Organic Solvent Composition Research Articles

Effect of polypropylene pyrolyzate as the solvent on hydrodeoxygenation of palm oil using Ni-Cu/ZrO2 catalyst

Green diesel is a biofuel that can be used directly in diesel engines and can be synthesized by hydrodeoxygenation (HDO) reaction of triglyceride (TG). Generally, this reaction requires a high hydrogen pressure (40–150 bar) and a high composition of organic solvent to facilitate a higher hydrogen solubility in the liquid phase. In many cases, long carbon-chain alkanes, mostly n-dodecane, have been used as solvents. The present work aims to investigate the potential of hydrogenated and non-hydrogenated polypropylene (PP) pyrolyzate as solvents in an effort to utilize plastic wastes in HDO reaction of palm oil. The reaction was carried out using bimetallic catalyst Ni-Cu/ZrO2 in a reactor with a hydrogen gas self-inducing impeller to facilitate a higher load-up hydrogen gas in the liquid phase. The effect of reaction time in HDO involving two solvents, i.e., PP pyrolyzate and hydrogenated PP pyrolyzate, was elucidated in this work. The results showed that hydrogenated PP pyrolyzate facilitates a higher deoxygenation activity than PP pyrolyzate. In addition, the synthesized bimetallic catalyst promoted the decarbonylation/decarboxylation route over the hydrodeoxygenation route at reaction temperatures of 280–350 °C. The conversion of TG increased from 51 % to 93 % by increasing the reaction temperature from 280 °C to 350 °C, with the corresponding highest yield of green diesel was 82 %. Therefore, the hydrogenated PP pyrolyzate can substitute the usual long carbon-chain alkanes.

Experimental design and re-parameterization of the Neue-Kuss model for accurate and precise prediction of isocratic retention factors from gradient measurements in reversed phase liquid chromatography

The present work describes a re-parameterization of the Neue Kuss (NK) model for describing retention in liquid chromatography, and this re-parameterized model is used to fit a large set of isocratic retention measurements with improved convergence properties relative to the original parameterization of the model. Next, an experimental design for retention measurements using mobile phase gradient elution conditions is proposed for the purpose of obtaining accurate and precise NK parameters. Simulated retention data for mobile phase gradient elution conditions with two different levels of noise, as well as an essentially zero noise level were fit with the re-parameterized model. The results showed that the re-parameterized fits yielded average (absolute value) prediction errors for the parameters at the highest noise level of 7.2 % for S1,ref, 18 % for S2,ref and 6.2 % for kref (the re-parameterized NK model parameters). These errors were significantly smaller than those for the original parameterization of the NK model, where the errors were 23 % for S1, 25 % for S2 and 160 % for kw (the original NK model parameters). Furthermore, isocratic retention factors predicted using these model parameters were found to have an average magnitude of error of 0.51 % for the re-parameterized model, as opposed to 6800 % for the model with the original parameterization. A further test of this approach was carried out for independent experimental measurements for five solutes on a C18 column. The average magnitude of error of the isocratic retention factors predicted from parameters obtained from fits of gradient data was 1.6 %, provided that the range of organic solvent compositions that the solute sampled in the mobile phase gradient experiments was consistent with the isocratic experiments. These results indicate that the re-parameterization of the NK model allows for significant improvements in the fitting process, and that the proposed experimental design allows for NK parameters to be extracted from mobile phase gradient experiments, with prediction accuracies of isocratic retention factors on the order of 1-2 %.

Equilibrium solubility, solvation and dissolution thermodynamics, and density functional theory study of albendazole in solutions of acetone/methanol/isopropanol + water

