Antimony speciation in soils: improving the detection limits using post-column pre-reduction hydride generation...

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Geochemistry

Background:

• High-performance liquid chromatography with hydride generation-atomic fluorescence spectrometry (HPLC/HG-AFS) is a sensitive, low-cost system for antimony speciation.
• Soil antimony speciation is challenging due to oxalic acid, a common extractant, inhibiting Sb(V) hydride generation and increasing detection limits.

Purpose of the Study:

• To reduce the detection limit of antimony(V) (Sb(V)) in soil samples.
• To develop a more effective antimony speciation analysis method for complex matrices like soil.

Main Methods:

• A post-column on-line reduction system using l-cysteine was coupled with HPLC/HG-AFS.
• The system was optimized using experimental design, identifying optimal conditions of 2% (w/v) l-cysteine and a 10°C temperature coil.
• The developed methodology was applied to analyze antimony species in Chilean soil samples.

Main Results:

• Detection limits for Sb(V) and Sb(III) in 0.25 mol L(-1) oxalic acid were improved from 0.3 and 0.1 μg L(-1) to 0.07 and 0.07 μg L(-1), respectively.
• The optimized system demonstrated effective antimony speciation in soil samples.
• Antimony(V) was identified as the predominant species in the analyzed Chilean soils.

Conclusions:

• The developed HPLC/pre-reduction/HG-AFS method significantly enhances the detection of Sb(V) in oxalic acid extracts.
• This improved methodology overcomes limitations of previous techniques for soil antimony speciation.
• The findings are crucial for accurate environmental monitoring and risk assessment of antimony in soils.