该研究建立了测定红糖中Mn、Fe、Co、Cu、Zn和Sr营养元素的稀酸微波消解-电感耦合等离子体质谱方法。通过单因素实验考察了硝酸浓度、过氧化氢体积和消解时间对红糖样品中元素回收率的影响,得到最佳消解条件。结果表明,稀酸微波消解的最佳工艺条件为:硝酸浓度1.0 mol/L,过氧化氢体积1 mL,消解时间27 min。该方法各元素的标准曲线线性关系良好,相关系数大于0.999 5,方法检出限和定量限分别为0.001~0.05 mg/kg和0.004~0.2 mg/kg,相对标准偏差小于5%,加标回收率为87.5%~110.2%。t检验表明,该方法与GB 5009.268—2016中微波消解-ICP-MS法测定结果无显著性差异(P＞0.05)。该方法操作简单、灵敏度高、结果准确,可为红糖中营养元素的测定提供参考。
Microwave-assisted digestion using diluted acid was developed for nutrient elements (Mn, Fe, Co, Cu, Zn and Sr) determination in brown sugar samples by inductively coupled plasma mass spectrometry (ICP-MS). The effects of different digestion conditions including HNO3 concentration, the volume of H2O2 and digestion time on the recoveries of elements were investigated by single factor experiment, and the optimum digestion conditions were obtained. The results showed that the optimum digestion conditions of microwave-assisted digestion using diluted acid were as follows: concentration of 1 mol/L HNO3, 1.0 mL of H2O2 and digestion for 27 min. The standard curve of each element was exhibited a good linear correlation with a coefficient higher than 0.999 5. The limits of detection (LODs) of 6 elements were 0.001-0.05 mg/kg, and the limits of quantification (LOQs) were 0.004-0.2 mg/kg. Moreover, the relative standard deviation (RSD) was less than 5%. Suitable recoveries (range from 87.5% to 110.2%) were obtained in three evaluations for all analytes. After the comparation with those obtained by the national standard method of China, and no statistical differences were observed (student′s t-test, confidence level of 95%, P＞0.05). The proposed method is simple, high sensitivity and accurate, which is suitable for the determination of the Mn, Fe, Co, Cu, Zn and Sr in brown sugar samples.
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