In this work, albendazole was dissolved in mixtures of acetone/methanol/isopropanol + water to examine its solubility, dissolution thermodynamics, solvation behavior, and intermolecular interactions. The shake-flask method was used to conduct solubility tests at a pressure of 101.0 kPa and temperatures from 278.15 to 323.15 K. In water and pure organic solvents, respectively, the lowest and greatest levels of albendazole solubility were found. XRD analysis-based experiments found no evidence of crystal solvation or transition. Jouyban-Acree, modified Wilson, QSPR and modified van't Hoff-Jouyban-Acree models correlated the solubility to solvent composition and temperature with the relative average deviations (RAD) of no more than 8.99 %. The equilibrium solubility at 298.15 K was examined using the approach of extended Hildebrand solubility parameter, which produced an average relative deviation of 3.63 %. The dipolarity-polarizability and solubility parameter of solutions have a considerable impact on the solubility fluctuation, according to the analysis of linear solvation energy relationship. The preferred solvation of albendazole by water and different organic solvents was quantitatively examined with the help of the inverse Kirkwood-Buff integrals. Albendazole was preferentially solvated by the organic solvents in moderate and rich organic solvent compositions in blends, where albendazole served as a Lewis acid. An enthalpy-driven mechanism and an endothermic process were identified by thermodynamic analysis of the entropy-enthalpy compensation and dissolution properties for albendazole dissolving in blends. The electrostatic characteristics of albendazole acidity/basicity were highlighted using analysis of Hirshfeld surface and molecular surface. The primary targets of nucleophilic and electrophilic assault are the –NH and -S-groups. An independent gradient model based on Hirshfeld partition analysis was used to visual the weak interactions between albendazole and different solvents.

Effect of Organic Carbonate Solvent Composition on the Volumetric and Viscometric Behavior of Linear Ethers

Effect of Organic Carbonate Solvent Composition on the Volumetric and Viscometric Behavior of Linear Ethers

Improving the extraction and the purification of fucoxanthin from Tisochrysis lutea using centrifugal partition chromatography

Fucoxanthin is the major carotenoid in oceans, found in golden-brown algae, and is considered as a bioactive molecule due to its numerous pharmaceutical and nutraceutical properties. This study aims to optimize the recovery and the purity of fucoxanthin from Tisochrysis lutea through an eco-extraction and eco-purification process, using the Centrifugal Partition Chromatography technique (CPC). CPC is based on the partition difference of fucoxanthin between two immiscible liquid phases, providing a complete sample recovery without fucoxanthin degradation, conducted at room temperature and being fast. Furthermore, CPC minimizes the amount of solvents to be effective. First, a solid-liquid US-assisted extraction was performed using dried T. lutea biomass with either acetone or ethanol. We obtained respectively 16.17 mg g−1DW and 13.54 mg g−1DW of fucoxanthin, and the specific consumption of extraction solvent was reduced by 20. Then, four experiments were conducted to optimize the organic solvent composition and the process operating conditions of the CPC. In the mobile phase, methanol used in the original method was replaced by ethanol, the amount of which has been reduced by 3 by adding H2O. The final CPC solvent system was cyclohexane:ethanol:H2O in 2:2:1 (v:v:v). Nine fractions with 100 % fucoxanthin (HPLC purity) were obtained, with 92 % of recovery yield.

Smart Protein-Based Fluorescent Nanoparticles Prepared by a Continuous Nanoprecipitation Method for Pesticides' Precise Delivery and Tracing.

It is highly desirable to develop smart and green pesticide nanoformulations for improving pesticide targeting and reducing their inherent toxicity. Herein, we demonstrate a continuous nanoprecipitation method to construct a novel type of enzyme-responsive fluorescent nanopesticides (denoted as ABM@BSA-FITC/GA NPs) based on abamectin, fluorescein isothiocyanate isomer (FITC)-modified protein, and food-grade gum arabic. The as-prepared ABM@BSA-FITC/GA NPs exhibit good water dispersibility, excellent storage stability, and enhanced wettability compared to commercial formulations. The controlled release of pesticides can be achieved through protein degradation caused by trypsin. Most importantly, the deposition, distribution, and transport of the ABM@BSA-FITC/GA NPs are precisely tracked on target plants (cabbage and cucumber) by fluorescence. Furthermore, the ABM@BSA-FITC/GA NPs show the high control efficacy against Plutella xylostella L., which is comparable with commercial emulsifiable concentrate formulation. In consideration of its eco-friendly composition and absence of organic solvent, this pesticide nanoformulation has promising potential in sustainable plant protection.

