A reliable method of quantification of trace copper in beverages with and without alcohol by spectrophotometry after cloud point extraction

A new cloud point extraction (CPE) method was developed for the separation and preconcentration of copper (II) prior to spectrophotometric analysis. For this purpose, 1-(2,4-dimethylphenyl) azonapthalen-2-ol (Sudan II) was used as a chelating agent and the solution pH was adjusted to 10.0 with borate buffer. Polyethylene glycol tert-octylphenyl ether (Triton X-114) was used as an extracting agent in the presence of sodium dodecylsulphate (SDS). After phase separation, based on the cloud point of the mixture, the surfactant-rich phase was diluted with acetone, and the enriched analyte was spectrophotometrically determined at 537 nm. The variables affecting CPE efficiency were optimized. The calibration curve was linear within the range 0.285-20 µg L-1 with a detection limit of 0.085 µg L-1. The method was successfully applied to the quantification of copper in different beverage samples.

Structural characterization and in vivo evaluation of retinyl palmitate in non-ionic lamellar liquid crystalline system

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of cosurfactant on the supramolecular structure and physicochemical properties of non-ionic biocompatible microemulsions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Process for producing biodiesel fuel with reduced viscosity and a cloud point below thirty-two (32) degrees fahrenheit

Triglycerides are reacted in a liquid phase reaction with methanol and a homogeneous basic catalyst. The reaction yields a spatially separated two phase result with an upper located non-polar phase consisting principally of non-polar methyl esters and a lower located phase consisting principally of glycerol and residual methyl esters. The glycerol phase is passed through a strong cationic ion exchanger to remove anions, resulting in a neutral product which is flashed to remove methanol and which is reacted with isobutylene in the presence of a strong acid catalyst to produce glycerol ethers. The glycerol ethers are then added back to the upper located methyl ethyl ester phase to provide an improved biodiesel fuel.

An environmentally friendly analytical procedure for nickel determination by atomic and molecular spectrometry after cloud point extraction in different samples

Cloud point extraction (CPE) was employed for separation and preconcentration prior to the determination of nickel by graphite furnace atomic absorption spectrometry (GFAAS), flame atomic absorption spectrometry (FAAS) or UV-Vis spectrophotometry. Di-2-pyridyl ketone salicyloylhydrazone (DPKSH) was used for the first time as a complexing agent in CPE. The nickel complex was extracted from the aqueous phase using the Triton X-114 surfactant. Under optimized conditions, limits of detection obtained with GFAAS, FAAS and UV-Vis spectrophotometry were 0.14, 0.76 and 1.5 mu g L-1, respectively. The extraction was quantitative and the enrichment factor was estimated to be 27. The method was applied to natural waters, hemodialysis concentrates, urine and honey samples. Accuracy was evaluated by analysis of the NIST 1643e Water standard reference material.

Cloud point extraction to avoid interferences by structured background on nickel determination in plant materials by FAAS

An analytical procedure based on microwave-assisted digestion with diluted acid and a double cloud point extraction is proposed for nickel determination in plant materials by flame atomic absorption spectrometry. Extraction in micellar medium was successfully applied for sample clean up, aiming to remove organic species containing phosphorous that caused spectral interferences by structured background attributed to the formation of PO species in the flame. Cloud point extraction of nickel complexes formed with 1,2-thiazolylazo-2-naphthol was explored for pre-concentration, with enrichment factor estimated as 30, detection limit of 5 mu g L(-1) (99.7% confidence level) and linear response up to 80 mu g L(-1). The accuracy of the procedure was evaluated by nickel determinations in reference materials and the results agreed with the certified values at the 95% confidence level.

Cloud point extraction and concentration of carbaryl from natural waters

An improved procedure is proposed for determination of the pesticide carbaryl in natural waters based on double cloud point extraction. The clean up step was carried out only with Triton X-114 in alkaline medium in order to avoid the use of toxic organic solvents as well as to minimise waste generation. Cloud point preconcentration of the product of the reaction of the analyte with p-aminophenol and cetyltrimethylammonium bromide was explored to increase sensitivity and improve the detection limit. Linear response was achieved within 10 and 500 mu g L-1 and the apparent molar absorptivity was estimated as 4.6 x 105 L mol-1 cm-1. The detection limit was estimated as 7 mu g L-1 at the 99.7% confidence level and the coefficient of variation was 3.4% (n = 8). Recoveries within 91 and 99% were estimated for carbaryl spiked water samples. The results obtained for natural water samples were in agreement with those achieved by the batch of spectrophotometric procedure at the 95% confidence level. The proposed procedure is then a simple, fast, inexpensive and greener alternative for carbaryl determination.

