Occurrence and temporal variations of TMDD in the river Rhine, Germany

Background, aim, and scope: The chemical substance 2,4,7,9-tetramethyl-5-decyne-4,7-diol (TMDD) is a non-ionic surfactant used as an industrial defoaming agent and in various other applications. Its commercial name is Surynol 104® and the related ethoxylates are also available as Surfynol® 420, 440, 465 and 485 which are characterized by different grades of ethoxylation of TMDD at both hydroxyl functional groups. TMDD and its ethoxylates offer several advantages in waterborne industrial applications in coatings, inks, adhesives as well as in paper industries. TMDD and its ethoxylates can be expected to reach the aquatic environment due its widespread use and its physico-chemical properties. TMDD has previously been detected in several rivers of Germany with concentrations up to 2.5 µg/L. In the United States, TMDD was also detected in drinking water. However, detailed studies about its presence and distribution in the aquatic environment have not been carried out so far. The aim of the present study was the analysis of the spatial and temporal concentration variations of TMDD in the river Rhine at the Rheingütestation Worms (443.3 km). Moreover, the transported load in the Rhine was investigated during two entire days and 7 weeks between November 2007 and January 2008. Materials and methods: The sampling was carried out at three different sampling points across the river. Sampling point MWL1 is located in the left part of the river, MWL2 in the middle part, and MWL4 in the right part. One more sampling site (MWL3) was run by the monitoring station until the end of 2006, but was put out of service due to financial constrains. The water at the left side of the river Rhine (MWL1) is influenced by sewage from a big chemical plant in Ludwigshafen and by the sewage water from this city. The water at the right side of the river Rhine (MWL4) is largely composed of the water inflow from river Neckar, discharging into Rhine 14.9 km upstream from the sampling point and of communal and industrial wastewater from the city Mannheim. The water from the middle of the river (MWL2) is largely composed of water from the upper Rhine. Water samples were collected in 1-L bottles by an automatic sampler. The water samples were concentrated by use of solid-phase extraction (SPE) using Bond Elut PPL cartridges and quantified by use of gas chromatography-mass spectrometry (GC-MS). The quantification was carried out with the internal standard method. Based on these results, concentration variations were determined for the day profiles and week profiles. The total number of analyzed samples was 219. Results: The results of this study provide information on the temporal concentration variability of TMDD in river Rhine in a cross section at one particular sampling point (443.3 km). TMDD was detected in all analyzed water samples at high concentrations. The mean concentrations during the 2 days were 314 ng/L in MWL1, 246 ng/L in MWL2, and 286 ng/L in MWL4. The variation of concentrations was low in the day profiles. In the week profiles, a trend of increasing TMDD concentrations was detected particularly in January 2008, when TMDD concentrations reached values up to 1,330 ng/L in MWL1. The mean TMDD concentrations during the week profiles were 540 ng/L in MWL1, 484 ng/L in MWL2, and 576 ng/L in MWL4. The loads of TMDD were also determined and revealed to be comparable in all three sections of the river. The chemical plant located at the left side of the Rhine is not contributing additional TMDD to the river. The load of TMDD has been determined to be 62.8 kg/d on average during the entire period. By extrapolation of data obtained from seven week profiles the annual load was calculated to 23 t/a. Discussion: The permanent high TMDD concentrations during the investigation period indicate an almost constant discharge of TMDD into the river. This observation argues for effluents of municipal wastewater treatment plants as the most likely source of TMDD in the river. Another possible source might be the degradation of ethoxylates of TMDD (Surfynol® series 400), in the WWTPs under formation of TMDD followed by discharge into the river. TMDD has to be considered as a high-production-volume (HPV) chemical based on the high concentrations found in this study. In the United States, TMDD is already in the list of HPV chemicals from the Environmental Protection Agency (EPA). However, the amount of TMDD production in Europe is unknown so far and also the biodegradation rates of TMDD in WWTPs have not been investigated. Conclusions: TMDD was found in high concentrations during the entire sampling period in the Rhine river at the three sampling points. During the sampling period, TMDD concentrations remained constant in each part of the river. These results show that TMDD is uniformly distributed in the water collected at three sampling points located across the river. ‘Waves’ of exceptionally high concentrations of TMDD could not be detected during the sampling period. These results indicate that the effluents of WWTPs have to be considered as the most important sources of TMDD in river Rhine. Recommendations and perspectives: Based also on the occurrence of TMDD in different surface waters of Germany with concentrations up to 2,500 ng/L and its presence in drinking water in the USA, more detailed investigations regarding its sources and distribution in the aquatic environment are required. Moreover, the knowledge with respect to its ecotoxicity and its biodegradation pathway is scarce and has to be gained in more detail. Further research is necessary to investigate the rate of elimination of TMDD in municipal and industrial wastewater treatment plants in order to clarify the degradation rate of TMDD and to determine to which extent effluents of WWTPs contribute to the input of TMDD into surface waters. Supplementary studies are needed to clarify whether the ethoxylates of TMDD (known as Surfynol 400® series) are hydrolyzed in the aquatic environment resulting in formation of TMDD similar to the well known cleavage of nonylphenol ethoxylates into nonylphenols. The stability of TMDD under anaerobic conditions in groundwater is also unknown and should be studied