CONDUCTIVITY STUDY OF SODIUM BROMIDE AND SODIUM CHLORIDE SALTS IN BINARY MIXTURES OFAQUEOUS AND ORGANIC SOLVENTS

The effect of solvent composition on the conductivity behaviour of sodium bromide (NaBr) and sodium chloride (NaCl) salts in binary mixed aqueous and organic solvents was evaluated using conductivity measurement. The specific conductivities of the salts in methanol-water, ethylene glycol-water and ethylene glycol-methanol mixtures were determined at different solvent compositions (0, 0.1, 0.4, 0.7 and 1) and concentrations (0.01, 0.02, 0.03, 0.04 and 0.05 M) of the salts with JENWAY 4510 conductivity meter at room temperature. The results show that the conductivities of the solutions of both salts in the mixed solvent systems were higher at lower organic solvent compositions and gradually decreased with increasing composition of the solvents. It was also observed that conductivity decreased as the hydrocarbon character of the organic solvent increased in all the binary mixtures. These results have been discussed on the basis of free-ion and ion-pair interactions as well as other chemical and physical properties of the single component solvents.

Unique selectivity of tetrahydrofuran-2-propanol-water ternary mobile phases on a superficially porous particle column in reversed-phase liquid chromatography

Three mixed mobile phase organic modifiers, tetrahydrofuran: 2-propanol 1:1 (v/v), tetrahydrofuran: 2-propanol: 1:3 (v/v), and tetrahydrofuran: 2-propanol: 3:1 (v/v) were studied at 20–70% (v/v) total organic solvent compositions. The solvent strength parameters for the three mixed organic modifiers and system properties were compared to those of more established binary solvent systems, acetonitrile-water and methanol-water. To interpret intermolecular interactions responsible for retention for the three mixed mobile phase organic modifiers, system maps were constructed and compared with acetonitrile and methanol. Three mixed organic mobile phase modifiers on one stationary phase chemistry (Kinetex C18) provide different selectivity than the more established acetonitrile and methanol mobile phase modifiers on the same stationary phase (Kinetex C18) as well as different stationary phase chemistries (Kinetex Biphenyl, Kinetex Phenyl-Hexyl, Kinetex F5, Kinetex XB-C18, and Kinetex EVO C18). The solvation parameter models for all three mixed mobile phase systems the coefficient of determination ranged from 0.991 to 0.999, the Fisher statistic from 338 to 1850, and the standard error of the estimate ranged from 0.024 to 0.097.

A facile cost-effective electrolyte-assisted approach and comparative study towards the Greener synthesis of silica nanoparticles.

Nowadays, silica nanoparticles are gaining tremendous importance because of their wide applications across different domains such as drug delivery, chromatography, biosensors, and chemosensors. The synthesis of silica nanoparticles generally requires a high percentage composition of organic solvent in an alkali medium. The eco-friendly synthesis of silica nanoparticles in bulk amounts can help save the environment and is cost-effective. Herein, efforts have been made to minimize the concentration of organic solvents used during synthesis via the addition of a low concentration of electrolytes, e.g., NaCl. The effects of electrolytes and solvent concentrations on nucleation kinetics, particle growth, and particle size were investigated. Ethanol was used as a solvent in various concentrations, ranging from 60% to 30%, and to optimize and validate the reaction conditions, isopropanol and methanol were also utilized as solvents. The concentration of aqua-soluble silica was determined using the molybdate assay to establish reaction kinetics, and this approach was also utilized to quantify the relative concentration changes in particles throughout the synthesis. The prime feature of the synthesis is the reduction in organic solvent usage by up to 50% using 68 mM NaCl. The surface zeta potential was reduced after the addition of an electrolyte, which made the condensation process faster and helped reaching the critical aggregation concentration in a shorter time. The effect of temperature was also monitored, and we obtained homogeneous and uniform nanoparticles by increasing the temperature. We found that it is possible to tune the size of the nanoparticles by changing the concentration of electrolytes and the temperature of the reaction using an eco-friendly approach. The overall cost of the synthesis can also be reduced by ∼35% by adding electrolytes.

