Study of liquid chromatography/electrospray ionization mass spectrometry matrix effect on the example of glyphosate analysis from cereals

Abstract

Glyphosate is one of the most common pesticides used in the pre-harvest treatment of cereals. This paper examines the matrix effect of glyphosate liquid chromatography/electrospray ionization mass spectrometric (LC/ESI-MS) analysis in wheat and rye. The matrix effect (ionization suppression) was found to be dependent on sample particle size taken for the extraction. If samples are ground to very small particles severe ionization suppression occurs. For lower glyphosate contents (<1 mg/kg) the signal may even be suppressed by more than 90%. The matrix effect was found to be dependent on the matrix - rye showed significantly stronger ionization suppression than wheat, although these matrices are not very different. The matrix effect also depends on the concentration of glyphosate in the post-extraction spiked samples. It is demonstrated that the isotope-labelled standard (13)C(2)-glyphosate undergoes different ionization suppression than glyphosate and is therefore not efficient in compensating for matrix effect. At the same time the extrapolative dilution approach allows to efficiently compensate for matrix effect.

An analytical investigation of 24 oxygenated-PAHs (OPAHs) using liquid and gas chromatography–mass spectrometry

“…One likely explanation for this discrepancy is matrix enhancement of the 254 m / z ion, which would make the internal standard response higher over that of standard addition. Similar LC-MS matrix enhancement has been described in previous methods [ 37 ]. Enhancement is also seen for 7,8/1,6-B[a]PYRD while suppression is shown for 2-ethANTQ, both below the LOQ (Fig.…”

“…5 ). The discrepancy for 2-ethANTQ could be ion suppression which is also common in LC-MS data [ 37 ]. Overall, there is excellent agreement between both quantitation strategies with seven out of ten compounds differing by less than 30 %.…”

Analysis of glyphosate and aminomethylphosphonic acid in water, plant materials and soil

“…Analyses in complex matrices such as some plant materials, soils and sediments and coextracted chemicals can cause MS and MS/MS signal suppression or enhancement (matrix suppression or enhancement), which affects accurate quantitation. Various methods have been used to compensate for or eliminate matrix effects, such as additional clean‐up steps, performing matrix‐matched calibration or using an extrapolative dilution approach . Occasionally, isotope‐labeled glyphosate and AMPA standards have been used in analyses with MS and MS/MS, which eliminate concerns of incomplete elution from SPE cartridges, sorbent effects and MS drift …”

“…7,8,18,29,44,85,98,101,108 -123 Corn, soybean and various forage berry species have also been extracted using water/chloroform, 124 -126 whereas water/methanol (with shaking or sonication) was used for extraction of glyphosate and AMPA from Arabidopsis leaves, maize, peas, barley, flax seed, spinach carrot and straw, 118,127 -129 and water/acetone (with shaking or sonication) was used to extract wheat 97 and Lolium multiflorum. 130 Other less commonly used extractants include water/dichloromethane for various plant samples (wheat, olives, tree leaves, tomato, tobacco, beans, turmeric, chili, coriander, coffee, rice, tea, ginger, blackcurrent, hazelnut); 62,80,114,131,132 water/methanol/dichloromethane for cereals; 129 water/EDTA for guava peel; 96 water/NH 2 silica for AMPA in tomato and water/NaH 2 PO 4 /NH 2 silica for glyphosate in tomato; 133 borate buffer for apple. 134 As with water analyses, the majority of which derivatized glyphosate and AMPA prior to analyses, 75% of the reviewed articles in the past 15 years used derivatization in analyses of plant materials (Table 2).…”

Simplified analysis of glyphosate and aminomethylphosphonic acid in water, vegetation and soil by liquid chromatography–tandem mass spectrometry

“…10,14 -16 Fewer new methods have been reported in the past 5 years for more complex matrices such as vegetative material, soil and sewage sludge. These have involved minor variations of previously published methods or a new matrix: use of a hydrophilic interaction chromatography (HILIC) column with UV-visible or electrospray ionization (ESI)-MS/MS detection for analysis of glyphosate in selected fruits and vegetables, 17 sample clean-up by protein precipitation for LC-MS/MS analysis of glyphosate and AMPA in soybean, 18 optimization of derivatization methods using 9fluorenylmethylchloroformate (FMOC) for analysis of glyphosate and AMPA in maize by HPLC coupled to fluorescence and ESI-MS, 19 an optimized extraction procedure and chromatographic separation for analysis of glyphosate and AMPA in soil, 20 online FMOC derivatization on a strong anion-exchange resin as a solid support for analysis of glyphosate and AMPA in sewage sludge 21 and LC-ESI-MS or MS/MS analysis of wheat and rye 22 and soybean. 18 In spite of these recently published methods, which have primarily been developed for a single matrix, there is a need for a simplified method of analysis for glyphosate and AMPA that will work for multiple, diverse matrices.…”