Simultaneous flow injection preconcentration of lead and cadmium using cloud point extraction and determination by atomic absorption spectrometry

A flow injection (FI) micelle-mediated separation/preconcentration procedure for the determination of lead and cadmium by flame atomic absorption spectrometry (FAAS) has been proposed. The analytes reacted with 1-(2-thiazolylazo)-2-naphthol (TAN) to form hydrophobic chelates, which were extracted into the micelles of 0.05% (w/v) Triton X-114 in a solution buffered at pH 8.4. In the preconcentration stage, the micellar solution was continuously injected into a flow system with four mini-columns packed with cotton, glass wool. or TNT compresses for phase separation. The analytes-containing micelles were eluted from the mini-columns by a stream of 3 mol L(-1) HCl solution and the analytes were determined by FAAS. Chemical and flow variables affecting the preconcentration of the analytes were studied. For 15 mL. of preconcentrated solution, the enhancement factors varied between 15.1 and 20.3, the limits of detection were approximately 4.5 and 0.75 mu g L(-1) for lead and cadmium, respectively. For a solution containing 100 and 10 mu g L(-1) of lead and cadmium, respectively, the R.S.D. values varied from 1.6 to 3.2% (n = 7). The accuracy of the preconcentration system was evaluated by recovery measurements on spiked water samples. The method was susceptible to matrix effects, but these interferences were minimized by adding barium ions as masking agent in the sample solutions, and recoveries from spiked sample varied in the range of 95.1-107.3%. (C) 2008 Elsevier B.V. All rights reserved.

POLYETHYLENE GLYCOL ADDITION DOES NOT IMPROVE EXOGENOUS SURFACTANT FUNCTION IN AN EXPERIMENTAL MODEL OF MECONIUM ASPIRATION SYNDROME

Meconium (MEC) is a potent inactivator of pulmonary surfactant. The authors studied the effects of polyethylene glycol addition to the exogenous surfactant over the lung mechanics and volumes. Human meconium was administrated to newborn rabbits. Animals were ventilated for 20 minutes and dynamic compliance, ventilatory pressure, and tidal volume were recorded. Animals were randomized into 3 study groups: MEC group (without surfactant therapy); S100 group (100 mg/kg surfactant); and PEG group (100 mg/kg porcine surfactant plus 5% PEG). After ventilation, a pulmonary pressure-volume curve was built. Histological analysis was carried out to calculate the mean alveolar size (Lm) and the distortion index (DI). Both groups treated with surfactant showed higher values of dynamic pulmonary compliance and lower ventilatory pressure, compared with the MEC group (P .05). S100 group had a larger maximum lung volume, V30, compared with the MEC group (P .05). Lm and DI values were smaller in the groups treated with surfactant than in the MEC group (P .05). No differences were observed between the S100 and PEG groups. Animals treated with surfactant showed significant improvement in pulmonary function as compared to nontreated animals. PEG added to exogenous surfactant did not improve lung mechanics or volumes.

Online estimation of respiratory mechanics in non-invasive pressure support ventilation: a bench model study.

An online algorithm for determining respiratory mechanics in patients using non-invasive ventilation (NIV) in pressure support mode was developed and embedded in a ventilator system. Based on multiple linear regression (MLR) of respiratory data, the algorithm was tested on a patient bench model under conditions with and without leak and simulating a variety of mechanics. Bland-Altman analysis indicates reliable measures of compliance across the clinical range of interest (± 11-18% limits of agreement). Resistance measures showed large quantitative errors (30-50%), however, it was still possible to qualitatively distinguish between normal and obstructive resistances. This outcome provides clinically significant information for ventilator titration and patient management.

Transcriptional and functional profiles of voltage-gated Na(+) channels in injured and non-injured DRG neurons in the SNI model of neuropathic pain.

Changes in expression and function of voltage-gated sodium channels (VGSC) in dorsal root ganglion (DRG) neurons may play a major role in the genesis of peripheral hyperexcitability that occurs in neuropathic pain. We present here the first description of changes induced by spared nerve injury (SNI) to Na(v)1 mRNA levels and tetrodotoxin-sensitive and -resistant (TTX-S/TTX-R) Na(+) currents in injured and adjacent non-injured small DRG neurons. VGSC transcripts were down-regulated in injured neurons except for Na(v)1.3, which increased, while they were either unchanged or increased in non-injured neurons. TTX-R current densities were reduced in injured neurons and the voltage dependence of steady-state inactivation for TTX-R was positively shifted in injured and non-injured neurons. TTX-S current densities were not affected by SNI, while the rate of recovery from inactivation was accelerated in injured neurons. Our results describe altered neuronal electrogenesis following SNI that is likely induced by a complex regulation of VGSCs.

