bromocresol green mixed indicator solution

0.1% methyl red ethanol solution of 20mL, plus 0.2% bromocresol green in ethanol 30mL, shake, that, too.
Procedure: Weigh the test sample 1g, accurately add water 50mL, precision by adding Sodium lactate solution (1mol / L) 25mL, boiled for 5 minutes, add 2 drops of phenolphthalein indicator solution, hot sulfuric acid titration solution (0.5mol / L) titration, to the solution was pink, and titration of the blank test correction, record consumption of magnessium lactate titrant volume number (mL), each 1mL of sodium hydroxide (0.1mol / L) is equivalent to 90.08mg lactic acid (C3H6O3).
Note 1: "Precision Weigh" means to check the weight should be accurately referred to take the weight of one-thousandth, "precise amount" means the amount of volume accuracy should be in line with national standards for the volume pipettes accuracy requirements.