Non-radioactive Rb+ Efflux Assay for Screening KATP Channel Modulators.

ATP-sensitive potassium (KATP) channels function as metabolic sensors that link cell membrane excitability to the cellular energy status by controlling potassium ion (K+) flow across the cell membrane according to intracellular ATP and ADP concentrations. As such, KATP channels influence a broad spectrum of physiological processes, including insulin secretion and cardiovascular functions. KATP channels are hetero-octamers, consisting of four inward rectifier potassium channel subunits, Kir6.1 or Kir6.2, and four sulfonylurea receptors (SURs), SUR1, SUR2A, or SUR2B. Different Kir6 and SUR isoforms assemble into KATP channel subtypes with distinct tissue distributions and physiological functions. Mutations in the genes encoding KATP channel subunits underlie various human diseases. Targeted treatment for these diseases requires subtype-specific KATP channel modulators. Rubidium ions (Rb+) also pass through KATP channels, and Rb+ efflux assays can be used to assess KATP channel function and activity. Flame atomic absorption spectroscopy (Flame-AAS) combined with microsampling can measure Rb+ in small volume, which provides an efficient tool to screen for compounds that alter KATP channel activity in Rb+ efflux assays. In this chapter, we describe a detailed protocol for Rb+ efflux assays designed to identify new KATP channel modulators with potential therapeutic utilities.

Determination of copper and cobalt in different tea samples at trace levels by FAAS after preconcentration with a novel iron PAMAM-OH-encapsulated magnetic nanoparticle as SPE sorbent.

Environmental contamination caused by heavy metals is a significant global concern. The presented study investigated the efficiency of iron PAMAM-OH encapsulated magnetic nanoparticles (Fe-MNP-G2-OH) as sorbent for the preconcentration of copper and cobalt from tea samples. High metal-chelating ethylenediamine core polyamidoethanol generation-2 (PAMAM-G2-OH) was encapsulated with iron oxide (Fe3O4) to synthesize the sorbent. Limit of detection (LOD) values for copper and cobalt extracted and detected by the developed Fe-MNP-G2-OH -SPE-FAAS method were 0.52 and 1.1 µg L-1, respectively. There were 230- and 101-fold improvement in detection limits for copper and cobalt, respectively, when compared to direct FAAS measurement. The percent recovery results for the analytes in green and black tea samples ranged from 93 to 107%, with low relative standard deviation (%RSD) values. The synthesis of nanoparticle was carried out through a unique method, which was characterized by thermogravimetric analysis (TGA), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) methods. The analytical results demonstrated the applicability and effectiveness of Fe-MNP-G2-OH nanoparticles on the preconcentration of copper and cobalt from tea samples and the developed method is suitable for the trace detection of heavy metals by FAAS method. To the best our knowledge, this is the first study where copper and cobalt in green and black tea samples were extracted by Fe-MNP-G2-OH adsorbent and precipitation of the adsorbent during its synthesis was carried out in acetone medium rather than aqueous one.

In-situ formation of the adsorbent based on octadecylamine for the extraction of Ag+ ions from aqueous solutions and its determination by microinjection flame atomic absorption spectrometry.

In this research, a dispersive solid phase extraction procedure based on changing the solubility of octadecylamine with pH was proposed to determine Ag+ ions in different water samples. For this purpose, first, the pH of sample solution containing the analyte was adjusted to 10.5. Then desired volume of the octadecylamine dissolved in acidic solution was injected into the solution. Because of the low solubility of octadecylamine in alkaline solution, a cloudy state was formed. The produced octadecylamine particles acted as a complexing agent for Ag+ ions and adsorbent for the formed complex. The obtained cloudy solution was centrifuged and the sedimented particles were removed and dissolved in a diluted nitric acid solution. It was injected into a flame atomic absorption spectrometry to determine the extracted amounts of the analyte. The effect of important parameters such as the amount of octadecylamine, volume of nitric acid, and centrifugation and vortexing conditions on the extraction efficiency of the procedure was studied and optimized. In optimal conditions, the developed method showed a linear range of 0.50-200 µg L-1. The limits of detection and quantification were 0.18 and 0.50 µg L-1, respectively. Extraction recovery was 93.6%. The relative standard deviations were less than 4%. The effectiveness of the method was investigated by determination of Ag+ ions in water and wastewater samples.

