EOX – Extractable organically bound halogens

EOX is a chemical-analytical sum parameter that, similar to AOX, is used to determine the total halogenated organic compounds. It provides the sum of the organic halogens that can be extracted using a solvent.

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What is EOX?

The sum parameter EOX represents the organically bound halogens chlorine, bromine and iodine contained in a sample that can be acquired during extraction using a non-polar solvent and subsequent combustion. Fluorine is, however, not acquired due to its high reactivity; instead it is acquired via the sum parameter EOF (extractable organically bound fluorine). EOX is used primarily during the analysis of solids, for instance waste of all types such as excavated soil and building rubble, as well as to some extent during the analysis of water samples.

What is a sum parameter?

A sum parameter is an analytical measurand that specifies the total concentration or overall levels of a specific group of compounds in a sample, instead of analysing each individual compound separately. This approach makes it possible to evaluate complex matrices efficiently. By means of the use of sum parameters, the time and costs for the analysis can be reduced while at the same time making possible a comprehensive evaluation of the sample.

The sum parameter EOX

In the case of extractable organically bound halogens (EOX) or adsorbable organically bound halogens (AOX), a sum parameter makes it possible, for example, to determine the total concentration of organic halogen compounds in a sample, without the need to analyse each individual compound separately. This situation makes it easier to monitor environmental pollution and ensure compliance with directives such as RoHS or WEEE.

Combustion ion chromatography (CIC) for EOX analysis

Quality Analysis analyses your sample for EOX

Quality Analysis undertakes precise EOX analyses to check your products reliably for freedom from halogens and to ensure compliance with the RoHS and WEEE directives. Our expertise enables us to identify and quantify extractable organic halogen compounds effectively in solid matrices such as soil and sediment. By providing you with precise data, we assist you with compliance with regulatory requirements, contribute to product quality and ensure the safety of your products.

The characteristics of extractable organically bound halogens

The characteristics of extractable organically bound halogens (EOX) are varied and play a crucial role in various environmental and industrial applications. Halogens are a group of chemical elements classified as non-metallic materials and are in the seventh main group of the periodic system. The most common halogens include chlorine (Cl), bromine (Br), iodine (I) and fluorine (F). Their chemical properties are characterised by high reactivity, in particular during the formation of salts and hydrogen halides. This reactivity makes halogens important raw materials in various industries, from the manufacture of disinfectants to plastics.

Why are extractable organically bound halogens monitored?

Organic halogens are a special group of compounds that contain carbon molecules in which halogen atoms are bound. These compounds can be persistent in the environment and accumulate in living organisms, which gives rise to potential environmental and health risks. For this reason the analysis and monitoring of EOX is of crucial importance for the identification of environmental hazards and the adoption of suitable risk reduction measures.

What is the difference between EOX and AOX?

While EOX extracts the total concentration of organic halogen compounds in a sample, independent of their adsorption characteristics, AOX (adsorbable organic halogen compounds) concentrates on the quantity of organic halogen compounds that can be adsorbed on activated carbon. EOX therefore permits a broader analysis of organic halogens in various sample matrices such as solids, liquids and gaseous samples, while AOX permits a more specific analysis of the adsorbable halogens in predominantly liquid samples such as waste water and surface water.

Analysis of the sum parameter EOX using combustion ion chromatography

For the determination of the parameter EOX, first the sample is extracted using a specified volume of a non-polar solvent such as an n-alkane, mostly pentane, hexane or heptane. This extraction is used to isolate the organic halogen compounds from the sample and to prepare them for subsequent analysis using combustion ion chromatography (CIC).

Combustion and absorption

After extraction, the extract is subjected to combustion; as a consequence the organic halogen compounds are converted to their ionic forms. The combustion at high temperatures ensures that all organic halogen compounds are completely converted into their ionic forms. Subsequent ion chromatography enables specific, sensitive measurement of the halogens. The resulting halides are passed through an absorption solution in which the EOX halogens, chlorine, bromine and iodine, are collected. This step makes it possible to extract the halides from the sample and to prepare them for subsequent analysis.

Conductivity measurement and result

The absorption solution is analysed using a conductivity measurement. Here the concentration of the halides (such as chloride, bromide, iodide) is determined; this concentration provides a direct measure of the quantity of organic halogen compounds present in the sample. The resulting EOX value reflects the total concentration of all organic halogen compounds in the sample that can be extracted using the method; in this way comprehensive evaluation of the halogen load is made possible.

Combustion ion chromatography (CIC)

EOX analytics for verification of freedom from halogens

By using EOX analysis, manufacturers and test laboratories can check materials and products are free from halogens by determining the total concentration of extractable organically bound halogens. A low EOX level is indicative of a low halogen load and can serve as an indicator for the freedom of a product from halogens. This verification is important to ensure that materials and products meet the requirements on the protection of the environment, health and safety, and they do not have any undesirable effects on humans or the environment. In particular, in sectors such as the electronics, food and textile industries, as well as during the manufacture of plastics and packaging, freedom from halogens is an important quality feature.

Summary: EOX

EOX (extractable organically bound halogens) is a sum parameter that measures the total concentration of organically bound halogens such as chlorine, bromine and iodine (but not fluorine) in samples to evaluate environmental and health risks. It is used above all during the analysis of solids such as waste and soil samples and plays a crucial role during the monitoring of environmental pollution as well as compliance with directives such as RoHS or WEEE.

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