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Determination of Antimony Forms in Soil by HPLC-ICP-MS
Date: 2025-11-08Read: 6
Antimony (Sb) is a toxic metal elementIn the world, antimony is the ninth metal in mining output, and its compounds are listed as key pollutants by the U.S. Environmental Protection Agency. Due to its widespread use and corresponding antimony mining activities, the environmental concern for the metallic antimony is increasing day by day. Natural phenomena such as weathering, biological activity, and volcanic activity, combined with anthropogenic inputs, result in the emission of antimony into the environment. Antimony emitted into the environment can undergo adsorption and redox reactions on organic or inorganic environmental media, thereby changing its form and causing toxic effects on ecosystems.
Antimony has multiple oxidation states(0，III，V) ， Among them, oxidation states III and V are the most common inorganic forms in natural environments. In humid environments, Sb (OH) 3 and Sb (OH) 6 are the main chemical forms. Generally speaking, inorganic antimony compounds are more toxic than organic antimony compounds, and Sb (III) is more toxic than Sb (V) 2. In soil solution, antimony mainly exists in the form of pentavalent oxide ion Sb (OH) 6. Therefore, determining the chemical form of antimony is crucial for environmental fate and behavior.
For the morphological analysis of Sb (III) and Sb (V), Gudny Okkenhaug3 reported the use of hydride generation inductively coupled plasma optical emission spectroscopy (HG-ICP-OES) to convert Sb (III) to SbH3 by mixing the sample solution with NaBH4. Reduce Sb (V) to Sb (III) using KI ascorbic acid solution and analyze the total Sb (Sbtot). The concentration of Sb (V) is calculated by the concentration difference between Sbtot and Sb (III). This method is time-consuming and requires two analyses of the sample. Faye Liu4 reported that HPLC-ICP-MS method can be used to determine the concentrations of total Sb, Sb (III), and Sb (V) in water.
In this studyAnion exchange methodRegarding soil samplesCharacterization of Sb (V) and Sb (III). UsePerkinElmer NexSAR ™ HPLC-ICP-MSMorphological analysis is a practical solution for analysis, which combines withNexION ® Composition of NexSAR Inert HPLC using 1100 ICP-MS.
Experimental Design
1 sample preparation
►The soil samples were collected from Guangzhou, China. Considering the heterogeneity of the samples, three soil samples (0.02 g) were accurately weighed using an analytical balance (Mettler Toledo, Columbus, Ohio, USA) and placed in a 15 mL polypropylene tube (Crystalgen, Connecticut, New York, USA). Add 100 μ L hydrochloric acid (UP grade, 68%, Suzhou Jingrui Chemical Co., Ltd., Suzhou, Jiangsu) to each sample, shake the test tube to ensure that the sample is completely immersed in hydrochloric acid. After standing for 20 minutes, add 9.9 mL of 1% citric acid for testing.
►Dissolve solid Sb2O3 (99.99%, Shanghai Aladdin Biochemical Technology Co., Ltd., Shanghai, China) in 37% HCl to prepare Sb (III) with a concentration of 1000 ppm. Prepare Sb (V) using a 1000 ppm Sb single element standard solution (PerkinElmer, Sheldon, Connecticut, USA), and then dilute to volume with 1% citric acid to prepare Sb (III) and Sb (V) standard solutions with concentrations of 1, 2, 5, and 10 μ g/L, respectively.
►Due to the lack of certified reference materials, spiked samples (spiked with 1 ppb μ g/L mixed antimony form) were prepared to verify the analytical accuracy of the method.
►Prepare a mobile phase using 20 mmol/L ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) and 15 mmol/L phthalate in ultrapure water. During this period, the calibration standards, soil samples, and blanks were transferred to metal free polypropylene HPLC bottles for direct analysis without dilution.
2 instrument
All analyses were conducted using a NexSAR morphological analysis ready to use HPLC system (PerkinElmer, Sheldon, Connecticut, USA), which consists of a NexSAR 200 Inert HPLC pump, a cooled inert automatic sampler, and a solvent tray with a degassing device. This system is used in conjunction with NexION 1100 ICP-MS (PerkinElmer). The detailed information of HPLC and ICP-MS analysis conditions are shown in Table 1 and Table 2, respectively. Both samples and standards operate in standard mode. All analysis and data collection were conducted using Clarity morphological analysis chromatography software (DataApex, Prague, Czech Republic).
