Analysis of polar hydrophilic aromatic sulfonates in waste water treatment plants by CE/MS and LC/MS

Abstract

The present work describes the development and optimization of a capillary (zone) electrophoresis/mass spectrometric (CE/MS) analysis method for polar hydrophilic aromatic sulfonates (ASs). The compounds were detected by negative ion electrospray ionization (NIESI) and selected ion monitoring (SIM). In comparison with CE/UV, for CE/MS a lower-concentration volatile ammonium acetate buffer (5 mM) without organic modifier and a higher separation voltage were better suited for separation. Sensitivity of CE/MS was slightly better than for CF/UV, with the limit of detection (LOD) ranging between 0.1 and 0.4 mg l(-1). For verification of the CE/MS results, ASs were also analysed by ion-pair liquid chromatography/diode array UV detection coupled in series with electrospray mass spectrometry (IPC/DAD/ESI-MS). Real water samples of different waste water treatment plants (WWTPs) in Catalonia (NE Spain) were extracted by solid-phase extraction (SPE) with LiChrolut EN and analysed with CE/MS and LC/MS. ASs were found in influent and effluent water samples of the WWTPs in the microg l(-1) concentration range. LC/MS offered a higher separation efficiency and sensitivity than CE/MS. Therefore with LC/MS more compounds could be identified in the WWTPs. The persistency of the ASs was distinct: some compounds were well degraded during the water treatment process, while others were quite persistent.

The evaluation and comparison of trigonal and linear tricationic ion-pairing reagents for the detection of anions in positive mode ESI-MS

“…Using our method and TTC 1, the LOD for the same analyte is 8.75 pg using SIM detection and 500 fg using LTC 1 and SRM detection. Other aromatic sulfonates were determined in concentration ranges of 0.1-1 ng/mL by solid-phase extraction-ion pair chromatography using UV detection [11] and 100 -400 ng/mL by CE/MS [3]. The LOD for napthalene-1,5-disulfonic acid was determined by ion interaction chromatography both by the direct injection of a large sample volume (100 uL) and preconcentration (sample volume of 50 mL) [16].…”

“…Low levels of organic acids have been determined in a variety of samples such as food, environmental, and biological matrices [1][2][3][4][5][6][7][8][9]. Some dicarboxylic acids, such as glutaric, fumaric, and adipic acids are marker compounds for certain metabolic disorders and have been determined in urine samples [10].…”

“…Aromatic sulfonates are used in many industrial processes and consumer products, such as laundry detergents. Many of these sulfonates end up in waste water and municipal water supplies, and have been determined by various methods [3,11]. Because of the ramifications of low levels of anions in the environment, fast and effective trace methods of analysis are very important.…”

“…Common separation methods include ion chromatography [1,[12][13][14][15], ion pair chromatography [3,11,16], reverse-phase mode chromatography [17][18][19], and capillary electrophoresis (CE) [4,5,20]. To enhance the spectroscopic detection of anions that do not contain a UV chromophore, some CE and high-performance liquid chromatography (HPLC) methods utilize sample derivatization [21,22] or indirect UV or fluorescence detection methods [23][24][25].…”

“…Ions have also been detected by ion-selective electrodes and conductivity [26 -31]. Mass spectrometry (MS) provides universal detection for anions and is being used more and more, either alone [13,32] or paired with a separation technique [3,6,18,33].…”