Pinocembrin was identified as the major compound responsible for the growth inhibition of Staphylococcus aureus displayed by samples of propolis. The pinocembrin content of samples of propolis was determined by two chromatographic techniques, densitometry and high performance liquid chromatography. In both techniquess the pinocembrin content was assessed using internal standards. The pinocembrin content of samples of propolis from different temperate geographical areas was found to be in the range 4.0 to 4.6% w/w.
The literature on the ethylenediaminetetra‐acetate method for determination of sulphate is reviewed and the limitations of the method are discussed. In the procedure now described, after precipitation of sulphate as barium sulphate, excess barium is precipitated with sodium lauryl sulphate and excess of the latter titrated with a suitable quaternary ammonium salt as described in Part I of this series.
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