Non-Markovian Dynamics of the Spin-Boson Model

Avointen kvanttisysteemien teoria tutkii, miten vuorovaikutus laajan ympäristön kanssa muuttaa kvanttisysteemin dynamiikkaa. Kaikki kvanttisysteemit ovat pohjimmiltaan avoimia, joten tällaisten systeemien ymmärtäminen on välttämätöntä kvanttimaailman ymmärtämiseksi. Spin-bosoni -malli kuvaa avointa kaksitasosysteemiä, joka vuorovaikuttaa bosoneista koostuvan ympäristön kanssa. Useat fysikaaliset systeemit käyttäytyvät kaksitasosysteemin tavoin matalissa lämpötiloissa, jonka vuoksi spin-bosoni -mallilla on merkittävä rooli avointen kvanttisysteemien tutkimuksessa. Tutkielman ensimmäinen luku käsittelee yleistä avointen kvanttisysteemien teoriaa ja menetelmiä ei-Markovisen liikeyhtälön johtamiseksi. Ei-Markovinen liikeyhtälö kuvaa ympäristöstä systeemiin takaisin virtaavan informaation vaikutusta systeemin dynamiikkaan. Toisessa luvussa on johdettu spin-bosoni -mallille ei-Markovinen liikeyhtälö ja tarkasteltu spin-systeemin dynamiikkaa joissain erityistapauksissa. Kolmannessa luvussa on esitelty kvanttihyppymenetelmiä avointen systeemien dynamiikan ratkaisemiseksi ja sovellettu ei-Markovisten kvanttihyppyjen teoriaa spinbosoni -mallin tutkimiseksi. Ei-Markovisten kvanttihyppyjen teoriaa käyttämällä voidaan selittää spin-systeemin tiheysmatriisin populaatioissa ja koherensseissa havaittavien ei-Markovisten efektien alkuperä käännettyjen kvanttihyppyjen avulla. Tutkielman viimeisessä osassa esitellään muutamia spin-bosoni -mallin sovellutuksia fysiikan eri alueilta.

Determination of triamterene in human plasma and urine after its cloud point extraction

A new analytical approach was developed involving cloud point extraction (CPE) and spectrofluorimetric determination of triamterene (TM) in biological fluids. A urine or plasma sample was prepared and adjusted to pH 7, then TM was quickly extracted using CPE, using 0.05% (w/v) of Triton X-114 as the extractant. The main factors that affected the extraction efficiency (the pH of the sample, the Triton X-114 concentration, the addition of salt, the extraction time and temperature, and the centrifugation time and speed) were studied and optimized. The method gave calibration curves for TM with good linearities and correlation coefficients (r) higher than 0.99. The method showed good precision and accuracy, with intra- and inter-assay precisions of less than 8.50% at all concentrations. Standard addition recovery tests were carried out, and the recoveries ranged from 94.7% to 114%. The limits of detection and quantification were 3.90 and 11.7 µg L-1, respectively, for urine and 5.80 and 18.0 µg L-1, respectively, for plasma. The newly developed, environmentally friendly method was successfully used to extract and determine TM in human urine samples.

Biochemical Effects of Anionic, Cationic and Non Ionic Surfactants on a Tropical Teleost Oreochromis Mossambicus(Peters) and a Marine Cyanobacterium Synechocystis Salina Wislouch

The present work is a base line attempt to investigate and assess the toxicities of three surfactants viz. anionic sodium dodecyl sulfate (SDS), non ionic Triton X-1OO (TX-IOO) and cationic cetyl trimethyl ammonium bromide (CTAB). These compounds represent simple members of the often neglected group of aquatic pollutants i.e. the anionic alkyl sulfates, non ionics and the cationics. These compounds are widely used In plastic industry, pesticide/herbicide formulations, detergents, oil spill dispersants, molluscicides etc. The test organisms selected for the present study are the cyanobacterium Synechocystis salina Wislouch representing a primary producer in the marine environment and a fresh water adapted euryhaline teleost Oreochromis mossambicus (peters) at the consumer level of the ecological pyramid. The fish species, though not indigenous to our country, is now found ubiquitously in fresh water systems and estuaries. Also it is highly resistant to pollutants and has been suggested as an indicator of pollution in tropical region .