A validated LC–MS/MS method for the determination of homocysteic acid in biological samples

Background: An Ionic Liquid-based based Dispersive Liquid-Liquid Microextraction (IL-DLLME) method was not applied to preconcentration and determination of bilirubin. Ionic Liquids (ILs) are new chemical compounds. In recent years, Ionic Liquids (ILs) have been employed as alternative solvents to toxic organic solvents. Due to these perfect properties, ILs have already been applied in many analytical extraction processes, presenting high extraction yield and selectivity for analytes. Methods: In this study, IL-DLLME was applied to biological samples (urine and serum) for the spectrophotometric detection of bilirubin. For bilirubin analysis, the full-color development was based on the reaction with periodate in the presence of hydrochloric acid. The high affinity of bilirubin for the ionic liquid phase gave extraction percentages above 98% in 0.3 M HCl solution. Results: Several IL-extraction parameters were optimized and room temperature ionic liquid 1-butyl- 1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and ethanol were used as extraction and disperser solution. The linear range was found in the range of 0.5-6.0 μM (0.3-3.5 μg mL-1) and the limits of detection of the proposed method was 0.5 μM (0.3 μg mL-1). The proposed method was applied for the preconcentration and separation of trace bilirubin in real urine samples. Also, the recoveries for bilirubin in spiked biological samples (urine and serum) were found to be acceptable, between 95-102%. Conclusion: The proposed IL-DLLMEapproach was employed for the enrichment and determination of trace levels of bilirubin in urine samples using NaIO4 as an oxidizing agent and Uv-vis spectrophotometric detection. The periodate oxidation of bilirubin is rapid, effective, selective, and simple to perform. The method contains only HCl, NaOI4, and an anionic surfactant. The method may be useful for economizing in the consumption of reagents in bilirubin determining. The IL-DLLMEmethod ensures a high yield and has a low toxicity no skin sensitization, no mutagenicity and no ecotoxicity in an aquatic environment since only very low quantities of an IL is required. For full-color formation, no any extra auxiliary reagents are required. Besides, the IL-DLLME technique uses a low-cost instrument such as Uv-vis which is present in most of the medical laboratories.

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A Review of Voltammetric Methods for Determination of Dopamine Agonists

Current Analytical Chemistry ◽

10.2174/1573411016999200526130915 ◽

2020 ◽

Vol 16 ◽

Author(s):

Fatma Ağin

Keyword(s):

Parkinson’S Disease ◽

Parkinson's Disease ◽

Biological Samples ◽

Dopamine Agonists ◽

Modified Electrodes ◽

Nerve Cells ◽

Electroanalytical Methods ◽

Voltammetry Methods ◽

Voltammetric Methods

Background: Dopamine agonists are useful drugs for the management of patients with Parkinson's disease in the early stages and in later stages of the disease. Parkinson's disease is a progressive neurodegenerative disease that primarily affects dopamine-producing nerve cells in the brain. They bind to dopamine receptors in nerve cells that regulate body movement and motor function. Electroanalytical methods are used in medicinal, clinical and pharmaceutical research. The voltammetry is one of the most commonly used electroanalytical methods. The aims of this review are to gather and discuss studies of voltammetric methods used in determination of dopamine agonists. Method: This review includes the use of various voltammetric methods for determination studies of dopamine agonists from pharmaceutical dosage forms and biological samples. These studies were examined in terms of used voltammetric method or methods, working electrode, buffer, pH and validation parameters. Results: Cabergoline, pramipexole, ropinirole have more studies, while bromocriptine and apomorphine have fewer studies in the literature. Differential pulse voltammetry and square wave voltammetry methods were the most applied methods for determination of dopamine agonist drugs from pharmaceuticals and biological samples. But, stripping, cyclic and lineer sweep voltammetry methods are less applied methods. In this studies, a lot of modified electrodes were developed and used to analyse of dopamine agonists. Conclusion: The voltammetric methods supply determination of therapeutic agents and/or their metabolites in clinical samples at extremely low concentrations without the necessity for the sample pre-treatment or time consuming extraction steps. Also the modified electrodes and validated voltammetric methods provide good stability, repeatability, reproducibility and high recovery for the analysis of the analyte.

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Is it necessary to calculate Young’s modulus in AFM nanoindentation experiments regarding biological samples?