Volumetric and Acoustic Properties of Binary and Ternary Mixtures of Butanol Isomers with Gasoline Surrogate Compounds

Substituting butanol, a renewable fuel for internal combustion engine, as the gasoline blend against the conventionally used ethanol requires the knowledge of their thermophysical properties as these properties decide the fuel injection system, flame propagation, and combustion process in a compression ignition engine. Butanols offer higher energy density and lower tendency to absorb moisture. To offer proof of concept of the influence of temperature and composition of various organic solvents in the isomers of butanol, herein, we had experimentally measured the values of densities (ρ) and speeds of sound (u) of butanol isomers with o-xylene, toluene, and 2,2,4-trimethylpentane at different temperatures (T = 298.15 and 308.15 K) and at 101.3 kPa pressure and over the entire composition range. Measured data have been used to calculate the thermodynamic properties, namely, excess molar volumes VmE and excess molar isentropic compressibilities Ks, mE. The behavior and influence of the temperature and proportion of butanol isomers on measured and calculated properties were studied. Experimental VmE data have been fitted to the Redlich–Kister polynomial equation, and standard errors in prediction were determined. Densities of the binary system are predicted by the PC-SAFT equation of state. We further have used the Prigogine–Flory–Patterson (PFP) theory to predict VmE of the studied systems. Results of predicted and experimentally determined VmE over the entire range of proportion of butanols are compared. Influence of isentropic compressibility on the resulting fuel’s combustion characteristics has been cursorily discussed.

Study of system properties in reversed-phase liquid chromatography for binary and ternary solvent mobile phase compositions using the solvation parameter model

System maps for the individual system constant of the solvation parameter model and five binary solvent containing 20–70% (v/v) acetonitrile, acetone, methanol, 2-propanol, and tetrahydrofuran on a single octadecylsiloxane-bonded silica column (Luna C18) are used to provide insight into the variation of system properties with mobile phase composition and solvent type. Selectivity differences are dominated by variation in solute size and hydrogen-bond basicity with solvent-dependent variation in dipole-type and hydrogen-bond acid interactions. Interactions involving lone pair electrons are important only in the case of the alcohols and to a lesser extent tetrahydrofuran. Selectivity differences are also dependent on solvent strength. To expand the selectivity space four ternary solvent systems (acetonitrile-methanol-water, acetonitrile-2-propanol-water, methanol-tetrahydrofuran-water, and tetrahydrofuran-2-propanol-water) 1:1:2% (v/v) containing 50% (v/v) total organic solvent are compared with the binary solvent systems at the same organic solvent composition. There is no simple model that links the system properties of the ternary solvents to the binary solvent systems, but it is demonstrated that the ternary solvent systems expand the selectivity space available for reversed-phase separations. The solvation properties of the bulk organic solvents provide insufficient information to predict selectivity in RPLC because of the dominant contribution of water and effects related to the selective solvation of the stationary phase and possible changes in the solvent-dependent microstructure of the mobile phase.

Engineering an integrated system with a high pressure polymeric microfluidic chip coupled to liquid chromatography-mass spectrometry (LC-MS) for the analysis of abused drugs

A microfluidic chip coupled to a liquid chromatography-mass spectrometry (LC-MS) system is a powerful tool to determine components of interest in tracing biological samples. However, producing a reusable and robust chip having chromatographic separation for LC-MS systems remains analytically challenging due to the high back pressure generally occurring when microfluidic channels are packed particles. In this study, a one-piece and high-pressure-resistant polymeric microfluidic chip was fabricated by commercial stereolithographic 3D printing with an inner diameter of 1 mm, packed with 5 µm diameter fluorophenyl propyl particles, and coupled to a regular LC-MS. The maximum pressure occurred up to 134 bar with a variation of 1 bar when using 70% methanol at a flow rate of 0.035 mL min-1. Ten drugs and two drug metabolites were analyzed in 15 min under continuous pressure change by LC-MS. The limit of detection was between 2 and 20 ng mL-1 in human urine. The coefficient of determination (R2) was > 0.991. The shift of retention time of each peak was maintained at < 2%. After a chip was eluted with a high organic solvent composition (90% methanol/water and 90% acetonitrile/water mixture) and a high back pressure for continuously 45 h, the cross-sectional areas were investigated and results showed that the microfluidic chip remained intact. The overall experiment results showed that this platform had significant reproducibility, robustness and stability without contamination, demonstrating that this 3D printing microfluidic chip coupled with LC-MS is an efficient and precise tool for bioanalysis.

Extraction of Aloesin from Aloe vera Rind Using Alternative Green Solvents: Process Optimization and Biological Activity Assessment.

