Simple isotope dilution assay for propionic acid and isovaleric acid

Area of Science:

• Analytical Chemistry
• Biochemistry
• Clinical Chemistry

Background:

• Propionic acid and isovaleric acid are important organic acids found in physiological fluids.
• Accurate quantification of these acids is crucial for diagnosing metabolic disorders.
• Existing methods may lack the sensitivity or specificity required for precise measurements.

Purpose of the Study:

• To develop and validate a sensitive gas chromatographic-mass spectrometric (GC-MS) method for quantifying propionic acid and isovaleric acid.
• To establish reference values for propionic acid and isovaleric acid in human plasma and urine using isotope dilution.

Main Methods:

• A gas chromatographic-mass spectrometric (GC-MS) method utilizing isotope dilution was employed.
• Propionic acid and isovaleric acid were derivatized to pentafluorobenzyl esters to enhance volatility for GC-MS analysis.
• Measurements were performed on human plasma and urine samples.

Main Results:

• Reference values for propionic acid in plasma were 0.54 ± 0.38 μmol/L and in urine were 1.7 ± 1.6 μmol/mmol creatinine.
• Reference values for isovaleric acid in plasma were 0.89 ± 0.93 μmol/L and in urine were 0.38 ± 0.51 μmol/mmol creatinine.
• The method demonstrated suitability for GC-MS analysis of these organic acids.

Conclusions:

• A reliable GC-MS method for assaying propionic and isovaleric acids in physiological fluids has been established.
• The study provides essential reference ranges for these organic acids in human plasma and urine.
• This method can aid in the clinical assessment of metabolic conditions related to propionic and isovaleric acid levels.