Environmentally friendly and novel solid-liquid phase microextraction of maneb fungicide in fruits and vegetables.

The dithiocarbamates class has been widely used in agriculture practices because of lower toxicity and instability than organophosphates and carbamates. Among them, the maneb has been used to produce several fruits and vegetables, but its high ingestion can adversely affect human health. This work developed the Solid-Liquid Phase Microextraction (SLPME) for extraction of the maneb in foods sample with posterior determination by Flow injection analysis-Flame Absorption Atomic Spectroscopy (FIA-FAAS). Curve analytical had a linear range from 0.9 to 20.0 µmol L-1 maneb (A = 5.94 × 10-4 C (µmol L-1) + 6.93 × 10-4), good repeatability (4.07%) and reproducibility (3.39%), limits of quantification (5.98 µmol L-1) and detection (0.197 µmol L-1), which was above of the established by regulatory agencies. The extraction of the maneb was performed using 685 µL of the solution of the 1.00 × 10-3 mol L-1 of EDTA, and it has excellent recovery values from 80.85 to 106.51%. Therefore, the developed SLPME demonstrated an alternative environmentally friendly for quickly extracting maneb from food samples (apple, papaya, and tomato).

Flame atomic absorption spectrometry combined with surface-modified magnetic mesoporous silica microspheres by polyethyleneimine for enrichment, isolation and determination of Cu2+ in preserved eggs after high-temperature digestion.

A new efficient magnetic solid-phase extractant based on a surface-modified magnetic mesoporous silica microsphere referred as MMSM-PEI was synthesised and used for the enrichment and isolation of copper ions (Cu2+) in preserved eggs. The physicochemical properties and morphology of MMSM-PEI were characterized by X-ray diffraction (XRD) spectroscopy, Fourier transform infrared spectroscopy (FT-IR), vibration sample magnetometry (VSM), scanning electron microscopy (SEM) and thermos-gravimetric analyses (TGA). The concentrations of trace Cu2+ in the preserved egg were determined by flame atomic absorption spectroscopy (FAAS). The effects of important parameters were examined. The most suitable pH values and temperature for adsorbing Cu2+ were 6.5 and 25 °C, respectively. According to the determination of Cu2+ in egg white, egg yolk and the outer coating mixture (TOCM) of preserved eggs, the spiked recovery and RSD were 94.1-103.8% and 0.96-4.35%, respectively. The limit of detection (LOD) and the limit of quantitation (LOQ) were 0.14 mg/kg and 0.46 mg/kg, respectively. The developed method improved the sensitivity and accuracy of FAAS for the determination of Cu2+ and it could be applied to the determination of trace Cu2+ in real samples.

Poly (deep eutectic solvents) as a new class of sustainable sorbents for solid phase extraction: application for preconcentration of Pb (II) from food and water samples.

A new class of polymeric sorbents based on deep eutectic solvents (DESs) is introduced. These materials are obtained from simple and inexpensive precursors via an energy-efficient process. The primary benefit of these sorbents is that they possess the unique characteristics of DESs and porous materials simultaneously. Moreover, the possibility of tailoring deep eutectic solvents allows designing a specific polymer for a desired analyte, based on its physical and chemical properties. In this work, the deep eutectic solvent of tetrabutylammonium bromide and acrylic acid (1:2 molar ratio) was prepared and then polymerized under solventless condition. The synthesized polymer was characterized by FT-IR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), and Brunauer, Emmett and Teller analysis (BET) to evaluate the properties of the sorbent. The poly (TBAB-2AA DES) was applied as a selective sorbent for preconcentration of lead from food and water samples prior to its quantification by flame atomic absorption spectroscopy (FAAS). Variable factors affecting the extraction were optimized, and under the optimum conditions, the calibration plot was linear in the range 5.0-250.0 µg L-1. The relative standard deviation was (for n = 5) (RSD) < 3%. The limit of detection (LOD) and the enhancement factor were found to be 2.0 µg L-1 and 50, respectively. Finally, the accuracy of the method was assessed by comparison of the results with those obtained by direct determination of lead using inductively coupled plasma mass spectrometry (ICP-MS) and spiked real samples. The obtained recoveries were between 92 and 106%. Graphical abstract.

