Mohamed A. Habila

Determination of Capsaicin and Dihydrocapsaicin in Capsicum Fruit Samples using High Performance Liquid Chromatography

The aim of the present study was to determine the content of capsaicin and dihydrocapsaicin in Capsicum samples collected from city markets in Riyadh (Saudi Arabia), calculate their pungency in Scoville heat units (SHU) and evaluate the average daily intake of capsaicin for the population of Riyadh. The investigated samples consisted of hot chillies, red chillies, green chillies, green peppers, red peppers and yellow peppers. Extraction of capsaicinoids was done using ethanol as solvent, while high performance liquid chromatography (HPLC) was used for separation, identification and quantitation of the components. The limit of detection (LOD) of the method was 0.09 and 0.10 µg/g for capsaicin and dihydrocapsaicin, respectively, while the limit of quantification (LOQ) was 0.30 and 0.36 µg/g for capsaicin and dihydrocapsaicin, respectively. Hot chillies showed the highest concentration of capsaicin (4249.0 ± 190.3 µg/g) and the highest pungency level (67984.60 SHU), whereas green peppers had the lowest detected concentration (1.0 ± 0.9 µg/g); green peppers, red peppers and yellow peppers were non pungent. The mean consumption of peppers for Riyadh city population was determined to be 15.5 g/person/day while the daily capsaicin intake was 7.584 mg/person/day.

Solid phase extraction of metal ions in environmental samples on 1-(2-pyridylazo)-2-naphthol impregnated activated carbon cloth

1-(2-Pyridylazo)-2-naphthol impregnated activated carbon cloth (PAN-imp-ACC) was prepared as a solid phase sorbent and, for the first time, was used for the simultaneous separation and preconcentration of trace amounts of lead, cadmium and nickel in water, soil and sewage sludge samples prior to determination by flame atomic absorption spectrometry (FAAS). The parameters governing the efficiency of the method were optimized, including the pH, the eluent type and volume, the sample and eluent flow rates, diverse ions effects and the sample volume. A preconcentration factor of 100 was achieved for all the metal ions, with detection limits of 0.1-2.8 µg L(-1) and relative standard deviations below 6.3%. The adsorption capacity of the PAN-imp-ACC for Pb(II), Cd(II) and Ni(II) ions was found to be 45.0 mg g(-1), 45.0 mg g(-1) and 43.2 mg g(-1), respectively. The method was validated by the analysis of the certified reference materials TMDA-64.2 fortified Lake Ontario water and BCR-146R Sewage Sludge Amended Soil (Industrial Origin). The procedure was applied to determine the analytes content in real samples.

Synthesis and application of Fe3O4@SiO2@TiO2 for photocatalytic decomposition of organic matrix simultaneously with magnetic solid phase extraction of heavy metals prior to ICP-MS analysis

Interference of organic compounds in the matrix of heavy metal solution could suppress their pre-concentration and detection processes. Therefore, this work aimed to develop simple and facile methods for separation of heavy metals before ICP-MS analysis. Fe3O4@SiO2@TiO2 core-double shell magnetic adsorbent was prepared and characterized by TEM, SEM, FTIR, XRD and surface area, and tested for Magnetic Solid Phase Extraction (MSPE) of Cu(II), Zn(II), Cd(II) and Pb(II). TEM micrograph of Fe3O4@SiO2@TiO2 reveals the uniform coating of TiO2 layer of about 20nm onto the Fe3O4@SiO2 nanoparticles and indicates that all nanoparticles are monodispersed and uniform. The saturation magnetization from the room-temperature hysteresis loops of Fe3O4 and Fe3O4@SiO2@TiO2 was found to be 72 and 40emug(-1), respectively, suggesting good separability of the nanoparticles. The Fe3O4@SiO2@TiO2 showed maximum adsorption capacity of 125, 137, 148 and 160mgg(-1) for Cu(II), Zn(II), Cd(II) and Pb(II) respectively, and the process was found to fit with the second order kinetic model and Langmuir isotherm. Fe3O4@SiO2@TiO2 showed efficient photocatalytic decomposition for tartrazine and sunset yellow (consider as Interfering organic compounds) in aqueous solution under the irradiation of UV light. The maximum recovery% was achieved at pH 5, by elution with 10mL of 2M nitric acid solution. The LODs were found to be 0.066, 0.049, 0.041 and 0.082µgL(-1) for Cu(II), Zn(II), Cd(II) and Pb(II), respectively while the LOQs were found to be 0.20, 0.15, 0.12 and 0.25µgL(-1) for Cu(II), Zn(II), Cd(II) and Pb(II), respectively.

