Environ. Sci. Technol. 1984, 18, 797-802
Organic Compounds in Water: Analysis Using Coupled-Column High-Performance Liquid Chromatography and Soft- Ionization Mass Spectrometry Brian Crathorne, Michael Fielding, Carole P. Steel, and Christopher D. Watts" Water Research Centre, Environment, Medmenham, Marlow, Buckinghamshire, England
rn The use of coupled-column high-performance liquid chromatography and mass spectrometry using field desorption and fast atom bombardment ionization for the separation and identification of organics isolated from river and drinking waters is reported. Complex mixtures of organics with a wide diversity of structural types have been shown to be present in water samples. Among the nonvolatile organics identified are polychlorinated terphenyls, nonionic and cationic surfactants, pharmaceuticals, pesticides, and epoxy resin constituents. The majority of the identified nonvolatiles are anthropogenic in origin, and many are biologically active. Only a small proportion of the nonvolatiles present have been identified, and the remainder await further application of the techniques used here and the development of new techniques.
Introduction The need to develop methods for identifying nonvolatile organics in water has become apparent over the last few years. It is a problem that has been highlighted by the fact that the large number of volatile organics which have been identified in water represents, at most, only 20% of the total organic material. The remaining 80% is generally referred to as the nonvolatile organic fraction. The identification of volatile compounds was facilitated by the application of high-resolution gas chromatography-mass spectrometry and the availability of suitable mass spectral data banks. This technique provides an ideal method for separation and identification of complex mixtures of volatile organics (1-3). No comparable combined separation-identification method or mass spectral data bank is available for nonvolatile organics (although liquid chromatography-mass spectrometry (LC-MS) is now showing promise in this area), and this has proved a major obstacle to more widespread research into nonvolatile organics in water. As a direct consequence, the composition of the nonvolatile organic fraction is largely unknown. Undoubtly, a large proportion consists of humic material (humic, fulvic, and hymatomelanic acids). This material is intractable to most methods of molecular structure elucidation although some insight into the structure of humic and fulvic acids has been obtained by subjecting them to controlled chemical degradation and identifying the reaction products ( 4 , 5 ) . The remainder of the nonvolatile reaction probably consists of discrete organic compounds that are nonvolatile by virtue of polarity, thermal instability, or high molecular weight. In fact, the available evidence (6-9) indicates that the nonvolatile organics present in water consist of mixtures a t least as complex as those found for volatiles. These data have shown that modern liquid chromatographic and field desorption mass spectrometric techniques can provide information on the nature of the nonvolatile organics present in water. Recently, another method of soft ionization, fast atom bombardment (FAB) (IO),has been applied to the analysis of nonvolatile organics (surfactants) in river water (11). 0013-936X184/0918-0797$01.50/0
In this paper we report results from the application of high-performance liquid chromatography (HPLC) and field desorption (FD) and FAB mass spectrometry to the analysis of a British lowland river, a West German lowland river (Main River), and British drinking waters derived from lowland river water and groundwater. Although identification of unknown compounds using a survey type approach is successful when modern techniques are used, it is undoubtedly slow. One way of overcoming this limitation is to use a "target" compound approach. This requires the selection of particular compounds or classes of compounds which could pose problems with respect to water quality. The criteria we adopted for selection of target compounds are that they must be (a) nonvolatile organics, (b) in widespread use, (c) produced in large amounts, (d) of potential toxicologicalconcern, and (e) likely to enter the water cycle. Examples of compounds that meet all of these criteria can be found among the most commonly used pesticides and pharmaceuticals. We have developed methods for certain pesticides and pharmaceuticals selected with these criteria in mind, and preliminary results are presented from the analysis of target pharmaceuticals in a river water. The importance of identifying the nonvolatile organics in water in addition to the volatiles has been stressed previously (6-9). It is worth stressing here that concern over possible health effects resulting from long-term exposure to organics in drinking water has arisen mainly from the volatile organics identified. Furthermore, most water quality standards referring to individual organic compounds are concerned with volatile organics (12). In order to make a properly balanced judgement of the possible health effects of organics in water, more information on the identity of nonvolatile organics is essential.
Experimental Section Isolation Techniques. Extracts of nonvolatile organics from samples of river and drinking water were obtained by either freeze-drying ( 6 0L), details of which have been published previously (6-7), or by XAD-2 resin adsorption. In the latter method water samples (