Simple SummaryAloesin is a bioactive constituent of Aloe spp. used primarily in cosmetic products. Its recovery from plant materials is affected by several variables that can compromise the process yield and profitability, which is why it is necessary to determine the best processing conditions. This study describes the design and optimization of a method for extraction of aloesin from Aloe vera rind, a leaf part often discarded as a by-product, using the response surface methodology. The effect of the variables time, temperature, solvent composition, and solid/liquid ratio were investigated. Green organic solvents (ethanol, propylene glycol, and glycerol) were used in aqueous mixtures. Aqueous propylene glycol was found to be the most promising solvent for aloesin recovery and a linear increase in extraction yields was verified with the increase in solid/liquid ratio. To assess the bioactivity of the extracts, their ability to inhibit lipid peroxidation and the fungal and bacterial growth, as well as their cytotoxic potential, was tested in vitro. Overall, it was possible to determine the best extraction conditions for aloesin and to better understand the antioxidant and antimicrobial properties of the aloesin-rich extracts, which may be produced and used by the industrial sector.Aloesin is an aromatic chromone with increasing applications in the cosmetic and health food industries. To optimize its extraction from the Aloe vera leaf rind, the independent variables time (10–210 min), temperature (25–95 °C) and organic solvent composition (0–100%, w/w) were combined in a central composite design coupled with response surface methodology. The solvents consisted of binary mixtures of water with ethanol, propylene glycol, or glycerol. The aloesin levels quantified in each extract were used as response for optimization. The theoretical models were fitted to the experimental data, statistically validated, and used to obtain the optimal extraction conditions. Then, a dose–response analysis of the solid/liquid ratio (S/L) was performed under the optimal conditions determined for each alcohol–water system and revealed that a linear improvement in extraction efficiency can be achieved by increasing the S/L ratio by up to 40 g/L. This analysis also allowed to experimentally validate the predictive models. Furthermore, the aloesin-rich extracts revealed antioxidant activity through thiobarbituric acid reactive substances (TBARS) formation inhibition, antimicrobial effects against bacterial and fungal strains, and no toxicity for PLP2 cells. Overall, this study provided optimal extraction conditions for the recovery of aloesin from Aloe vera rind through an eco-friendly extraction process and highlighted its bioactive potential.

Solubility modeling and solvation behavior of 3,3′-diamino diphenylsulfone in binary aqueous mixtures of isopropanol, methanol, ethanol and N,N-dimethylformamide

Experimentation of equilibrium solubility of 3,3′-diamino diphenylsulfone (DDS) in binary solvents of isopropanol/N,N-dimethylformamide (DMF)/methanol/ethanol + water was executed by means of the shake-flask technique under pressure of 101.2 kPa ranging from 283.15 to 328.15 K. At the experimental conditions of same temperature and same compositions of solvent species, the maximum solubility magnitude of DDS in mole fraction was found in the DMF + water solution system; and the minimum one, in the isopropanol + water solution system. Solubility correlation was made by employing four parametric expressions, e.g. modified Wilson, Jouyban–Acree, mixture response surface (MRS) and modified Jouyban–Acree–van’t Hoff, getting the root-mean-square and relative average deviations of no greater than 323.9 × 10−5 and 7.30 %, respectively. The extended Hildebrand solubility approach was practiced here to investigate the inter- and intra-molecule interactions of studied systems. In the regions of poor organic solvent composition, association behavior appears between DDS and solvent species in solutions. What's more, quantitative evaluation of the local compositions of DMF (methanol, isopropanol or ethanol) and water in the vicinity of DDS were carried out by employing the technique of Inverse Kirkwood–Buff integrals. In rich proportions of organic solvents for the studied solution systems, DDS was preferentially solvated by DMF (methanol, isopropanol or ethanol). DDS could mostly serve as a Lewis acid in front to the molecules of DMF (methanol, isopropanol or ethanol).

Separation of short and medium-chain fatty acids using capillary electrophoresis with indirect photometric detection: Part I: Identification of fatty acids in rat feces.

