High-temperature, microwave-assisted UV digestion: a promising sample preparation technique for trace element...

Area of Science:

• Analytical Chemistry
• Environmental Science
• Spectroscopy

Background:

• Trace element analysis in diverse liquid matrices is crucial for environmental and health monitoring.
• Existing methods for sample digestion, particularly for dissolved organic carbon (DOC), can be time-consuming and limited in efficiency.
• High concentrations of DOC can interfere with accurate trace element determination.

Purpose of the Study:

• To develop and evaluate a novel, accelerated microwave-assisted high-temperature UV digestion procedure.
• To enhance the decomposition of interfering dissolved organic carbon (DOC) in liquid samples.
• To improve the efficiency and speed of sample preparation for trace element analysis.

Main Methods:

• A closed, pressurized microwave digestion device utilizing immersed electrodeless Cd discharge lamps (228 nm) for UV irradiation.
• An antenna was incorporated to enhance UV excitation efficiency.
• The system achieved reaction temperatures of 250-280°C for efficient mineralization.

Main Results:

• Decomposition time was reduced by a factor of 5 compared to open UV digestion devices.
• The maximum initial concentration of DOC that could be handled increased by at least a factor of 50.
• Accurate trace element recovery (Cd, Cu, Fe, Pb) was demonstrated in skimmed milk certified reference material.

Conclusions:

• The developed microwave-assisted UV digestion is a highly efficient method for sample preparation.
• This technique significantly accelerates the mineralization of DOC in various liquid samples.
• The method provides accurate trace element determination, suitable for complex matrices like wastewater and biological fluids.