The following are the determination methods of total acid content and amino acid nitrogen content.

Method 1:

Take 1.0ml sample in 10 ml colorimetric tube, add water to the scale of 10.0ml, cover and mix well, put 1.0ml sample in 100ml triangular flask, add 60ml distilled water and 4 drops of NO. 1 developer, shake well. Shake every drop of 1. When the solution turns pink (it can be used as a reference substance for easy observation), calculate its content according to the total acid equivalent to 0.45% g per drop of the determination solution (if the determination solution consumes 5.5 drops, it means that the total acid exceeds the standard and should be sent to the laboratory for accurate quantification). Add10.0ml of 36% formaldehyde solution and No.2 to the solution. Calculate the content of amino acid nitrogen equivalent to 0.078% g per drop of measuring solution, and do reagent blank test (that is, the number of measuring drops consumed when no sample is added). For example, the sample consumption 1 1 drop of measuring solution, the reagent blank consumption 7 drops of measuring solution, and the sample actually consumes 4 drops of measuring solution. The content of amino acid nitrogen in this sample is 4× 0.078% = 0.

Method 2:

Take 1.0ml sample in 10 ml colorimetric tube, add water to the scale of 10.0ml, cover and mix well, put 1.0ml into 200ml beaker, add 60ml distilled water, and soak the calibrated portable pen-type acidity meter in water for 3min before use. Shake every drop of 1 evenly, stop titration when the pH meter shows 8.2, calculate its content according to the total acid equivalent to 0.45% g per drop, add 10.0ml36% formaldehyde solution to the solution, shake evenly and continue titration until the pH of the solution is 9.2, and calculate according to the amino acid nitrogen equivalent to 0.078% g per drop.