title: Poor interoperability of the Adams-Harbertson method for analysis of anthocyanins: comparison with AOAC pH differential method.
abstract: The poor interoperability of anthocyanin glycosides measurements by two pH differential methods is documented. Adams-Harbertson, which was proposed for commercial winemaking, was compared to AOAC Official Method 2005.02 for wine. California bottled wines (Pinot Noir, Merlot, and Cabernet Sauvignon) were assayed in a collaborative study (n=105), which found mean precision of Adams-Harbertson winery versus reference measurements to be 77 +/- 20%. Maximum error is expected to be 48% for Pinot Noir, 42% for Merlot, and 34% for Cabernet Sauvignon from reproducibility RSD. Range of measurements was actually 30 to 91% for Pinot Noir. An interoperability study (n=30) found Adams-Harbertson produces measurements that are nominally 150% of the AOAC pH differential method. Large analytical chemistry differences are: AOAC method uses Beer-Lambert equation and measures absorbance at pH 1.0 and 4.5, proposed a priori by Flueki and Francis; whereas Adams-Harbertson uses "universal" standard curve and measures absorbance ad hoc at pH 1.8 and 4.9 to reduce the effects of so-called co-pigmentation. Errors relative to AOAC are produced by Adams-Harbertson standard curve over Beer-Lambert and pH 1.8 over pH 1.0. The study recommends using AOAC Official Method 2005.02 for analysis of wine anthocyanin glycosides.
authors.affiliation: lmbrooks@pacbell.net
authors.forename: Larry M
authors.initials: LM
authors.lastname: Brooks
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Kuhlman
authors.forename: Doug W
authors.initials: DW
authors.lastname: McKesson
authors.forename: Leo
authors.initials: L
authors.lastname: McCloskey
mesh_terms: D000872:Anthocyanins / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D015203:Reproducibility of Results
chemical_list: D000872:Anthocyanins