Rhodamine B - as New Chromophore for the Determination of Melatonin in Biological, Food, and Pharmaceutical Samples.

AIM AND OBJECTIVE: Melatonin is an essential biomarker for sleep-related disorders. Reliable methods of analysis are needed for melatonin. Therefore, a new chromophore (Rhodamine B) was proposed for the assay of melatonin; this method succeeded to enlarge the working concentration range and to decrease the limit of determination comparing with the method that just used the native fluorescence of melatonin. MATERIALS AND METHODS: Rhodamine B was proposed as a new chromophore for the assay of melatonin in biological, food, and pharmaceutical samples. Fluorescence was used for the determination of melatonin. RESULTS: The results obtained using Rhodamine B were compared with those obtained by the native fluorescence of melatonin. Using the new chromophore, melatonin was determined in the concentration range between 0.01 and 50 pmol L-1, with the detection limit of 2.4 fmol L-1. The recovery of melatonin was higher than 98.00% with a relative standard deviation of less than 0.10%, when the method was applied for the assay of melatonin in samples such as breast milk, whole blood, milk powder, and pharmaceutical formulations. CONCLUSION: Utilization of Rhodamine B enlarged the linear concentration range for the assay of melatonin and decreased the detection limit, making possible the assay of melatonin in a variety of samples such as pharmaceuticals, food, and biological samples.

Vibrational Spectroscopy in Body Fluids Analysis.

Vibrational spectroscopy offers a unique opportunity to investigate the composition of unknown substances on a molecular basis. The spectroscopy of molecular vibrations using mid-infrared or Raman techniques has been applied to samples of body fluids. This review presents some applications related to body fluids published in the period 2005-2015.

Vibrational Micro-Spectroscopy of Human Tissues Analysis: Review.

Vibrational spectroscopy (Infrared (IR) and Raman) and, in particular, micro-spectroscopy and micro-spectroscopic imaging have been used to characterize developmental changes in tissues, to monitor these changes in cell cultures and to detect disease and drug-induced modifications. The conventional methods for biochemical and histophatological tissue characterization necessitate complex and "time-consuming" sample manipulations and the results are rarely quantifiable. The spectroscopy of molecular vibrations using mid-IR or Raman techniques has been applied to samples of human tissue. This article reviews the application of these vibrational spectroscopic techniques for analysis of biological tissue published between 2005 and 2015.

Recent Applications for in Vitro Antioxidant Activity Assay.

This review presents some of the most recent aspects related to antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Taking into account the reactions involved, in the antioxidant activity determinations, the assays can be classified into two main types: hydrogen atom transfer reactions and electron transfer. This review focuses on analytical methods used for antioxidant activity assay, published in the period 2009-2014.

Vibrational spectroscopy used in milk products analysis: A review.

Milk is a fluid containing several substances, and its composition depends on several factors. Vibrational spectroscopy is a powerful tool to determine the constituent concentrations and qualitative characteristics of dairy products. Vibrational spectrometry covers a series of well-established analytical methodologies suitable to be employed for both qualitative and quantitative purposes. In the first part of this review, theoretical aspects on vibrational techniques are presented; in the second part, the most important papers, published during the period 2009-2015, related to milk analysis are discussed.

Analytical Applications of Transport Through Bulk Liquid Membranes.

This review discusses the results of research in the use of bulk liquid membranes in separation processes and preconcentration for analytical purposes. It includes some theoretical aspects, definitions, types of liquid membranes, and transport mechanism, as well as advantages of using liquid membranes in laboratory studies. These concepts are necessary to understand fundamental principles of liquid membrane transport. Due to the multiple advantages of liquid membranes several studies present analytical applications of the transport through liquid membranes in separation or preconcentration processes of metallic cations and some organic compounds, such as phenol and phenolic derivatives, organic acids, amino acids, carbohydrates, and drugs. This review presents coupled techniques such as separation through the liquid membrane coupled with flow injection analysis.

X-ray diffraction: instrumentation and applications.

X-ray diffraction (XRD) is a powerful nondestructive technique for characterizing crystalline materials. It provides information on structures, phases, preferred crystal orientations (texture), and other structural parameters, such as average grain size, crystallinity, strain, and crystal defects. X-ray diffraction peaks are produced by constructive interference of a monochromatic beam of X-rays scattered at specific angles from each set of lattice planes in a sample. The peak intensities are determined by the distribution of atoms within the lattice. Consequently, the X-ray diffraction pattern is the fingerprint of periodic atomic arrangements in a given material. This review summarizes the scientific trends associated with the rapid development of the technique of X-ray diffraction over the past five years pertaining to the fields of pharmaceuticals, forensic science, geological applications, microelectronics, and glass manufacturing, as well as in corrosion analysis.

Applications of FT-IR spectrophotometry in cancer diagnostics.

This review provides a brief background to the application of infrared spectroscopy, including Fourier transform-infrared spectroscopy, in biological fluids. It is not meant to be complete or exhaustive but to provide the reader with sufficient background for selected applications in cancer diagnostics. Fourier transform-infrared spectroscopy (FT-IR) is a fast and nondestructive analytical method. The infrared spectrum of a mixture serves as the basis to quantitate its constituents, and a number of common clinical chemistry tests have proven to be feasible using this approach. This review focuses on biomedical FT-IR applications, published in the period 2009-2013, used for early detection of cancer through qualitative and quantitative analysis.

