Reduction of matrix effects and improvement of sensitivity during determination of two chloridazon degradation products in aqueous matrices by using UPLC-ESI-MS/MS

Abstract

The development and validation of a sensitive and reliable detection method for the determination of two polar degradation products, desphenyl-chloridazon (DPC) and methyl-desphenyl-chloridazon (MDPC) in surface water, ground water and drinking water is presented. The method is based on direct large volume injection ultra-performance liquid chromatography electrospray tandem mass spectrometry. This simple but powerful analytical method for polar substances in the aquatic environment is usually hampered by varying matrix effects, depending on the nature of different water bodies. For the two examined degradation products, the matrix effects are particularly strong compared with other polar degradation products of pesticides. Therefore, matrix effects were studied thoroughly with the aim of minimising them and improving sensitivity during determination by postcolumn addition of ammonia solution as a modifier. An internal standard was used in order to compensate for remaining matrix effects. The calibration curve shows very good coefficients of correlation (0.9994 for DPC and 0.9999 for MDPC). Intraday precision values were lower than 5 % for DPC, 3 % for MDPC and the limits of detection were 10 ng/L for both substances. The method was successfully used in a national round robin test with a deviation between 3 and 8 % from target values. Finally, about 1,000 samples from different water bodies have been examined with this method in the Rhine and Ruhr region of North-Rhine-Westphalia (Germany) and in the European Union. Approximately 76 % of analysed samples contained measurable amounts of DPC at concentrations up to 8 μg/L while 53 % of the samples showed MDPC concentrations up to 2.3 μg/L.

Evaluation of the matrix effect of different sample matrices for 33 pharmaceuticals by post-column infusion

“…The matrix evaluation by Kittlaus et al [24] demonstrated the beneficial effect of multiple sequential sample preparation steps. However, sample clarification could not completely remove the matrix influence on the measurement [17,21,24,27,30,31]. Due to incomplete removal of matrix compounds, methods for quantification have been implemented to compensate the occurring matrix impact, for example the use of isotopically labeled internal standards.…”

13C- and 15N-Isotope Analysis of Desphenylchloridazon by Liquid Chromatography–Isotope-Ratio Mass Spectrometry and Derivatization Gas Chromatography–Isotope-Ratio Mass Spectrometry

“…For 13 C/ 12 C isotope analysis, liquid chromatography is the method of choice [35][36][37][38] . LC-IRMS has the advantage that compounds can be analyzed directly without derivatization, but the liquid chromatography presents the challenge that carbon isotope measurements must be conducted without organic eluents, which otherwise would be converted to CO2 and would interfere with 13 C/ 12 C analysis of the analyte 39,40 .…”

Matrix effects in the analysis of polar organic water contaminants with HILIC-ESI-MS

“…In analytical methods employing RPLC, the influence of inorganic ions on the ESI ionisation efficiency can be disregarded due to their elution in the void volume. Even with polar RPLC columns, coelution of salts is limited to early eluting compounds [25]. Therefore, they are rarely considered as problematic matrix effect causing substance in RPLC.…”