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World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Monday, 29 October 2012

Just Published:Analytica Chimica Acta


A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:
Selected papers from the latest issue:

Preparation and evaluation of mesoporous cellular foams coating of solid-phase microextraction fibers by determination of tetrabromobisphenol A, tetrabromobisphenol S and related compounds

29 October 2012, 11:01:51
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Xuemei Wang, Jiyan Liu, Aifeng Liu, Qian Liu, Xinzhen Du, Guibin Jiang
Two kinds of mesoporous cellular foams (MCFs), including mesoporous silica materials (MCF-1) and phenyl modified mesoporous materials (Ph-MCF-1), were synthesized and for the first time used as fiber-coating materials for solid-phase microextraction (SPME). By using stainless steel wire as the supporting core, four types of fibers were prepared by sol–gel method and immobilized by epoxy-resin method. To evaluate the performance of the home-made fibers for SPME, seven brominated flame retardants (BFRs), including tetrabromobisphenol A (TBBPA), tetrabromobisphenol S (TBBPS) and related compounds were selected as analytes. The main parameters that affect the extraction and desorption efficiencies, such as extraction temperature, extraction time, desorption time, stirring rate and ionic strength of samples were investigated and optimized. The optimized SPME coupled with high performance liquid chromatography (HPLC) was successfully applied to the determination of the seven BFRs in water samples. The linearity range was from 5.0 to 1000μgL−1 for each compound except TBBPS (from 1.0 to 1000μgL−1), with the correlation coefficients (r 2) ranging from 0.9993 to 0.9999. The limits of detection of the method were 0.4–0.9μgL−1. The relative standard deviations varied from 1.2 to 5.1% (n =5). The repeatability of fiber-to-fiber and batch-to-batch was 2.5–6.5% and 3.2–6.7%. The recoveries of the BFRs from aqueous samples were in the range between 86.5 and 103.6%. Compared with three commercial fibers (100μm PDMS, 85μm PA and 65μm PDMS/DVB), the MCFs-coated fiber showed about 3.5-fold higher extraction efficiency.

Graphical abstract

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Graphical abstract Highlights

► Two novel mesoporous cellular foams were synthesized and used as SPME coating. ► Four SPME fibers were prepared by sol–gel technology and immobilized resin method. ► New coating had excellent extraction ability to seven brominated flame retardants.

Review on recent advances in the analysis of isolated organelles

29 October 2012, 11:01:51
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Chad P. Satori, Vratislav Kostal, Edgar A. Arriaga
The analysis of isolated organelles is one of the pillars of modern bioanalytical chemistry. This review describes recent developments on the isolation and characterization of isolated organelles both from living organisms and cell cultures. Salient reports on methods to release organelles focused on reproducibility and yield, membrane isolation, and integrated devices for organelle release. New developments on organelle fractionation after their isolation were on the topics of centrifugation, immunocapture, free flow electrophoresis, flow field-flow fractionation, fluorescence activated organelle sorting, laser capture microdissection, and dielectrophoresis. New concepts on characterization of isolated organelles included atomic force microscopy, optical tweezers combined with Raman spectroscopy, organelle sensors, flow cytometry, capillary electrophoresis, and microfluidic devices.

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Graphical abstract Highlights

► Advancements in organelle release. ► New approaches to fractionate organelles. ► Updates on new techniques to characterize isolated organelles.

Discriminant analysis in the presence of interferences: Combined application of target factor analysis and a Bayesian soft-classifier

