Add another 0.5 to 1.0 g alundum granules. Remove digestion flask and titrating flask from unit, rinsing the condenser tube with distilled water as the flask is being removed. Reagent proportions, heat input and digestion time are critical factors - do not change. Each gram of fat consumes 10 mL sulfuric acid and each gram of carbohydrate consumes 4 mL sulfuric acid during digestion. Catalyst mixtures are commercially available in powdered or tablet form.
Dispensers are available for convenient delivery of powdered catalyst mixtures.
Check with local authorities for proper disposal procedures of copper containing waste solution. Include a reagent blank and at least one sample of high purity lysine hydrochloride in each day's run as check of correctness of digestion parameters. If digestion is not complete, make appropriate adjustments. Lysine and nicotinic acid are difficult to digest, therefore serve as a check on digestion efficiency. Include at least one set of duplicates in each run if single determinations are being made.