LC-MS analysis in the aquatic environment and in water treatment technology ? a critical review

Abstract

Environmental contaminants of recent concern are pharmaceuticals, estrogens and other endocrine disrupting chemicals (EDC) such as degradation products of surfactants, algal and cyanobacterial toxins, disinfection by-products (DBPs) and metalloids. In addition, pesticides (especially their transformation products), microorganisms, and humic substances (HS), in their function as vehicles for contaminants and as precursors for by-products in water treatment, traditionally play an important role. The present status of the application of LC-MS techniques for these water constituents are discussed and examples of application are given. Solid-phase extraction with various non-selective materials in combination with liquid chromatography (LC) on reversed-phase columns have been the most widely used methods for sample preconcentration and separation for different compound classes like pesticides, pharmaceuticals or estrogens. Electrospray ionization (ESI) and atmospheric pressure ionization (APCI) are the most frequently used ionization techniques for polar and ionic compounds, as well as for less polar non-ionic ones. The facilities of LC-MS have been successfully demonstrated for different compound classes. Polar compounds from pharmaceuticals used as betablockers, iodinated X-ray contrast media, or estrogens have been determined without derivatization down to ultratrace concentrations. LC-MS can be viewed as a prerequisite for the determination of algal and cyanobacterial toxins and the homologues and oligomers of alkylphenol ethoxylates and their metabolites. Tandem mass spectrometric techniques and the use of diagnostic ions reveal their usefulness for compound-class specific screening and unknown identification, and are also valid for the analysis of pesticides and especially for their transformation products. Structural information has been gained by the application of LC-MS methods to organometallic species. New insights into the structural variety of humic substances have been made possible by FT-ICR-MS due to its ultrahigh mass resolution. Finally, exciting possibilities for rapid detection and identification of microorganisms have been made possible by MALDI and LC-MS methods.

Environmental aspects of using gas chromatography for determination of pharmaceutical residues in samples characterized by different composition of the matrix

“…Despite its many advantages, particularly the considerable simplifi cation of sample preparation, this technique has a number of drawbacks. These include the interference of analytes with matrix components, which directly affects the method quantifi cation limit (MQL) and method detection limit (MDL), problems with repeatability and reproducibility of results, the signifi cant effect of the type of mobile phase on the effi cacy of analyte ionization and fragmentation, the lack of a mass spectra library, and the high cost of LC-MS analysis (Reemtsma 2001, Zwiener andFrimmel 2004) An interesting alternative is gas chromatography, especially when the target drugs are present at very low concentrations in complex matrices, and when such matrices negatively infl uence the proper determination of these compounds by means of LC-MS/MS. The lower cost of GC analysis and the smaller amounts of solvent consumed also favour such approach.…”

Determination of Surfactants in Environmental Samples. Part III. Non-Ionic Compounds

“…The liquid chromatography for analysis of non-ionic compounds can be coupled with different types of detectors: fluorescence (FLD) [58], ultra-violet (UV) [59,60], mass spectrometry (MS) [61] or their combination (MS-MS, UV-FLD, UV-MS [25,62]). The facilities of LC-MS can be successfully applied for determination different types of the homologues and oligomers of alkylphenol ethoxylates and their metabolites [63]. The MS-MS detector can be used to identification of non-ionics analytes (due to their mass spectra contain characteristic fragments that constitute additional confirmation) and usually provides higher selectivity at quantitative determination step [64].…”

“…The MS-MS detector can be used to identification of non-ionics analytes (due to their mass spectra contain characteristic fragments that constitute additional confirmation) and usually provides higher selectivity at quantitative determination step [64]. For ionization of non-ionic analytes were applied two techniques: atmospheric pressure chemical ionization (APCI) [26] and electrospray ionization ESI (has demonstrated higher sensitivity) [17,63]. The identification and quantitative analysis of non-ionic SAA was performed with the ion trap mass, quadrupole and triple-quadrupole mass spectrometers [64][65][66][67].…”

Confirmation and determination of carboxylic acids in root exudates using LC–ESI‐MS

“…However, the eluent used in conventional LC is not compatible with ESI-MS because this detection technique requires a volatile mobile phase. On the other hand, eluents used in conventional LC decrease the background noise and do not suppress the ionization efficiency of analytes [12]. This is the reason why only a limited number of studies have been reported on the use of LC -MS for the analysis of highly polar (hydrophilic) compounds [13 -15].…”

“…However, one of the major problems in ESI-MS is the suppression of analytical signals in the presence of matrix compounds [12]. To achieve our aims, it was necessary to examine the separation and ESI-MS detection conditions, as well as the compensation of matrix effect.…”