On-line coupling of Micro-Extraction by Packed Sorbent with Sequential Injection Chromatography system for direct extraction and determination of betaxolol in human urine

•Automation of Micro-Extraction by Packet Sorbent in flow manifold.•On-line hyphenation of MEPS and chromatography in one SIC system.•Extending of capabilities of the Sequential Injection Chromatography.•Automated, fast and sensitive determination of betaxolol in human urine.•Extending of capabilities of MEPS automation in biomedical analysis.

A novel approach for automation of Micro-Extraction by Packed Sorbent (MEPS), a solid phase extraction technique, is presented, enabling precise and repeatable liquid handling due to the employment of sequential injection technique. The developed system was used for human urine sample clean-up and pre-concentration of betaxolol before its separation and determination. A commercial MEPS C-18 cartridge was integrated into an SIChrom™ system. The chromatographic separation was performed on a monolithic High Resolution C18 (50×4.6 mm) column which was coupled on-line in the system with Micro-Extraction using an additional selection valve. A mixture of acetonitrile and aqueous solution of 0.5% triethylamine with acetic acid, pH adjusted to 4.5 in ratio 30:70 was used as a mobile phase for elution of betaxolol from MEPS directly onto the monolithic column where the separation took place. Betaxolol was quantified by a fluorescence detector at wavelengths λex=220 nm and λem=305 nm. The linear calibration range of 5–400 ng mL−1, with limit of detection 1.5 ng mL−1 and limit of quantification 5 ng mL−1 and correlation r=0.9998 for both the standard and urine matrix calibration were achieved. The system recovery was 105±5%; 100±4%; 108±1% for three concentration levels of betaxolol in 10 times diluted urine – 5, 20 and 200 ng  mL−1, respectively.

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