Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were ut ilized in the detection of the adulteration of locust bean gum with guar gu m. For CE analyses, standards of locust bean and guar gums were extracted w ith 30% CH3CN, removing the residual proteins from the gum matrix. a 8.75 m M NaH2PO4-20.6 mM Na2B4O7 buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These m arkers did not co-migrate with components in the extracts of mechanically p rocessed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locu st bean gum samples were distinguished from mixed samples through the diffe rential staining of components in locust bean versus guar and tara gums. Th ese experiments in the use of CE and PLM provide orthogonal and complementa ry methods for the verification of 'true' positives and the elimination of 'false' positives.