• Spectrometric mixture analysis: An unexpected wrinkle

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    • Keywords


      Spectrometric mixture analysis; caffeine; theobromine; ultraviolet absorption.

    • Abstract


      The spectrometric analysis of a mixture of two chemically and spectroscopically similar compounds is illustrated for the simultaneous spectrometric determination of caffeine and theobromine, the primary stimulants in coffee and tea, based on their ultraviolet absorbances. Their analysis indicates that such measurements may need an unexpectedly high precision to yield accurate answers, because of an artifact of inverse cancellation, in which a small noise or drift signal is misinterpreted in terms of a concentration difference. The computed sum of the concentrations is not affected.

    • Author Affiliations


      Robert De Levie1

      1. Chemistry Department, Bowdoin College, Brunswick ME 04011, USA
    • Supplementary Material

  • Journal of Chemical Sciences | News

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