GB/T 5009.91-2003 in English

《GB/T 5009.91-2003食品中钾、钠的测定》由361（国家卫生健康委员会）归口，主管部门为国家卫生健康委员会。
本标准规定了用火焰发射光谱法测定食品中钾和钠。本标准适用于各种食品中钾、钠的测定。本方法检出限：钾为0.05μg、钠为0.3μg；线性范围：钾为0.1μg～0.5μg;钠为1.0μg～4.0μg。

1 Scope

This standard specifies determination of potassium and sodium in foods by flame emission spectrometric method.
This standard is applicable to the determination of potassium and sodium in various foods.
Detection limits of this method: 0.05μg for potassium and 0.3μg for sodium; linear range: 0.1μg~0.5μg for potassium; 1.0μg~4.0μg for sodium .

2 Principle

Treat the samples, transfer it into flame photometer; after the sample is atomized by the flame, and determine the emission intensity of potassium and sodium respectively. The emission wavelength of potassium is 766.5nm and that of the sodium is 589nm. Their emission intensity is directly proportional to their content and is compared with standard series to determine their content.

3 Reagents

3.1 Nitric acid.
3.2 Perchloric acid.
3.3 Digestive fluid of mixed acid: nitric acid + perchloric acid=4+1.

Foreword I
1 Scope
2 Principle
3 Reagents
4 Apparatuses
5 Analysis Procedures
6 Result Calculation
7 Precision