On‐line biodegradation monitoring of nitrogen‐containing compounds by membrane inlet mass spectrometry

Abstract

Membrane inlet mass spectrometry (MIMS) has been developed for the on-line monitoring of compounds in a continuous stirred tank bioreactor (CSTB) used to simulate a wastewater treatment plant (WWTP). A mixture of four industrially relevant nitrogen-containing volatile and semi-volatile compounds was fed to a 3 dm 3 CSTB with a hydraulic retention time (HRT) of 24 h. In-membrane preconcentration/thermal desorption was used for the on-line monitoring of semivolatile compounds (n-methylpyrrolidinone and tetramethylethylenediamine), while volatile organic compounds (3-bromopyridine and 2-chloro-5-trifluoromethylaniline) were determined by continuous infusion through the membrane. Quantification of the four compounds was achieved by MS. The CSTB was run for 160 h and, after reaching steady state, n-methylpyrrolidinone showed removal to levels below the limit of detection, while there was partial biodegradation of 2-chloro-5-trifluoromethylaniline and 3-bromopyridine. There was no evidence of significant biodegradation for tetramethylethylenediamine. Intermediates in the metabolite pathways of 2-chloro-5-trifluoromethylaniline and 3-bromopyridine were identified by MIMS, gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS). COD was measured off line, and results agreed well with MIMS, although COD data did not provide information on the removal of the individual compounds.

A universal temperature controlled membrane interface for the analysis of volatile and semi-volatile organic compounds

“…Aqueous samples of 5-chloro-2-trifluoromethylaniline (CFA), 3-bromopyridine (3BP), n-methylpyrrolidinone (NMP) and tetramethylethylenediamine (TMEDA) (100 mg l 21 ) were introduced into the TCMI at room temperature for 5 min, and the membrane was flushed with nitrogen (50 ml min 21 ) for 5 min. The membrane was then heated to 200 °C at a rate of 4 °C s 21 On-line monitoring of a bioreactor was carried out using a 5 l bioreactor containing activated sludge 21,22 spiked with CFA (25 mg l 21 ), TMEDA (100 mg l 21 ) and 3BP (100 mg l 21 ). The pH was maintained at 7.00, the temperature was set to 35 °C, and the reactor was stirred at 150 rpm.…”

“…The TCMI-GC-MS interface was used to identify metabolites produced during the biodegradation studies on TMEDA, NMP, 3BP and CFA. The metabolites identified by GC-MS, using direct injection of the aqueous sample, were also identified by TCMI-GC-MS, but one of the CFA metabolites, tentatively identified as 2-trifluoromethylaniline by TCMI-GC-MS, was not detected by GC-MS. 22 The TCMI-GC-MS analysis shows the metabolite has a retention time of 6.8 min, with an EI mass spectrum containing peaks at m/z 161 (M + •), m/z 142 ([M 2 F] + ) and m/z 111 ([M 2 CF 2 ] + •). A possible explanation for the detection of this metabolite by TCMI-GC-MS and not by GC-MS is that the sample is introduced into an injector held at higher temperature in the GC-MS analysis, than the temperature used in the thermal desorption step for TCMI-GC-MS.…”

Monitoring of an esterification reaction by on-line direct liquid sampling mass spectrometry and in-line mid infrared spectrometry with an attenuated total reflectance probe

“…Such low detection limits are possible due to the preferential permeability of the analyte compounds through the membrane material relative to the matrix. MIMS has been used for on-line monitoring of various analytes such as ethanol, acetic acid and lactic acid in fermentation broths [19], nitrogen-containing compounds in a bioreactor [20], methanol and ethanol in chloroform [21], and aromatic halides in ethanol-water [22]. For samples where the analytes are chemically similar to the matrix, e.g.…”

Chloroform formation by chlorination of aqueous algae suspensions: online monitoring via membrane introduction mass spectrometry

“…Membrane introduction mass spectrometry (MIMS) 6 is one of the simplest, fastest, and most sensitive techniques for the analysis of volatile [7][8][9] and semi-volatile 10,11 organic compounds in water as well as in other matrixes such as air, soil and other solvents. [12][13][14][15][16][17][18] In this technique volatile and semi-volatile organic compounds permeate hydrophobic membranes, usually polydimethylsiloxanes (PDMS), preferentially to water and other polar substances.…”