Određivanje kadmija u vinu atomskom apsorpcijskom spektrometrijom

The objective of the present investigation was to develop a bilayer-floating tablet (BFT) for captopril using direct compression technology. HPMC, K-grade and effervescent mixture of citric acid and sodium bicarbonate formed the floating layer. The release layer contained captopril and various polymers such as HPMC-K15M, PVP-K30 and Carbopol 934p, alone or in combination with the drug. The floating behavior and in vitro dissolution studies were carried out in a USP 23 apparatus 2 in simulated gastric fluid (without enzyme, pH 1.2). Final formulation released approximately 95% drug in 24 h in vitro, while the floating lag time was 10 min and the tablet remained floatable throughout all studies. Final formulation followed the Higuchi release model and showed no significant change in physical appearance, drug content, floatability or in vitro dissolution pattern after storage at 45 oC/75% RH for three months. Placebo formulation containing barium sulphate in the release layer administered to human volunteers for in vivo X-ray studies showed that BFT had significantly increased the gastric residence time.Opisana je izravna metoda određivanja kadmija u uzorcima vina elektrotermičkom atomskom apsorpcijskom spektrometrijom (ETAAS). Za atomizaciju su upotrebljene pirolitičke grafitne cjevčice i grafitne cjevčice sa standardnom pirolitičkom platformom po L’vovu. Granica određivanja bila je 0,08 microg L1 kadmija. Relativna standardna devijacija za koncentracijsko područje od 0,2 do 10 g L-1 bila je između 1 i 7%. Točnost metode potvrđena je usporedbom rezultata s rezultatima dobivenih iz vlažno digeriranih uzoraka i spiked uzoraka. Pomoću ove metode određeno je da se koncentracija kadmija u makedonskim vinima kreće u rasponu od 0,10 do 0,90 microg L-1

Svojstva bakar(II)-histidin kompleksa izoliranog iz dijalizirane humane plazme s histidinom

The copper(II)-histidine complex obtained following dialysis of human plasma with histidine was investigated using various types of extraction systems and ion exchange resins. According to the results obtained, the Cu(II)-histidine complex formed under the dialysis conditions has one positive charge. Preconcentration of copper from the dialysis solution was achieved by its extraction as a dithiocarbamate complex and by sorption on cation-exchange resin or onto chelate sorbent.U radu su ispitivani različiti sustavi za ekstrakciju i ionske-izmjenjivačke smole za izolaciju bakar(II)-histidin kompleksa iz dijalizirane humane plazme s histidinom. Prema dobivenim rezultatima, bakar(II)-histidin kompleks ima jedan pozitivan naboj. Prekoncentracija bakra iz otopine za dijalizu postignuta je ekstrakcijom ditiokarbamatnog kompleksa i sorpcijom na kation-izmjenjivačku smolu ili stvaranjem kelata

On CV-AAS determination and speciation of mercury in wine

The possibilities of cold vapor - atomic absorption spectrometry (CV-AAS) for the determination and speciation of mercury in wine samples are critically discussed in the present study. In a first step, the direct determination of Hg using SnCl2 and NaBH4 as reducing agents is attempted. The influence of the type of reducing agent and its concentration, as well as the concentration of HCl on the absorbance signal of the different Hg species (Hg2+ and CH3Hg1+) is investigated. The results show that direct determination of both Hg species is possible: inorganic Hg can be selectively determined by using 0.04% NaBH4 and 1 mol/l HCl directly in an untreated wine sample; both Hg species are determined simultaneously by using 0.9% NaBH4 and 1 mol/l HCl again directly in an untreated wine sample. The recoveries obtained by using HCl at a concentration below 1 mol/l are lower than 85% which can be considered as evidence that the mercury in the wine sample is bound in some complex compounds. In the second step, a separation and preconcentration method for Hg determination in wine is proposed. The quantitative sorption of both Hg species was achieved by using Chelex 100 at pH 4. Quantitative elution of the Hg retained on the resin is possible with 2 mol/l HNO3. The limits of determination of the analytical procedure consist of Hg pre-concentration on Chelex 100 followed by CV-AAS measurement of eluted Hg, allows the determination of total Hg in all types of wine samples with their natural contents

ESAC Opinion on the Scientific Validity of the Bioelution Test Method: ESAC Opinion No. 2019-03 of 2 December 2019