A hybrid material composed of multiwalled carbon nanotubes and MoSe2 nanorods as a sorbent for ultrasound-assisted solid-phase extraction of lead(II) and copper(II).

A MWCNT@MoSe2 nanorod hybrid material was synthesized by a hydrothermal method and used as an adsorbent for trace levels of Pb(II) and Cu(II). The material was characterized by Raman spectroscopy, XRD, SEM, SEM-EDX, SEM-mapping and BET methods. The hybrid material is demonstrated to be a viable sorbent for ultrasound-assisted solid phase extraction of Pb(II) and Cu(II) at pH 5.5. Following desorption with 3 M HNO3, the two elements were quantified by FAAS. Key parameters affecting the extraction efficiency, including eluent conditions, amount of adsorbent, sample volume were optimized. No significant interference by other ions is observed. The accuracy of the method was evaluated by the analysis of the certified reference materials TMDA-53.3 (lake water) and SPS-WW2 (waste water level 2). The recoveries were in good agreement with certified values. The method was successfully applied to the extraction/preconcentration of Pb(II) and Cu(II) in different real samples. Graphical abstract A hybrid material of type MWCNT@MoSe2 was synthesized, characterized, and used as adsorbent for Pb(II) and Cu(II). Key parameters affecting the extraction efficiency, including eluent conditions, amount of adsorbent, sample volume were optimized. The method was applied to the extraction of analytes in water samples.

Accurate and sensitive determination of lead in black tea samples using cobalt magnetic particles based dispersive solid-phase microextraction prior to slotted quartz tube-flame atomic absorption spectrometry.

Newly developed combination of magnetic cobalt particles based dispersive solid-phase microextraction (Co-MP-DSPME) and slotted quartz tube attached flame atomic absorption spectrometry (SQT-FAAS) was utilized to determine lead at trace levels in tea samples. Co-MPs' adsorbent properties were tested and validated for their selectiveness to lead. Only with a few and short extraction steps (i.e. adding MPs, mixing, decanting and eluting) analyte was extracted from sample solution rapidly and efficiently. Limit of detection (LOD) and limit of quantification (LOQ) for the developed method (Co-MP-DSPME-SQT-FAAS) were found to be 7.77 µg/L and 25.9 µg/L, respectively. Matrix matching strategy was performed and outcomes indicated that the developed method is applicable with the high percent recovery values of 110.1 ±â€¯4.5 and %102.9 ±â€¯4.2 for 100 and 300 µg/kg lead standard spiked black tea samples, respectively. The method was also applied to standard reference material to check the accuracy of the method.

Level of selected heavy metals in surface dust collected from electronic and electrical material maintenance shops in selected Western Oromia towns, Ethiopia.

