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Hyperfine Interactions - A solution of Fe(NO3)3 with a pH 9 was processed with a hydrothermal method in an autoclave. During the heating process samples were extracted at 140°C, 160°C,... 相似文献
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Bolaños PP Moreno JL Shtereva DD Frenich AG Vidal JL 《Rapid communications in mass spectrometry : RCM》2007,21(14):2282-2294
A new method was developed and validated for the simultaneous determination of 151 pesticide residues in strawberry by gas chromatography coupled to a triple quadrupole mass analyzer (GC/QqQ-MS/MS), mainly using the selected reaction monitoring (SRM) mode. The list of target compounds included various classes of pesticides such as organochlorine (OCPs), organophosphorus (OPPs), carbamates, pyrethroids, triazoles and dicarboximides. A single extraction of 10 g of sample with acetonitrile followed by liquid-liquid partition formed by the addition of 4 g of MgSO4 and 1 g of NaCl was applied in sample preparation. Cleanup of the extracts was carried out by applying dispersive solid-phase extraction (D-SPE) with primary secondary amine (PSA). The analysis time was 21 min. The method was subjected to a thorough validation procedure. The recovery data were obtained by spiking blank samples at two concentration levels (11.5 and 50 microg/kg), yielding recoveries in the range 70-110%. Precision values expressed as relative standard deviation (RSD) were lower than 18% and 22% for the intraday and interday precision, respectively. Linearity was studied in the range 10-200 microg/kg and determination coefficients (R(2)) were higher than 0.98% for all compounds. Limits of detection (LODs) and limits of quantification (LOQs) were established as 4 and 10 microg/kg, respectively. The overall uncertainty of the method was estimated at two different concentrations (11.5 and 50 microg/kg), being lower than 25% in both cases. According to the validation data and performance characteristics as well as the high sample throughput and low cost, the proposed method is suitable for routine application. 相似文献
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Juan Antonio Padilla‐Sánchez Patricia Plaza‐Bolaños Roberto Romero‐González Ángel Grande‐Martínez Earl Michael Thurman Antonia Garrido‐Frenich 《Journal of mass spectrometry : JMS》2012,47(11):1458-1465
The determination of compounds showing a very low molecular weight (i.e. < 200 Da) can be complicated when low‐resolution mass spectrometry is used in the selected‐reaction monitoring mode, since the possible number of product ions is reduced and the obtained reactions are not selective enough to overcome background noise and/or matrix interferences. In this study, the use of high‐resolution mass spectrometry based on Exactive Orbitrap was applied for the determination of a group of polar organophosphonate pesticides and transformation products (TPs), which show the aforementioned features, in agricultural soils. Namely, glyphosate, glufosinate, ethephon and their TPs, aminomethyl phosphonic acid (AMPA), 3‐methylphosphinicopropionic acid, N‐acetyl‐glufosinate and 2‐hydroxyethylphosphonic acid were analyzed. The [M‐H]‐ ions 168.00564, 180.04202, 142.96593, 110.00016, 151.01547, 222.05259 and 124.99982 were used, respectively, for the detection and identification of the compounds. Confirmation was carried out by using accurate mass measurements of ion fragments for each compound, from neutral losses of CO2, H2O and H2CO (formaldehyde). Furthermore, the recently reported tool, relative isotopic mass defect (RΔm), was also used to support the confirmation protocol. The optimized method was fully validated at low levels, including the estimation of a not commonly used parameter: the limit of confirmation (LOC). This LOC is expressed as the lowest concentration of compound that can be confirmed using a fragment or the RΔm, and it ranged from 10 to 50 µg kg?1 for all compounds. All the data was obtained in a single injection. Finally, the method was applied to real soil samples, and glyphosate and AMPA were found at 265 µg kg?1 and 105 µg kg?1, respectively. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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