Pollutant analysis applications of solid-phase analytical derivatizations

The increased accumulation of organic pollutants in various ecological systems in recent decades is a growing concern since these pollutants have detrimental effects on humans, animals, and plants. Two major contributing factors are pharmaceuticals and industrial waste chemicals from anthropogenic sources. To better understand the hazards environmental pollutants, represent to living beings, it is essential to develop sensitive, rapid, and reliable analytical methods. A subset of functional group analysis termed ''analytical derivatization'' modifies an analyte's structure to make it better suited for chromatographic analysis. Despite being an extra time-consuming step in sample preparation, analytical derivatization improves sensitivity, chromatographic separation, and selectivity in analytical method development. Solid-phase analytical derivatization, which combines extraction and derivatization steps, satisfies many requirements for an efficient sample preparation technique, which include reduced organic solvent usage, low cost, simplicity in automation with gas and liquid chromatographic systems, and applicability in a wide range of complex sample matrices. The focus of this review is on solid-phase analytical derivatization methodologies applied to analytical method development in environmental analysis, such as monitoring air pollution, water quality, and soil matrices. This review discusses the benefits and drawbacks of the solid-phase analytical derivatization approach in environmental analysis, the challenges ahead, and potential applications

A polemic on the use of reversed-phase liquid chromatography to determine descriptors for the solvation parameter model

Revised descriptors for 74 varied compounds recommended for the characterization of reversed-phase silica columns using the solvation parameter model are assigned by the Solver method from experimental retention factors for calibrated gas-liquid and reversed-phase liquid chromatographic (RPLC) and biphasic liquid-liquid partition systems. These descriptors are taken as the best estimate of the true descriptor values and used to evaluate several RPLC systems as a single-technique approach for descriptor assignments. Various combinations of isocratic single column and multiple mobile phase compositions, multiple columns with a single mobile phase composition, and multiple columns and multiple mobile phase compositions are evaluated. A multiple column (Discovery HS C18 and HS F5, Fluophase-RP, and XBridge Shield RP18, Phenyl, and C18) with acetonitrile- and methanol-water mobile phases provided the best results with an absolute average deviation (AAD) of 0.043 for the electron lone pair interaction descriptor E, 0.047 for the dipole-type interaction descriptor S, 0.020 for the hydrogen-bond acid descriptor A, and 0.010 for the hydrogen-bond base descriptor B° for 46 varied compounds. These values compare favorably with the larger all columns and mobile phase composition RPLC dataset with the best estimate of the true descriptors, or all data set, with AAD = 0.026 for E, 0.044 for S, 0.027 for A, and 0.011 for B° for 74 varied compounds. The preferred RPLC systems for descriptor assignments contain columns identified as belonging to different selectivity groups that maximize the relative magnitude of the dipole-type contribution, s system constant, hydrogen-bond basicity, a system constant, and electron lone pair interactions, e system constant. RPLC systems are well suited to assigning the B° descriptor and, with proper system selection, the A and S descriptors. The E descriptor for compounds unavailable by calculation is more problematic and a few extreme values with an AAD > ± 0.1 were observed and can affect the reliability of the S descriptor assignments for these compounds. The likelihood of poor descriptor assignments using the Solver method can be identified by evaluating descriptor wells

Effect of liposomal encapsulation of curcumin and α-tocopherol on sensory and physicochemical properties, and retention of antioxidant capacity of fortified cookies during baking

Curcumin and α-tocopherol, which are potent antioxidants usable for food fortification, are sensitive to heat and air, thus showing the need for protection. The aim of this study was to increase the antioxidant capacity retention of curcumin and α-tocopherol in fortified cookies via liposomal encapsulation. Liposomes were prepared using the homogenization method and the liposomes were multilamellar according to light microscopic images. Liposomal encapsulation exhibited encapsulation efficiencies greater than 90 %. The sensory tests, conducted using a 5-point hedonic scale for nine attributes, revealed that the incorporation of liposomal antioxidants did not compromise the sensory attributes of the cookies. The color of liposomal-curcumin incorporated cookie deviated greater than that of free-curcumin incorporated cookie from the regular cookie. Nevertheless, the color of the α-tocopherol incorporated cookies improved on using the liposomal compound as opposed to the free compound. The antioxidant capacity of the cookies, along with the controls, was measured using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. As expected, liposomal encapsulation of curcumin or α-tocopherol mitigated the reduction of antioxidant capacity of fortified cookies during baking. Briefly, liposomal encapsulation proves to be a potent method for retaining the antioxidant capacity of curcumin or α-tocopherol in cookies during baking

Phthalylglycyl Chloride as a Derivatization Agent for UHPLC-MS/MS Determination of Adrenaline, Dopamine and Octopamine in Urine

Dopamine, adrenaline and octopamine are small polar molecules that play a vital role in regulatory systems. In this paper, phthalylglycyl chloride was proposed as a derivatization agent for octopamine, adrenaline and dopamine determination in urine for the first time. The derivatization procedure facilitated the use of reversed-phase liquid chromatography with positive electrospray ionization–high-resolution mass spectrometry. An LC-HRMS method was developed that provided quantification limits of 5 ng/mL and detection limits of 1.5 ng/mL for all analytes. The 95–97% yield of derivates was observed after a 10 min derivatization with phthalylglycyl chloride at pH 6.5 and 30 °C. The proposed method was successfully applied to the analysis of human urine samples. The obtained results were compared with those of conventional derivatization procedures with 9-fluorenyl-methoxycarbonyl chloride and dansyl chloride

The hydrogen bond acidity and other descriptors for oximes

The solvation descriptors for cyclohexanone oxime and acetone oxime have been obtained from measurements on water-solvent partitions, and gas-liquid chromatographic retention data. These yield values of 0.33 and 0.37 for the Abraham hydrogen bond acidity, A , in reasonable agreement with a value of 0.37 for cyclohexanone oxime obtained by our recent n.m.r. method. The other descriptors E, S , B, L and V have also been obtained for cyclohexanone oxime and acetone oxime, and have been estimated for a number of other oximes as well. The value for A, the overall or effective hydrogen bond acidity of the oximes is reasonably close to the 1:1 hydrogen bond acidity, α2 H = 0.39 to 0.46, that can be deduced from previous literature measurements on oximes, and to the 1:1 hydrogen bond acidity, α2 H = 0.43 for another NOH compound, N,N-dibenzylhydroxylamine, that again can be deduced from literature measurements

The hydrogen bond acidity and other descriptors for oximes

The solvation descriptors for cyclohexanone oxime and acetone oxime have been obtained from measurements on water-solvent partitions, and gas-liquid chromatographic retention data. These yield values of 0.33 and 0.37 for the Abraham hydrogen bond acidity, A , in reasonable agreement with a value of 0.37 for cyclohexanone oxime obtained by our recent n.m.r. method. The other descriptors E, S , B, L and V have also been obtained for cyclohexanone oxime and acetone oxime, and have been estimated for a number of other oximes as well. The value for A, the overall or effective hydrogen bond acidity of the oximes is reasonably close to the 1:1 hydrogen bond acidity, α2 H = 0.39 to 0.46, that can be deduced from previous literature measurements on oximes, and to the 1:1 hydrogen bond acidity, α2 H = 0.43 for another NOH compound, N,N-dibenzylhydroxylamine, that again can be deduced from literature measurements