微波消解火焰原子吸收光谱法测定土壤中六价铬

张伟琦; 谢涛; 孙稚菁; 王茂林; 蔡喜运

doi:10.13198/j.issn.1001-6929.2022.11.27

微波消解火焰原子吸收光谱法测定土壤中六价铬

doi: 10.13198/j.issn.1001-6929.2022.11.27

1.
大连产品质量检验检测研究院有限公司，辽宁大连　116021
2.
大连理工大学环境学院，工业生态与环境工程教育部重点实验室，辽宁大连　116024

基金项目: 国家重点研发计划项目(No. 2019YFC1803803)

详细信息

作者简介:
张伟琦（1985-），女，黑龙江五常人，252886022@qq.com

通讯作者:
蔡喜运(1978-)，男，山东菏泽人，教授，博士，博导，主要从事土壤污染化学与修复研究，xiyuncai@dlut.edu.cn

中图分类号: X53
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出版历程
- 收稿日期: 2022-09-08
- 修回日期: 2022-11-15

Developments of the Method of Microwave Digestion and Flame Atomic Absorption Spectrometry for Determination of Hexavalent Chromium in Soils

1.
Dalian Product Quality Inspection and Testing Institute Co., Ltd., Dalian 116021, China
2.
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China

Funds: National Key Research and Development Program of China (No. 2019YFC1803803)

摘要

摘要: 目前用于土壤中六价铬检测的提取方法较为单一，一般是使用HJ 1082—2019《土壤和沉积物六价铬的测定碱溶液提取-火焰原子吸收分光光度法》中提到的碱溶液提取法. 但该方法在进行大批量土壤检测时存在耗时长、试剂用量大、温度不易控制等问题. 因此，建立高效、准确的土壤中六价铬测试方法，对开展土壤中六价铬污染风险评价及修复工作具有十分重要的意义. 本研究提出了微波消解火焰原子吸收光谱法，用于快速、准确测试土壤中六价铬. 通过开展提取剂组成与用量、微波消解方式、消解液过滤及pH调整等参数优化研究，确定了土壤中六价铬提取与测试的优化条件：消解液组成为碱性提取液20 mL、氯化镁100 mg、磷酸氢二钾-磷酸二氢钾缓冲溶液0.2 mL，3次微波消解，消解液用中速定量滤纸过滤，待测液pH调节至7.0~8.0. 在优化条件下，土壤六价铬的有证标准样品的测量结果均在标准值范围内，土壤基体加标回收率为85.5%~88.7%，相对标准偏差为7.6%~8.0%. 与HJ 1082—2019相比，本文建立的微波消解火焰原子吸收光谱法更适用于大批量土壤样品的六价铬检测分析，所采用的微波消解技术，操作相对简单、提取效率较高，易于在不同种类实验室中普及和推广，可为土壤中六价铬的快速准确检测提供技术支持和方法补充.
- 碱溶液提取 /
- 微波消解 /
- 六价铬 /
- 土壤
Abstract: The alkali solution extraction method is commonly used to extract hexavalent chromium in soils, according to the standard for Alkali Solution Extraction-Flame Atomic Absorption Spectrophotometry (HJ 1082-2019). This method has some problems for the detection of batch soils, including long extraction time, high reagent consumption, and large temperature variations. Therefore, it is highly desirable to develop a determination method of hexavalent chromium in soils with high efficiency and accuracy for risk assessments and remediation decisions of hexavalent chromium in soils. In this study, we developed a microwave digestion-flame atomic absorption spectrometry method of hexavalent chromium in soils. By conducting the effect experiments of extraction agents, microwave digestion conditions, digestion solution filtration treatments, we optimized the conditions for extracting and determining hexavalent chromium in soils. The digestion solution was composed of 20 mL of alkaline extract, 100 mg of magnesium chloride, 0.2 mL of dipotassium hydrogen phosphate buffer solution. Microwave digestion was conducted three times. The digested solution was filtrated with medium speed quantitative filter paper, and pH values of the solution were adjusted to 7.0-8.0. Under the optimized conditions, the observed concentrations of certified standard samples of soil were all within the range of standard values, and the recoveries of soil matrix spiked ranged from 85.5% to 88.7%, with the relative standard deviations of 7.6%-8.0%. Compared to the standard method of Alkali Solution Extraction-Flame Atomic Absorption Spectrophotometry (HJ 1082-2019), the method established in this study is suitable for the determination of hexavalent chromium in a large number of soil samples. Microwave digestion technology not only has high extraction efficiency, but also is technically facile and popular in different levels of laboratories. The method of microwave digestion-flame atomic absorption spectrometry proposed in this study will provide technical support for the rapid and accurate determination of hexavalent chromium in soils.
- alkali solution extraction /
- microwave digestion /
- hexavalent chromium /
- soils