Short and medium-chain fatty acids (SMCFAs) are known as essential metabolites found in gut microbiota that function as modulators in the development and progression of many inflammatory conditions as well as in the regulation of cell metabolism. Currently, there are few simple and low-cost analytical methods available for the determination of SMCFA. This report focuses on SMCFA analysis utilizing CE with indirect photometric detection (CE-IPD). A ribonucleotide electrolyte, 5'-adenosine mono-phosphate (5'-AMP), is investigated as an IPD reagent due to its high molar absorptivity and dynamic reserve compatible with separation and detection of SMCFA. The operating parameters like the composition of organic solvent, millimolar concentrations of the complexing agent (alpha-cyclodextrin), 5'-AMP and non-absorbing electrolyte (boric acid), as well as the applied voltage, are optimized for resolution, efficiency, and signal-to-noise ratio. A baseline resolution of all nine SMCFAs is achieved in less than 15min. Additionally, the developed CE-IPD method shows promising potential to identifying SMCFA in rat fecal supernatant. The presented analytical assay is simple, economical, and has considerably good repeatability. The intraday and interday RSD of less than 1 and 2% for relative migration time, as well as less than 14 and 15% for peak area, respectively, were obtained for SMCFA in fecal solution.

Unexpected effects of mobile phase solvents and additives on retention and resolution of N-acyl-D,L-leucine applying Cinchonane-based chiral ion exchangers

Chiral ion exchangers based on quinine (QN) and quinidine (QD), namely Chiralpak QN-AX and QD-AX as anionic and ZWIX(+) and ZWIX(-) as zwitterionic ion exchanger chiral stationary phases (CSPs) have been investigated with respect to their retention and chiral resolution characteristics. For the evaluation of the effects of the composition of the polar organic bulk solvents of the mobile phase (MP) and those of the organic acid and base additives acting as displacers necessary for a liquid chromatographic ion-exchange process, racemic N-(3,5-dinitrobenzoyl)leucine and other related analytes were applied. The main aim was to evaluate the impact of the MP variations on the observed, and thus the apparent enantioselectivity (αapp), and the retention factor. Significant differences were found using either polar protic methanol (MeOH) or polar non-protic acetonitrile (MeCN) solvents in combination with the acid and base additives as counter- and co-ions. It became clear, that the charged sites of both the chiral selectors of the CSPs and the analytes get specifically solvated, accompanied by the adsorption of all MP components on the CSP, thereby building a stagnant “stationary phase layer” with a composition different from the bulk MP. Via a systematic change of the MP composition, trends of resulting αapp and retention factors have been identified and discussed.In a detailed set of experiments, the effect of the concentration of the acid component in the MP containing MeOH or MeCN was specifically investigated, with the acid considered to be a displacer in anion-exchange type chromatographic systems.Surprisingly, all four chiral columns retained and resolved the tested N-acyl-Leu analytes with αapp values up to 21 within a retention factor window of 0.03 and 10 with pure MeOH as eluent. However, using pure MeCN as eluent, an almost infinite-long retention of the acidic analyte was noticed in all cases. We suggest that the rather different thickness of the solvation shells generated by MeOH or MeCN around the charged/chargeable sites of the chiral selector determines eventually the strength of the electrostatic selector–selectand interactions.As a control experiment we included the non-chiral N-acylglycine derivatives as analyte in all cases to support the interpretations with respect to the contribution of the enantioselective and non-enantioselective retention factor increments as a part of the observed αapp.

Fluorescent polymer cubosomes and hexosomes with aggregation-induced emission.

Fluorescent polymer cubosomes and hexosomes with aggregation-induced emission (AIE) were prepared from amphiphilic block copolymers PEG-b-PTPEMA where the hydrophobic block PTPEMA was a polymethacrylate with tetraphenylethene (TPE) as the AIE side group. Four highly asymmetric block copolymers with hydrophilic block weight ratio fPEG ≤ 20% were synthesized. Cubosomes and hexosomes with strong fluorescence emission were obtained by nanoprecipitation of polymers with fPEG < 9% in dioxane/water and THF/water systems. Their ordered internal structures were studied by electron microscopy (cryo-EM, SEM and TEM) and the X-ray scattering technique (SAXS). To elucidate the formation mechanisms of these inverted colloids, other parameters influencing the morphologies, like the water content during self-assembly and the organic solvent composition, were also investigated. This study not only inspires people to design novel building blocks for the preparation of functional cubosomes and hexosomes, but also presents the first AIE fluorescent polymer cubosome and hexosome with potential applications in bio-related fields.