ESAC, the EURL ECVAM Scientific Advisory Committee, advises EURL ECVAM on scientific issues. Its main role is to conduct independent peer review of validation studies of alternative test methods and to assess their scientific validity for a given purpose. The committee reviews the appropriateness of study design and management, the quality of results obtained and the plausibility of the conclusions drawn. ESAC peer reviews are formally initiated with a EURL ECVAM Request for ESAC Advice, which provides the necessary background for the peer-review and establishes its objectives, timelines and the questions to be addressed. The peer review is normally prepared by specialised ESAC Working Groups. ESAC's advice to EURL ECVAM is formally provided as 'ESAC Opinions' and 'Working Group Reports' at the end of the peer review. ESAC may also issue Opinions on other scientific issues of relevance to the work and mission of EURL ECVAM but not directly related to a specific alternative test method. The ESAC Opinion expressed in this report relates to the peer-review of the Bioelution in vitro test method.JRC.F.3-Chemicals Safety and Alternative Method

Atomic absorption Spectrometry in wine analysis – A review

This article reviews methods for the determination and identification of trace elements in wine by using atomic absorption spectrometry (AAS). Wine is one of the most widely consumed beverages and strict analytical control of trace elements content is required during the whole process of wine production from grape to the final product. Levels of trace elements in wine are important from both points of view: organoleptic -Fe, Cu, Mn and Zn concentrations are directly related to the destabilization and oxidative evolution of wines, and toxicological -toxic elements content should be under the allowable limit, wine identification. The identification of metals in wine is subject of increasing interest since complexation may reduce their toxicity and bioavailability. AAS is one of widely used methods for routine analytical control of wine quality recommended by the International Organization of Vine and Wine. Two main approaches -preliminary sample digestion and direct instrumental measurement combined with AAS for trace element determination in wines are reviewed and discussed. Procedures for various sample pretreatments, for trace element separation and preconcentration are presented. Advances in metal identification studies in wines based on AAS are presented. Key words: wine; trace elements; determination; speciation; AAS АТОМСКАТА АПСОРПЦИОНА СПЕКТРОМЕТРИЈА ВО АНАЛИЗАТА НА ВИНО -ПРЕГЛЕД -Во трудот е направен преглед на методите за определување и специјација на елементите застапени во траги во вино со примена на атомската апсорпциона спектрометрија (ААС). Виното претставува еден од најупотребуваните пијалaци и затоа е потребна добра аналитичка контрола на застапеноста на елементите во траги за време на целиот производен процес од грозје до финалниот производ. Нивото на застапеност на елементите во траги во виното е важно, пред сè поради неколку причини: органолептички -концентрациите на Fe, Cu, Mn и Zn се директно поврзани сo дестабилизацијата и оксидативниот процес на виното, токсико-лошки -содржината на токсичните елементи треба да биде под дозволените граници, како и поради идентификација на виното. Определувањето на хемиските форми на елементите во виното е исто така важно поради тоа што нивното комплексирање може да ја намали нивната токсичност и биорасположливост. ААС е еден од широко применуваните методи за рутинска аналитичка контрола на квалитетот на виното препорачан и од Меѓународната организација за лозарство и винарството. Во трудот е даден преглед и дискусија за два главни пристапа при определувањето на елементите во траги во вино со ААС: прелиминарното разложување на примероците и директното определување. Дадени се и постапките за различни преттретмани на примеро-ците, за сепарирање на елементите во траги и за нивно претконцентрирање. Презентирани се и предностите на определувањето на хемиските форми на елементите во вино со примена на ААС. Клучни зборови: вино; елементи во траги; определување; специјација; ААС 18 T. Stafilov, I. Karadjova Maced

Ionic Liquid Modified Polymer Gel for Arsenic Speciation

A new ionic liquid modified polymer gel containing methylimidazolium groups (poly(MIA)) is proposed as a sorbent for the separation and enrichment of trace inorganic and organic arsenic species in surface waters. The poly(MIA) was synthesized by chemical modification of polymeric precursor using post-polymerization modification of poly(glycidyl methacrylate-co-trimethylolpropane trimethacrylate). The composition, structure, morphology, and surface properties of the prepared particles were characterized using elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption–desorption measurements. Optimization experiments showed that at pH 8, monomethylarsonic acid (MMAs), dimethylarsinic acid (DMAs), and As(V) were completely retained on the poly(MIA), while the sorption of As(III) was insignificant. The desorption experiments revealed that due to the weaker binding of organic arsenic species, selective elution with 1 mol/L acetic acid for MMAs + DMAs, followed by elution with 2 mol/L hydrochloric acid for As(V), ensured their quantitative separation. The adsorption kinetic and mechanism were defined. The analytical procedure for As(III), As(V), MMAs, and DMAs determination in surface waters was developed and validated through the analysis of certified reference material

