ARISTOT, ODOROUS COMPOUNDS ENRICHMENT TOOL AT CONSUMER · PDF fileCOMPOUNDS ENRICHMENT TOOL AT...

ARISTOT, ODOROUS COMPOUNDS ENRICHMENT TOOL AT CONSUMERS TAP VALIDATION AND SETTING UP
EXPERIMENTAL REPORT
Techneau, 10. MARCH 2010

2006 TECHNEAU TECHNEAU is an Integrated Project Funded by the European Commission under the Sixth Framework Programme, Sustainable Development, Global Change and Ecosystems Thematic Priority Area (contractnumber 018320). All rights reserved. No part of this book may be reproduced, stored in a database or retrieval system, or published, in any form or in any way, electronically, mechanically, by print, photoprint, microfilm or any other means without prior written permission from the publisher
ARISTOT, ODOROUS COMPOUNDS
ENRICHMENT TOOL AT CONSUMERS TAP VALIDATION AND SETTING UP
EXPERIMENTAL REPORT
Techneau, 10 March 2010

This report is: PU = Public
Colophon
Title
Aristot, odorous compounds enrichment tool at consumers tap Validation and setting up Experimental Report Author(s)
Christophe TONDELIER Anjou Recherche, Veolia Water Quality Assurance Pascal ROCHE David BENANOU Anjou Recherche, Veolia Water Deliverable number D 5.3.9 Aristot, odorous compounds enrichment tool at consumers tap Validation and setting up

TECHNEAU Aristot, odorous compounds enrichment tool at tap
TECHNEAU - 1 - March 2010
Summary
ARISTOT (Advanced and Relevant Investigation Sampler for Taste and Odor at Tap) is a passive sampler for odorous compounds which can be directly fixed on the tap of consumers who are disturbed by TO phenomena, so as to counter the problems related to these molecules fugacity. This ACS accredited tool was optimized in laboratory on a pilot as part of the Techneau project and was set up at the places of many consumers experiencing TO nuisances. Equipped with seven Twisters usually used for SBSE, ARISTOT exhibits a very high sensitivity and can extract molecules at concentration below 1ppt. The analysis of the seven traps can be performed by TDS-GC/MS in SIM mode with the multishot method for increased sensitivity. ARISTOT became the essential tool for tracking down and identifying odorous compounds. A possible evolution of the tool involves the use of different stationary phases.

Contents
Summary 1
Contents 2
Introduction 5
1 LABORATORY STUDY 6 1.1.1 Target compounds 6 1.1.2 The ARISTOT tool 7 1.1.3 The twister tap pilot 9 1.1.4 Twisters analysis 10
1.2 Qualitative study 11 1.2.1 Monitoring the tool enrichment 11 1.2.2 Unloading study 12 1.2.3 Influence of twisters dimensions 13 1.2.4 Influence of water flow rate 14 1.2.5 Influence of temperature 16 1.2.6 Conclusion 16
1.3 Progress toward quantitative measurement 17 1.3.1 Target compounds 17 1.3.2 Multishot method 18 1.3.3 Calibration 19 1.3.4 Quantitative applications on the pilot 21 1.3.4.1 Determination of extraction yields 21 1.3.4.2 ARISTOT evolution during low flow rates tests 21 1.3.4.3 Application of the tool 22 1.3.4.4 Enrichment monitoring at various concentrations and flow rates 23 1.3.5 Conclusion 27
2 REAL CASES STUDY 28
2.1 The ARISTOT kit 28
2.2 First installation of ARISTOT at consumers places 29
2.3 Analysis of ARISTOT components in contact with water 31 2.3.1 Twister cleaning 31 2.3.2 Cleaning of the Teflon boxes 33 2.3.3 ARISTOT cleaning 33
2.4 Real cases study, the next step 35 2.4.1 The case of consumer No. 1 35 2.4.2 The case of consumer No. 2 37 2.4.3 The case of consumer No. 3 38 2.4.3.1 The PAH problem 38 2.4.3.2 Supplementary tests under hot water 39 2.4.4 Introduction in a big city 40 2.4.5 Conclusion 41