29 October 2012, 11:01:51
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Caitlin N. Rinke, Mary R. Williams, Christopher Brown, Matthieu Baudelet, Martin Richardson, Michael E. Sigman
A method is described for performing discriminant analysis in the presence of interfering background signal. The method is based on performing target factor analysis on a data set comprised of contributions from analyte(s) and interfering components. A library of data from representative analyte classes is tested for possible contributing factors by performing oblique rotations of the principal factors to obtain the best match, in a least-squares sense, between test and predicted vectors. The degree of match between the test and predicted vectors is measured by the Pearson correlation coefficient, r, and the distribution of r for each class is determined. A Bayesian soft classifier is used to calculate the posterior probability based on the distributions of r for each class, which assist the analyst in assessing the presence of one or more analytes. The method is demonstrated by analyses performed on spectra obtained by laser induced breakdown spectroscopy (LIBS). Single and multiple bullet jacketing transfers to steel and porcelain substrates were analyzed to identify the jacketing materials. Additionally, the metal surrounding bullet holes was analyzed to identify the class of bullet jacketing that passed through a stainless steel plate. Of 36 single sample transfers, the copper jacketed (CJ) and non-jacketed (NJ) class on porcelain had an average posterior probability of the metal deposited on the substrate of 1.0. Metal jacketed (MJ) bullet transfers to steel and porcelain were not detected as successfully. Multiple transfers of CJ/NJ and CJ/MJ on the two substrates resulted in posterior probabilities that reflected the presence of both jacketing materials. The MJ/NJ transfers gave posterior probabilities that reflected the presence of the NJ material, but the MJ component was mistaken for CJ on steel, while non-zero probabilities were obtained for both CJ and MJ on porcelain. Jacketing transfer from a bullet to steel as the projectile passed through the steel also proved difficult to analyze. Over 50% of the samples left insufficient transfer to be identified. Transfer from NJ and CJ jacketing was successfully identified by posterior probabilities greater than 0.8.

Graphical abstract

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Graphical abstract Highlights

► A novel background-independent soft classification method is described. ► Target factor analysis is combined with Bayesian decision theory. ► Target factors are taken from a library of target analytes. ► Trace metal transfers to complex backgrounds are analyzed by LIBS. ► The method is shown to be both conservative and accurate.

Ultrasensitive one-step rapid detection of ochratoxin A by the folding-based electrochemical aptasensor

29 October 2012, 11:01:51
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Jingjing Wu, Huaqin Chu, Zhanlong Mei, Yi Deng, Feng Xue, Lei Zheng, Wei Chen
A one-step electrochemical aptasensor using the thiol- and methylene blue- (MB-) dual-labeled aptamer modified gold electrode for determination of ochratoxin A (OTA) was presented in this research. The aptamer against OTA was covalently immobilized on the surface of the electrode by the self-assembly effect and used as recognition probes for OTA detection by the binding induced folding of the aptamer. Under the optimal conditions, the developed electrochemical aptasensor demonstrated a wide linear range from 0.1pgmL−1 to 1000pgmL−1 with the limit of detection (LOD) of 0.095pgmL−1, which was an extraordinary sensitivity compared with other common methods for OTA detection. Moreover, as a practical application, this proposed electrochemical aptasensor was used to monitor the OTA level in red wine samples without any special pretreatment and with satisfactory results obtained. Study results showed that this electrochemical aptasensor could be a potential useful platform for on-site OTA measurement in real complex samples.

Graphical abstract

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Graphical abstract Highlights

► One-step electrochemical aptasensor for OTA detection. ► Rapid and ultrasensitive OTA detection with LOD of 0.095pgmL−1 in less than 15min. ► Successful application of the electrochemical aptasensor in OTA spiked samples. ► Providing a potential tool for on-site quality control of OTA related pollutions.

Layer by layer assembly of catalase and amine-terminated ionic liquid onto titanium nitride nanoparticles modified glassy carbon electrode: Study of direct voltammetry and bioelectrocatalytic activity

29 October 2012, 11:01:51
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Shagayegh Saadati, Abdollah Salimi, Rahman Hallaj, Amin Rostami
A novel, simple and facile layer by layer (LBL) approach is used for modification of glassy carbon (GC) electrode with multilayer of catalase and nanocomposite containing 1-(3-Aminopropyl)-3-methylimidazolium bromide (amine terminated ionic liquid (NH2-IL)) and titanium nitride nanoparticles (TiNnp). First a thin layer of NH2-IL is covalently attached to GC/TiNnp electrode using electro-oxidation method. Then, with alternative self assemble positively charged NH2-IL and negatively charged catalase a sensitive H2O2 biosensor is constructed, whose response is directly correlated to the number of bilayers. The surface coverage of active catalase per bilayer, heterogeneous electron transfer rate constant (k s) and Michaelis–Menten constant (K M) of immobilized catalase were 3.32×10−12 molcm−2, 5.28s−1 and 1.1mM, respectively. The biosensor shows good stability, high reproducibility, long life-time, and fast amperometric response with the high sensitivity of 380μAmM−1 cm−2 and low detection limit of 100nM at concentration range up to 2.1mM.

