Analysis of Biological Fluids by Direct Combination of Solid Phase Extraction and Desorption Electrospray Ionization Mass Spectrometry

• Published in: Analytical chemistry (Washington) Vol. 81; no. 4; pp. 1669 - 1675
• Main Authors: Dénes, Júlia, Katona, Mária, Hosszú, Ádám, Czuczy, Noémi, Takáts, Zoltán
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15-02-2009
• Subjects: Adsorption; Analytic Sample Preparation Methods - methods; Analytical chemistry; Aqueous solutions; Blood Chemical Analysis - methods; Chemistry; Cyclosporine - blood; Desorption; Exact sciences and technology; Fluids; Humans; Mass spectrometry; Membranes, Artificial; Rhodamines - analysis; Solid Phase Extraction - methods; Spectrometric and optical methods; Spectrometry, Mass, Electrospray Ionization - methods; Surface Properties; Time Factors; Water - chemistry; Human; Drug; Solid phase extraction; Biological fluid; Rhodamine; Desorption; Cyclosporine; Electrospray; Chemical ionization; Chemical enrichment; Sensitivity; Sample preparation; Detection limit; Serum; Ciclosporin; Aqueous solution; Mass spectrometry; Monitoring
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac8024812

A novel, solid phase extraction (SPE)-based sample preparation method was developed for desorption electrospray ionization (DESI) mass spectrometry. Conventional SPE sample preparation was followed by a custom elution procedure. The eluate was evaporated from the closing frit of the cartridge using a gas jet. Thus the analyte was concentrated on the surface of the frit, which is ideal for DESI analysis. Application of the above SPE protocol allowed the concentration of the analyte content of up to 1 L liquid sample into a 1 mm diameter circular spot. The sample preparation procedure can improve the overall sensitivity of the method by up to 6 orders of magnitude if the sample volume is sufficient. The device has been tested using aqueous solutions of Rhodamine 116; the limit of detection was comparable to the LOD of electrospray analysis. Methodology was tested for drug monitoring applications in human serum. Levels of Cyclosporine A were determined using a 0.1 mL serum sample. Dynamic range of the method exceeded 3 orders of magnitude; the detection limit was below the therapeutic serum concentration of the drug.