Conclusion 42
Bibliography 43

Introduction
Water intended for human consumption must comply with very strict chemical, microbiological, physical and taste quality criteria. This last criterion, related to the control of water tastes and odors (TO), is gathering more and more attention from the industry. Indeed, consumers are able to assess the water organoleptic quality which they may wrongfully associate to health hazard. In France 65% of all consumers drink bottled water because of their dissatisfaction with tap water. Water industry within the framework of the European Techneau project is trying to understand the origin and generation of these palatable compounds so as to solve this TO issue. In order to do so, it is essential to develop and validate state-of-the-art technologies to analyze and identify the compounds responsible for the nuisances. Although these molecules can be found only in trace amounts, these very low concentrations are sufficient to give water a taste and an odor. But what is the origin of these tastes and odors in drinking water? The origins are very diverse and not all have the same impact on water quality. Odorous molecules can either come from the natural organic matter or the piping, or be an outcome of the potabilization treatment. Analytical methods currently available to identify these compounds are more and more sensitive with a detection threshold below 1ng/L. However, a difficulty remains at the sampling step due to the high fugacity of these compounds which appear only occasionally in the households. The development of a passive sampler adaptable to the consumers tap which would trap the molecules each time the tap is open could, therefore, be a solution to counter the fugacity problem. The Twister Tap project is born out of this passive sampler concept. This ACS (Health Compliance Accreditation) accredited tool was named ARISTOT (Advanced Relevant Investigation Sampler for Taste and Odor at Tap). It demonstrated a capacity to trap odorous compounds in laboratory as well as at many consumers places, and is currently used as a field investigation tool to solve TO nuisance cases. A Twister Tap kit was developed in the form of a case containing one ARISTOT, seals, and adaptors to facilitate the shipment and setting up at consumers places. This report presents the laboratory tests performed on ARISTOT: the monitoring of the traps enrichment over time, the study of potential unloading, the influences of the traps dimensions, tap water flow rate and water temperature. A second part focuses on real cases studies. A first campaign allowed us to consider the practical aspect of the tool and the kit, and to optimize the cleaning procedures of all the components in contact with water. A second campaign was then carried out to solve TO problems of some employees of the Water Research Center and residents of a French city.

1 LABORATORY STUDY
1.1 Material and methods
[1]
1.1.1 Target compounds
Table 1: List of compounds used for the ARISTOT tool validation
Name Structure
2-4-6-trichloro-anisole (246-TCA)
O
Cl
Cl
Cl
2,4-dichloro-6-bromoanisole (24-diCl-6-BrA)
and 2,6-dichloro-4-bromoanisole (26-diCl-4-BrA)
2,4-dibromo-6-chloroanisole (24-diBr-6-ClA)
and 2,6-dibromo-4-chloroanisole (26-diBr-4-ClA)
2-4-6-trichloro-anisole (246-TCA)
O
Br
Br
Br
Deutered 2,4,6-trichloroanisole (246-TCA, d5) was used as internal standard. For some tests (internal standard addition in particular), Twisters preliminary spiking was carried out manually by deposit of 1l of a concentrated solution

of the appropriate compounds, prepared in ethanol. After deposit, compounds were absorbed by the Twister PDMS and ethanol was evaporated. Studies have shown that repeatability of this kind of spiking is excellent, even better than spiking by SBSE.
1.1.2 The ARISTOT tool
Designed after the shape of daisy flowers, the tool is made of a solid stainless steel tube (or Teflon in the case of the first prototype) with 7 cavities of less than 3mm in diameter and 3cm in depth which can each accommodate a trap. Similar to a pistol cylinder, this 4cm long sampler can be adjusted to a faucet in place of the tap-nozzle (see next figure).
Figure 1 : Final aspect of the cylinder prototype on a pilot tap
Twisters were used as trapping supports. Twisters are magnetic stir bars encapsulated in glass coated with a PolyDiMethylSiloxane (PDMS) layer. These supports were originally developed to carry out Stir Bar Sorptive Extraction (SBSE), an extraction technique based on the sorption onto the PDMS layer of organic compounds found in water [2].

Figure 2 : Diagram of a TwisterTM
Twisters used in the ARISTOT support are 2cm long and have a 1mm thick PDMS layer (126l of PDMS).
NB: SBSE is usually performed in a 100ml vial containing the sample. The protocol is very simple; the sample is just spiked with an internal standard to quantify the molecules. After adding the stir bar, the vial is left on a stirrer plate for a 1 to 2 h extraction depending of the compounds to be analyzed. This method can be used to analyze many odorous compounds such as haloanisoles, poly-aromatic hydrocarbons (PAHs), and even halophenols after in situ derivatization of alcohol functions. Thus, each

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