Micro and Nanosystems ◽

10.2174/1876402912666200214123734 ◽

2020 ◽

Vol 12 ◽

Author(s):

S.V. Kontomaris ◽

A. Malamou ◽

A. Stylianou

Keyword(s):

Young’S Modulus ◽

Biological Samples ◽

Young's Modulus ◽

Reference Sample ◽

Nonlinear Behavior ◽

Accurate Method ◽

Accurate Solution ◽

Hertz Model ◽

Work Done

Background: The determination of the mechanical properties of biological samples using Atomic Force Microscopy (AFM) at the nanoscale is usually performed using basic models arising from the contact mechanics theory. In particular, the Hertz model is the most frequently used theoretical tool for data processing. However, the Hertz model requires several assumptions such as homogeneous and isotropic samples and indenters with perfectly spherical or conical shapes. As it is widely known, none of these requirements are 100 % fulfilled for the case of indentation experiments at the nanoscale. As a result, significant errors arise in the Young’s modulus calculation. At the same time, an analytical model that could account complexities of soft biomaterials, such as nonlinear behavior, anisotropy, and heterogeneity, may be far-reaching. In addition, this hypothetical model would be ‘too difficult’ to be applied in real clinical activities since it would require very heavy workload and highly specialized personnel. Objective: In this paper a simple solution is provided to the aforementioned dead-end. A new approach is introduced in order to provide a simple and accurate method for the mechanical characterization at the nanoscale. Method: The ratio of the work done by the indenter on the sample of interest to the work done by the indenter on a reference sample is introduced as a new physical quantity that does not require homogeneous, isotropic samples or perfect indenters. Results: The proposed approach, not only provides an accurate solution from a physical perspective but also a simpler solution which does not require activities such as the determination of the cantilever’s spring constant and the dimensions of the AFM tip. Conclusion: The proposed, by this opinion paper, solution aims to provide a significant opportunity to overcome the existing limitations provided by Hertzian mechanics and apply AFM techniques in real clinical activities.

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A single-step purification method for the precise determination of the antimony isotopic composition of environmental, geological and biological samples by HG-MC-ICP-MS

Journal of Analytical Atomic Spectrometry ◽

10.1039/d0ja00452a ◽

2021 ◽

Author(s):

Ferrari Colin ◽

Resongles Eléonore ◽

Freydier Rémi ◽

Casiot Corinne

Keyword(s):

Isotopic Composition ◽

Biological Samples ◽

Precise Determination ◽

Single Step ◽

Functionalized Silica ◽

Purification Method ◽

Silica Powder ◽

Icp Ms ◽

Single Step Purification

Thiol-functionalized silica powder allowed single-step purification of antimony for exploring stable Sb isotope signatures in the environment.

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Ion Mobility–Mass Spectrometry for Bioanalysis

Separations ◽

10.3390/separations8030033 ◽

2021 ◽

Vol 8 (3) ◽

pp. 33

Author(s):

Xavier Garcia ◽

Maria del Mar Sabaté ◽

Jorge Aubets ◽

Josep Maria Jansat ◽

Sonia Sentellas

Keyword(s):

Mass Spectrometry ◽

Liquid Chromatography ◽

Ion Mobility Spectrometry ◽

Ion Mobility ◽

Biological Samples ◽

Ion Mobility Mass Spectrometry ◽

Exogenous Compounds ◽

Analytical Separation

This paper aims to cover the main strategies based on ion mobility spectrometry (IMS) for the analysis of biological samples. The determination of endogenous and exogenous compounds in such samples is important for the understanding of the health status of individuals. For this reason, the development of new approaches that can be complementary to the ones already established (mainly based on liquid chromatography coupled to mass spectrometry) is welcomed. In this regard, ion mobility spectrometry has appeared in the analytical scenario as a powerful technique for the separation and characterization of compounds based on their mobility. IMS has been used in several areas taking advantage of its orthogonality with other analytical separation techniques, such as liquid chromatography, gas chromatography, capillary electrophoresis, or supercritical fluid chromatography. Bioanalysis is not one of the areas where IMS has been more extensively applied. However, over the last years, the interest in using this approach for the analysis of biological samples has clearly increased. This paper introduces the reader to the principles controlling the separation in IMS and reviews recent applications using this technique in the field of bioanalysis.

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