Develop and Test Capillary Electrophoresis Methods for Cations
As discussed in the interim report, the cation method has been modified to allow the separation and quantification of ammonium, potassium, calcium and magnesium, as well as arginine, in less than six minutes per sample. Further modifications to the method, which will be tested in the upcoming weeks, may allow the separation of other amino acids as well. As this separation has not proven suitable for the analysis of copper and iron, other methods from the literature are being evaluated for those metals. The comparison of results from this method with results from the atomic absorption spectrometer and flame photometer will be conducted later in the summer as juices from the 1996 season become available. The separation of amino acids in wine has proven to be somewhat more difficult than anticipated. Of the methods tested to date, none provide a means of analyzing all of the important amino acids in a single analysis. The use of low pH phosphate buffer allows a very rapid separation of arginine, the aromatic amino acids, the sulfur containing amino acids and some of the other basic amino acids; there are several methods in the literature which could be used for the analysis of the remaining amino acids. We are currently evaluating the best combination of methods that will allow rapid separation of the majority of amino acids of interest. We will also evaluate the rapid derivitization technique developed by Waterhouse and Butzke under a separate AVF grant for its potential use in capillary electrophoretic separations of the amino acids. Juice samples from the 1996 harvest will be collected and analyzed using the separation methods developed above. Previously collected samples from the 1995 harvest will be analyzed as test samples during the developmental stage. The goal to field test methods developed during the course of this project will be met through an ongoing process. Several California wineries now have capillary electrophoresis instrumentation in-house; we maintain regular contact with these wineries for the testing of new methods of analysis as they are developed. In May Tom Collins taught a University Extension course on the use of capillary electrophoresis in wine analysis; several winery representatives expressed interest in participating in future field trials with the instrument. Collins will continue to pursue the involvement of these wineries in such trials, as well as contacting the instrument manufacturers concerning the use of their instruments for these trials.