Graphical abstract

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Graphical abstract Highlights

► Catalase and amine-terminated ionic liquid were immobilized to GC/TiNnp with LBL assembly method. ► First a thin layer of NH2-IL is covalently attached to GC/TiNnp electrode using electro-oxidation. ► With alternative assemble of IL and catalase with positive and negative charged, multilayer was formed. ► Immobilized catalase shows excellent electrocatalytic activity toward H2O2 reduction. ► Biosensor response is directly correlated to the number of bilayers.

Sulfide determination in hydrothermal seawater samples using a vibrating gold micro-wire electrode in conjunction with stripping chronopotentiometry

29 October 2012, 11:01:51
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Virginie Aumond, Matthieu Waeles, Pascal Salaün, Kristoff Gibbon-Walsh, Constant M.G. van den Berg, Pierre-Marie Sarradin, Ricardo D. Riso
A rapid electrochemical stripping chronopotentiometric procedure to determined sulfide in unaltered hydrothermal seawater samples is presented. Sulfide is deposited at −0.25V (vs Ag/AgCl, KCl 3M) at a vibrating gold microwire and then stripped through the application of a reductive constant current (typically −2μA). The hydrodynamic conditions are modulated by vibration allowing a short deposition step, which is shown here to be necessary to minimize H2S volatilization. The limit of detection (LOD) is 30nM after a deposition step of 7s. This LOD is in the same range as the most sensitive cathodic voltammetric technique using a mercury drop electrode and is well below those reported previously for other electrodes capable of being implemented in situ.

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Halogen bonding: A new retention mechanism for the solid phase extraction of perfluorinated iodoalkanes

29 October 2012, 11:01:51
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Xiao Qing Yan, Qian Jin Shen, Xiao Ran Zhao, Hai Yue Gao, Xue Pang, Wei Jun Jin
For the first time, halogen-bonding interaction is utilised in the solid phase extraction of perfluorinated iodoalkane (PFI). Nine PFIs, as model analytes, were tested, and analyses by UV, 19F NMR and Raman spectroscopies demonstrate that the PFIs are extracted by a strong anion exchange (SAX) sorbent from n-hexane due to the CI⋯Cl halogen-bonding interactions. The results also show that the adsorptivities of SAX for the diiodoperfluoro-alkanes (diiodo-PFIs) were much stronger than those for the perfluoroalkyl iodides (monoiodo-PFIs). Specifically, the recoveries for 1,6-diiodoperfluorohexane and 1,8-diiodoperfluorooctane were higher than 80% when 100mL of sample spiked with a 5ngmL−1 analyte mixture was extracted. Interestingly, SAX had no adsorption for hexafluorobenzene at all, which is known to be unable to form a halogen bond with Cl. The analytical performance of the halogen bond-based SPE-GC–MS method for the diiodo-PFIs was also examined in soil samples. The sorbent SAX enabled the selective extraction of four diiodo-PFIs successfully from soil samples. The recoveries of the diiodo-PFIs extracted from 5g soil sample at the 100ngg−1 spike level were in the range of 73.2–93.8% except 26.8% for 1,2-diiodoperfluoroethane. The limit of detection varied from 0.02 to 0.04ngg−1 in soil samples. Overall, this work reveals the great application potential of halogen bonding in the field of solid phase extraction to selectively extract compounds with strong halogen-bonding abilities.

Graphical abstract

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Graphical abstract Highlights

► Halogen bonding (XB) is firstly utilised in solid phase extraction. ► The perfluorinated iodine alkanes can be extracted by CI⋯Cl halogen bonding. ► The CI⋯Cl halogen bond is well characterised by spectroscopy methods. ► The analytes with strong halogen-bonding abilities can be selectively extracted.

Determination of hydroxylated metabolites of polycyclic aromatic hydrocarbons in sediment samples by combining subcritical water extraction and dispersive liquid–liquid microextraction with derivatization

