Open Access

Sulfamethoxazol (SMX),a sulfonamide, is a widely used bacteriostatic antibiotic and therefore a promising marker for the entry of anthropogenic Pollution in the environment. SMX is frequently found in wastewater and surface water. This study presents the production of high affinity and selective polyclonal antibodies for SMX and the development and Evaluation of a direct competitive enzyme-linked immunosorbent assay(ELISA)for the quantification of SMX in environmental watersamples. The crystal structures of the cross-reacting compounds sulfamethizole, N4-acetyl-SMX andsuccinimidyl-SMX were determined by x-ray diffraction aiming to explain their high cross-reactivity. These crystal structures are described for the first time. The quantification range of the ELISA is 0.82–63 µg/L. To verify our results, the SMX concentration in 20 environmental samples,including wastewater and surfacewater,was determined by ELISA and tandem mass spectrometry(MS/MS).A good Agreement of the measured SMX concentrations was found with average recoveries of 97–113%for the results of ELISA compared to LC-MS/MS.

The non-steroidal anti-inflammatory drug (NSAID) diclofenac (DCF) is an important environmental contaminant occurring in surface waters all over the world, because, after excretion, it is not adequately removed from wastewater in sewage treatment plants. To be able to monitor this pollutant, highly efficient analytical methods are needed, including immunoassays. In a medical research project, monoclonal antibodies against diclofenac and its metabolites had been produced. Based on this monoclonal anti-DCF antibody, a new indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed and applied for environmental samples. The introduction of a spacer between diclofenac and the carrier protein in the coating conjugate led to higher sensitivity. With a test midpoint of 3 mg L−1 and a measurement range of 1–30 mg L−1, the system is not sensitive enough for direct analysis of surface water. However, this assay is quite robust against matrix influences and can be used for wastewater. Without adjustment of the calibration, organic solvents up to 5%, natural organic matter (NOM) up to 10 mg L−1, humic acids up to 2.5 mg L−1, and salt concentrations up to 6 g L−1 NaCl and 75 mg L−1 CaCl2 are tolerated. The antibody is also stable in a pH range from 3 to 12. Cross-reactivity (CR) of 1% or less was determined for the metabolites 40-hydroxydiclofenac (40-OH-DCF), 5-hydroxydiclofenac (5-OH-DCF), DCF lactam, and other NSAIDs. Relevant cross-reactivity occurred only with an amide derivative of DCF, 6-aminohexanoic acid (DCF-Ahx), aceclofenac (ACF) and DCF methyl ester (DCF-Me) with 150%, 61% and 44%, respectively. These substances, however, have not been found in samples. Only DCF-acyl glucuronide with a cross-reactivity of 57% is of some relevance. For the first time, photodegradation products were tested for cross-reactivity. With the ELISA based on this antibody, water samples were analysed. In sewage treatment plant effluents, concentrations in the range of 1.9–5.2 mg L−1 were determined directly, with recoveries compared to HPLC-MS/MS averaging 136%. Concentrations in lakes ranged from 3 to 4.4 ng L−1 and were, after pre-concentration, determined with an average recovery of 100%

A frequently studied environmental contaminant is the active substance diclofenac, which is removed insufficiently in sewage treatment plants. Since its inclusion in the watch list of the EU Water Framework Directive, the concentrations in surface waters will be determined throughout Europe. For this, still, more precise analytical methods are needed. As a reference, HPLC-MS is frequently employed. One of the major metabolites is 4’-hydroxydiclofenac (4’-OH-DCF). Also, diclofenac lactam is important for assessing degradation and transformation. Aceclofenac (ACF), the glycolic acid ester of diclofenac is used as a drug, too, and could potentially be cleaved to yield diclofenac again. In various sewage treatment plant influent samples, diclofenac, 4’-OH-DCF, DCF lactam and ACF could be determined with detection limits of 3 µg/L, 0.2 µg/L, 0.17 µg/L and 10 ng/L, respectively.

Emissions of volatile organic compounds (VOCs) from consumer products may have a negative impact on indoor air quality, potentially also affecting human wellbeing. Since consumers may be exposed to these VOCs immediately after e.g. unwrapping of newly purchased products, reliable analytical methods are needed to determine air concentration profiles in the early phase of VOC emissions. Concerning typical sample sizes of consumer products, micro-scale test chambers (μ-chambers) were considered suitable for this purpose. In addition, compared to medium- or large-scale test chambers, μ-chambers require lower initial investment and operational costs, and offer options for emissions screenings where higher sample throughput is essential. For these reasons, a μ-chamber-based method to determine initial concentrations of VOCs emitting within the first hours of simulated product use was developed. The chamber air was frequently sampled on desorption tubes loaded with Tenax® TA, followed by quantification of emitted VOCs via thermal desorption gas chromatography mass spectrometry (TD-GC-MS). The method was assessed in a round robin test involving eight participating laboratories from 2 countries. Pieces of a rain poncho (sample area A: 2.01·10-4 m2) emitting cyclohexanone, phenol, 2-ethylhexanol, naphthalene and isophorone in significant concentrations were distributed as sample material. Each laboratory conducted triplicate emission tests over a period of 48 h in μ-chambers with volumes of 44 or 114 mL. The loading factors L of 4.57 m2·m-3 (44 mL) or 1.76 m2·m-3 (114 mL) and air flow rates of 24 mL·min-1 resulted in area-specific air flow rates q of 7.17 m3·m-2·h-1 in both chamber types. The temperature was set to 23°C and, if possible, relative humidity was set to approx. 50%. The chamber air was sampled after 0.5, 1, 2, 4, 24 and 48 hours. In addition, to assess the analytical performance, each participating laboratory received two analyte-spiked Tenax® TA-loaded desorption tubes for quality control (QC). Very low relative standard deviations (11–17%) were obtained for the QC test. The results of the emissions tests in the early phase (0.5–4 h) were also adequate, with acceptable z scores (|z|≤2.00) received by six to seven participating laboratories. All eight laboratories obtained acceptable z scores after the longer sampling periods (24 and 48 h). Hence, the inter-laboratory comparability of the results obtained with the developed μ-chamber method was successfully confirmed.