Nevertheless, the authors reported relative standard
deviations of up to 40% in off-flavored wines, attributed to varying
interfering compounds in the matrix wine [7]. Similar methods
were described by Christoph et al. [8] and Hühn et al. [9], who
used ethyl vanillin and naphthalene, respectively, as internal standards
and extracted wine samples with trichlorofluoromethane [8]
and methylene chloride [9], but reduced the extraction times to
7 h and 12 h, respectively