Using standard additions to improve extraction and quantification of inositol hexakisphosphate in sediment samples by ion chromatography electrospray ionization mass spectrometry.

Several key aspects for the analysis of inositol hexakisphosphate (InsP6) have been investigated in order to establish a suitable method for the study of sediment samples from different aquatic systems. Apparent matrix effects for the ion chromatography electrospray ionization tandem mass spectrometric detection (IC-ESI-MS/MS) method were accounted for with a standard addition approach, which also compensated for variation in extraction efficiency. Several parameters of the extraction method were optimized to improve the extraction efficiency for different sediment types. We observed an improvement in the extraction efficiency between 18% and 720%. Finally, the method was used to gain first insights into the relevance of InsP6 in two aquatic systems located at the German Baltic coastal area. InsP6 was detected in several sediment samples with concentrations between 2.3 and 15.2 µg InsP6-P/g dry weight (DW).

The influence of salt matrices on the reversed-phase liquid chromatography behavior and electrospray ionization tandem mass spectrometry detection of glyphosate, glufosinate, aminomethylphosphonic acid and 2-aminoethylphosphonic acid in water.

The analysis of highly polar and amphoteric compounds in seawater is a continuing challenge in analytical chemistry due to the possible formation of complexes with the metal cations present in salt-based matrices. Here we provide information for the development of analytical methods for glyphosate, glufosinate, AMPA, and 2-AEP in salt water, based on studies of the effects of salt matrices on reversed-phase liquid chromatography-heated electrospray ionization-tandem mass spectrometry (RP-LC-HESI-MS/MS) after derivatization of the target compounds with FMOC-Cl. The results showed that glyphosate was the only analyte with a strong tendency to form glyphosate-metal complexes (GMC), which clearly influenced the analysis. The retention times (RTs) of GMC and free glyphosate differed by approximately 7.00min, reflecting their distinct RP-LC behaviors. Divalent cations, but not monovalent (Na+, K+) or trivalent (Al3+, Fe3+) cations, contributed to this effect and their influence was concentration-dependent. In addition, Cu2+, Co2+, Zn2+, and Mn2+ prevented glyphosate detection whereas Ca2+, Mg2+, and Sr2+ altered the retention time. At certain tested concentrations of Ca2+ and Sr2+ glyphosate yielded two peaks, which violated the fundamental rule of LC, that under the same analytical conditions a single substance yields only one LC-peak with a specific RT. Salt-matrix-induced ion suppression was observed for all analytes, especially under high salt concentrations. For glyphosate and AMPA, the use of isotopically labeled internal standards well-corrected the salt-matrix effects, with better results achieved for glufosinate and 2-AEP with the AMPA internal standard than with the glyphosate internal standard. Thus, our study demonstrated that Ca2+, Mg2+, and Sr2+ can be used together with FMOC-Cl to form GMC-FMOC which is suitable for RP-LC-HESI-MS/MS analysis.