Determination of Adsorbable Organic Halogens in Highly Saline Water Samples after Solid Phase Extraction (SPE-AOX) Application Note · multi X 2500

Introduction

An easy and fully automated method for the correct determination of AOX contents in the presence of extremely high (c > 1 g/L) quantities of inorganic halides is often needed when analyzing marine water samples, industrial wastewater and brine applications (SPE-AOX according to ISO 9562:2004). The presence of high amounts of inorganic halogen compounds negativetely affects the determination of AOX. When such samples are analyzed directly by means of common AOX methods (adsorption on charcoal and combustion), results will be falsified and too high. To avoid this, the interfering compounds have to be removed before the adsorption. Solid phase extraction (SPE) has proven to be the most efficient and easy method to do this.

For the measurement, the samples were enriched on SPE cartridges. To achieve an easy and effective segregation between organic and inorganic matter, a polymer resin was used for separation. The resin captures only the organic halogen compounds, while letting the inorganic material pass through. The AOX was then eluted with methanol and diluted in ultrapure water. This mixture was adsorbed on prefilled charcoal columns, followed by a final washing process to ensure a complete separation of inorganic and organic halogen compounds.

Since this is a time-consuming process, laboratories facing increasing time and work pressure strive to facilitate the workflow. The sample preparation unit APU 28 SPE enables fast and unattended, fully automated preparation of SPE-AOX samples, thus highly shortening processing time. Combined with the multi X® 2500 AOX analyzer, the APU 28 SPE ensures fast, precise and reliable results, which are mandatory for laboratories.