Table 1. Analysis Conditions of NexSAR Inert HPLC
Table 2. NexION ICP-MS Instrument Parameters
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Results and Discussion
►The correlation coefficients of Sb (III) and Sb (V) standards (1-10 μ g/L, n=5) were 0.99934 and 0.99983, respectively (as shown in Figure 1a and Figure 1b).
Figure 1. (a) Linear regression and corresponding correlation coefficients of calibration standards for 1% citric acid solution of Sb (III) and 1% citric acid solution of Sb (V) at concentrations of 1-10 μ g/L (click to view the larger image)
►The spectrum overlay of 1-10 μ g/L calibration standard (Figure 2) shows consistent peak positions, indicating that the NexSAR 200 Inert HPLC pump can provide reliable flow rates, ensure accurate identification of chromatographic peaks, and always present sharp peak shapes, thereby obtaining high-precision data and excellent signal-to-noise ratio.
Figure 2. Spectral overlay of calibration standards (1-10 μ g/L, n=5) in mobile phase (click to view larger image)
In this study, Clarity was used ™ The ASTM noise evaluation function in the software determines the quantitative limit of each form, that is, the concentration corresponding to the peak generated being 10 times the baseline noise amplitude (i.e. 10 S/N (signal-to-noise ratio)). The quantification limits of Sb (III) and Sb (V) using the defined mobile phase are 65 ng/L and 48 ng/L, respectively. If a lower limit of quantification is required, it can be achieved through various methods, such asExtend residence time to improve signal-to-noise ratio and increase column temperature(If allowed by chromatographic column specifications)Replace the chromatographic column(Narrow diameter)andFlow is equal.
►Figures 3a-c show the spectral superposition of three unlabeled soil samples and one spiked (1 μ g/L) soil sample. Table 3 shows the measured values of three soil samples and the Sb (III) and Sb (V) recovery rates for each sample. The superposition of spectra indicates that the sample matrix does not affect the retention time of different antimony forms, demonstrating the robustness of this method, and this characteristic is further improved by the accuracy of chromatographic pump flow rate. The excellent spiked recovery rate further confirms the method and demonstrates its accuracy for quantitative analysis of Sb (III) and Sb (V) in soil matrix.
Figure 3. Spectral overlay of soil sample (blue) and 1 ppb spiked soil sample (red) (click to view larger image)
Table 3. Numerical values and recovery rates of soil samples
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Conclusion
This study adoptsNexSAR HPLC-ICP-MS Morphological SolutionThe evaluation of Sb (III) and Sb (V) in soil was conducted using a system consisting ofComposition of Inert NexSAR Inert HPLC System and NexION ICP-MSIsocratic elution can achieve complete baseline separation of Sb (III) and Sb (V) within 4 minutes.
As shown in this study, NexION ICP-MSrobustPlasma and NexSAR HPLC PumppreciseMobile phase transport,It is crucial to achieve consistent and reproducible separation and analysisNexSAR's inert tubing without metal residue canEnsure that the HPLC system does not produce contaminationThe active sealing and cleaning function reduces system maintenance requirements, increases instrument normal operation time, and ultimately improves laboratory throughput.
►Consumables used
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reference document
1. Water Related Fate of the 129 Priority Pollutants. USEPA, 1979 Washington, DC, USA.
2. Filella, M et al, “Antimony in the environment: a review focused on natural waters II”, Relevant solution chemistry. Earth-Science Reviews 59, 265-285.
3. Gudny Okkenhaug et al，“Distribution, speciation and availability of antimony (Sb) in soils and terrestrial plants from an active Sb mining area”, Environmental Pollution,Vol. (159) 2427-2434, 2011.
4. Faye Liu et al, “Antimony speciation and contamination of waters in the Xikuangshan antimony mining and smelting area, China”, Environ Geochem Health, Vol. (32) 401-413,2010.