What is AOX analysis?

AOX analysis is used for compliance with DIN ISO 9652, EPA 1650 for AOX in water and wastewater, and EPA 9020B for TOX in wastewater


Halogenated organic compounds (HOC) have increasingly been used within various industries over the years. Some man-made halogenated compounds are toxic, mutagenic, or carcinogenic and they may have harmful effects on human health and the environment.

Adsorbable Organic Halogen (AOX) Compounds (X = Cl, Br, I)) is a sum parameter for describing the organic halogen compound load in water, sewage sludge and soils. The parameter covers a large group of substances from simple volatile substances such as trichloromethane (chloroform), or complex organic molecules such as dioxins/furans with a large variety of toxic properties. Most AOXs are chlorine-containing molecules, but bromo- and iodo-AOXs do also occur.

AOX compounds pose a potential concern because they resist breaking down in the environment, and therefore they have long half-life periods. Some of these molecules toxic and can pose a threat to aquatic organisms living in estuaries because they can bioaccumulate in the food chain. Hence, AOX can be important in effluent quality monitoring from both landfill leachates, and industry, in order to meet discharge limits.


There are a number of AOX/TOX regulations in force, for example, DIN ISO 9652, EPA 1650 for AOX in water and wastewater, and EPA 9020B for TOX in wastewater.

The overall concept is relatively simple; the AOX compounds will adsorb onto activated charcoal under certain conditions so once the sample has been acidified, we can collect the AOX onto the charcoal, combust the charcoal and measure the AOX using microcoulometric titration.



  • Easy to handle
  • Reduced maintenance
  • Intelligent Multiwin software
  • Fast changeover between batch and column methods
  • High sample throughput
  • Automated sample preparation and sample analysis



The Multi X 2500 is suitable for all matrices, is more than ‘just’ an AOX analyser as it is also suitable for EOX, POX, TOX, TX and TOC applications, and works with a range of autosamplers and sample preparation systems to ensure that there is a configuration that will suit your requirements.


If you are looking to analyse solid samples (typically sludge, sediment, paper and pulp) then we can provide the AFU 3 sample preparation unit.


Automatic Filtration Unit AFU 3
Automatic Filtration Unit AFU 3
  • The Automatic Filtration Unit AFU 3 offers semi-automated AOX sample preparation for the batch method. This is a simple and quick alternative to the classical membrane filtration. Up to 3 samples of up to 180 mL volume can be processed simultaneously.


  • With an optional extension kit, the AFU 3 can also be used for AOX sample preparation for the column method. In this case the sample preparation unit can be equipped with either duplex or triplex column holders.


  • The flow rate is predefined by the integrated nozzles. If needed the pump may also be operated with an inert auxiliary gas.


  • Pressure-tested sample vessels and an acrylic glass screen high operational safety.






For liquid analyses we offer a range of sample preparation systems that fit the requirement of your laboratory and sample matrix.

If you have liquid samples then one of the first things you need to consider is whether you need to perform an SPE extraction before the AOX adsorption. One example of needing to do this extraction first would be in the event of high levels of inorganic chlorine in your sample.

We have a range of sample prep systems that will do this SPE extraction for you.


The APU Sim
The APU Sim
  • The APU Sim can simultaneously process six samples in three separate enrichment channels.


  • The sample volume, the rinse volume and adsorption rate are all independently selectable


  • It complies with a range of legislation, e.g., DIN 9652


  • It can be used with duplex and triplex columns; indeed, it can work with any column up to 150 mm in length.






All of the APU 28 sample preparation systems can be used with a variety of different sized AOX adsorption columns.

The APU 28 series
The APU 28 series


  • The APU 28 series is fully automated and comes in a range of different options


  • The APU 28 Basic processes up to 28 samples in succession


  • The APU S; simultaneous prep of 2 samples, with up to 112 samples per day


  • The APU SPE; can perform standard AOX and SPE-AOX sample preparation. Fully automated SPE extraction and elution and adsorption onto the active charcoal.


Can I use an Autosampler on an AOX  analyser?

We have a choice of autosamplers available fpr the analysis of solids and liquid samples


The autoX 36 autosampler
The autoX 36 autosampler
AOX120 for solid samples
AOX120 for solid samples
AOX112 autosampler for liquids
AOX112 Liquid TOC Analysis


  • The autoX 36 autosampler can introduce up to 36 batch or column samples in one run.
  • The autoX 36 delivers the active carbon container to the furnace whereas the autoX 36d inserts only the active carbon to the furnace.
  • The autoX 112 can transport samples to either the vertical or horizontal furnace, can work with liquids, pastes or solids.
  • EOX analysis can be automated with the autoX 112
  • And samples can be analysed for TOC content using the autoX 112 autosampler.


The double furnace design allows complete flexibility for all sample types.

The vertical furnace is particularly suited to liquid samples where there is choice of analysing just the active charcoal or the complete container, and the horizontal furnace can analyse up to 112 solid samples in one run.

AOX Double furnace
AOX Double furnace

To analyse for AOX we use a unique patented wide-range coulometer; it has a lightproof cell, is Peltier cooled and has a self-cleaning silver anode.



AOX electrolyte cell
AOX electrolyte cell

It has a very wide working range of 10 ng Cl (absolute) up 1000 ug Cl (absolute)

The electrolyte solution can’t become ‘exhausted’ during use

It requires no diaphragm or salt-bridge, and is maintenance free

The Multi X 2500 analyser is the highest performing AOX analyser available and can be extended to EOX, POX, TOX, TX, TC, TIC and TOC applications.

Whatever your sample, whatever your halogen – we can analyse it.


Are there application notes describing AOX measurement compliance?

The following application notes are available ( on request):

  1. AOX in wastewater by the column method complying with DIN EN ISO 9562 legislation
  2. AOX in sewage and sludge samples by the batch method according to EN 16166
  3. AOX in high saline water samplers after SPE extraction
  4. AOX linearity test, using the column method, to conform to DIN EN ISO 9562

Make reference to the relevant applicaiton note for it to be sent to you by one of our product managers

What sample preparation options are available for AOX analysis?

A detailed flier is available on request as a PDF document:

  1. AOX sample preparation options:
  2. AOX sample preparation options when performing the column method

To find out more about the Multi X2500 AOX analyser, CLICK HERE