Improvement of Official Chemical Analysis of Tea (Part 2)
Examination of Water Extract Determination
1966 Volume 1966 Issue 26 Pages 69-73
Details
1966 Volume 1966 Issue 26 Pages 69-73
The accuracy of analytical method and the personal error of analyst were examined with A.O.A.C. method for determining water extract in tea.
The accuracy of analysis was computed as C. V. 1.63% ; the error accompanied with a single determination by an analyst was C. V. 3.17% and that with a mean value of double determinations by an analyst was C. V. 2.96%.
By modifying some procedures, the following operation is decided as the official method for determining water extract in tea.
Add 200ml. of hot water to 2g. of pulverized tea in a 500ml. flask, and reflux slowly on an electric heater or gas flame for 2 hours.
Cool in current water, make up the volume to 500ml., and filter through dry paper (Toyo No. 2). Transfer 50ml. aliquot into a weighed bottle and evaporate to dryness on a steam bath. Place in an oven (98-100°C) and dry to a constant weight.