Membrane filtration of Sudan orange G on a cellulose acetate membrane filter for separation-preconcentration and spectrophotometric determination in water, chili powder, chili sauce and tomato sauce samples.

A simple membrane filtration procedure for separation-enrichment of Sudan orange G is presented. The method is based on the adsorption of Sudan orange G on a cellulose acetate filter and its elution from the membrane with 10 mL of ethanol. Sudan orange G in the eluent was determined by UV-visible spectrophotometry at 388 nm. The effect of analytical conditions, including pH, flow rates and eluent, sample volume, type of membrane for quantitative preconcentration and separation of Sudan orange G were examined. The influences of matrix components on Sudan orange G recoveries were studied. The preconcentration factor was 125. The detection limit was 4.9 μg L(-1). The relative standard deviation was 4.3%. The presented procedure was applied to chili powder, chili sauce, tomato sauce, powdered beverage and water samples.

KINETIC, EQUILIBRIUM AND THERMODYNAMIC STUDIES OF CADMIUM (II) ADSORPTION BY MODIFIED AGRICULTURAL WASTES

Agricultural wastes have great potential for the removal of heavy metal ions from aqueous solution. The contamination of water by toxic heavy metals is a worldwide environmental problem. Unlike organic pollutants, the majority of which are susceptible to biological degradation, heavy metals do not degrade into harmless end products. Discharges containing cadmium, in particular, are strictly controlled because of the highly toxic nature of this element and its tendency to accumulate in the tissues of living organisms. This work aims to develop inexpensive, highly available, effective metal ion adsorbents from natural wastes as alternatives to existing commercial adsorbents. In particular, Tamrix articulata wastes were modified chemically by esterification with maleic acid to yield a carboxyl-rich adsorbent. The adsorption behavior of treated Tamrix articulata wastes toward cadmium ions in aqueous solutions in a batch system has been studied as a function of equilibration time, adsorbent dose, temperature and pH. Results showed that the maximum adsorption capacity was 195.5 mg/g in a pH 4 solution at 30 °C with a contact time of 120 min, an initial concentration of 400 mg/L and an adsorbent dose of 0.3 g/L. The kinetic data were analyzed using pseudo-first-order and pseudo-second-order kinetic models. It was shown that the adsorption of cadmium could be described by a pseudo-second-order equation. The experimental data were also analyzed using the Langmuir and Freundlich models of adsorption. Thermodynamic parameters such as ΔGo, ΔHo and ΔSo have been evaluated and it has been found that the sorption process was spontaneous and exothermic in nature. From all of our data, we conclude that the treated Tamrix articulata wastes investigated in this study showed good potential for cadmium removal from aqueous solutions.

Determination of capsaicinoids in Capsicum species using ultra performance liquid chromatography-mass spectrometry

In the present work, a rapid and sensitive ultra performance liquid chromatography-mass spectrometry method has been proposed for the analysis of capsaicinoids (nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin) present in different Capsicum samples. Extraction of capsaicinoids was carried out by liquid-liquid extraction using ethanol as an extracting solvent, while the chromatographic separation was achieved by reversed phase C(18) column with gradient mobile phase (solvent A: acetonitrile and solvent B: water with 0.1% formic acid). Under the optimum experimental conditions, the linear ranges were 0.5-50 μg/g with correlation coefficient (r(2) ) >0.999 for each capsaicinoids and detection limits were 0.15, 0.05, 0.06, 0.2, and 0.1 μg/g for nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin, respectively. Run-to-run and day-to-day precisions of the method with relative standard deviations <1.5% were achieved for all analyzed capsaicinoids. The robustness of the method was determined by utilizing different injection volumes of the extracts. Furthermore, to validate the system robustness, a run of high number of capsaicinoids present in different varieties of Capsicum samples was performed in this study. All the capsaicinoids were separated in a time of less than 9 min by employing the proposed method.

