Polyketide analysis using mass spectrometry, evaporative light scattering, and charged aerosol detector systems

Area of Science:

• Analytical Chemistry
• Biotechnology
• Organic Chemistry

Background:

• Polyketide compounds, like the erythromycin precursor 6-deoxyerythronolide B, often lack natural chromophores, complicating their detection.
• Accurate quantification and identification are crucial for optimizing polyketide production schemes.

Purpose of the Study:

• To compare the analytical capabilities of mass spectrometry (MS), evaporative light scattering detection (ELSD), and charged aerosol detection (CAD) for analyzing a non-chromophoric polyketide.
• To evaluate each detector's limit of detection (LOD), dynamic range, and precision for polyketide analysis.
• To identify the most suitable detector for analyzing low-concentration, poorly characterized polyketides.

Main Methods:

• Analysis of 6-deoxyerythronolide B using MS, ELSD, and CAD.
• Evaluation of detector performance based on LOD, dynamic range, and precision.
• Comparative assessment of the three detection techniques.

Main Results:

• Mass spectrometry (MS) exhibited the lowest limit of detection (LOD) and provided molecular weight information, making it ideal for identifying unknown polyketides.
• Evaporative light scattering detection (ELSD) offered the best precision (3%) but had a higher LOD (≥1 mg/L).
• Charged aerosol detection (CAD) demonstrated a low LOD (0.012 mg/L) and a dynamic range comparable to MS, presenting a cost-effective option.

Conclusions:

• Mass spectrometry is the preferred method for analyzing complex, low-concentration polyketides requiring molecular weight data.
• Charged aerosol detection (CAD) serves as a viable and economical alternative to MS for polyketide analysis, especially in production settings with low titers.
• Both CAD and ELSD provide better precision and accuracy than MS for certain polyketide analysis scenarios.