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Chromatography and mass spectrometry based techniques are the most commonly employed procedures to quantitate the analytes in pharmaceutical research. However, sensitivity of analytical methods significantly varies due to the difference in physicochemical characteristics of analytes. Sensitivity of methods greatly affects the quality of analytical results. Establishment of a sufficiently sensitive method ensures the suitability of a technique for its intended purpose. Although various types of advancement in chromatographic science are witnessed, issues related to sensitivity remain a major challenge for the analyte with low detection limit. Highly sensitive analytical methods are specifically essential to quantitate the analytes in the samples from dissolution study of sustained release formulations, cross-contamination study, impurity analysis, metabolite profiling, bioanalysis of highly potent and low bioavailable drugs. In recent years, huge involvement of researchers toward sensitivity enhancement of quantitative methods is evidenced. Wide verities of approaches are being reported in the field. Derivatization technique, introduction of ion-pairing reagents, sample pretreatment, and utilization of innovative methods such as 2-dimensional liquid chromatography, nano liquid chromatography, 2-dimensional gas chromatography, supercritical fluid chromatography, use of microcolumn are some approaches that are being employed. Online sample preparation techniques can significantly improve the sensitivity of a method by reducing sample loss and degradation. This review summarizes and critically discussed the approaches to improve the sensitivity of chromatographic and mass spectrometry based analytical methods. This article can guide the researchers to select suitable approaches for achieving the desired detection limit of analytical and bioanalytical methods based on their specific requirements. [ABSTRACT FROM AUTHOR]

The principal intention of this study is presenting the attempts carried out for extracting, separating, and determining of the pesticide and insecticide residues existing in food and plant samples. In this regard, a set of content, including the explanations about the supercritical fluid extraction (SFE), supercritical fluid chromatography, and various types of pesticides are indicated. Besides, the parameters affecting the pesticides extraction composed of temperature, pressure, modifier, drying agent, and so on are discussed. Also, examples of insecticides extraction by SFE technique as an important subset of pesticides are indicated. Along with these items, some interesting works, concerning the innovations implemented in the field of SFE of pesticide and insecticide residues from foodstuff and plants are depicted. [ABSTRACT FROM AUTHOR]

Supercritical fluid chromatography employing chiral stationary phases is a popular separation technique to perform enantioselective separations. The main advantages of supercritical fluid chromatography are low analysis time, low consumption of organic modifiers, and therefore lower costs and higher environmental friendliness. A novel method for the separation of chlorthalidone enantiomers, widely used diuretic drug, is reported that clearly demonstrates the advantages of supercritical fluid chromatography. The effects of the amount and type of organic modifiers, temperature, and back pressure on enantioselectivity and resolution of the enantiomers were evaluated. The baseline separation was achieved in less than 2.5 min in the optimized system composed of Chiralpak AD column, mobile phase CO2/MeOH 50/50 (v/v), temperature 40°C, a flow rate of 4.0 mL/min, and 120 bar back pressure. Moreover, enantiomers of chlorthalidone were determined in two commercially available pharmaceuticals. The proposed method may be easily transferred to a semi-preparative scale. [ABSTRACT FROM PUBLISHER]

Poly(ethylene glycol) nonylphenyl ether (PEG NPE) is a nonionic surfactant used widely as a detergent or industrial product, but the toxicity of nonylphenol, which is decomposed from PEG NPE, should be controlled to meet regulatory requirements. Under these situations, we plan to investigate the certified reference material in order to be able to exactly determine not only the average molecular weight but also all of the mole fractions of PEG NPE samples through the use of a well-calibrated evaporative light scattering detector coupled with high-performance supercritical fluid chromatography. In addition, experimental uncertainty was determined in accordance with the ISO's Guide to the Expression of Uncertainty in Measurement. [ABSTRACT FROM AUTHOR]

The interfacial properties between carbon fiber and blend of diglycidyl ether of bisphenol A and polyglycol diglycidyl ether based epoxy resins containing different loadings (0–2.5 wt%) of surface modified montmorillonite clay — Nanomer 1.30E (nanoplatelets) — were studied using single fiber composite (SFC) technique. Carbon fibers were also treated with ethylene/ammonia polymerizing plasma to obtain a coating containing amino groups. Young's modulus and tensile strength of the nanoplatelet-filled epoxy resin (nanocomposite) increased with nanoplatelet loading up to 1.5% and decreased thereafter. The fracture strain decreased steadily with the nanoplatelet loading. The interfacial shear strength (IFSS) was found to increase with increase in nanoplatelet loading up to 1.5% but decreased thereafter for higher loadings, following the trend observed for the Young's modulus. Plasma-treated fibers showed significant increase in IFSS compared to untreated fiber for all resins, with or without nanoplatelets. SFC with plasma-treated fibers showed no noticeable crack propagation patterns as were seen in the SFC of untreated fibers. Transmission electron microscopy (TEM) used to characterize the nanoplatelet exfoliation and dispersion in the nanocomposties showed better dispersion in 1.5% nanoplatelet-loaded nanocomposites as compared to other compositions under investigation. [ABSTRACT FROM AUTHOR]

