GB/T 14924.10-2008Laboratory animal - Determination of amino acids for - Formula feeds (English PDF)

3.1

Determination of Amino Acid in Feed with

Performed in GB/T 18246-2000 or GB/T 5009.124 relevant provisions.

3.2 Determination of feed with tryptophan

3.2.1 The first method HPLC

According to GB/T 18246-2000 Appendix A "Tryptophan by RP-HPLC" regulations.

3.2.2 Method II fluorospectrophotometry

3.2.2.1 Principle

In alkaline hydrolysis fluid protein, only tryptophan and tyrosine fluorescence can be detected. At pH 11, the tryptophan fluorescence intensity

100 times larger than the degree of tyrosine, tyrosine and tryptophan fluorescence peak difference of 40nm or more. According to the characteristics, the alkaline hydrolysis process protein

Quality, and then by measuring the natural fluorescence of tryptophan, tryptophan quantitative analysis.

3.2.2.2 Reagents

Unless otherwise indicated, all reagents were of analytical grade, water was used a water.

3.2.2.2.1

soluble starch.

3.2.2.2.2

sodium hydroxide (NaOH).

3.2.2.2.3 sodium hydroxide solution (5mol/L) containing soluble starch

soluble starch 20g of sodium hydroxide solution (5g/L) was dissolved

Solutions and set the volume to 100mL. Pro preparation before use.

3.2.2.2.4

urea solution (4mol/L, pH11).

3.2.2.2.5 hydrochloric acid solution (1 + 1)

1 part of concentrated hydrochloric acid (excellent pure) plus 1 part by weight of distilled water.

3.2.2.2.6

bromothymol blue solution (0.5g/L). 0.1g bromothymol blue, plus 0.1mol/L sodium hydroxide solution 1.6mL solution

Solution, add water to 200mL.

3.2.2.2.7

high purity nitrogen (content 99.99%).

3.2.2.2.8 octanol toluene solution

Take 1mL octanol mixed with 99mL toluene.

3.2.2.2.9

tryptophan standard stock solution (1.00mg/mL). Weigh accurately tryptophan 100.0mg, with 0.005mol/L sodium hydroxide […]