Biomedical investigations using Fourier transform-infrared microspectroscopy.

One of the most exciting recent developments in infrared spectroscopy has been the coupling of the spectrometer to an infrared microscope. The combination of the new infrared spectrometer and a microscope was a natural thought of scientists in these fields. This development has been so rewarding and so useful in solving today's chemical problems that infrared microspectroscopy has quickly become a significant subclassification of infrared spectroscopy. Infrared microspectroscopy has a much longer history than the recent enthusiasm would imply, however. The great interest in the use of infrared spectroscopy to solve biomedical problems that occurred in recent years shortly spread into the medical and biological fields. The aim of this review is to discuss the new developments in applications of FT-IR microspectroscopy in biomedical analysis, covering the period between 2008 and 2013.

Validation and quality control of an ICP-MS method for the quantification and discrimination of trace metals and application in paper analysis: an overview.

Questioned documents analysis includes: handwriting comparison, analysis of the ink and the printer used in the production of the documents, and the physical and chemical characterization of the cellulosic substrate (paper) of the documents. In many situations in life, for financial, social, and personal concerns, we depend on different documents. Therefore, over time, various analytical methods have been developed in order to determine their authenticity, source, and age or to differentiate various papers. In this study a quantitative analytical method for the determination of eight trace level chemical elements (Al, Ba, Fe, Mg, Mn, Pb, Sr, Zn) from document paper samples using inductively coupled plasma-mass spectrometry (ICP-MS) was validated and applied. The evaluation of the performance parameters of the method (applicability, fitness for purpose, linearity, working range, limit of detection and limit of quantification, sensitivity, accuracy, and precision) was accomplished. An overview of the validation parameters are presented and discussed in detail.

A new method for a quantitative determination of piroxicam in pharmaceutical formulations using FT-IR spectrometry.

A Fourier transform infrared (FT-IR) spectrometric method was developed for the rapid, and direct measurement of piroxicam (Pir) in pharmaceutical drugs. Pir is a well known and very effective antiinflammatory drug. Pir can be determined by various methods and now we are adding a new one that uses a Fourier transform infrared spectrophotometric technique. Conventional spectra were compared for best determination of active substance in pharmaceutical formulations. The Beer-Lambert law and two chemometric approaches, partial least squares (PLS) and principal component regression (PCR+) methods, were tried in data processing.

Determination of diosmin in pharmaceutical formulations using Fourier transform infrared spectrophotometry.

A Fourier transform infrared (FT-IR) spectrometric method was developed for the rapid, direct measurement of diosmin in different pharmaceutical drugs. Conventional KBr-spectra were compared for best determination of active substance in commercial preparations. The Beer-Lambert law and two chemometric approaches, partial least squares (PLS) and principal component regression (PCR+) methods, were tried in data processing.

FT-IR spectrophotometric analysis of coenzyme Q10 (CoQ10) and its pharmaceutical formulations.

A Fourier transform infrared (FT-IR) spectrometric method was developed for the rapid, direct measurement of coenzyme Q10 (CoQ10) in different pharmaceutical products. Conventional KBr spectra were compared for the best determination of active substance in drug preparations. Lambert-Beer's law and two chemometric approaches, partial least squares (PLS) and principal component regression (PCR+) methods, were used in data processing.

Quantitative analysis of bucillamine and its pharmaceutical formulation using FT-IR spectroscopy.

A Fourier transform infrared (FT-IR) spectrometric method was developed for the rapid, direct measurement of bucillamine. Conventional KBr-spectra and DRIFTS spectra were compared for best determination of active substance in its tablet formulation. Two chemometric approaches, partial least squares (PLS) and principal component regression (PCR+) methods were used in data processing. Similar results were obtained with both chemometric methods.

Synthesis and analytical characteristics of new progesterone skeleton haptens.

This article describes the synthesis of new conjugated progesterone-bovine serum albumin substances, used to obtain specific antisera toward this hormone and for progesterone assay kits. In general, these kits are designed to be used on the farm or at the local veterinary clinics.

FT-IR spectrophotometric analysis of dehydroepiandrosterone and its pharmaceutical formulation.

A Fourier transform infrared (FT-IR) spectrometric method was developed for the rapid, direct measurement of dehydropeiandrosterone. Conventional KBr spectra and KBr + 2.0 mg microcrystalline cellulose (MCC) spectra were compared for best determination of active substance in drug formulation. Two chemometric approaches, partial least-squares (PLS) and principal component regression (PCR+) methods were used in data processing. The best results were obtained with PCR+ method.

Analysis of mebendazole polymorphs by Fourier transform IR spectrometry using chemometric methods.

A diffuse reflectance IR Fourier transform IR spectrometry (DRIFTS) method was developed for the rapid, direct measurement of mebendazole in drugs. Conventional KBr spectra and DRIFTS spectra were compared for the best determination of the active substance in the drug formulations. Two chemometric approaches were used in the data processing: multicomponent partial least squares (PLS2) and principal component regression. The best results were obtained with the PLS2 method.