Development of a dispersive liquid–liquid microextraction combined with flame atomic absorption spectrometry using a microinjection system for the enrichment, separation, and determination of nickel in water samples

AbstractA simple, rapid dispersive liquid–liquid microextraction procedure was combined with flame atomic absorption spectrometry and has been established for the determination of trace amounts of nickel. A mixture of carbon tetrachloride, 2-(5-bromo-2-pyridylazo)-5-diethylamino-phenol (5-Br-PADAP), and acetonitrile was swiftly injected with a syringe into a sample containing nickel(II) resulting in the formation of a cloudy solution. The cloudy solution was centrifuged and fine droplets settled at the bottom of the test tube. After centrifuging, the settled organic phase was dissolved to a total volume of 250 μL in concentrated nitric acid, from which 25 μL was introduced into the flame atomic absorption spectrometer using the microinjection system. The effect of parameters such as pH, the amount of 5-Br-PADAP, the volume and types of the extraction, and dispersion solvents have been examined. The limit of detection, the preconcentration factor, and enhancement factors were 0.13 μg L−1, 200, and 99, resp...

Supramolecular microextraction of cobalt from water samples before its microsampling flame atomic absorption spectrometric detection

ABSTRACT The supramolecular solvent system consists of tetrahydrofuran (THF) and 1-decanol, that was used as an extraction solvent for a microextraction procedure for the preconcentration and separation of Co(II). The proposed supramolecular-based procedure was combined with microsampling flame atomic absorption spectrometry for the determination of cobalt at trace levels in water samples. N-Benzoyl-N,N-diisobutylthiourea was used to chelate Co(II) in an aqueous solution. Quantitative extraction efficiency was obtained at pH 6.5. The effects of analytical parameters including pH, amount of ligand, type, ratio and volume of supramolecular solvent, sample volume and interfering ions were investigated for optimisation of the procedure. The proposed supramolecular solvent-based microextraction procedure (Ss-ME) exhibits a limit of detection (LOD) of 1.29 µg L−1 and a limit of quantification (LOQ) of 3.88 µg L−1. The procedure was validated by addition/recovery tests and by applying TMDA 64.2 and TMDA 53.3 water certified reference materials. The microextraction method was successfully applied for the preconcentration and determination of cobalt in water samples.

A membrane filtration procedure for the enrichment, separation, and flame atomic absorption spectrometric determinations of some metals in water, hair, urine, and fish samples

AbstractA cellulose acetate membrane filter was applied for solid-phase extraction of Cd(II), Co(II), Cu(II), Fe(III), Ni(II), and Pb(II) from urine, hair, fish, and various water samples. The analyte ions were adsorbed on membrane filter as Cochenille red complexes and then eluted using 10 mL 3 M CH3COOH. The matrix effects from concomitants and analytical parameters, including pH, sample volume, membrane type, and flow rates, were investigated. The analyte ion detection limit for the proposed method was in the range 1.0–5.2 μg/L. The preconcentration factors were calculated as 30 for Cu(II), 40 for Co(II), Ni(II), Cd(II) as well as Pb(II), and 50 for Fe(III). The proposed method was validated by analyzing certified reference materials. This method was successfully applied to water, hair, fish, and urine samples with good results.

Determination of Copper in Food and Water by Dispersive Liquid-Liquid Microextraction and Flame Atomic Absorption Spectrometry

A new, simple, and rapid ionic liquid based dispersive liquid-liquid microextraction method is reported for the determination of copper with flame atomic absorption spectrometry. The ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate, was used to extract a copper(II)- curcumin complex. The optimum extraction efficiency of copper was obtained after optimization of the ionic liquid volume, pH, centrifugation speed and time, ultrasonic bath time and temperature, and mass of curcumin. The effects of various ions on the recovery of copper(II) were also investigated. The preconcentration factor was 135. In the optimum experimental conditions, the limit of detection and the relative standard deviation were 0.19 microgram per liter and 4.1 percent, respectively. The method was validated by the analysis of certified reference materials and applied to food and water.