Towards early detection of the hydrolytic degradation of poly(bisphenol A)carbonate by hyphenated liquid chromatography and comprehensive two-dimensional liquid chromatography

The hydrolytic degradation of poly(bisphenol A)carbonate (PC) has been characterized by various liquid chromatography techniques. Size exclusion chromatography (SEC) showed a significant decrease in molecular mass as a result of hydrolytic degradation, while 'liquid chromatography at critical conditions' (LC-CC) was very successful for observing differences in functionality due to degradation, i.e. the formation of OH end-groups. To characterize and identify the observed differences semi on-line coupling of liquid chromatography to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and Fourier transform infrared spectroscopy (FT-IR) has proved to be very useful. Comprehensive two-dimensional liquid chromatography (2D-LC) was also applied to study the hydrolytic degradation of poly(bisphenol A)carbonate. LC-CC × SEC showed that the formation of poly(bisphenol A)carbonate with OH end-groups occurred over the whole molecular mass range. This information could not be obtained with the separate liquid chromatographic techniques, thereby illustrating the usefulness of 2D-LC. The main degradation processes of poly(bisphenol A)carbonate under the applied hydrolysis conditions turned out to be disappearance of cyclic PC oligomers, chain scission of PC and (subsequent) formation of OH end-groups. FT-IR, SEC and LC-CC have been used to follow the hydrolytic degradation with time. LC-CC proved to be the most promising technique to detect the degradation of poly(bisphenol A)carbonate at an early stage. © 2005 Elsevier Ltd. All rights reserved

Optimization of large-volume on-column injection conditions in gas chromatography by monitoring the actual carrier gas flow.

The change of the evaporation rate of the solvent during injection and evaporation is the most critical aspect during optimization of large-volume on-column injection conditions in gas chromatography. The change is caused by the pressure drop along the retention gap when using an early solvent vapour exit (SVE) and can be described by a mathematical model. Four procedures for the optimization of the injection conditions were compared. It was found that different procedures often yield different evaporation rates, which may also depend on the injection speeds used during optimization. For optimization of a new set-up, i.e. if little is known about the optimal injection conditions, the evaporation rate should be determined by increasing the injection time at a fixed injection speed, injection temperature and head pressure; subsequently, an appropriate injection speed can be calculated. If a mere re-optimization is required as e.g. after the exchange of the retention gap, adjusting the evaporation rate to the injection speed by varying the injection temperature at a constant injection speed is the preferred procedure. With both methods, optimization can be achieved by means of 2-5 injections of pure solvent and monitoring the helium carrier gas flow. That is, optimization of the injection conditions takes less than 1 h. When using this strategy, analytes as volatile as monochlorobenzene can be determined in aqueous samples by in-vial liquid-liquid extraction-gas chromatography-mass spectrometry. Closing the SVE at the very end of solvent evaporation results in a considerable increase of the capacity of the retention gap compared to closing the SVE before all solvent is evaporated. Copyright (C) 1999 Elsevier Science B.V

On-line coupling of immunoaffinity-based solid-phase extraction and gas chromatography for the determination of s-triazines in aqueous samples.