Uranium(VI) is extracted with N‐phenyl‐(1,2‐methano‐fullerene C60)61‐formohydroxamic acid, PMFFHA, in dichloromethane by supercritical carbon dioxide (SF‐CO2)‐dichloromethane (modifier) medium. A 2.0 µL aqueous uranium is extracted accurately and also preconcentrated in an especially designed extraction vessel of 80 µL capacity. The extracted microdrop orange‐red colored uranium(VI)‐PMFFHA complex in dichloromethane was online measured by fiber optics spectrometry and ICP‐MS. The distribution ratio (DUO22+) of U(VI) was determined. The slopes of log DUO22+ versus PMFFHA concentration plot, the extracted species both in SF‐CO2 extraction (SFE) and the solvent extraction (SE) were determined to be 2.0 as UO2(PMFFHA)2 complex. The uranium is determined as low as 0.10 ng mL-1 in presence of several cations and anions. The effect of diluents, modifier concentration, temperature and pressure on the extraction and separation of uranium was studied. The uranium is determined in human blood serum, natural water, seawater, standard samples and also in monazite sand. The PMFFHA has been successfully used as carrier for the selective and efficient transport of uranium(VI). The feed comprised of a solution of uranium(VI) and aqueous solution of diverse cations and anions in pH 4.5, while 1M HNO3 was used as a stripping agent in the receiving compartment of permeated cell. Maximum transportation was observed for 12 minutes with t1/2 equal to 6.3 min. The uranium(VI) was determined in presence of uranium(IV). [ABSTRACT FROM AUTHOR]

The object of this study was to measure parthenolide in feverfew by supercritical fluid chromatography (SFC). The precision and linearity of the detector response were excellent, the RSD was 2.67% and 0.70%, respectively, for retention time and peak area, and the value of correlation coefficient (r² ) was 0.9996. The sample was determined directly after extracting in an ultrasonic bath with methanol for 30 min. It was finished within 3 min. This method could be used to determine the content of parthenolide in feverfew rapidly. [ABSTRACT FROM AUTHOR]

This review presents a concise survey of articles dealing with the separation of cis‐trans (Z)‐(E) isomers. The geometric isomerism generated by ethylene bonds (carbon‐carbon double bond) is the only one treated. An introduction focuses on the existing chemical nomenclature and the encountered problems in modern analytical and pharmaceutical chemistry. Next, the study is divided into three parts: synthetic compounds, natural compounds, and fatty acids and vitamins. Within this framework, articles have been selected to describe past and current trends in analytical chemistry and outline relevant research interests. Afterwards, the different mechanistic approaches that could explain the separation of such geometrical isomers is reviewed. These approaches may be used to design and to describe more interesting methodologies. [ABSTRACT FROM AUTHOR]

One of the most challenging problems encountered during the development of a new pharmaceutical compound is linked to purification. The synthesis schemes are more and more complex and the request for rapid and efficient methods to isolate the target molecule from mixtures is crucial to ensure the success of the future drug. Preparative chromatography is widely used at the developmental stages. The technology offers a perfect answer to the main challenge of the developers: “go fast and be efficient.” The development of a chromatographic separation is easy at this stage; it is often possible to modify an analytical HPLC method to quickly isolate the purified product on a larger column. At the production scale, preparative chromatography can also be applied. An optimization of the chromatographic conditions at an analytical scale (selection of stationary phase and solvent), together with the selection of the appropriate chromatographic process (discontinuous or continuous), lead to a cost effective, efficient, and robust industrial process. Preparative chromatography is applied at a very large scale for the purification of small organic molecules, peptides and proteins, carbohydrates, and chiral molecules under conditions required for pharmaceutical applications. Even though preparative gas chromatography is successfully implemented for some applications at the industrial scale concerning low molecular weight and/or very volatile compounds, liquid eluents are by far the most common and competitive choice for the preparative chromatography process. [ABSTRACT FROM AUTHOR]

Many organic environmental pollutants are mixtures of their chiral isomers. Studies have revealed that these isomers have different enantioselective distribution, metabolism and toxicity. Today, analysis of chiral pollutants represents an urgent need. This review discusses the analysis of chiral pollutants using gas chromatography (GC), high performance liquid chromatography (HPLC), capillary electro-chromatography (CEC), micellar electrokinetic chromatography (MEKC), super critical fluid chromatography (SFC) and thin layer chromatography (TLC). [ABSTRACT FROM AUTHOR]