Extraction of the insecticide dieldrin from water and biological samples by metal affinity chromatography

Thin Films of Lanthanide Stearates as Modifiers of the Q-Sense Device Sensor for Studying Insulin Adsorption

This article presents new possibilities of using thin films of lanthanide stearates as sorbent materials. Modification of the Q-sense device resonator with monolayers of lanthanide stearates by the Langmuir-Schaeffer method made it possible to study the process of insulin protein adsorption on the surface of new thin-film sorbents. The resulting films were also characterized by compression isotherms, chemical analysis, scanning electron microscopy, and mass spectrometry. The transition of stearic acid to salt was recorded by IR spectroscopy. Using the LDI MS method, the main component of thin films, lanthanide distearate, was established. The presence of Eu²⁺ in thin films was revealed. In the case of europium stearate, the maximum value of insulin adsorption was obtained, -1.67·10^-10 mole/cm². The findings suggest the possibility of using thin films of lanthanide stearates as a sorption material for the proteomics determination of the quantitative protein content in complex fluid systems by specific adsorption on modified surfaces and isolation of such proteins from complex mixtures.

High-Throughput Fingerprinting of Rhizobial Free Fatty Acids by Chemical Thin-Film Deposition and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

Fatty acids (FAs) represent an important class of metabolites, impacting on membrane building blocks and signaling compounds in cellular regulatory networks. In nature, prokaryotes are characterized with the most impressing FA structural diversity and the highest relative content of free fatty acids (FFAs). In this context, nitrogen-fixing bacteria (order Rhizobiales), the symbionts of legumes, are particularly interesting. Indeed, the FA profiles influence the structure of rhizobial nodulation factors, required for successful infection of plant root. Although FA patterns can be assessed by gas chromatography-(GC-) and liquid chromatography-mass spectrometry (LC-MS), sample preparation for these methods is time-consuming and quantification suffers from compromised sensitivity, low stability of derivatives and artifacts. In contrast, matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) represents an excellent platform for high-efficient metabolite fingerprinting, also applicable to FFAs. Therefore, here we propose a simple and straightforward protocol for high-throughput relative quantification of FFAs in rhizobia by combination of Langmuir technology and MALDI-TOF-MS featuring a high sensitivity, accuracy and precision of quantification. We describe a step-by-step procedure comprising rhizobia culturing, pre-cleaning, extraction, sample preparation, mass spectrometric analysis, data processing and post-processing. As a case study, a comparison of the FFA metabolomes of two rhizobia species-Rhizobium leguminosarum and Sinorhizobium meliloti, demonstrates the analytical potential of the protocol.

Application of lanthanum stearate monolayers as a metal-affinity sorbent for the selective sorption of soman adducts to human serum albumin

A new metal-affinity sorbent based on lanthanum stearate monolayers has been developed and characterized. The prospect of its application to specific extraction of organophosphorous compound (OP) adducts of blood proteins was demonstrated. For this, the patterns of soman adducts of human serum albumin (HSA) were comprehensively characterized by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS).