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.
Savary
Brett J
BJ
Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA. bsavary@arserrc.gov
Nuñez
Alberto
A
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