Combination of ESI and MALDI-MS Imaging Enhances Analysis on Brain Gangliosides

Recent advances in matrix-assisted laser desorption ionization (MALDI) mass spectrometry imaging (MSI) have led to the direct analysis of tissue slices. The major advantage of MSI is its capability of simultaneously localizing and identifying a parent molecule and its metabolites without any labeling or any prior knowledge. MSI has been extensively employed to detect the differentiated pattern of lipids in various organs in different diseases, such as brains in Alzheimer’s disease. Poor reproducibility of MALDIMSI analysis due to the heterogeneity of the matrix-analyte crystals, hindersits use on quantitative analysis. In addition, discontinuous ion flow due to quickly consumption of the samples under laser irradiation on specific site affects its ability in qualitative analysis. Although electrospray ionization mass spectrometry (ESI-MS) cannot directly be used for imaging, ESI tandem mass spectrometry (LC/ESI-MS/MS) can separate and distinguish gangliosides.

Zhang et al. have presented a promising workflow for qualitative, semi-quantitative and in situ analysis of gangliosides by combiningthe MALDI MSI and ESI-MS. Following obtaining the brain from the mice, fresh-frozen murine brain sections were prepared and coated with matrix for subsequent MALDI MSI analysis.

Synthesis and Characterization of Deshydroxy Posaconazole

A general scheme is set for the estimation of the impurities in bulk drug substances by the rational use of chromatographic, spectroscopic and analytical techniques. The various parameters to be fulfilled in an impurity profiling of drug substances are discussed. Impurity is definedas any substance coexisting with the original drug, such as starting materialor intermediates or these formed, due to any side reactions. The presence of these unwanted chemicals, even in small amounts, may influence the efficacy and safety of the pharmaceutical products. Impurity profiling (i.e., the identity as well as the quantity of impurity in the pharmaceuticals), is now gaining critical attention from regulatory authorities. 

The different Pharmacopoeias, such as the British Pharmacopoeia (BP), United States Pharmacopeia (USP), and Indian Pharmacopoeia (IP) are slowly incorporating limits for allowable levels of impurities present in the APIs or formulations. The process-relatedimpurities in an active pharmaceutical ingredient (API) can have a significantimpact on the quality and safety of the drug products. The impurity levels in any drug substance are described as per its biological or toxicological data. It is quite important for “regulatory” aspect of drug approval to provide limitation of “related impurities.” Therefore, it is necessary to study the impurity profile of any API and control it during the manufacturing of a drug product.

Electrochemical Biosensors; A Promising Tool in Pharmaceutical Analysis

In analytical chemistry, the main challenges are concerned with rapid and simultaneous detection of compounds occurred in clinical, environmental and food samples. Due to this reason biosensors are called as promising tools which can be used for detecting many chemical and biological parameters. It consists of a bio component used in the molecular recognition and a transducer, electronic signal processor. The main principle of biochemical sensors is the specific molecular recognition of the analyte which can be performed by the use of enzymes, antibodies, nucleic acids, germs, cells and tissues. In this reaction, some physiochemical changes may takes place between the bio component and the analyte, which is converted into electrical signal with the transducer. 

Researchers have studied that these biosensors are divided into three types such as amperometric and potentiometric, conductive. In electrochemical biosensor the transducer act as an electrode and the transduction is mostly realized by means of amperometry or potentiometry. According to scientific significance the two primary classes of electrochemical biosensors are the chemical and DNA biosensors.