白糖二氧化硫测定

4.0 Method 方法

1. Dissolve 1g of sugar in D.W. to approximately 8 cm3 in a graduated test tube.
在一个 刻度试管中，将1g糖溶解于大约8 cm3脱盐水中。 0-5 mg SO2/kg use 4g sugar.
5-15 mg SO2/kg use 2g sugar.
15-30 mg SO2/kg use 1g sugar.
0-5 mg SO2/kg 用4g糖
5-15 mg SO2/kg用2g糖
15-30 mg SO2/kg用1g糖。
2. Add 0.4 cm3 of 0.1M sodium hydroxide into the flask and makeup to the 10 ml mark on the test tube with D.W. Mix well.
在刻度试管中加入0.4 cm3的0.1M氢氧化钠，并用脱盐水定容到10ml处。充分混合。 Reagent 1.
Use Autopipette
试剂 1
使用自动移液器。
3. Add 0.2 cm3 of the 0.2% bleached rosaniline solution and mix.
加入0.2 cm3 的 0.2%漂白玫瑰苯胺溶液，混合。 Reagent 2.
Use Autopipette
试剂 2
使用自动移液器
4. Add, 0.2 cm3 of the 0.2% formaldehyde solution and mix.
加入0.2 cm3的0.2%甲醛溶液，混合。 Reagent 3.
Use Autopipette
试剂 3
使用自动移液器
5. Stand at room temperature for 30 ± 5 min.
在室温下静置30 ± 5分钟。
6. Measure the absorbance of the test solution in a 1 cm cell, at 570 nm wavelength against a D.W. blank.
7. 用1 cm的比色皿，测量测试溶液的吸收率，570 nm 波长对照空白脱盐水 Note the absorbance, A.
记录消光值，A.

5.0 Calculation of Results 结果计算

Using the formula supplied with the standard absorption curve,determine the amount of sulphur dioxide in the test solution from theabsorbance measured.
用标准消光曲线提供的公式，从测量的吸收率来测定测试溶液中二氧化硫的量。

The amount of sulphur dioxide in the sugar sample is then amount ofsulphur dioxide calculated from the formula or curve divided by theweight of sample used.
在样品糖中二氧化硫的量是由所用样品重量分成的公式或曲线计算出的二氧化硫的量。

5.1 Worked Example 举例

If the calculated amount of SO2 from the formula is 7.32 and the sample weight = 4g
then mg/kg of SO2 in sugar sample = 7.32 = 1.834
如果从公式中计算的SO2 的量是7.32，并且样品重量 = 4g
那么mg/kg 的样品糖中 SO2 = 7.32 = 1.834