The potential of immunoaffinity-based solid-phase extraction (IASPE) coupled on-line to gas chromatography (GC) for the determination of micropollutants was studied with emphasis on the interfacing of the immunoaffinity-based SPE and GC parts of the system. The cartridge containing the immobilized antibodies was coupled to the gas chromatograph via a reversed-phase cartridge (copolymer sorbent). After trace enrichment of the analytes on the immunoaffinity cartridge, they were desorbed and recollected on the reversed-phase cartridge by means of an acidic buffer. After clean-up and drying with nitrogen, desorption and transfer to the GC was done with ethyl acetate via an on-column interface in the partially concurrent solvent evaporation mode. The antibodies used in the immunoaffinity cartridge were raised against atrazine; several s-triazines were used as test compounds. Triazines that were structurally similar to atrazine, showed quantitative recovery. As an application, immunoaffinity SPE-GC was used for the analysis of river and waste water and orange juice. The selectivity of the system was such that non-selective flame ionization detection (FID) could be used to detect the analytes of interest in these complex matrices. The detection limits for 10-ml water samples were 15-25 ng/l for FID and about 1.5 ng/l for the nitrogen-phosphorus detection. Copyright (C) 1999 Elsevier Science B.V

At-line spe-gc-ms of micropollutants in water using the prepstation

An automated at-line SPE-GC-MS system for the determination of micropollutants in aqueous samples, which is based on the PrepStation and uses large-volume on-column injections, has been redesigned. A cartridge made from stainless steel and polychlorotrifluoroethylene and a 2-needle system was constructed which allow the determination of micropollutants at the low ng/L level without interferences from impurities extracted from the septa of the vials or the commercial cartridges. No time-consuming pre-cleaning of the cartridges or septa is required. The SPE sample extract (300 μL) is transferred from the sample preparation module to the autosampler of the GC-MS and 50 or 100 μL are injected. The analytical characteristics of the integrated procedure such as analyte recovery (typically 80-105%) and repeatability (RSDs, 2-9%), were satisfactory. Several micropollutants were detected in (unfiltered) river water at the 0.2-400 ng/L level using full-scan MS acquisition. The system proved to be robust during the analysis of more than 100 tap and river water samples. © Springer-Verlag 1999

Comparison of on-line flow-cell and off-line solvent-elimination interfaces for size-exclusion chromatography and Fourier-transform infrared spectroscopy in polymer analysis

Two commercial liquid chromatography-Fourier-transform infrared spectroscopy interfaces (LC-FTIR), viz. a flow cell and a solvent-elimination interface have been assessed for use in size-exclusion chromatography (SEC) with respect to their chromatographic integrity (i.e. peak asymmetry, chromatographic resolution), quantitative and qualitative aspects. A polycarbonate/aliphatic polyester (PC/APE) blend and a polycarbonate-co-polydimethylsiloxane (PC-co-PDMS) copolymer were selected for the assessment. Both samples were successfully and selectively analyzed. The relatively large volume of the flow cell and the inherent deposition characteristics of the solvent-elimination interface led to a comparable decrease in the chromatographic resolution. The separation of oligomers was diminished in comparison with SEC-ultra-violet (UV). However, the peak asymmetry was not significantly affected by either interface. For both interfaces, a linear relationship was obtained for the FTIR response versus the injected concentration. The sensitivity was found to be higher for the solvent-elimination interface. For the current model compounds, the flow-cell interface detection limits are worse. However, the repeatability of flow-cell SEC-FTIR, evaluated by means of four SEC-FTIR analyses of polycarbonate, was considerably better than for solvent-elimination SEC-FTIR. This is probably due to the well-defined optical path length of the sample in the flow cell. By spectral subtraction, it was very well possible to obtain qualitative (functional group) information for compound identification also with flow-cell SEC-FTIR. © 2003 Elsevier B.V. All rights reserved

