离子色谱柱后衍生紫外法测定面制品中的水溶性硅酸盐

Determination of soluble silicates in flour products by ion chromatography and postcolumn derivatization with ultraviolet detection

中文关键词:  水溶性硅酸盐  离子色谱法  柱后衍生  紫外检测法  面制品

英文关键词:soluble silicate  ion chromatography  postcolumn derivatization  ultraviolet detection  flour products

中文摘要:

      目的 建立离子色谱柱后衍生紫外检测法测定面制品中水溶性硅酸盐含量的分析方法。方法 面制品经烘干、粉碎后, 称取适量样品, 以水为溶剂超声提取30 min, 随后在10000 r/min转速下离心10 min, 上清液经0.22 μm微孔滤膜过滤后待上机分析。以25 mmol/L NaOH-0.5 mmol/L Na2CO3为淋洗液, 流速 0.7 mL/min, 柱温45 ℃, 进样量250 μL。柱后衍生试剂为200 mmol/L HNO3+20 mmol/L钼酸钠溶液, 衍生试剂流速0.3 mL/min, 衍生反应温度45 ℃, 紫外检测器波长设定为360 nm, 外标法定量。结果 硅酸根离子在0.01~0.80 mg/L浓度范围内线性关系良好, 相关系数为0.9999, 方法检出限为0.005 mg/L (以SiO32-计)。面制品样品的加标回收率介于98.4%~106.0%之间, 相对标准偏差为4.5%~6.3% (n=3)。采用本方法测定了46种市售面制品(包括碱水面)中硅酸根离子的含量, 面制品中硅酸根离子含量在4.64~51.15 mg/kg之间。结论 本方法选择性和灵敏度高、准确性好、分析速度快, 尤其适合大批量面制品样品中可溶性硅酸盐含量的测定。

英文摘要:

      Objective To establish an analytical method for soluble silicates determination in flour products using ion chromatography and postcolumn derivatization with ultraviolet detection. Methods After flour products were dried and reduced to powders, moderate powders were weighed and dissolved in water. The above solution was sonicated for 30 min, then it was centrifugated at 10000 r/min for 10 min, followed with filtration through a 0.22 μm membrane. The prepared solution was injected into the instrument for analysis. Eluent flow rate was 0.7 mL/min by employing 25 mmol/L NaOH mixed with 0.5 mmol/L Na2CO3 as eluent. The column temperature was set at 45 ℃ and the injection volume was 250 μL. The postcolumn derivatization reagent was 20 mmol/L sodium molybdate in 200 mmol/L HNO3 with flow rate of 0.3 mL/min and the reaction temperature fixed at 45 ℃. The ultraviolet detector wavelength was set at 360 nm and external standard method was used for quantification. Results Silicate ions were lined between 0.01 and 0.80 mg/L with a correlation coefficient 0.9999. The limit of detection for silicate ions was 0.005 mg/L (calculated by SiO32-). The recoveries ranged from 98.4% to 106.0% flour products fortified with silicate ions and the relative standard deviations were 4.5%?6.3% (n=3). Soluble silicates were analyzed for 46 kinds of flour products saled on the market, and 4.64?51.15 mg/kg were obtained for silicate ions. Conclusion This method has high selectivity and sensitivity, good accuracy and fast analysis speed, which is especially suitable for the determination of soluble silicate in large quantities of flour products.