Gas chromatography-mass spectrometry method for determining the methanol and acetic acid contents of pectin using headspace solid-phase microextraction and stable isotope dilution.
A simple, fast, and direct procedure was developed for the simultaneous determination of the methanol and acetic acid present as esters in the plant cell wall polysaccharide pectin. After base-hydrolysis of esters and acidification of pectin samples, headspace solid-phase microextraction (SPME) was performed using a Carboxen-PDMS fiber assembly. Methanol and acetic acid were separated by gas chromatography with a Chrompak PoraPlot Q capillary column and detected using electron impact mass spectrometry with selected ion monitoring. Stable deuterated isotopomers (d3-methanol and d3-acetic acid) were used as internal standards and for constructing calibration curves, providing accurate and absolute quantification of analytes. The methanol and acetic acid contents in 1 mg quantities of fruit and vegetable pectins were readily quantified by this procedure.
Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA. bsavary@arserrc.gov
Brett J
BJ
Savary
Alberto
A
Nuñez
D019342:Acetic Acid / Q000032:analysis*; D002138:Calibration; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D007554:Isotopes; D000432:Methanol / Q000032:analysis*; D010368:Pectins / Q000737:chemistry*; D012680:Sensitivity and Specificity
D007554:Isotopes; D010368:Pectins; D019342:Acetic Acid; D000432:Methanol