Uranium Determination in Waters, Wine and Honey by Solid Phase Extraction with New Ion Imprinted Polymer

An analytical method for uranium determination in waters, wine and honey was developed based on solid phase extraction (SPE) with new ion imprinted polymer. The sorbent was synthesized using 4-(2-Pyridylazo)resorcinol (PAR) as a ligand via dispersion polymerization and characterized by SEM for morphology and shape of polymer particles and nitrogen adsorption–desorption studies for their surface area and total pore volume. The kinetic experiments performed showed that the rate limiting step is the complexation between U(VI) ions and chelating ligand PAR incorporated in the polymer matrix. Investigations by Freundlich and Langmuir adsorption isotherm models showed that sorption process occurs as a surface monolayer on homogeneous sites. The high extraction efficiency of synthesized sorbent toward U(VI) allows its application for SPE determination of U(VI) in wine and honey without preliminary sample digestion using ICP-OES as measurement method. The recoveries achieved varied: (i) between 88 to 95% for surface and ground waters, (ii) between 90–96% for 5% aqueous solution of honey, (iii) between 86–93% for different types of wine. The validity and versatility of proposed analytical methods were confirmed by parallel measurement of U in water samples using Alpha spectrometry and U analysis in wine and honey after sample digestion and ICP-MS measurement. The analytical procedure proposed for U determination in surface waters is characterized with low limits of detection/quantification and good reproducibility ensuring its application for routine control in national monitoring of surface waters. The application of proposed method for honey and wine samples analysis provides data for U content in traditional Bulgarian products

Raffinose Capped Silver Nanoparticles: A New Localized Surface Plasmon Resonance Based Sensor for Selective Quantification of Cr(VI) in Waste Waters

In this study, a new method for selective determination of Cr(VI) in water samples at pH 4 is presented using raffinose capped silver nanoparticles (Ag/Raff NPs) as an optical sensor. The method is based on the variation of LSPR absorption band intensity as a result of electrostatic interaction between the negatively charged Ag/Raff NPs and positive Cr(III) ions, in-situ produced by chemical reduction of Cr(VI) with ascorbic acid, combined with the fast kinetics of Cr(III) coordination to the –OH groups of the capping agent on the nanoparticle surface, further causing the nanoparticle aggregation. The calibration curve for Cr(VI) is linear in the range 2.5–7.5 μmol L−1, the limit of quantification achieved is 1.9 μmol L−1, and values of relative standard deviation vary from 3 to 5% for concentration level 1.9–7.5 μmol L−1. The interference studies performed in the presence of various metal ions show very good selectivity of Ag/Raff NPs toward Cr(VI) species. The added–found method is used to confirm the accuracy and precision of developed analytical approach

Application of Starch-Stabilized Silver Nanoparticles as a Colorimetric Sensor for Mercury(II) in 0.005 mol/L Nitric Acid

A sensitive and selective Hg2+ optical sensor has been developed based on the redox interaction of Hg2+ with starch-coated silver nanoparticles (AgNPs) in the presence of 0.005 mol L−1 HNO3. The relative intensity of the localized surface plasmon absorption band of AgNPs at 406 nm is linearly dependent on the concentration of Hg2+ with positive slope for the concentration range 0–12.5 μg L−1 and negative slope for the concentration range 25–500 μg L−1. Experiments performed demonstrated that metal ions (Na+, K+, Mg2+, Ca2+, Pb2+, Cu2+, Zn2+, Cd2+, Fe3+, Co2+, and Ni2+) do not interfere under the same conditions, due to the absence of oxidative activity of these ions, which guarantees the high selectivity of the proposed optical sensor towards Hg2+. The limits of detection and quantification were found to be 0.9 µg L−1 and 2.7 µg L−1, respectively, and relative standard deviations varied in the range 9–12% for Hg content from 0.9 to 12.5 μg L−1 and 5–9% for Hg levels from 25 to 500 μg L−1. The method was validated by analysis of CRM Estuarine Water BCR505. A possible mechanism of interaction between AgNPs and Hg2+ for both concentration ranges was proposed on the basis of UV-Vis, TEM, and SAED analyses