Flow Injection Analysis of Maleic Hydrazide Using an Electrochemical Sensor Based on Palladium-Dispersed Carbon Paste Electrode

Fast determination of four polar contaminants in soy nutraceutical products by liquid chromatography coupled to tandem mass spectrometry

An analytical method based on a modified QuPPe (quick polar pesticide) extraction procedure coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was evaluated for the determination of four polar compounds (chlorate, fosetyl-Al, maleic hydrazide, and perchlorate) in nutraceutical products obtained from soy. Experimental conditions including extraction such as solvent, acidification, time, and clean-up sorbents were varied. Acidified acetonitrile (1 % formic acid, v/v) was used as extraction solvent instead of methanol (conventional QuPPe), which provides a doughy mixture which cannot be injected into the LC. Clean-up or derivatization steps were avoided. For analysis, several stationary phases were evaluated and Hypercarb (porous graphitic carbon) provided the best results. The optimized method was validated and recoveries ranged between 46 and 119 %, and correction factors can be used for quantification purposes bearing in mind that inter-day precision was equal to or lower than 17 %. Limits of quantification (LOQs) ranged from 4 to 100 μg kg-1. Soy-based nutraceutical products were analyzed and chlorate was detected in five samples at concentrations between 63 and 1642 μg kg-1. Graphical Abstract Analysis of polar compounds in soy-based nutraceutical products.

Surface-enhanced Raman spectroscopic analysis of maleic hydrazide adsorbed on gold surface

In this paper, surface-enhanced Raman scattering (SERS) spectra of maleic hydrazide (MH, 6-hydroxy-3(2H)-pyridazinone) were studied by using citrate-reduced gold colloidal nanoparticles. Comparisons between the prominent SERS bands and the precise mode descriptions predicted through density functional theory (DFT) simulations at the B3LYP/6-311++g(d,p) level allowed an in-depth orientation analysis of the adsorbed species on gold surfaces. And main forms of hydrogen bonds in the solid state of MH were also determined to be O-H⋯O. Furthermore, the effects of concentration and pH on the SERS spectra of the molecule were discussed. It is found that with the different adsorbate concentration, the SERS spectra of MH show significant changes in their features, indicating different orientations and adsorption sites of the molecule on the gold colloidal surface. The SERS and absorption spectra under different pH conditions show that a basic environment leads to the deprotonation of N2 and the nearly parallel orientation of the MH molecule on the gold surface. Moreover, the enhanced characteristic bands were observed at MH concentrations down to about 1 ppm with the gold colloids, demonstrating a potential of the technique in the analysis of MH residues.