Temperature-induced dispersive solid-phase extraction as a new approach for preconcentration of Sudan dyes in water and food samples prior to the determination by high-performance liquid chromatography.

This study introduced a new microextraction method named temperature-induced dispersive solid-phase extraction. The performance of the method was demonstrated with the determination of Sudan dyes in food and natural water samples. In this method, a low quantity of sorbent was added to the aqueous solution and the mixture was shaken manually for about one minute. Then, the solution was heated in an ultrasonic water bath, and the sorbent was dissolved. Subsequently, the solution was cooled down with ice water, and consequently, the solubility of the sorbent was reduced in the sample solution and became cloudy. The phase separation was accelerated by centrifugation. The upper liquid phase was picked up using a syringe, and the remainder was solved in methanol and introduced into the HPLC for analysis. Various parameters affecting the extraction yield were evaluated. Analytical parameters, including limits of detection (0.011-0.016 µg/L) and quantification (0.038-0.055 µg/L), relative standard deviations (2.3%-3.1%), and preconcentration factor (40) proved the high efficiency of the developed method for the analysis of Sudan dyes. The proposed method was used to measure Sudan dyes in water and food samples and showed good extraction recoveries (95.0%-103.5%).

Relationship between body mass index, risk of venous thromboembolism and pulmonary embolism: A systematic review and dose-response meta-analysis of cohort studies among four million participants.

BACKGROUND: The relationship between body mass index (BMI) and risk of venous thromboembolism (VTE) and pulmonary embolism (PE) is a controversial issue. This dose-response meta-analysis was performed to investigate the association between BMI and risk of VTE and PE incidence based on cohort studies. METHOD: A comprehensive systematic search was conducted up to August 2019 in MEDLINE/PubMed, SCOPUS, and Cochrane. DerSimonian and Laird random-effects models were run to estimate combined hazard ratios (HRs) with 95% confidence intervals (CIs). Dose-response analysis was also carried out based on BMI values. RESULTS: Eleven articles with 16 arms and 3,910,747 participants were eligible for inclusion in this systematic review and meta-analysis. Pooled results showed a positive association between BMI and risk of VTE in the obese participants compared to participants classified in the normal BMI category (HR: 1.62, 95% CI: 1.29-2.04, I2 = 95%). Furthermore, results showed a significant association between lower BMI (underweight versus normal BMI category) and reduced risk of PE (HR: 0.80, 95% CI: 0.70-0.92, I2 = 9%) and higher risk of PE in obese versus normal BMI participants (HR: 2.24, 95% CI: 1.93-2.60, I2 = 0%). There was a significant linear relationship between BMI and risk of VTE (p < 0.001) and PE (p < 0.001). CONCLUSIONS: This systematic review and dose-response meta-analysis with 3,910,747 participants highlights obesity as a significant risk factor related to the incidence of VTE and PE.

The Association Between Quality of Sleep and Health-related Quality of Life in Military and Non-military Women in Tehran, Iran.

OBJECTIVES: Quality of sleep (QoS) in individuals is affected by their occupation and is one of the factors affecting the quality of life (QoL). Few studies have evaluated the relationship between QoS and QoL in military women personnel. The aim of this study was to assess QoL and QoS, and compare their relationship among military and non-military women in Tehran. METHODS: This cross-sectional study was carried out on 90 women working in Tehran during 2014, 30 were military forces, 30 were military staff, and 30 were civilian organizations staff. The female subjects were selected from Amin Police University and Tehran Health Insurance Organization using simple random sampling. The 36-Item Short Form Health Survey (SF-36) and Pittsburgh Sleep Quality Index (PSQI) were used to measure QoL and QoS, respectively. The relationship between QoL and QoS was assessed using Pearson's correlation coefficient. RESULTS: The mean scores of QoL in the military forces, military staff, and civilian organizations staff were 58.94±17.71, 67.18±13.52, and 69.10±12.51, respectively. Among the study participants, 62.9% of military forces, 20.0% of military staff, and 17.1% of the civilian organizations staff had poor QoS. Mental health as one of the dimensions of QoL was significantly different between military forces and civilian organizations staff. The association between QoL and QoS was statistically significant in military forces and military staff women. CONCLUSIONS: Low QoS and QoL in the army necessitates that the authorities offer programs and appropriate strategies to improve mental health of QoL and promotion of QoS.

Determination of pholcodine in syrups and human plasma using the chemiluminescence system of tris(1,10 phenanthroline)ruthenium(II) and acidic Ce(IV).