29 October 2012, 11:01:51
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Xiaowei Wang, Li Lin, Tiangang Luan, Lihua Yang, Nora F.Y. Tam
A sample preparation method for the determination of hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in sediment samples was developed using gas chromatography–mass spectrometry (GC–MS). Dispersive liquid–liquid microextraction (DLLME) with derivatization was performed following the subcritical water extraction (SWE) that provided which was provided by accelerated solvent extraction (ASE). Several important parameters that affected both SWE extraction and DLLME, such as the selection of organic modifier, its volume, extraction temperature, extraction pressure and extraction time were also investigated. High sensitivity of the hydroxylated PAHs derivatives by N-(tert-butyldimethylsilyl)-N-methyl-trifluoroacetamide (MTBSTFA) could be achieved with the limits of detection (LODs) ranging from 0.0139 (2-OH-nap) to 0.2334μgkg−1 (3-OH-fluo) and the relative standard deviations (RSDs) between 2.81% (2-OH-phe) and 11.07% (1-OH-pyr). Moreover, the proposed method was compared with SWE coupled with solid phase extraction (SPE), and the results showed that ASE–DLLME was more promising with recoveries ranging from 57.63% to 91.07%. The proposed method was then applied to determine the hydroxylated metabolites of phenanthrene in contaminated sediments produced during the degradation by two PAH-degraders isolated from mangrove sediments.

Graphical abstract

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Graphical abstract Highlights

► We combine subcritical water extraction (SWE) with dispersive liquid–liquid microextraction (DLLME). ► Subcritical water is used as the extraction solvent for SWE and the sample solution for the following DLLME. ► Acetonitrile is used as the organic modifier for SWE and disperser solvent for DLLME in succession. ► We examine changes of OH-PAHs during the degradation by microorganism.

Highly specific revelation of rat serum glycopeptidome by boronic acid-functionalized mesoporous silica

29 October 2012, 11:01:51
Publication year: 2012
Source:Analytica Chimica Acta, Volume 753
Liting Liu, Ying Zhang, Lei Zhang, Guoquan Yan, Jun Yao, Pengyuan Yang, Haojie Lu
Although the specific profiling of endogenous glycopeptides in serum is highly inclined towards the discovery of disease biomarkers, studies on the endogenous glycopeptides (glycopeptidome) have never been conducted because of several factors. These factors include the high dynamic range of serum proteins, the inadequacy of traditional sample preparation techniques in proteomics for low-molecular-weight (LMW) proteins, and the relatively low abundances of glycopeptides. Boronic acid-functionalized mesoporous silica was synthesized in this study to overcome the limitations of the state-of-the-art methods for glycopeptidome research. The boronic acid-functionalized mesoporous silica exhibited excellent selectivity by analyzing glycopeptides in the mixture of glycopeptides/non-glycopeptides at molar ratio of 1:100, extreme sensitivity (the limit of detection was at the fmol level), good binding capacity (40mgg−1), as well as the high post-enrichment recovery of glycopeptides (up to 88.10%). The as-prepared material possessing both glycopeptide-suitable pore size and glycopeptide-specific selectivity has shown special capability for enriching the endogenous glycopeptides. Fifteen unique glycosylation sites mapped to 15 different endogenous glycopeptides were identified in rat serum. The established protocol revealed for the first time the rat serum glycopeptidome.

Graphical abstract

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Graphical abstract Highlights

A highly ordered boronic acid-functionalized mesoporous silica was synthesized and applied for the revelation of rat serum glycopeptidome for the first time.
► A highly ordered boronic acid-functionalized mesoporous silica was synthesized. ► The as-prepared material possessed both glycopeptide-suitable pore size and glycopeptide-specific selectivity. ► The as-prepared material showed highly efficient ability for enrichment of endogenous glycopeptides from serum. ► Rat serum glycopeptidome was reveled for the first time.

SHEL LAB Announces New Humidified Large Capacity CO2 Incubator


Sheldon Manufacturing, Inc. introduces the SHEL LAB Model 2428H, the newest addition to its large capacity CO2 incubator line. (http://www.shellab.com/store/categories/large-co2-incubator/) This 27 cubic foot incubator features active humidity control up to 95%.
“The three most critical incubator components that ensure high yields in cell culture are humidity, CO2 and temperature uniformity” states Dan Sheldon, President of Sheldon Manufacturing, Inc. “Not only does this unit have exceptional CO2 and temperature uniformity, it also includes a user controllable humidity system that is more accurate and responsive to door openings than a traditional water pan humidity system."

