Total Organic Halides (TOX) Determination

The presence of total organic halides in soils and sediments is a good indicator, and is often used to detect whether soils or subsurface aquifers are contaminated. Many halogenated organic compounds are highly toxic to human health, some of them are even carcinogenic, while naturally occurring organohalides are very limited, so their presence can be a clear indication of manmade toxic contamination. Organohalogens are often routinely determined as group parametres in water and wastewater samples, such as organic halogens (AOX), extractable organic halogens or purgable organic halogens (POX). Generally, organic halogens with a tendency to bioaccumulate are present in the EOX-fraction of the water or wastewater. And extractable organic halogens contain chlorine, bromine, or iodine are detected. BOC Sciences has been specializing in the measurement of organic halogens and has a reputation for providing accurate and reliable testing services. We offer a variety of standards and adapted methods for specific sample applications, including PAPTAC, ISO, US EPA, PTS-RH and SCAN. Our chemists are able to perform fast and accurate organic halogen analysis in a wide range of liquid and solid matrices. In our pyrolysis/microcoulometry method, the sum of those organic halogens refer to halides contaning chlorine, bromine or iodine.

Applications of Our TOX Determination

• Drinking water
• Waste water
• Cooling water
• Process water
• Effluent water
• Pulp and paper
• Sediment
• Solid wastes
• Soils
• Suspended solids isolated from industrial wastewater

TOX Determination Workflow

TOX Analysis Method

At BOC Sciences, we can detect all organic halides containing chlorine, bromine, and iodine (TOX) as chloride in drinking water and ground waters through carbon adsorption. We employ tow methods to perform TOX analysis:

The first method is to investigate total halides (TX), inorganic halides (IX) and extractable organic halides (EOX) in the sample. The TX are determined by post-combustion microcoulometric titration of all halides present in the sample; The IX are determined by aqueous extraction of the sample followed by direct injection into the titration cell; and the EOX are determined by using the method of EP Document 600/4-84-008. The results are then compared to see if the mass balance is true: TX - IX= EOX.

The second method is completed by investigating the leachable organic halides (LOX). The LOX is determined by extracting soil with water and then analyzing the water for TOX by the carbon adsorption method (EPA Method 9020 in SW846).

Figure 1. Total organic halogen (TOX) species formation. (Kim, D.; et al. 2018)

TOX Quantification Method - Titration Method

• Firstly, a 1 g solid sample is extracted with ethyl acetate by sonification to isolate organic halides
• Then, a 25 mL aliquot of the extraction solution is injected or delivered by boat inlet a pyrolysis furnace oven using a stream of CO/O (or an appropriate alternative gas mixture)
• Finally, the pyrolysis products of hydrogen halides (HX) are determined by using microcoulomb titration