两种前处理方法在钠含量检测中的对比研究

针对食品中钠含量检测的国标前处理方法(湿法消解)操作繁琐、效率低下的问题,开展干灰化法和微波消解两种前处理方法的对比研究,以加标回收率评价方法的可行性,还考察了原子发射法检测钠含量过程中调整单色器的标液浓度、标准曲线浓度范围、样品稀释倍数等方面的影响。结果表明,用于调整单色器的钠标准溶液选择1 mg/L优于2 mg/L;选择浓度范围(0~2 mg/L)进行标准曲线的二次曲线拟合结果较好;合适的稀释倍数就是使得稀释后样液浓度接近用于调整单色器的中间浓度的稀释倍数;在酱油、火腿肠、乳饮等三种不同钠含量水平的食品中,微波消解前处理的测定结果均比干灰化法高,就乳饮而言,微波消解的回收率96.88%,而干灰化法的回收率87.18%,两种前处理方法的估算结果无显著差异。因此,干灰化法、微波消解可以作为食品中钠含量检测的前处理方法,是对国标方法的补充。

Determination of Sodium in Food by Two Pretreatment Methods

Aiming at the problem of complicated operation and low efficiency of the normal pretreatment method (wet digestion) in sodium determination, comparative study was carried out with two pretreatment methods (dry ashing and microwave digestion). The feasibility of the methods was evaluated by the recovery of standard addition, and the effects of monochromator adjustment concentration, the concentration range of standard curve and the dilution multiple of sample on the determination of sodium by atomic emission method were investigated. The monochromator adjustment concentration of 1 mg/L was better than that of 2 mg/L. The quadratic curve fit well in the concentration range of 0~2 mg/L. The proper dilution multiple of the sample solution was close to the monochromator adjustment concentration. In three different sodium-contenting foods, including sauce, sausage and milk drink, the determination result of microwave digestion was higher than dry ashing. For milk drink, the recovery of microwave digestion was 96.88%, while dry ashing was 87.18%. There was no significant difference between the estimated results of two methods. Thus, dry ashing and microwave digestion could be the pretreatment methods for sodium determination in food, as supplement to the national standard method.