Determination of Bromine in Brine by Wavelength Dispersive X-ray Fluorescence Spectrometry with Film Adsorption Pretreatment
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摘要:
溴主要以离子形式分布在地壳水圈的溴化物型卤水、卤化物硫酸盐型卤水中, 目前应用波长色散X射线荧光光谱(WDXRF)测定卤水中的溴, 主要采用粉末载体压片法前处理待检样品, 制样工作量大, 制样均匀性和制样过程中的污染都会影响准确度, 方法实用性不强。本文借助薄膜吸附前处理卤水样品, 通过优化筛选薄膜材料及卤水取样量, 确定移取50 μL卤水样品滴于Ф=40 mm的3#层析滤纸的圆心位置, 自然晾干后高压压平来前处理待检样品, 采用人工配制标准样品校正溴的标准曲线, 用WDXRF测定溴的含量。钾钠钙镁氯和硫酸根等共存离子的影响可以忽略, 方法检出限(3σ)为0.95 mg/L, 精密度(RSD, n=11) 不大于0.8%, 加标回收率为99.4%~101.2%。本方法操作简便, 不需要使用化学试剂, 解决了现行卤水中溴的分析方法流程复杂、分析成本高的问题。
Abstract:Bromine exists mainly as ions in bromide brine and halide sulfate brine in the hydrosphere of the crust. Powder carrier pellet method is commonly used in analyzing bromine in brine by Wavelength Dispersive X-ray Fluorescence Spectrometry (WDXRF). However, this sample preparation method has the disadvantages of large work load, sample inhomogeneity and outer contamination, which affects the analytical accuracy. Samples were pretreated by film adsorption, and film material and sample weight were optimized and are reported in this paper. Firstly, 50 μL of brine is dropped to the center of a chromatography filter paper (Ф=40 mm), air dried, and then flattened by high pressure to prepare the film sample for WDXRF test. A standard curve of Br was calibrated by self-prepared standard solution. Experimental results show that the impact of coexisting ions such as K+, Na+, Ca2+, Mg2+, Cl- and SO42- on the detection of Br is negligible. The detection limit of this method is 0.95 mg/L, the precision is less than 0.8% (n=11), and the recoveries are 99.4%-101.2%. The new sample preparation method is very economical and easy to operate, avoiding the use of chemical reagent.
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Key words:
- brine /
- bromine /
- thin film adsorption /
- X-ray Fluorescence Spectrometry
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表 1 卤水中溴的仪器工作条件
Table 1. Working conditions of the XRF instrument for determination of Br in brine
元素 谱线 晶体 准直器
(μm)探测器 滤光片 电流
(kV)电压
(mA)2θ(°) PHD 测量时间(s) 康普顿
内标峰值 背景 LL UL 峰值 背景 Br Kα LiF200 150 Scint. Al200 60 60 29.9404 1.0604 20 78 20 10 √ Rh Kα-C LiF200 150 Scint. Al200 60 60 18.4698 - 26 78 10 10 - 表 2 不同载体中溴的信号强度
Table 2. Signal intensities of different bromine carriers
薄膜材料名称 计数率
(kcps)薄膜材料名称 计数率
(kcps)PE保鲜膜 0.0482 淀粉 2.1946 麦勒膜 0.0413 硬脂酸 2.2238 超高分子量聚乙烯膜 0.0583 聚乙烯醇 1.6630 玻璃纸 0.0532 氯化钠 1.5090 普通定性滤纸 0.1537 硫酸钠 0.6959 快速定性滤纸 0.1090 纤维素 1.9468 中速定性滤纸 0.1275 硼酸 1.6962 慢速定性滤纸 0.1101 硼酸、纤维素 1.9229 3号层析滤纸 0.2237 硼酸、纤维素、滤纸 2.2732 硼酸、滤纸 1.8840 表 3 共存离子对溴分析结果的影响
Table 3. Effect of coexisting ions on the analytical results of Br
样品编号 Br标准值
(mg/L)加入物质 基体组分含量
(mg/L)Br测定值
(mg/L)样品1 200.0 人工卤水 2倍 199.16 样品2 200.0 人工卤水 3倍 201.68 样品3 200.0 NaCl 150 201.29 样品4 200.0 NaCl 300 199.45 样品5 200.0 MgCl2 50 201.42 样品6 200.0 MgCl2 100 198.13 样品7 200.0 MgCl2 150 201.32 样品8 200.0 CaCl2 5 198.95 样品9 200.0 CaCl2 10 201.88 样品10 200.0 CaCl2 15 200.65 样品11 200.0 KCl 5 201.16 样品12 200.0 KCl 10 198.01 样品13 200.0 KCl 15 200.84 样品14 200.0 Na2SO4 15 201.73 样品15 200.0 Na2SO4 30 198.45 样品16 200.0 Na2SO4 60 198.72 注:人工卤水配制方法详见“1.2节主要材料”中说明;2倍或3倍人工卤水样品是添加2次或3次人工卤水样品。 表 4 方法准确度和加标回收率
Table 4. Accuracy and spiked recoveries of the method
准确度实验 加标回收率实验 样品编号 Br测定值(mg/L) 样品编号 Br含量(mg/L) 回收率
(%)平均回收率
(%)容量法 离子色谱法 ICP-MS法 本法 样品含量 加标量 回收量 1# 27.55 26.25 26.67 27.63 10# 28.70 20 20 99.9 100.6 2# 226.55 234.06 227.04 221.22 60 60.72 101.2 3# 169.40 169.64 179.53 173.71 100 100.51 100.5 4# 81.10 77.37 84.33 80.73 11# 151.26 100 100.51 100.5 99.9 5# 316.20 321.68 311.20 304.44 333.33 331.27 99.4 6# 240.60 250.79 243.29 239.62 500 499.28 99.9 7# 305.75 318.72 313.19 308.64 12# 290.36 100 100.45 100.4 99.8 8# 194.40 195.44 200.26 188.71 333.33 331.80 99.5 9# 138.90 136.14 141.06 135.79 500 496.90 99.4 -
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