Applyability of large volumes injection gaschromatography with infrared spectrometric detection

Onderzoek is uitgevoerd naar verbetering van de relatieve detectiegrenzen van gaschromatografie met infraroodspectrometrische detectie (GC-IR) door toepassing van zogenaamde large-volume injectie (LVI) technieken. Twee technieken zijn onderzocht, loop-type interfacing en on-column interfacing. Optimalisatie is uitgevoerd met n-alkanen in verschillende oplosmiddelen. Pesticiden, polyaromatische koolwaterstoffen en andere contaminanten zijn gebruikt voor het testen van de bruikbaarheid van het ontwikkelde systeem in de milieu-analyse. Bij 100 ul injecties blijkt de relatieve detecteerbaarheid van de niet vluchtige analieten in vergelijking met 1 ul split/splitless injecties, voor beide typen interfacing vrijwel evenredig toe te nemen met het geinjecteerde volume. Bij injectie van grotere volumes (200-400 ul) wordt de winst in relatieve gevoeligheid gedeeltelijk teniet gedaan door verontreinigingen in het oplosmiddel. De prestaties van de on-column interfacing zijn relatief beter door het geringere verlies aan vluchtige componenten en de inbouw van een detector-schakelsysteem. De praktische mogelijkheden van LVI-GC-IR worden gedemonstreerd aan de hand van de analyse van enkele monsters drink- en oppervlaktewater waaraan veel voorkomende contaminanten zijn toegevoegd op een niveau van 0.1-1 ug/l. De toegevoegde componenten zijn gedetecteerd en geidentificeerd (i) via injectie van extracten verkregen via vloeistof-vloeistof extractie en (ii) door on-line desorptie van elders bemonsterde solid phase extracted (SPE) cartridges. De mogelijkheid van (LVI-)GC-IR om door middel van functionele groepschromatogrammen te screenen op de aanwezigheid van specifieke stofklassen is een waardevolle aanvulling op gaschromatografie met massaspectrometrische en atoomemissie detectie.Research has been carried out to enlarge the analyte detectability of gaschromatography with infrared spectrometric detection (GC-IR) by techniques that allow injection of large volumes of liquid samples (100 ul typical). Two techniques have been investigated; loop-type and on-column interfacing. Alkanes dissolved in various solvents have been used for optimisation. Pesticides, polyaromatic hydrocarbons and other micro-contaminants have been used to test the usefulness of the eveloped system in environmental trace analysis. The increase in analyte detectability of high boiling compounds compared to conventional 1 ul split/splitless injection is almost proportional to the injected volume for injection of 100 ul. At larger sample volumes, the increase of the relative sensitivity is partly detracted by impurities of the solvent. The performance of the on-column interface is better due to the reduced loss of volatiles and the incorporation of a detector switching module that minimizes interfering solvent condensation in the IR detection interface. The potentials of LVI-GC-IR are demonstrated by the analysis of samples of drinking and surface water spiked at levels of 0.1-1 ug/l with components that commonly occur as micro-contaminants. Analytes have been detected and identified (i) by direct injection of solutions obtained by liquid-liquid extraction and (ii) by on-line desorption of at site sampled solid phase extracted cartridges. The possibility of (LVI-)GC-IR of selective screening on the prescence of specific compound classes by means of functional group chromatograms makes the technique a valuable tool in addition to GC with mass spectrometric and atomic emission detection.RIV