Work Practices and Health Problems of Spray Painters Exposed to Organic Solvents in Ile-Ife, Nigeria.

Background.Automobile spray painters in Nigeria are exposed to organic solvents due to the hazardous nature of their work. Inadequate use of personal protective equipment (PPE) may intensify exposure to high levels of chemical hazards with resultant health problems.Objectives.The present study assessed PPE use and work practices and compared work-related health problems of spray painters and controls in Ile-Ife, Nigeria.Methods.A cross-sectional study was conducted among 120 spray painters and 120 controls (electronic technicians). Data on socio-demographics, work practices, knowledge about organic solvent-related hazards and self-reported health symptoms were obtained using a semi-structured questionnaire. Clinical examinations were performed for all respondents and the composition of organic solvents in paints and paint products were derived from material safety data sheets.Results.All respondents were male, and the mean age was 32.7±13.8 years for painters and 33.9±15.5 years for controls. Few (7.5%) painters perceived their use of PPE to be adequate. All spray painters worked in enclosed workshops and N-butyl acetate was the most commonly used organic solvent. Spray painters reported excessive tear production, recurrent cough, and short-term memory loss more frequently than controls (P<0.05). In addition, 89% of painters noticed paint-stained sputum immediately after spray painting. The prevalence ratio of respiratory symptoms was higher in spray painters than controls (prevalence ratio=21.0, CI=2.9–153.6). On clinical examination, more spray painters had corneal opacity and dry skin when compared with controls (P<0.05).Conclusions.Spray painters in the study area worked amidst chemical hazards and had poor use of PPE. Exposure to organic solvents may be responsible for the higher prevalence of self-reported health problems among spray painters. Interventions to enforce the use of PPE and improve the knowledge of organic solvent-related hazards among spray painters are essential.Participant Consent. ObtainedEthics Approval.Ethical approval to conduct the study was obtained from the Health Research and Ethics Committee of the Institute of Public Health, Obafemi Awolowo University, Ile-Ife Nigeria (HREC No: IPHOAU/12/463).Competing Interests.The authors declare no competing financial interests.

Solubility Measurement and Correlation of Ceftiofur Sodium Trihydrate in Four Binary Solvent Mixtures

The solubility of ceftiofur sodium trihydrate (CST) in binary solvent mixtures of water + acetonitrile, water + ethanol, water + n-propanol, and water + iso-propanol at temperatures from 273.15 to 313.15 K (P = 0.1 MPa) was measured by a laser dynamic method. The experimental results show that the solubility is positively correlated with temperature. In the four binary solvent systems, the solubility value of CST initially increases first and then decreases with increasing organic solvent composition. The maximum solubility values occur in the molar content of organic solvent of about 0.5 for water + acetonitrile, 0.5 for water + ethanol, 0.4 for water + n-propanol, and 0.4 for water + iso-propanol. The accuracy of experimental results was examined by the Apelblat model, the Van’t-JA model, and the Apel-JA model, and the Apelblat model shows the best fitting performance.

Sensitive Simultaneous Measurement of Metformin and Linagliptin in Plasma Samples by Couple of Nano Graphene Oxide-based Dispersive Solid Phase Extraction Method and Liquid Chromatography.

A simple, rapid, and ultra sensitive dispersive solid phase extraction based on nano graphene oxide was developed for simultaneous measurement of trace amounts of metformin (MET) and linagliptin (LIN) in plasma samples by HPLC-UV-Vis. Affecting factors on the extraction of these drugs, including adsorbent weight, extraction time, organic solvent type, desorption situations, and composition of solvent were examined and optimized. In optimum conditions, the LOD (limit of detection) and LOQ (limit of quantification) of the suggested technique were 2.0 ngmL-1 and 6.1 (ngmL-1) for LIN and 3.0 ngmL-1 and 9.2 ngmL-1 for MET, respectively. Suitable linear behavior in the considered ranges of concentration (10-2000 ngmL-1) and good correlation coefficient of 0.9901 and 0.9903 (r2) for LIN and MET were obtained, respectively. The RSD (relative standard deviations) according to three replicate measurements at 2, 20, 200 ngmL-1 levels of these drugs was less than 8.0%. In the last step, applicability of the suggested technique was examined by analyzing the drugs in plasma samples and reasonable results were achieved.