水蒸气蒸馏-离子色谱法测定锰矿石中氟和氯

摘要

A method for determination of fluorine and chlorine in manganese ore by ion chromatography was proposed with steam distillation for sample pretreatment. The experiments indicated that the sample was distilled at 160~180℃ for 20 - 25 min with sulfuric acid of the high boiling point as distillation solvent to realize the separation and enrichment of fluorine and chlorine, which could eliminate the interference caused by coexisting ions in the ore sample and avoid the pollution of chromatographic column. After the absorption liquid was filtered through 0. 22 μm millipore membrane, fluorinion and chloridion were separated with AS-19 type anion separation column and continuous automatic regeneration chemical suppressor using 30. 00 mmol/L NaOH solution as eluent. The correlation coefficients of the calibration curves for fluorine and chlorine were both more than 0. 999, and the detection limits (S/N = 3) were 2 mg/kg and 3 mg/kg,respectively. This method was applied in the determination of fluorine and chlorine in manganese ore certified reference material. The results were consistent with the certified value, and the relative standard deviations (RSDs, n=12) were 2. 9% and 3. 8%, respectively. Control trials showed that the measured values by this method were consistent with those obtained by national standard method GB/T 6730. 28-2006 and GB/T 3050-2000, respectively.%采用水蒸气蒸馏法对样品进行前处理,建立了离子色谱法测定锰矿石中氟和氯的方法.实验表明,采用高沸点的硫酸作为蒸馏剂,将样品在160～180℃温度下蒸馏20～25 min对氟和氯进行分离富集后,可消除矿产品中大量共存离子的干扰及避免对色谱柱的污染.吸收液经0.22 μm微孔膜过滤,以30.00 mmol/L NaOH溶液作淋洗液,采用AS-19型阴离子分离柱和连续自动再生化学抑制器对氟和氯阴离子进行分离.方法的线性相关性好(r＞0.999),氟和氯的检出限(S/N=3)分别为2 mg/kg和3 mg/kg.方法用于锰矿石标准样品和实际样品中氟和氯的测定,结果与认定值相吻合,相对标准偏差(RSD)为2.9％和3.8％(n=12).方法对照试验表明本方法测定值分别与国标法GB/T 6730.28-2006测得的氟含量、GB/T 3050-2000测得的氯含量一致.