Compared to water pan humidity generation, the 2428H humidity system provides less evaporation of culture media and eliminates a potential source for contamination.
The 2428H also has a heated glass door that minimizes condensation, another potential source for contamination. This triple-paned glass door allows easy viewing of samples without having to open the incubator door, so samples can thrive in the stable environment within the chamber. The 2428H SHEL LAB Humidified CO2 Incubator (http://www.shellab.com/store/lab-products/2428H) also features an antimicrobial copper drain.
The 2428H carbon dioxide incubator uses a gentle horizontal air flow heating system to obtain superior temperature uniformity and quick temperature recovery after door openings. This airflow system minimizes drying and disturbing sample conditions. The CO2 is accurately controlled with an IR sensor, providing overall CO2 stability and recovery after door openings.
The 2428H is available through SHEL LAB distribution partners and at www.shellab.com

Thursday, 25 October 2012

Reactors with Ultimate Mixing Performance Offer Simpler Scale-Up


Asynt Ltd. in conjunction with Innovative Physical Organic Solutions (IPOS), a research group based within the University of Huddersfield, UK, have cooperated over the last 2 years to develop a new generation of chemical reactor.

By better understanding and improving the flow and thermal dynamics of the Asynt ReactoMate system the co-operation is able to now produce reactors that offer ultimate mixing performance.  The benefits of this development for chemists will be simpler process development and scale-up, faster reactions, better reproducibility and improved selectivity.

Martyn Fordham, Managing Director of Asynt Ltd. commented "We were pleased to cooperate with IPOS on this development because of their considerable expertise in chemical engineering and experience in advising chemists on scaling reactions that were often rate limited by poor mixing". He added "At the start of our cooperation -  Asynt ReactoMate reaction systems as with all of our competitors did not offer optimised mixing.  Today however, we can offer customers the option to use ReactoMate to scale chemistries with well designed mixing by IPOS.  This consideration has proven especially important when reaction chemistries are exothermic for example".

Dr Nicholas Powles, a Senior Research Fellow at IPOS commented "The complexities associated with optimising and scaling-up laboratory reactions are of critical importance in industrial process development.  Our co-operation with Asynt will help commercialise the essential tools and 'know-how' for efficient process understanding and optimisation".

Asynt is a leading supplier of affordable products, consumables and services for chemists in industry and academia.  With staff of trained chemists - Asynt is able to draw upon this in-depth applications knowledge to provide a high level of customer support for its DrySyn Heating Blocks, Controlled Lab Reactors, Synthesis Tools, Evaporators, Circulators, Temperature Control Systems, Vacuum Pumps and Laboratory Safety Equipment.

IPOS is a research group based within the Department of Chemical and Biological Sciences at the University of Huddersfield (UK). The primary focus of IPOS is delivery of external customer contracts. The group consists of a team of highly skilled, industrially experienced chemists specialising in the application of physical organic chemistry towards efficient optimisation of chemical processes. It is the aim of IPOS to provide these services on a contract basis to the chemical industry as a cost-effective means of process development.

For further information about ReactoMate Reactors with optimised mixing performance please contact Asynt on +44-1638-781709 or sales@asynt.com. For further information about IPOS please visit http://www-old.hud.ac.uk/ipos/  

Wednesday, 24 October 2012

Flow Reactors Improve Process Reproducibility, Scalability & Yields

The FlowSyn™ range of integrated, flow reactor systems from Uniqsis Ltd. has been designed to handle everything from homogeneous single reactions to complex, multi-reagent reactions. A range of optional gas addition, microwave, low temperature and binary pump (4-channel) modules further enhance the operational versatility of the FlowSyn system.

Flow chemistry in micro-reactors has many advantages over batch processing notably better reproducibility and scalability, improved yields and fewer problems with unstable intermediates or exothermic reactions.

Developed by chemists for chemists, the Uniqsis FlowSyn system is available with the widest range of reactors (2 - 60ml) in a choice of inert materials including stainless steel, Hastelloy®, PFA, PTFE or even Copper.  As a consequence the FlowSyn System is able to perform an unmatched range of chemistries. Reactions requiring the use of strong acids such as nitric acid (nitrations) and powerful organometallic bases such as butyl lithium (metallations) are now routinely possible. A unique 2- or 3-channel borosilicate glass mixer chip reactor enables the FlowSyn system to undertake high throughput applications, fast mixing dependent reactions and even highly exothermic reactions requiring temperature control.

Within the FlowSyn system, two high pressure pumps operating at up to 100 bar (1400 psi) deliver reagents, via a mixer, into electrically heated flow reactors. Back pressure regulators pressurise the system, allowing solvents to be superheated to a maximum of 260°C*.

