Gentamicin assay in human serum by solid-phase extraction and capillary electrophoresis

Area of Science:

• Analytical Chemistry
• Pharmacology
• Clinical Chemistry

Background:

• Gentamicin is a critical antibiotic requiring precise therapeutic drug monitoring to ensure efficacy and minimize toxicity.
• Existing methods for gentamicin quantification may lack the specificity or sensitivity needed for comprehensive analysis of its components.

Purpose of the Study:

• To develop and validate a capillary electrophoresis (CE) method for the simultaneous determination of major gentamicin components (C1, C1a, C2a, C2) in human serum.
• To establish a sensitive, accurate, and reliable analytical technique for gentamicin therapeutic drug monitoring.

Main Methods:

• Solid-phase extraction (SPE) was employed for sample preparation, followed by derivatization with 1,2-phthalic dicarboxaldehyde/mercaptoacetic acid.
• Separation was achieved using capillary electrophoresis with a background electrolyte containing CHES buffer and methanol.
• Quantification was performed using UV-light absorption detection at 230 nm, with identity confirmation by mass spectrometry.

Main Results:

• The developed SPE-CE method demonstrated high recovery rates (78%-93%) for gentamicin components.
• The method achieved low limits of quantitation (LOQ) and detection (LOD) for all gentamicin components, with LOQs ranging from 0.23 to 0.33 mg/L.
• Excellent linearity (r=0.9) was observed when comparing CE results with immunoassay, and intra- and inter-assay precision (RSD) values were within acceptable limits.

Conclusions:

• The developed capillary electrophoresis method provides a robust and sensitive means for quantifying gentamicin C1, C1a, C2a, and C2 in human serum.
• This method is suitable for therapeutic drug monitoring across the entire therapeutic concentration range of gentamicin.
• The validated CE technique offers a valuable alternative for clinical laboratories requiring accurate gentamicin analysis.