Nanofiltration for enhanced removal of disinfection by-product (DBP) precursors in swimming pool water-retention and water quality estimation.

Three nanofiltration (NF) membranes with a chlorine tolerance > or = 1 mg L-1 were applied to reduce DBPs and their precursors in swimming pool water. A lab scale plant with crossflow modules was installed in by-pass at the sand filter outlet of a swimming pool for a period of several weeks. The chlorine tolerances of the membranes SB90 and NP030 were found to be adequate for filtration under swimming pool water conditions over the given experimental period. Retention of dissolved organic carbon (DOC) and adsorbable organic halogens (AOX) were about 70% and 80% for SB90 and 50% and 40% for NP030, respectively. DOC accumulation in the pool and the expected fresh water consumption for a treatment system consisting of ultrafiltration (UF) and NF with backwash water treatment were estimated by mass balances based on the results. Mass balances were calculated also for a German public swimming pool with a conventional water treatment system (flocculation-sand filtration-chlorination) and were compared to DOC on-line measurements. Calculation of DOC mass balances for different UF-NF treatment scenarios showed that pool water quality could be improved significantly compared to the conventional treatment system.

Metabolites from the biodegradation of pharmaceutical residues of ibuprofen in biofilm reactors and batch experiments.

The three metabolites hydroxyibuprofen (OH-Ibu), carboxyibuprofen (CA-Ibu), and carboxyhydratropic acid (CA-HA), also known from human metabolism of ibuprofen, could be identified in biodegradation experiments. Identification was based on EI mass spectra and comparison with literature data. Detection was performed by selective MS-MS measurements by GC-ion-trap MS and online methylation. Ibuprofen (Ibu), OH-Ibu, and CA-Ibu could be detected with a signal-to-noise ratio of 10:1 at a concentration of 2 nmol L(-1), CA-HA at 0.5 nmol L(-1). Degradation experiments in both biofilm reactors (BFR) and batch experiments with activated sludge (BAS) reveal OH-Ibu as the major metabolite under oxic conditions, and CA-HA under anoxic conditions. CA-Ibu was found under oxic and anoxic conditions almost only in the BAS. The metabolites together do not account for more than 10% of the initial concentration of Ibu.

Method optimization for the determination of carbonyl compounds in disinfected water by DNPH derivatization and LC-ESI-MS-MS.

A method has been developed for quantitative determination of carbonyl disinfection by-products (DBP) from aqueous samples by derivatization with 2,4-dinitrophenylhydrazine combined with high-performance liquid chromatography (HPLC) and electrospray ionization (ESI) tandem mass spectrometry (MS-MS). The effect of excess of derivatization reagent and derivatization time, the effect of buffer and dry-gas temperature in the ESI process, and the effect of focus potential and collision energy in MS measurement are shown. Major fragment ions for compound identification on the basis of collision-induced dissociation (CID) mass spectra (MS) are given, as are common fragments for screening analyses by MS experiments such as the use of precursor ion scans. Detection limits in the microg x L(-1) range could be achieved by selected ion monitoring measurements without sample preconcentration. Solid-phase extraction improved the sensitivity by a factor of 25 to 250. The applicability of the method is illustrated by DBP analyses of samples from outdoor swimming pools after chlorination. Several carbonyl compounds, e.g. aldehydes, ketones, hydroxybenzaldehyde, and dicarbonyl compounds were identified.

Lack of effect of enoximone on the pharmacokinetics of digoxin in patients with congestive heart failure.

The aim of this study was to investigate if the concomitant administration of the positive inotropic drug enoximone (100 mg tid) has any effect on the morning through levels of the cardiac glycoside digoxin in 17 patients with congestive heart failure (NYHA II-IV). Plasma concentrations of digoxin were 1.05 +/- 0.37 ng/mL before enoximone, 0.95 +/- 0.31 ng/mL at the end of the enoximone treatment period of 1 week and 0.95 +/- 0.36 ng/mL 1 week after cessation of enoximone treatment. Thus, concomitant administration of enoximone had no effect on plasma concentrations of digoxin while on the other hand the hemodynamics as assessed by NYHA-classification and determination of the heart volume improved significantly.