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图 1 不同消解方案对六价铬提取效率的影响

Figure 1. Effects of different digestion schemes on extraction efficiency of hexavalent chromium

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表 1 正交试验因素与水平设计

Table 1. Orthogonal test factors and horizontal design

因素	水平
因素	1	2	3
碱性提取液/mL	10	15	20
氯化镁/mg	100	200	300
磷酸缓冲溶液/mL	0.1	0.2	0.3

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表 2 正交试验方案及结果

Table 2. Orthogonal test scheme and results

项目		碱性提取液(A)	氯化镁(B)	磷酸缓冲溶液(C)	土壤中六价铬的测量值/(mg/kg)
试验号	1	10	100	0.1	34.95
	2	10	200	0.2	40.60
	3	10	300	0.3	12.20
	4	15	100	0.2	41.45
	5	15	200	0.3	18.70
	6	15	300	0.1	24.49
	7	20	100	0.3	38.76
	8	20	200	0.1	42.58
	9	20	300	0.2	43.00
K₁		87.75	115.16	102.02
K₂		84.64	101.88	125.05
K₃		124.34	79.69	69.66
k₁		29.250	38.387	34.007
k₂		28.213	33.960	41.683
k₃		41.447	26.563	23.220
r		13.234	11.824	18.463
主次因素：C>A>B
最优组合：C₂A₃B₁

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表 3 微波消解升温程序

Table 3. Heating procedure of microwave digestion

步骤	升温或降温时间/min	目标温度/℃	保持时间/min
1	10	93	60
2	10	20	5
3	10	93	30
4	10	20	5
5	10	93	30
6	10	20	5

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表 4 不同过滤方式下六价铬的提取效率

Table 4. Extraction efficiency of hexavalent chromium under different filtration methods

过滤方式	加标量为0.2 mg/L
	六价铬浓度/(mg/L)			平均值/ (mg/L)	平均加标回收率/%	标准偏差/(mg/L)	相对标准偏差/%
	平行样1	平行样2	平行样3	平均值/ (mg/L)	平均加标回收率/%	标准偏差/(mg/L)	相对标准偏差/%
中速定量滤纸	0.170	0.161	0.168	0.166	83.2	0.0047	2.8
0.45 μm滤膜抽滤	0.164	0.172	0.173	0.170	84.8	0.0049	2.9
离心机分离过滤	0.166	0.169	0.159	0.165	82.3	0.0051	3.1

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表 5 有证标准品测试数据

Table 5. Test data of certified standards

有证标准品	六价铬测量值/(mg/kg)			平均值/(mg/kg)	相对标准偏差/%	标准值及不确定度/(mg/kg)
有证标准品	平行样1	平行样2	平行样3	平均值/(mg/kg)	相对标准偏差/%	标准值及不确定度/(mg/kg)
GBW(E)070254	6.5	6.6	6.9	6.7	3.1	7.1±0.7
GBW(E)070255	63.7	60.7	61.6	62.0	2.5	68±7
GBW(E)070253	4.1	3.4	3.6	3.7	9.7	3.8±0.4
GBW(E)070252	2.7	3.2	3.1	3.0	8.8	2.9±0.3
GBW(E)070251	0.7	0.8	1.0	0.8	19.1	0.92±0.09