Pholcodine is an opiate derivative drug which is widely used in pediatric medicine. In this study, a chemiluminescence (CL) method is described that determines pholcodine in human plasma and syrup samples. This method is based on the fact that pholcodine can greatly enhance the weak CL emission of reaction between tris(1,10 phenanthroline)ruthenium(II), Ru(phen)32+ , and acidic Ce(IV). The CL mechanism is described in detail using UV-vis light, fluorescence and CL spectra. Effects of chemical variables were investigated and under optimum conditions, CL intensity was proportional to the pholcodine concentration over the range 4.0 × 10-8 to 8.0 × 10-6  mol  L-1 . The limit of detection (LOD) (S/N = 3) was 2.5 × 10-8  mol  L-1 . Percent of relative standard deviations (%RSD) for 3.0 × 10-7 and 3.0 × 10-6  mol  L-1 of pholcodine was 2.9 and 4.0%, respectively. Effects of common ingredients were investigated and the method was applied successfully to the determination of pholcodine in syrup samples and human plasma.

Study on column SPE with synthesized graphene oxide and FAAS for determination of trace amount of Co(II) and Ni(II) ions in real samples.

A selective method for the preconcentration and separation of trace amounts of Co(II) and Ni(II) by column solid phase extraction has been developed. The method is based on the adsorption of metal ions as N-(5-methyl-2-hydroxyacetophenone)-N'-(2-hydroxyacetophenone) ethylene diamine (MHE) complex on synthesized graphene oxide. Computational modeling based on PM6 semi-empirical potential energy surface was utilized to investigate the interaction of metallic complexes with graphene oxide sheet. The adsorption was achieved quantitatively on graphene oxide at pH6.0 and then the retained analyte contents on the column were quantitatively eluted with 3.0 mol L(-1) HNO3. Experimental conditions for effective separation of trace levels of the analyte ions such as pH, flow rate, concentration of eluent, sample volume and interference ions were investigated. A preconcentration factor of 250 was achieved by passing 1250 mL of sample through the solid phase, while the limit of detection of Co(II) and Ni(II) ions were found to be 0.25 and 0.18 ng mL(-1), respectively. The method was applied to the determination of analyte ions in water, black tea and tomato samples.

Preconcentration and trace determination of cadmium in spinach and various water samples by temperature-controlled ionic liquid dispersive liquid phase microextraction.

A sensitive and selective method for the preconcentration and separation of sub µg L-1 levels of cadmium ions in aqueous solutions with high salt contents is described. The developed method is based on temperature-controlled ionic liquid dispersive liquid phase microextraction of cadmium using the 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide (ionic liquid (IL)) as an extractant followed by flame atomic absorption spectrometry determination. The extraction of cadmium ions from the aqueous solution into the fine droplets of IL was performed with dithizone as the chelating agent. Some predominant factors affecting the preconcentration of cadmium ions were evaluated and optimized. Under the optimum conditions, the calibration graph was linear over the concentration range from 0.6-20.0 µg L-1 of cadmium and the limit of detection (LOD) was 0.2 µg L-1. The enrichment factor was found to be 25. The developed method was successfully applied to the determination of cadmium in spinach and water samples.

Solvent-assisted dispersive solid phase extraction.

In this research, a novel extraction technique termed solvent-assisted dispersive solid phase extraction (SADSPE) was developed for the first time. The new method was based on the dispersion of the sorbent into the sample to maximize the contact surface. In this method, the dispersion of the sorbent at a very low milligram level was achieved by injecting a solution of the sorbent into the aqueous sample. Thereby, a cloudy solution formed. The cloudy state resulted from the dispersion of the fine particles of the sorbent in the bulk aqueous sample. After extraction, phase separation was performed by centrifugation and the enriched analyte in the sedimented phase could be determined by instrumental methods. The performance of SADSPE was illustrated with the determination of the trace amounts of cobalt(II) as a test analyte in food and environmental water samples by using flame atomic absorption spectrometry detection. Some key parameters for SADSPE, such as sorbent selection and amount, type and volume of dispersive solvent, pH, chelating agent concentration, and salt concentration, were investigated. Under the most favorable conditions, good limit of detection (as low as 0.2 µg L(-1)) and repeatability of extraction (RSD below 2.2%, n=10) was obtained. The accuracy of the method was tested with standard reference material (SRM-1643e and SRM-1640a) and spiked addition. The advantages of SADSPE method are simplicity of operation, rapidity, low cost, high recovery, and enrichment factor.

Rapid spectrophotometric determination of trace amounts of palladium in water samples after dispersive liquid-liquid microextraction.

