超声提取-离子色谱法测定铁矿石中水溶性氟氯溴及硝酸根

铁矿石样品经超声提取、离心机分离沉淀后,分别通过IC-RP柱、IC-Na柱及0.22μm微孔过滤膜过滤,25.00 mmol/L NaOH溶液作为淋洗液,利用AS-19型阴离子分离柱和ASRS 300-4 mm连续自动再生化学抑制器分离样品中氟、氯、溴和硝酸根多种水溶性阴离子和采集数据。经过IC-RP柱可吸附样品溶液中有机质,通过IC-Na柱可将溶液中重金属离子置换成Na+,使之与淋洗液的阳离子成分一致。对水溶性阴离子的提取效率进行实验,确定提取时间为30 min。在标准溶液及待测样品溶液中加入一定量相应的淋洗液,使溶液和淋洗液的电导值相匹配来消除水负峰的影响。F-、Cl-、Br-、NO3-的方法检出限分别为2.1、3.5、2.5、2.0μg/g,工作曲线的相关系数>0.999。用铁矿石标准样品GBW 07218a验证方法的准确度与精密度,测定值与标准值基本吻合,精密度(RSD,n=10)小于5%,加标回收率为96%～104%。用于实际样品的分析,测定值与离子选择电极法结果接近。方法线性范围宽,操作简单,快速高效,适用于实验室日常检测工作。

Determination of Water Soluble Fluoride, Chloride, Bromide and Nitrate in Iron Ores by Supersonic Extraction-Ion Chromatography

An ion chromatography method with ultrasonic extraction has been developed to simultaneously determine the water solubility of fluoride,chloride,bromide and nitrate in iron ores.The sample solution was extracted ultrasonically and precipitation separation was carried out by centrifugation.The clarified solution was passed through IC-RP,IC-Na and a 0.22 μm filter membrane.The anions were separated and data were collected by using AS-19 type anion separation column and ASRS 300-4 mm self-electric chemistry suppressor with the 25.00 mmol/L NaOH as eluent.The organic matter in the sample solution was absorbed by IC-RP column and the heavy metal ions were replaced by IC-Na column,which is the same cation as that in eluent.Based on the study of the extraction efficiency for water solubility anions,the extraction time was 30 min.In order to eliminate the effect of a negative peak from water,a certain amount of eluent was added into the standard and sample solutions to make the conductivity in each solution match each other.Under optimal conditions,the detection limits of F-,Cl-,Br-and NO-3 were 2.1,3.5,2.5 and 2.0 μg/g,respectively.The linear correlation was good for the work curve,and the linearly dependent coefficient was greater than 0.999.The accuracy and precision of this method was verified by iron ore standard material GBW 07218a and the results were consistent with certified values.The RSD(n=10) was less than 5% and recovery rates with interior standard were 96%-104%.The results for the actual samples were consistent with those obtained by ion selective electrode method.The method has the benefits of applying to a wide linear range,is simple and has rapid and high efficiency,making it suitable for routine lab inspection work.