Reaction outputs from the FlowSyn system can be fractionated or optimised at steady state, after which the system automatically flushes itself ready for the next experiment. The whole process, from start to finish, is controlled using the highly intuitive integrated FlowSyn control interface.

To find out more about how FlowSyn Continuous Flow Chemistry Systems can enhance your chemical syntheses please visit www.uniqsis.com/paFlowSystem.aspx  or contact Uniqsis now on +44-845-864-7747 / info@uniqsis.com.

Tuesday, 23 October 2012

Just Published: Microchemical Journal


A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:
Selected papers from the latest issue:

Use of ground crawfish shells for the removal of chromium in solution

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Anita Morris, Srujana Beeram, Carey J. Hardaway, Joel C. Richert, Joseph Sneddon
Crawfish shells are an abundant waste product that has the potential to remediate contaminated bodies of water. This study demonstrates that ground crawfish shell could be used as an effective biosorbent material for the treatment of chromium in contaminated aqueous solutions. Phase I experiments determined that the adsorption was completed within 2h. For the time periods examined it could be concluded that the maximum chromium adsorption occurs within the first 2h. Phase II experiments demonstrated that chromium adsorption increased with sample volume and concentration, however the efficiency decreased with increasing sample volume for the relative high concentrations of chromium. Phase III experiments showed that chitin is a major constituent for biosorption of chromium and likely other metals in crustacean species including crawfish. Salinity experiments showed that salt (sodium chloride) at the 30ppt (parts per thousand) concentrations does not affect the crawfish shell ability to adsorb chromium. The pH was the most important factor for chromium adsorption by the crawfish powder. Chromium adsorption increased with increasing pH. The presence of lead ions did not significantly interfere with the adsorption of chromium ions onto the crawfish shell powder for the relatively high concentrations examined. However, for relatively low concentrations the chromium adsorption was somewhat suppressed by the lead ions.

Highlights

► Use of crawfish shells for biosorption ► Uptake of chromium in solution in less than 2h ► pH affected uptake. ► Salt at ppt and lead ions had no effect on uptake.

Method development for the determination of alkali metals in samples from pyrochemical reprocessing using ICP-OES and comparison with sector field ICP-MS

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Michael Krachler, Stefaan Van Winckel, Mariangela Cardinale, Brian Lynch, Tsuyoshi Murakami
An analytical procedure for the reliable determination of the alkaline elements Na, K, and Li in radioactive samples was developed and validated. To this end, a high efficiency, desolvating nebulizer (Apex E) was coupled to a commercial high resolution ICP-OES instrument operated at 1000W. Because of their radioactive nature, all investigated samples were handled in appropriate glove boxes operated in under-pressure, following strict safety and security procedures. After optimization of the ICP-OES operational parameters, detection limits (LODs) of 0.15μg/L, 0.8μg/L, and 1.3μg/L were obtained for Li (λ=670.784nm), Na (λ=589.592nm), and K (λ=766.490nm). Compared to conventional sample uptake rates of 1–2mL/min, the 350μL/min used in this study helped to lower the radiation dose to the ICP-OES operator and produced much less radioactive waste while at the same time improving LODs. Calibration curves were linear up to 4mg/L with a correlation coefficient of better than 0.999. Because of its robust and reproducible performance, no internal standard was required to correct for potential drifts in sensitivity of the ICP-OES. Three certified water reference materials (BCR®-617, LGC6177, SRM® 1643a) were employed to assess the accuracy of the developed ICP-OES procedure, the results of which underpin its reliability. In addition, Na and K concentrations calculated from emission intensities measured at two wavelengths confirmed that each dataset is consistent in itself. A comparison of sector field ICP-MS results of 23 samples originating from pyrochemical reprocessing with the data obtained applying the newly developed ICP-OES procedure revealed that the latter provides a reliable, straightforward and more robust analytical approach to determine Na, K, and Li in radioactive specimens.