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表 6 基体加标测试数据

Table 6. Test data of matrix addition

采样区域	基体六价铬测量值/(mg/kg)	六价铬测量值/(mg/kg)			平均值/(mg/kg)	加标量/(mg/kg)	加标回收率 /%
采样区域	基体六价铬测量值/(mg/kg)	平行样1	平行样2	平行样3	平均值/(mg/kg)	加标量/(mg/kg)	加标回收率 /%
瓦房店	2.0	8.1	7.7	7.9	7.9	8.0	73.8
盘锦	2.1	8.3	7.5	7.8	7.9	8.0	72.1
石灰石矿	2.0	8.1	7.1	7.9	7.7	8.0	71.3

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表 7 微波消解火焰原子吸收光谱法基体加标测试数据

Table 7. Sample marking test data of microwave digestion flame atomic absorption spectrometry

采样区域	样品值/(mg/kg)	六价铬测量值/(mg/kg)			平均值/(mg/kg)	加标量/(mg/kg)	加标回收率 /%
采样区域	样品值/(mg/kg)	平行样1	平行样2	平行样3	平均值/(mg/kg)	加标量/(mg/kg)	加标回收率 /%
瓦房店	2.0	8.2	8.7	9.4	8.8	8.0	84.6
盘锦	2.1	8.3	8.9	8.5	8.6	8.0	80.8
石灰石矿	2.0	8.1	8.8	9.0	8.6	8.0	82.9

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表 8 六价铬土壤污染样本测试结果

Table 8. Test of soil samples contaminated with hexavalent chromium

检测方法	六价铬测量值/(mg/kg)						平均值/(mg/kg)	标准偏差/(mg/kg)	相对标准偏差/%
检测方法	平行样1	平行样2	平行样3	平行样4	平行样5	平行样6	平均值/(mg/kg)	标准偏差/(mg/kg)	相对标准偏差/%
HJ 1082—2019	34.1	29.1	29.8	31.7	34.5	33.5	32.1	2.3	7.1
微波消解火焰原子吸收光谱法	35.7	35.1	30.6	36.7	33.4	36.6	34.7	2.3	6.7

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表 9 三价铬加标测试数据

Table 9. Trivalent chromium spiked test data

有证标准品	六价铬标准值及不确定度/(mg/kg)	三价铬加标量/(mg/kg)	加标后六价铬测量值/(mg/kg)
有证标准品	六价铬标准值及不确定度/(mg/kg)	三价铬加标量/(mg/kg)	平行样1	平行样2	平行样3
GBW(E)070255-1	68±7	20	63.4	61.7	66.5
GBW(E)070255-2	68±7	50	61.9	66.1	71.8
GBW(E)070255-3	68±7	100	62.4	65.6	70.4

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表 10 精密度测定结果

Table 10. Precision measurement results

样品编号	六价铬测量值/(mg/kg)	加标回收率/%	六价铬测量值平均值/(mg/kg)	加标量/(mg/kg)	加标回收率平均值/%	标准偏差/(mg/kg)	相对标准偏差/%
1-1	31.1	112	28.5	10	85.5	2.15	7.6
1-2	28.7	88.0
1-3	26.1	62.0
1-4	26.8	69.0
1-5	30.9	110
1-6	27.1	72.0
2-1	55.9	90.0	55.1	40	88.0	4.31	7.8
2-2	55.1	88.0
2-3	52.8	82.3
2-4	62.9	107
2-5	50.2	75.8
2-6	53.6	84.3
3-1	74.4	90.8	73.1	60	88.7	5.83	8.0
3-2	69.5	82.7
3-3	84.3	107
3-4	71.6	86.2
3-5	69.9	83.3
3-6	68.9	81.7

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表 11 土壤中六价铬的方法检出限

Table 11. Method detection limits of hexavalent chromium in soil

六价铬含量/(mg/kg)							标准偏差/(mg/kg)	检出限/(mg/kg)	测定下限/(mg/kg)
样品1	样品2	样品3	样品4	样品5	样品6	样品7	标准偏差/(mg/kg)	检出限/(mg/kg)	测定下限/(mg/kg)
3.24	3.18	2.79	3.18	2.85	3.06	2.73	0.21	0.66	2.64

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