2.1.2. Vitamin B1 standard solution:
A stock solution containing 500 g ml−1 of vitamin
B1was prepared by dissolving 0.025 g of
vitamin B1 (biochemical reagent, 99.9%, Shanghai
Chemical Reagent Company) in doubly distilled
water, then transferring into a 50 ml calibrated
flask and diluting to the mark with water. Then it
was stored in the refrigerator and can be used in
1 month. The working concentration of VB1 was
10 g ml−1 prepared daily from the stock solution
by appropriate dilution. All the other
reagents were of analytical-reagent grade and
doubly distilled water was used throughout.