Surface dusts from electronic and electrical material maintenance workshops may present significant environmental contamination. The aim of this study was to determine levels of selected heavy metals (Cu, Ni, Co, Cd, Cr, Pb, Zn, and Fe) in surface dust samples collected from electronic and electrical device maintenance workshops located in Ambo, Gedo, and Nekemte towns in Ethiopia. An optimized wet digestion procedure (acid mixture, 3 mL HNO3, 2 mL HClO4, and H2O2; digestion time, 2 h; digestion temperature, 200 °C) was employed prior to the metals determination by flame atomic absorption spectroscopy. The average amounts of the metals were found to be in the ranges of 73,970-58,980, 59,290-51,120, 8570-5778, 1273-1126, 708.9-261.6, 111.7-101.0, 114.9-89.50, and 12.30-9.620 mg/kg for Pb, Fe, Cu, Cr, Zn, Co, Ni, and Cd, respectively. The results showed that the investigated surface dust samples contained significant levels of the analyzed heavy metals compared to soil samples collected from the corresponding control sites. The heavy metal concentrations in the investigated samples from the three towns followed a decreasing order Pb > Fe >> Cu >> Cr > Zn > Co > Ni > Cd, indicating the presence of elevated amount of Pb in the surface dust samples. The significantly high levels of heavy metals detected in all surface dust samples from electronic and electrical device maintenance shops could be inferred to the seepage of these metals from electronic materials during the maintenance procedures. Based on the result obtained, we strongly recommend a strict monitoring and disposal (policy issue) of wastes generated from electronic and electrical device maintenance shops.

Elemental Characterization of Medicinal Plants and Soils from Hazarganji Chiltan National Park and Nearby Unprotected Areas of Balochistan, Pakistan.

The aim of this work was to evaluate the variability in elemental composition of seven medicinal plants and their respective soils belonging to protected and nearby unprotected sites of the Hazarganji Chiltan National Park. The medical plants under study were Achillea wilhelmsii C. Koch, Peganum harmala Linn, Sophora mollis (Royle) Baker, Perovskia atriplicifolia Benth, Seriphidium quettense (Podlech.) Ling, Hertia intermedia (Bioss) O. Ktze, and Nepeta praetervisa Rech. F. Macro (C, H, N, S, K, Ca), micro (Cl, Cu, Fe, Mn, and Zn), beneficial (Al, Co, Na), others (As, Br, Cr, Cs, Hf, Pb, Rb, Sb, Sr, Sn, V and Th) and rare earth elements (Ce, Eu, La, Lu, Nd Sc, Sm, Tb and Yb) were characterized by means of standard organic elemental and instrumental neutron activation methodologies and by flame atomic absorption spectroscopy. Results showed that, among macro nutrients, carbon concentration was the highest element in both plant and soil samples followed by H and K. Elements such as Cl, Na and Fe were detected in considerably good amounts; all the other elements were found in trace quantities. Principal component analysis (PCA) was applied to identify spatial variation in elemental composition of medicinal plants, in which 80-90% of the total variance in whole set of data was found. In particular, the findings highlighted the presence of essential and beneficial elements such as C, H, N, K, Ca, Fe, Mn and Na, in samples from protected sites, while potentially dangerous elements such as Al, As, Br and Cr were detected in samples from unprotected sites. These results emphasized on the need for rational exploitation of valuable medicinal plants and supporting protected areas as an excellent source of biodiversity conservation.

Synthesis, characterization, and application of a Zn (II)-imprinted polymer grafted on graphene oxide/magnetic chitosan nanocomposite for selective extraction of zinc ions from different food samples.

A novel Zn(II) imprinted polymer was synthesized via a co-precipitation method using graphene oxide/magnetic chitosan nanocomposite as supporting material. The synthesized imprinted polymer was characterized by Fourier transform infrared spectrometry (FTIR) and scanning electron microscopy (SEM) and applied as a sorbent for selective magnetic solid phase extraction of zinc followed by its determination by flame atomic absorption spectrometry. The kinetic and isothermal adsorption experiments were carried out and all parameters affecting the extraction process was optimized. Under the optimal experimental conditions, the developed procedure exhibits a linear dynamic range of 0.5-5.0µgL-1 with a detection limit of 0.09µgL-1 and quantification limit of 0.3µgL-1. The maximum sorption capacity of the sorbent was found to be 71.4mgg-1. The developed procedure was successfully applied to the selective extraction and determination of zinc in various samples including well water, drinking water, black tea, rice, and milk.

Vortex-assisted ionic liquid-based dispersive liquid-liquid microextraction for assessment of chromium species in artificial saliva extract of different chewing tobacco products.