Overview of hyphenated techniques using an ICP-MS detector with an emphasis on extraction techniques for measurement of metalloids by HPLC–ICPMS

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
William Maher, Frank Krikowa, Michael Ellwood, Simon Foster, Rajani Jagtap, George Raber
In this review we present an overview of hyphenated techniques using an ICPMS detector with an emphasis on extraction techniques for the measurement of metalloids by high pressure liquid chromatography–inductively plasma mass spectrometry (HPLC–ICPMS). Five modes of using hyphenated ICPMS systems; HPLC–ICPMS, HPLC–hydride generation-ICPMS, Cryogenic trapping ICPMS, in-situ Cryogenic trapping ICPMS and Gas Chromatography–ICPMS are described together with their application for the measurement of arsenic, selenium, mercury and antimony species. Two classes of metalloid species are described; “Easy to extract species,” stable species existing as discrete molecules or relatively weakly bound to cellular constituents, and Hard to extract species,” unstable species that dissociate on extraction and species incorporated within cellular constituents such as proteins. Measurements described include, arsenic species: arsenobetaine, arsenoribosides, arsenic bound to lipids and phytochelatins and other minor arsenic species including thioarsenic species. Selenium species: selenocysteine and selenomethionine, Se-methyl selenomethionine, Se-methyl selenocysteine, y-glutamyl-Se-methylselenocysteine, dimethylselenide and dimethyldiselenide. Mercury species: inorganic Hg and methyl Hg. Antimony species: antimonite and antimonate. Germanium species: inorganic. Extraction methods are discussed in terms of their extraction efficiencies, stability of species and artifact formation.

Highlights

► Five modes of using hyphenated ICPMS systems are described. ► Extraction of species is reviewed in terms of their extraction efficiencies, stability of species and artifact formation. ► Easy to extract species are identified as species existing as discrete molecules or weakly bound to cellular constituents. ► Hard to extract species are identified as species that dissociate or incorporated within cellular constituents e.g. proteins.

Mass spectrometry-based multiplexing for the analysis of biomarkers in drug development and clinical diagnostics — How much is too much?

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Uwe Christians, Jacek Klepacki, Touraj Shokati, Jost Klawitter, Jelena Klawitter
Biomarkers, or more specifically molecular markers, can detect biochemical changes associated with disease processes and drug effects before histopathological and pathophysiological changes occur. Multiplexing technologies such as high-performance liquid chromatography/ mass spectrometry (LC-MS) allow for the measurement of molecular marker patterns that confer significantly more information than the measurement of a single parameter alone. The use of multiplexing assays for drug development, and as diagnostic tools, is attractive but will require regulatory review and approval and thus requires validation following regulatory guidance. Multiplexing assays always constitute a compromise. The number of analytes that can reasonably be included in a mass spectrometry-based multiplexing assay depend on the physico-chemical properties of the analytes and their integration into a single assay in terms of extraction, HPLC separation, ionization conditions and mass spectrometry detection. Another aspect includes biomedical considerations such as the differences in physiological concentrations of analytes, the required concentration range, and how much variability is acceptable before the clinical utility of a marker is negatively affected. Regulatory considerations include validation and quality control during sample analysis. Current bioanalytical regulatory guidelines have mostly been developed for single drug compounds and are not always adequate for multiplexing molecular marker assays that often quantify endogenous compounds. Specific guidances for multiplexing assays should be developed. Even if it is possible to integrate a wide variety and large number of analytes into a multiplexing assay, it should always be taken into consideration that a set of shorter, more specialized assays, may offer a more manageable and efficient alternative.

A review on approaches to bio distribution studies about gold and silver engineered nanoparticles by inductively coupled plasma mass spectrometry

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Petra Krystek
This paper gives a general overview about bio distribution studies which are especially related to engineered nanoparticles (NPs) made of gold and silver. The analysis of biological materials from bio distribution studies plays a significant role in the application of atomic spectrometry to study NPs. Therefore, special focus is given to the generally applied strategy as well as the use of the inductively coupled plasma mass spectrometry (ICP-MS) technique for the determination of the NPs containing metals. An overview of the recent research applications on gold and silver NPs is also presented. While for gold NPs a large variety of very different sizes, shape and coating are known, they also provide many opportunities in imaging, diagnostics, and therapies of nanomedicine. Hence, their bio kinetics in the body are prerequisites for specific tailoring of nanomedicinal applications and for a comprehensive risk assessment. Silver NPs are applied in a lot of consumer products; therefore it is useful to get a better understanding of their in vivo distribution.

Identification of volatile iron species generated by UV photolysis

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Patricia Grinberg, Ralph E. Sturgeon, Graeme Gardner
The volatile products of photochemical generation (PVG) of iron from solutions of formic and acetic acids were examined by GC-MS. Iron pentacarbonyl was the sole analytical species detected in both cases, as confirmed by comparison of the results with a NIST reference spectrum. Silylation of the interior surfaces of the quartz tubing comprising the photochemical reactor essentially eliminated memory effects such that signal duration was determined simply by the residence time of the sample solution.

