This laboratory has been using the following rapid method which gives
results agreeing closely with results obtained by the analysis of the
ash:
Weigh out 20 grams of pulp, dilute in a volumetric flask to 200 cc.,
filter and titrate an aliquot portion with standard silver nitrate
solution, using potassium chromate as indicator. The acidity of tomato
pulp is not sufficient to interfere with this determination.