IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 BOOK OF ABSTRACTS 48 Analysis and Characterization Tuesday, 25 August 2026 / Hall B+C SL18 Control of Biopolymers for Chlorine-free Tap Water With High-Resolution Liquid Chromatography – Organic Carbon Detection (LC-OCD) Stefan Alexander Huber DOC-LABOR GmbH, 76229 Karlsruhe, Germany, doc@doc-labor.de A “biologic stable water” that does not promote bacterial regrowth in the water net is a pre-requisite – if not “the” prerequisite – for the supply of chlorine-free tap water to households. This precludes that the mass of bioavailable organic matter in the treated water is below certain threshold values. For example, a recent survey has suggested that the maximum allowable value for biopolymers in biologic stable drinking waters should not exceed a value of 47 ppb biopolymers (as mass) [1]. Achieving such a low value for a surface water as raw water source (ground waters are devoid of biopolymers) is a challenge and certainly a matter of pride for the designers of the plant. The analysis and the control of the “biopolymer value” is another challenge. A recent publication compared two off-line methods for biopolymer analysis [2], one preparative approach based on isolation of biopolymers by membrane cascades followed by DOC-analysis of the extracts in a TOC-analyzer (PHMOC) and another analytical approach based on chromatographic separation of biopolymers followed by continuous DOC-detection (LC-OCD) [3]. Both approaches showed a good correlation but results for LC-OCD were consistently lower by about 10-20 %. As manufacturer of LC-OCDs we know that the reason is insufficient separation of biopolymers from humics. Humics cut into the right slope of the biopolymer signal and this leads to a lower value for the biopolymer peak area. To overcome this problem, we have developed a new size-exclusion column which allows a better resolution of the biopolymer peak. With this new column data for PHMOC and LC-OCD should be in better agreement. Fig. 1: LC-OCD chromatogram of a surface water (River Pfinz, Karlsruhe) with new column
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