Multiclass determination of 66 organic micropollutants in environmental water samples by fast gas chromatography–mass spectrometry

Abstract

A multiresidue method has been developed for quantification and identification of 66 multiclass priority organic pollutants in water by fast gas chromatography (GC) coupled to mass spectrometry (MS). Capabilities and limitations of single quadrupole mass spectrometer as detector in fast GC were studied evaluating the chromatographic responses in terms of sensitivity and chromatographic peak shapes, as they were influenced by scan time. The number of monitored ions in a selected ion monitoring (SIM) group strongly conditioned the scan time and subsequently the number of data points per peak. A compromise between peak shape and scan time was adopted in order to reach the proper conditions for quantitative analysis. An average of 10 to 15 points per peak was attained for most compounds, involving scan times between 0.1 and 0.22 s.The method was validated for mineral, surface and groundwater. A solid phase extraction (SPE) preconcentration step using C 18 cartridges was applied. Four isotopically labeled standards were added to the samples before extraction, and used as surrogates to ensure a reliable quantification. Analyses were performed by GC-MS in electron ionization mode, monitoring the three most abundant and/or specific ions for each compound and using the intensity ratios as a confirmatory parameter. With a chromatographic run of less than 10 minutes, SIM mode provided excellent sensitivity and

Application of Fast Gas Chromatography–Mass Spectrometry in Combination with the QuEChERS Method for the Determination of Pesticide Residues in Fruits and Vegetables

“…GC and MS parameters optimized in our previous paper (Cherta et al 2012) were used, since several pesticides in common were determined in both cases. Injection mode was the only change to be considered on the chromatographic system, so optimization was focused on the PTV injection mode parameters.…”

“…MS parameters were optimized previously (Cherta et al 2012); ion source and interface temperatures were maintained at 225 and 300 °C, respectively, and scan time was set at 0.1 s in scan mode (scan speed of 3333 amu/s), allowing the acquisition of 10 to 15 data points per peak.…”

“…In this way, an increase in sensitivity was required for an adequate quantification at low concentration levels, so a SIM method was created from the scan injection selecting the target and reference ions to be acquired. As the increase in the number of ions included in a SIM group also increases the scan time, resulting in the acquisition of less data points per peak, we established for our mass spectrometer a maximum of 20 ions in a SIM group (corresponding to a scan time of 0.2 s) to obtain good peak shape and satisfactory quantification (Cherta et al 2012;Maštovská and Lehotay 2003). Finally, compounds were sorted into 16 SIM groups with 3 to 20 ions monitored in each one (from 1 to 7 compounds included in the different groups).…”

“…The relevance of fast GC also comes from the attainment of better instrumental sensitivity, comparable in some cases to that reached with analyzers working under MS/MS mode. Thus, in a previous study (Cherta et al 2012), low limits of quantification (LOQs) were achieved for pesticides and other organic pollutants in water matrices working with fast GC-MS using single quadrupole. A challenge would be to demonstrate the same capabilities for more complex matrices as fruits and vegetables.…”

Application of gas chromatography–(triple quadrupole) mass spectrometry with atmospheric pressure chemical ionization for the determination of multiclass pesticides in fruits and vegetables

“…However, many pesticides are also amenable to gas chromatography (GC) coupled to mass spectrometry (MS) which makes it a valuable complementary technique, especially because it is the only option for certain pesticide classes and therefore has to be used anyway. Several quantitative applications have been described in literature using GC-MS with a single quadrupole analyzer operating in selected ion monitoring (SIM) [7], [8] and [9], especially for multi-residue analysis with a limited number of compounds. However, the determination of a larger number of analytes usually requires more selective techniques, as tandem mass spectrometry (MS/MS).…”