Home > Determination of Inorganic Micro Pollutants in Soil and Water through Microwave Digestion

Determination of Inorganic Micro Pollutants in Soil and Water through Microwave Digestion

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article image Milestone ETHOS 1 Microwave Digestion System

John Morris Scientific  is a major distributor of an advanced range of scientific, testing, analysis and laboratory equipment in Australia.  

Sample preparation is a critical part of any analytical process and also the most restricting. Results are totally dependent on the quantitative conversion of a solid into a homogeneous solution.  

Matrix dissolution is a traditional method for wet sample preparation wherein a large volume of reagent is heated for several hours using a hot plate or oven. This process is finished when the analyst visually confirms that the digestion is complete.

Key shortcomings of this method include:

  • Large quantities of reagents required
  • Potential for contamination
  • Continuous release of hot acid vapour into the laboratory environment

Microwave decomposition  

A more efficient method involves microwave decomposition, which uses a completely different technology that improves digestion efficiency and increases the safety of laboratory personnel.  

This is because microwave instruments have been specifically designed to improve the process of sample preparation.

Given the advantages of microwave assisted sample preparation, the USA Environmental Protection Agency (US-EPA) has developed a range of methods that employs this innovative technology in water and soil analysis for determination of organic and inorganic micro pollutants.  

These procedures enable the rapid analysis of metals in water samples and metals in soils. The US-EPA3052 method describes the procedure for total sample digestion. In particular, it refers to the treatment of matrices containing silicates (soils and sediments) as well as organic matrices (soil polluted by oil and hydrocarbons).

The microwave technique can also be applied to determination of organic pollutants such as pesticides, herbicides, phenols, PCB and PCDD/PCDF.  

For example, the most commonly used method is US-EPA3546: its application enables the sample preparation needed for chromatographic analysis.

US-EPA3546 requires a treatment time of just 30 minutes. The main advantage apart from time-reduction is the efficiency of the process in which solvent and solute are at the same extraction temperature.

Instrumentation  

Using modern microwave digestion systems for sample preparation to determine micro pollutants in soil and water is effective primarily due to the high technological level and maximum ease of use.

  • All parts including software and hardware have been built to reach maximum quality standards allowing the operator to optimise the sample preparation process
  • These units are equipped with the latest generation sensors for temperature and pressure control in all vessels
  • Various types of vessels used in the sample preparation process have been engineered carefully in terms of choice of materials and safety systems

Future Possibilities and Versatility of the Technique  

Since analytical laboratories need different products and matrices are very heterogeneous, manufacturers have decided to develop and produce carousels with different technical specifications, both for varying temperature and pressure limits.  

These solutions increase the versatility of microwave platforms and offer the best solution for all the application fields.  

The Milestone ETHOS 1 available from John Morris Scientific is designed to facilitate four major applications with one system: in addition to acid digestion, the sample preparation equipment can also manage solvent extraction, evaporation and microwave fusion.

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