高海拔条件下不同浸提方法测定蔬菜硝酸盐的对比研究

Comparative Study on Determination of Nitrate in Vegetables by Different Extraction Methods under High-altitude Conditions

国标规定蔬菜硝酸盐的浸提,需要沸水浴15 min,但在高海拔条件下,沸水浴温度无法达到100℃,为此,探讨浸提温度对测定结果的影响,并采用沸水浴法、油浴法、饱和盐水浴法对比测定蔬菜硝酸盐含量.研究结果表明,水浴的温度确实会对蔬菜硝酸盐的浸提程度产生影响,浸提温度越高,测定值越高.高原条件下,与沸水浴相比,饱和盐水浴和油浴均能提高蔬菜硝酸盐浸提的温度,但油浴温度不易控制,样品受热不均,平行样的精确度较差,不宜用于例行分析;而盐水浴具备水浴的全部优点,且精确度良好,可以用于高原条件下蔬菜硝酸盐的测定.

The nitrate in vegetable was extracted by means of boiling water bath for 15 min in the prescribed method of national standard,but the boiling temperature is unable to reach 100℃under high-altitude conditions.The influence of extraction temperature to nitrate in vegetables was explored,and the methods used to determine nitrate by boiling bath method,saturation solution of NaCl and oil bath in vegetables under high-altitude condition.The results showed that increasing extraction temperature was benefit to increasing extraction ratio for nitrate in vegetables.The higher extractive temperature was beneficical to nitrate in vegetables.Both methods of the boiling and oilbath could,therefore,increase the extraction temperature,but oil bath method had some shortcomings low accuracy of control and uneven heating of aqueous extracts.Saturation solution of NaCl bath method was suitable for the determination of nitrate in vegetables under high-altitude conditions because the determination results were stable and with high precision.