Analysis of phenolic acids as chloroformate derivatives using solid phase microextraction-gas chromatography

Area of Science:

• Analytical Chemistry
• Environmental Science
• Food Chemistry

Background:

• Phenolic acids are crucial compounds with diverse biological activities.
• Accurate and sensitive quantification of phenolic acids is essential for various scientific disciplines.
• Existing derivatization and analytical methods may lack optimal sensitivity or efficiency.

Purpose of the Study:

• To modify and optimize a procedure for derivatizing phenolic acids.
• To determine the suitability of methyl chloroformate derivatization coupled with solid-phase microextraction (SPME) for enhanced phenolic acid analysis.
• To validate key performance parameters of the optimized analytical method.

Main Methods:

• Optimization of phenolic acid derivatization using methyl and ethyl chloroformate in an aqueous acetonitrile/methanol/ethanol/pyridine medium.
• Analysis of derivatized phenolic acids (caffeic, ferulic, gallic, p-coumaric, protocatechuic, syringic, vanillic) using gas chromatography-flame ionization detection (GC-FID).
• Optimization and application of direct solid-phase microextraction (SPME) with various fibers (PA, PDMS, CAR/PDMS, PDMS/DVB) for pre-concentration prior to GC-FID analysis.

Main Results:

• Optimized methyl chloroformate derivatization offered a shorter GC analysis time (24 min) compared to ethyl chloroformate (30 min).
• The polyacrylate (PA) fiber demonstrated superior performance for SPME under optimized conditions (50 min extraction, 25°C, 10 min desorption).
• The combined SPME-GC method achieved approximately 10-fold higher sensitivity, with limits of quantitation (LOQ) as low as 0.02 µg/mL for p-coumaric acid.

Conclusions:

• The optimized methyl chloroformate derivatization combined with SPME-GC provides a highly sensitive and efficient method for analyzing phenolic acids.
• This improved analytical approach enables more accurate quantification of phenolic acids in various sample matrices.
• The method's enhanced sensitivity facilitates the detection of lower concentrations of phenolic acids, crucial for health and environmental studies.