A simple, rapid, and efficient dispersive liquid-liquid microextraction method, followed by UV-Vis spectrophotometry was developed for the preconcentration and determination of Pd ions in water samples. Pd ions react with α-furildioxime (chelating agent) to form a hydrophobic complex. Various parameters were altered to study and optimize their effects on the extraction efficiency, such as pH, ligand concentration, the type and volume of extraction and dispersive solvents, extraction time, and salt concentration. Under optimized conditions, the method exhibited an enrichment factor (C org/C aq) of 25 and recovery more than 98 % within a very short extraction time. The linearity of the method ranged from 10 to 200 µg L(-1). The limit of detection was 1.1 µg L(-1). The relative standard deviation for the concentration of 100 µg L(-1) of Pd was 2.3 % (n = 10). Finally, the developed method was successfully applied to the extraction and determination of Pd in tap, river, mineral, and sea water samples.

Spectrophotometric determination of trace levels of nickel in water samples after dispersive liquid liquid microextraction using 2,2'-furildioxime as the complexing agent.

A new method of dispersive liquid-liquid microextraction (DLLME) combined with UV-Vis spectrophotometry was proposed for the determination of trace nickel using 2,2'-Furildioxime as chelating and spectrophotometric reagent. In the proposed approach chloroform and ethanol were used as extraction and dispersive solvents, respectively. Some factors influencing the extraction efficiency of nickel and its subsequent determination were studied and optimized, such as the extraction and dispersive solvent type and volume, pH of the sample solution, extraction time and ionic strength. Under the optimal conditions, the calibration curve was linear within the range of 5-180 µg L-1 of nickel with R2 = 0.9960. Limit of detection (3Sb/m) was 0.6 µg L-1 in the original solution and the relative standard deviation for ten replicate determination of 100 µg L-1 nickel was 2.9%. The proposed method has been applied for the determination of nickel in various water samples with satisfactory results.

Simultaneous extraction and preconcentration of uranium and thorium in aqueous samples by new modified mesoporous silica prior to inductively coupled plasma optical emission spectrometry determination.

A new synthesized modified mesoporous silica (MCM-41) using 5-nitro-2-furaldehyde (fural) was applied as an effective sorbent for the solid phase extraction of uranium(VI) and thorium(IV) ions from aqueous solution for the measurement by inductively coupled plasma optical emission spectrometry (ICP OES). The influences of some analytical parameters on the quantitative recoveries of the analyte ions were investigated in batch method. Under optimal conditions, the analyte ions were sorbed by the sorbent at pH 5.5 and then eluted with 1.0 mL of 1.0 mol L(-1) HNO(3). The preconcentration factor was 100 for a 100mL sample volume. The limits of detection (LOD) obtained for uranium(VI) and thorium(IV) were 0.3 microg L(-1). The maximum sorption capacity of the modified MCM-41 was found to be 47 and 49 mg g(-1) for uranium(VI) and thorium(IV), respectively. The sorbent exhibited good stability, reusability, high adsorption capacity and fast rate of equilibrium for sorption/desorption of uranium and thorium ions. The applicability of the synthesized sorbent was examined using CRM and real water samples.

Dispersive liquid-liquid microextraction combined with graphite furnace atomic absorption spectrometry: ultra trace determination of cadmium in water samples.

Dispersive liquid-liquid microextraction (DLLME) technique was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GF AAS). In this extraction method, 500 microL methanol (disperser solvent) containing 34 microL carbon tetrachloride (extraction solvent) and 0.00010 g ammonium pyrrolidine dithiocarbamate (chelating agent) was rapidly injected by syringe into the water sample containing cadmium ions (interest analyte). Thereby, a cloudy solution formed. The cloudy state resulted from the formation of fine droplets of carbon tetrachloride, which have been dispersed, in bulk aqueous sample. At this stage, cadmium reacts with ammonium pyrrolidine dithiocarbamate, and therefore, hydrophobic complex forms which is extracted into the fine droplets of carbon tetrachloride. After centrifugation (2 min at 5000 rpm), these droplets were sedimented at the bottom of the conical test tube (25+/-1 microL). Then a 20 microL of sedimented phase containing enriched analyte was determined by GF AAS. Some effective parameters on extraction and complex formation, such as extraction and disperser solvent type and their volume, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor 125 was obtained from only 5.00 mL of water sample. The calibration graph was linear in the rage of 2-20 ng L(-1) with detection limit of 0.6 ng L(-1). The relative standard deviation (R.S.D.s) for ten replicate measurements of 20 ng L(-1) of cadmium was 3.5%. The relative recoveries of cadmium in tap, sea and rivers water samples at spiking level of 5 and 10 ng L(-1) are 108, 95, 87 and 98%, respectively. The characteristics of the proposed method have been compared with cloud point extraction (CPE), on-line liquid-liquid extraction, single drop microextraction (SDME), on-line solid phase extraction (SPE) and co-precipitation based on bibliographic data. Therefore, DLLME combined with GF AAS is a very simple, rapid and sensitive method, which requires low volume of sample (5.00 mL).