A novel dispersive liquid-liquid microextraction (ILDLLµE) method using an extracting solvent (ionic liquid) and dispersant (Triton X-114) was developed for the separation and preconcentration of hexavalent chromium (Cr6+) in artificial saliva extract (ASE) of chewing tobacco products, gutkha, and mainpuri (n = 23). In the proposed method, the extraction of Cr6+ was accomplished by using ammonium pyrrolidinedithiocarbamate (APDC) as complexing agent and 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM] [PF6] as extracting solvent. The tiny droplet of metal chelate was then dispersed into TX-114 emulsion, using vortex mixer. Various parameters such as concentration of APDC, pH of the solution, volume of [C4MIM] [PF6], and TX-114 as well as extraction time were studied. Under the most favorable conditions, the limit of detection was found to be 0.068 µg/L with the relative standard deviation <5 %. The enrichment factor of developed method was found as 62.5, and method has been effectively applied for the analysis of Cr species in artificial saliva extract of gutkha and mainpuri products. The Cr6+ was quantitatively recovered (<97 %) under optimal conditions, while the recovery of trivalent specie (Cr3+), at the same experimental conditions, was observed to be <5 %. The Cr3+ was determined by the difference of total Cr and Cr6+ in artificial saliva extract of selected STP. Health risks associated with the intake of total Cr in gutkha and mainpuri were assessed in terms of estimated daily intake, such as carcinogenic and noncarcinogenic risks. Estimated daily intake of Cr via chewing 10 g/day of gutkha and mainpuri was found to be below the maximum tolerable daily intake, whereas the calculated risk of cancer for Cr was observed in the acceptable range of 10E-6-10E-4, except some brands of gutkha. Graphical Abstract ᅟ.

Iron migration from undamaged and dented juice tinplate cans.

BACKGROUND: Iron migration from tinplate cans to pineapple drink was studied over time using flame atomic absorption spectroscopy, taking into consideration storage temperature, sell-by date and can condition (dented/undamaged). An organoleptic test, at the sell-by date, was also performed. RESULT: Analysis of iron in drinks from tinplate cans, glass and polyethylene terephthalate (PET) bottles was performed up until the sell-by date. For undamaged canned drinks stored at room temperature, iron was found to remain constant at 0.23 ± 0.01 mg L(-1) , from the 24th day until 1 year after production. Iron found in glass and PET bottles also remained constant until the sell-by date, at 0.15 ± 0.04 and 0.12 ± 0.04 mg L(-1) , respectively. However, migration of iron from dented cans was found to be significant. Twelve months after production, iron content in dented cans, stored at room temperature (22 °C) and in a refrigerator chamber (4 °C) was 14.4 ± 1.0 and 5.5 ± 0.4 mg L(-1) , respectively. CONCLUSION: Results showed that for a 35 kg child the intake of three damaged canned drinks may contribute to more than 50% of the iron provisional maximum tolerance daily intake. © 2015 Society of Chemical Industry.

Ion imprinted polymeric nanoparticles for selective separation and sensitive determination of zinc ions in different matrices.

Preparation of Zn(2+) ion-imprinted polymer (Zn-IIP) nanoparticles is presented in this report. The Zn-IIP nanoparticles are prepared by dissolving stoichiometric amounts of zinc nitrate and selected chelating ligand, 3,5,7,20,40-pentahydroxyflavone, in 15 mL ethanol-acetonitrile (2:1; v/v) mixture as a porogen solvent in the presence of ethylene glycol-dimethacrylate (EGDMA) as cross-linking, methacrylic acid (MAA) as functional monomer, and 2,2-azobisisobutyronitrile (AIBN) as initiator. After polymerization, Cavities in the polymer particles corresponding to the Zn(2+) ions were created by leaching the polymer in HCl aqueous solution. The synthesized IIPs were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectroscopy and thermal analysis techniques. Also, the pH range for rebinding of Zn(2+) ion on the IIP and equilibrium binding time were optimized, using flame atomic absorption spectrometry. In selectivity study, it was found that imprinting results increased affinity of the material toward Zn(2+) ion over other competitor metal ions with the same charge and close ionic radius. The prepared IIPs were repeatedly used and regenerated for six times without any significant decrease in polymer binding affinities. Finally, the prepared sorbent was successfully applied to the selective recognition and determination of zinc ion in different real samples.

