticals