Atomic absorption spectroscopy with a resistively heated carbon furnace

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Determination of Aflatoxins B1 and B2 in Powdered Milk Using Modified Liquid Chromatography Method

Abstract: Background & Aims: In this study, using a liquid-liquid microextraction method for pre-concentration trace amounts of aflatoxins, the amount of Aflatoxins B1 and B2 in powdered milk was determined. Determination of aflatoxins was done by using high-performance liquid chromatography coupled with fluorescent detector. Method: Samples were extracted by immunoaffinity column (IAC) clean-up, and their eluents were used as dispersants of the subsequent DLLME, for further enrichment of aflatoxins. Various parameters (the type of elution solvent, the type and volume of extraction solvent and disperser solvent, extraction time and centrifugation time) that affect the efficiency of two steps were optimized. Results: Under the optimum conditions, the calibrations for B1 and B2 were found to be linear in the range of 0.03¬¬¬-5.0 and 0.006-1.0 ng ml-1 with 0.98 and 0.99 coefficient of estimation (R2), respectively. Conclusion: The results showed that dispersive liquid–liquid microextraction combined with HPLC is a selective, simple, sensitive and effective analytical method for the pre-concentration and determination of ultra trace amounts of aflatoxins. The method is suggested for pre-concentration and determination of B1 and B2 aflatoxins in milk powder. Keywords: Aflatoxins, High pressure liquid chromatography (HPLC), Immunoaffinity cleanup, Powdered Milk, DLLM

Separation study of some heavy metal cations through a bulk liquid membrane containing 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane

Competitive permeation of seven metal cations from an aqueous source phase containing equimolar concentrations of Co2+, Fe3+, Cd2+, Cu2+, Zn2+, Ag+ and Pb2+ metal ions at pH 5 into an aqueous receiving phase at pH 3 through an organic phase facilitated by 1,13-bis(8-quinolyl)-1,4,7,10,13-pentaoxatridecane (Kryptofix5) as a carrier was studied as bulk liquid membrane transport. The obtained results show that the carrier is highly selective for Ag+ cation and under the employed experimental conditions, it transports only this metal cation among the seven studied metal cations. The effects of various organic solvents on cation transport rates have been demonstrated. Among the organic solvents involving nitrobenzene (NB), chloroform (CHCl3), dichloromethane (DCM) and 1,2-dichloroethane (1,2-DCE) which were used as liquid membrane, the most transport rate was obtained for silver (I) cation in DCM. The sequence of transport rate for this cation in organic solvents was: DCM > CHCl3 > 1,2-DCE > NB. The competitive transport of these seven metal cations was also studied in CHCl3–NB and CHCl3–DCM binary solvents as membrane phase. The results show that the transport rate of Ag+ cation is sensitive to the solvent composition and a non-linear relationship was observed between the transport rate of Ag+ and the composition of these binary mixed non-aqueous solvents. The influence of the stearic acid, palmitic acid and oleic acid as surfactant in the membrane phase on the transport of the metal cations was also investigated

Photoinduced Polymer Chain Scission of Alkoxyphenacyl Based Polycarbonates

We report the design and development of a new class of alkoxyphenacyl based photodegradable polycarbonates. These polymers incorporate the photoactive moiety in the backbone and, when irradiated at 300 nm, undergo controlled chain scission. Micropatterned thin films of these polymers were fabricated by photolithographic techniques. The use of these photodegradable polymers for controlled release applications was demonstrated by the release of Nile Red from polymeric nanoparticles. In addition, these polymers are mechanically robust, thermally stable, and hydrolytically degradable

Preconcentration of lead using solidification of floating organic drop and its determination by electrothermal atomic absorption spectrometry

A simple microextraction method based on solidification of a floating organic drop (SFOD) was developed for preconcentration of lead prior to its determination by electrothermal atomic absorption spectrometry (ETAAS). Ammonium pyrolidinedithiocarbamate (APDC) was used as complexing agent, and the formed complex was extracted into a 20 μL of 1-undecanol. The extracted complex was diluted with ethanol and injected into a graphite furnace. An orthogonal array design (OAD) with OA16 (45) matrix was employed to study the effects of different parameters such as pH, APDC concentration, stirring rate, sample solution temperature and the exposure time on the extraction efficiency. Under the optimized experimental conditions the limit of detection (based on 3 s) and the enhancement factor were 0.058 μg L−1 and 113, respectively. The relative standard deviation (RSD) for 8 replicate determinations of 1 μg L−1 of Pb was 8.8%. The developed method was validated by the analysis of certified reference materials and was successfully applied to the determination of lead in water and infant formula base powder samples

Vortex-assisted ionic liquid microextraction coupled to flame atomic absorption spectrometry for determination of trace levels of cadmium in real samples

A simple and rapid vortex assisted ionic liquid based liquid–liquid microextraction technique (VALLME) was proposed for preconcentration of trace levels of cadmium. According to this method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Cadmium preconcentration was mediated by chelation with the 8-hydroxyquinoline (oxine) reagent and an IL, 1-octyl-3-methylimidazolium hexafluorophosphate ([Omim][PF6]) was chosen as the extraction solvent to extract the hydrophobic complex. Several variables such as sample pH, concentration of oxine, volume of [Omim][PF6] and extraction time were investigated in details and optimum conditions were selected. Under the optimum conditions, the limit of detection (LOD) was 2.9 μg L−1 for Cd (ІІ) and relative standard deviation (RSD%) for five replicate determinations of 125 μg L−1 was 4.1%. The method was successfully applied to the determination of cadmium in tap water, apple and rice samples

Formulation and photoirradiation parameters that influenced photoresponsive drug delivery using alkoxylphenacyl-based polycarbonates

Recently, we reported the synthesis and biocompatibility of alkoxylphenacyl-based polycarbonates (APP); a promising new class of polymers that undergo photo-induced chain scission. In the current study, nanoparticles (NPs) were prepared from the APP Polymer (APP-NPs) and loaded with doxorubicin (DOX) (DOX-APP-NPs) in order to identify and evaluate formulation and photoirradiation parameters that influence photoresponsive efficacy. Stable and spherical APP-NPs were prepared with diameters between 70-80 nm depending on APP concentration (10-40 mg/mL). There was a direct relationship between APP concentration and resultant particle size. Drug release studies indicated that exposure to the phototrigger was capable of altering the rate and extent of DOX released. Photoresponsive DOX release was markedly influenced by the frequency of photoirradiation while the effect of APP concentration was most likely propagated through NP size. DOX released by photoactivation retained its efficacy as assessed by cytotoxicity studies in human lung adenocarcinoma (A549) cells. Studies in BALB/c mice indicated that DOX-APP-NPs induce less cardiotoxicity than DOX alone and that DOX-APP-NPs are not susceptible to dose dumping after photoirradiation. (C) 2014 Elsevier B.V. All rights reserved