Speciation of chromium in environmental samples by dual electromembrane extraction system followed by high performance liquid chromatography.

This study proposes the dual electromembrane extraction followed by high performance liquid chromatography for selective separation-preconcentration of Cr(VI) and Cr(III) in different environmental samples. The method was based on the electrokinetic migration of chromium species toward the electrodes with opposite charge into the two different hollow fibers. The extractant was then complexed with ammonium pyrrolidinedithiocarbamate for HPLC analysis. The effects of analytical parameters including pH, type of organic solvent, sample volume, stirring rate, time of extraction and applied voltage were investigated. The results showed that Cr(III) and Cr(VI) could be simultaneously extracted into the two different hollow fibers. Under optimized conditions, the analytes were quantified by HPLC instrument, with acceptable linearity ranging from 20 to 500 µg L(-1) (R(2) values≥0.9979), and repeatability (RSD) ranging between 9.8% and 13.7% (n=5). Also, preconcentration factors of 21.8-33 that corresponded to recoveries ranging from 31.1% to 47.2% were achieved for Cr(III) and Cr(VI), respectively. The estimated detection limits (S/N ratio of 3:1) were less than 5.4 µg L(-1). Finally, the proposed method was successfully applied to determine Cr(III) and Cr(VI) species in some real water samples.

Comparison Study on Determination of Trace Element Content in Peach Pulp between Wet Digestion Method and Carbonize Acid Dissolution Method / 世界科学技术-中医药现代化

This study was aimed to determine trace elements in Peach pulp . The wet digestion method and car-bonize acid dissolution method were applied to digest the sample, and flame atomic absorption spectroscopy was used to determine the content of trace elements (Fe, Cu, Mn) in Peach pulp . The results showed that the content is not consistent among different pretreatment methods. However, the metalion content among these three methods are in the order of Fe > Mn > Cu, with the average recovery rate between 92.6% and 119.6%. The RSD is less than 2.86%. It was concluded that this method is with high accuracy and stability as well as reliable accurate re-sults. It also proved that Peach pulp . is rich in Fe, Cu and Mn. It provides some useful information for further pharmacological study of Peach pulp .

Evaluation of safety profile of black shilajit after 91 days repeated administration in rats.

OBJECTIVE: To evaluate the safety of shilajit by 91 days repeated administration in different dose levels in rats. METHODS: In this study the albino rats were divided into four groups. Group I received vehicle and group II, III and IV received 500, 2 500 and 5 000 mg/kg of shilajit, respectively. Finally animals were sacrificed and subjected to histopathology and iron was estimated by flame atomic absorption spectroscopy and graphite furnace. RESULTS: The result showed that there were no significant changes in iron level of treated groups when compared with control except liver (5 000 mg/kg) and histological slides of all organs revealed normal except negligible changes in liver and intestine with the highest dose of shilajit. The weight of all organs was normal when compared with control. CONCLUSIONS: The result suggests that black shilajit, an Ayurvedic formulation, is safe for long term use as a dietary supplement for a number of disorders like iron deficiency anaemia.

Determination of Sodium Content in Danshen Injection by Atomic Absorption Spectroscopy / 中国中医药信息杂志

Objective To determine the total sodium in Danshen for injection.Methods Flame atomic absorption spectroscopy was used to determine the total sodium in Danshen for injection.Results The calibration curves were linear in the range of 0.5～10 mg/L for sodium chloride.The average recovery rates of sodium chloride were 101.8%,RSD=1.60%.Conclusion This method was found to be simple,quick and accurate for simultaneous determination of sodium in Danshen for injection.