Gas phase conversion of triphosphate to trimetaphosphate

Gas-Phase Internal Ribose Residue Loss from Mg-ATP and Mg-ADP Complexes: Experimental and Theoretical Evidence for Phosphate-Mg-Adenine Interaction

Gas-phase decompositions of magnesium complexes with adenosine-5'-triphosphate (ATP) and adenosine-5'-diphosphate (ADP) were studied by using electrospray ionization-collision-induced dissociation-tandem mass spectrometry, in the negative ion mode. The loss of internal ribose residue was observed and was found to occur directly from the [ADP-3H+Mg]^- ion. The occurrence of this process indicates the presence of a strong phosphate-Mg-adenine interaction. The performed quantum mechanics calculations confirmed the occurrence of this interaction in the [ADP-3H+Mg]^- ion, namely the presence of Mg-N7 bond and hydrogen bond between the phosphate oxygen atom and amino group. Although the finding concerns the gas phase, it indicates that phosphate-Mg-adenine interaction may be also of importance for biological processes. The loss of an internal ribose residue was also observed for calcium and zinc complexes with ATP/ADP as well as for magnesium complexes with guanosine-5'-triphosphate (GTP) or guanosine-5'-diphosphate (GDP). Therefore, it is reasonable to conclude that the presence of the phosphate-metal-nucleobase interaction is a feature of gas phase [NDP-3H+metal]^- ion (NDP, nucleoside-5'-diphosphate) and may also be important for biological processes.

Fragmentation pathway of hypophosphite (H2PO2-) in mass spectrometry and its determination in flour and flour products by LC-MS/MS

The fragmentation pathway of H₂PO₂^- in MS was obtained by Orbitrap HRMS and the reverse confirmation was carried out by the neutral loss detection experiment. The results showed that H₂PO₂^- with even electron ion would produce the neutral loss of 2H and form a new even electron ion with a pair of lone-pair electrons. Based on this, a LC-MS/MS method was developed for the determination of H₂PO₂^- in flour and flour products. The H₂PO₂^- was separated on an Acclaim Trinity P1 composite ion exchange column, and then detected by MS/MS under MRM mode. Finally, the developed method was validated in terms of the linearity, selectivity, accuracy, precision and matrix effect. The method showed a good linearity (R²＞0.999) in the concentration range of 50 ∼ 1500 μg/L. The LOD and LOQ for H₂PO₂^- were 10.0 mg/kg and 30.0 mg/kg, respectively. The average recoveries and RSDs (n = 6) were 93.0%∼102.9% and 2.6 ∼ 5.6%, respectively.