AREA 6.3 • METHODS, MODELING, MONITORING OF CHEMICALS • RESEARCH ARTICLE Evaluation of resin and fatty acid concentration levels by online sample enrichment followed by atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) Piia Valto & Juha Knuutinen & Raimo Alén Received: 31 October 2007 / Accepted: 23 September 2008 / Published online: 14 October 2008 # Springer-Verlag 2008 Abstract Background, aim, and scope In papermaking, there is a continuous interest both to minimize fresh water consump- tion and to reduce discharges into the environment. These general trends mean an increase in the amounts of detrimental substances, such as resin and fatty acids, in papermaking process waters. Resin acids, in particular, are responsible for much of the toxicity typically present in paper mill effluents and, for this reason, the routine and rapid monitoring of these compounds in various process streams is necessary. This also means that there is a continuous need to develop straightforward offline and online techniques to clarify problems occurring, for example, as a result of the introduction of more intensively closed systems of water circulation. In the present study, we describe the use of a novel, online, sample enrichment technique followed by atmospheric pressure chemical ionization–mass spectrometry (APCI-MS) suitable for monitoring the concentration levels of common resin and fatty acids in papermaking process waters. Materials and methods The representative process water samples were taken from the grinding zone of a thermo- mechanical pulping mill. The samples were first preconcen- trated in a precolumn C18, and the analytes were transferred online to MS. The high intensive [M–H] - ion was used for the identification of each analyte since, according to the present ionization method, no other fragmentation was observed. Laboratory-scale, online measurements with an online sample feed were carried out by connecting a centrifugal pump and a ceramic filter to the APCI-MS. Results Quality parameters, such as repeatability, linearity, and limit of detection (LOD), were determined by using dehydroabietic acid (DHAA) in order to evaluate the suitability of the method for the rapid screening of concentration levels. This method provided satisfactory linearity and a good correlation between analyte concen- tration and peak area. The suitability of the system for the continuous analysis of the same acids was evaluated in laboratory-scale, online experiments. In all cases, the response to changes in the analyte concentration was linear, and the repeatability of the system was also satisfactory. Discussion Only a few studies have been published on the analysis of resin and fatty acids with MS techniques. The present method was applied to the monitoring of dehy- droabietic, oleic, and stearic acids. The quality parameters were highly comparable with those reported earlier, and the LOD values of the DHAA were below the levels usually encountered in process waters. The quality parameters were only slightly higher than those obtained by the traditional methods of analysis, probably due to the absence of an effective sample clean-up before analysis. Conclusions The results of the laboratory-scale, online experiments indicated that the online enrichment APCI- MS system is a suitable alternative for monitoring the concentration levels of selected resin and fatty acids in papermaking process waters. The method can be used, for example, to provide useful information about the concen- tration levels of these acids in different stages of the process, thus signaling possibly impending problems. In general, faster and simpler measurements are needed to Environ Sci Pollut Res (2009) 16:287–294 DOI 10.1007/s11356-008-0050-z Responsible editor: Peter Luthardt P. Valto (*) : J. Knuutinen : R. Alén Laboratory of Applied Chemistry, Department of Chemistry, University of Jyväskylä, P.O. Box 35, Jyväskylä 40014, Finland e-mail: piia.k.valto@jyu.fi