Gas-liquid chromatographic determination of adipate content of acetylated di-starch adipate.
A gas-liquid chromatographic method is described for rapid, quantitative determination of adipate content of acetylated di-starch adipate. The adipate group is very labile and, under mild alkaline conditions at ambient temperature, is easily hydrolyzed from the starch. Free adipic acid is formed by acidification of the solution with HCl, and then extracted with ethyl acetate. Ethyl acetate is removed under vacuum distillation, and a silyl derivative of the adipic acid is formed. Glutaric acid internal standard is introduced into the original starch sample before hydrolysis. An aliquot of the silylated solution is injected into a gas chromatograph fitted with a column having silicone oil as the active phase. A flame ionization detector is also incorporated. Results correlate well the amount of adipylating reagent used. No adipic acid is detectable when a hydrolyzed, extracted sample of acetylated di-starch adipate is subjected to a second extraction. Recovery levels of adipic acid, from starches fortified with 100-500 ppm, are in the range of 97-102.5%.
D000272:Adipates / Q000032:analysis*; D002849:Chromatography, Gas / Q000379:methods; D005503:Food Additives / Q000032:analysis*; D013213:Starch / Q000031:analogs & derivatives* / Q000032:analysis
D000272:Adipates; D005503:Food Additives; C034337:acetyl di-starch adipate; C029900:adipic acid; D013213:Starch