(CuSO4.5H2.K2SO4). Nitrogen tree Catalyst 3. Procedure Weight 0.5g ground dry sample into a 125ml Erlenmeyer flask. Add 50ml of distilled water. Allow to stand 30 min. Add 10ml 10% TCA. Let Stand 20-30 min ข.-เ Filter on Whatman #54 or 541paper by gravity and collect ntrate. Rinse the Erlenmeyer flask twice with TCA solution. Pour mixture from flaSk through Same filter paper used earlier. Collect entire filtrate. Filtrate should be clear and free of particulate matter. At this point: filtrate is no longer needed and may be discarded in the appropriate manner. Let the ter paper dry Off and then transfer paper to the Kjeldahl flaSk (take care notto lose any precipitate). Add 3gof-catalyst and 15mlofH2SO Digest until white fumes develop. Increase temperature to 400"C and digest until clear. Total digestion time 3 hr. At the end of digestion, digest should ca be clear and free Ofundigested material. Cool digest to room temperature. Place 40% MOH in kali tank of distillation unit. Adjust volume dispensed to 60 ml for 40% NaOH and 70ml for distilled wated Attach digestion tube