Application of thiophene-2-carbaldehyde-modified mesoporous silica as a new sorbent for separation and preconcentration of palladium prior to inductively coupled plasma atomic emission spectrometric determination.

A new and efficient method was described for an easy synthesis of functionalized mesoporous silica (MCM-41) using thiophene-2-carbaldehyde. This new chemically bonded analytical reagent was used as an effective sorbent for the solid phase extraction of palladium(II) ion from aqueous solutions. Conditions for effective adsorption of trace levels of palladium concentration were optimized with respect to different experimental parameters in batch process. Thiourea solution could efficiently elute adsorbed palladium(II) ion from the surface of the sorbent which then was determined by inductively coupled plasma atomic emission spectrometer (ICP-AES). Common coexisting ions did not interfere with the separation and determination. The preconcentration factor was 100 (1ml elution volume) for a 100ml sample volume. The limit of detection of the proposed method is 0.2ngml(-1). The maximum sorption capacity of sorbent under optimum conditions has been found to be 5mg of palladium per gram of sorbent. The relative standard deviation under optimum conditions was 3.2% (n=10). Accuracy and application of the method was estimated by using test samples of natural and synthetic water spiked with different amounts of palladium(II) ion.

Part-per-trillion determination of chlorobenzenes in water using dispersive liquid-liquid microextraction combined gas chromatography-electron capture detection.

In this study, a simple, rapid and efficient method, dispersive liquid-liquid microextraction (DLLME) combined gas chromatography-electron capture detection (GC-ECD), for the determination of chlorobenzenes (CBs) in water samples, has been described. This method involves the use of an appropriate mixture of extraction solvent (9.5 microl chlorobenzene) and disperser solvent (0.50 ml acetone) for the formation of cloudy solution in 5.00 ml aqueous sample containing analytes. After extraction, phase separation was performed by centrifugation and the enriched analytes in sedimented phase were determined by gas chromatography-electron capture detection (GC-ECD). Our simple conditions were conducted at room temperature with no stiring and no salt addition in order to minimize sample preparation steps. Parameters such as the kind and volume of extraction solvent, the kind and volume of disperser solvent, extraction time and salt effect, were studied and optimized. The method exhibited enrichment factors and recoveries ranging from 711 to 813 and 71.1 to 81.3%, respectively, within very short extraction time. The linearity of the method ranged from 0.05 to 100 microgl(-1) for dichlorobenzene isomers (DCB), 0.002-20 microgl(-1) for trichlorobenzene (TCB) and tetrachlorobenzene (TeCB) isomers and from 0.001 to 4 microgl(-1) for pentachlorobenzene (PeCB) and hexachlorobenzene (HCB). The limit of detection was in the low microgl(-1) level, ranging between 0.0005 and 0.05 microgl(-1). The relative standard deviations (R.S.D.s) for the concentration of DCB isomers, 5.00 microgl(-1), TCB and TeCB isomers, 0.500 microgl(-1), PeCB and HCB 0.100 microgl(-1) in water by using the internal standard were in the range of 0.52-2.8% (n=5) and without the internal standard were in the range of 4.6-6.0% (n=5). The relative recoveries of spiked CBs at different levels of chlorobenzene isomers in tap, well and river water samples were 109-121%, 105-113% and 87-120%, respectively. It is concluded that this method can be successfully applied for the determination of CBs in tap, river and well water samples.

Synthesis of salicylaldehyde-modified mesoporous silica and its application as a new sorbent for separation, preconcentration and determination of uranium by inductively coupled plasma atomic emission spectrometry.

A new functionalized mesoporous silica (MCM-41) using salicylaldehyde was utilized for the separation, preconcentration and determination of uranium in natural water by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of trace levels of U(VI) were optimized. The preconcentration factor was 100 (1.0 mL of elution for a 100 mL sample volume). The analytical curve was linear in the range 2-1000 microg L(-1) and the detection limit was 0.5 ng mL(-1). The relative standard deviation (R.S.D.) under optimum conditions was 2.5% (n=10). Common coexisting ions did not interfere with the separation and determination of uranium at pH 5. The sorbent exhibited excellent stability and its sorption capacity under optimum conditions has been found to be 10mg of uranium per gram of sorbent. The method was applied for the recovery and determination of uranium in different water samples.