Highlights

► The volatile products of PVG of Fe were examined by GC-MS. ► Iron pentacarbonyl was the specie detected in the presence of formic and acetic acid. ► Comparison of the results with a NIST reference spectrum. ► Silylation of the interior surfaces of the quartz tubing eliminated memory effects.

Roles of electrode material and geometry in liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma emission spectroscopy

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
C. Derrick Quarles, Benjamin T. Manard, Carolyn Q. Burdette, R. Kenneth Marcus
The roles of the electrode material and geometry on the performance of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) optical emission spectroscopy source are described. The LS-APGD source has been interfaced to a high resolution JY RF-5000 polychromator allowing for simultaneous multiple element detection. This LS-APGD source operates at currents of 20–60mA and solution flow rates of 0.1–0.4mLmin−1. A glow discharge is generated between the surface of the electrolyte test solution exiting a glass capillary and the end of a metallic counterelectrode. Described here is an evaluation of how the counterelectrode material identity (copper, nickel, and stainless steel) and the electrode configuration (geometry) influence the analyte emission responses for a test solution containing Ag, Cr, Cu, Mg, Ni, and Zn in 1M HNO3. Studies of the effect of liquid flow rates reveal that 0.3mLmin−1 provides optimal analyte emission responses as it relates to peak intensity, peak area, and peak widths. Use of nickel as the counterelectrode material provided the best reproducibility for analyte emission responses with 8.9–13.0%RSDs for 50μL injections of 100μgmL−1 test solutions, while copper and stainless steel electrodes had %RSDs of 3–5 times higher than the nickel electrode. The role of the electrode geometries were evaluated previously-used 180° (co-linear) arrangement as well as for different configurations with the electrodes mounted at 90° with respect to each other, with the most intense optical emission responses found for the 180° geometry. Solution-based limits of detection (LOD) were found to be in the range of 0.44–0.93μgmL−1 for Ag, Cu, Mg, Ni, and Zn using the nickel electrode at the 180° geometry. Based on the use of 50μL injections, this represents absolute detection limits of 22–46ng. LODs were approximately an order of magnitude higher for the copper and stainless steel electrodes.

Highlights

► Key operation parameters of the LS-APGD-OES microplasma source are studied. ► Electrode powering schemes effect emission and temporal responses of analytes. ► Ni counterelectrodes produce superior performance in all aspects of OES analysis. ► Collinear electrodes show better analytical performance than a 90° arrangement.

Stability of arsenic speciation in fish muscle samples, under different storage and sample preparation conditions

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
John Lewis, Penny Stokes, Nicola Brereton, Malcolm Baxter, Roy Macarthur
As part of a major survey investigating the levels of total and inorganic arsenic in a range of fish, shellfish and seaweed, a stability study was undertaken so as to ensure that the arsenic speciation profile in samples which had been stored for a number of months was likely to have remained unchanged. The potential for different sample preparation regimes to impact on arsenic speciation profiles was also assessed. The data from an initial time-based investigation suggested that the relative levels of inorganic arsenic did not vary over the 9month period of the study. However, as it had taken 10days to land, transport and process the fish material, prior to starting the stability study, a second study was undertaken, where the death-to-testing time was reduced to 3days. The data from this second study confirmed that from the first, showing that the speciation profile did not change, even during the early stages, when poorly controlled sample handling was potentially at its maximum. Data from the sample preparation experiment indicated that the preparation format, i.e., “wet” vs. “freeze-dried,” could influence the relative levels of inorganic arsenic, with less being measured in the latter format (0.14%±0.08%). Possible explanations were given, including microbiological activity within the “wet” samples. However, it was thought most likely to be due to analytical variation encountered when working at, or below, the methodological LOQ. It is hoped that this information will assist others regarding issues to be considered when performing similar studies.

Highlights

► Chemical speciation often dictates the toxicity of an element. ► Sample storage conditions can affect metal speciation stability. ► Arsenic species are stable in fish flesh, under different sample preparation formats. ► Arsenic species are stable in fish flesh, under different sample storage conditions. ► Results prove data accuracy, obtained from long-term stored samples, in FSA survey.

Levels of mercury and polychlorobiphenyls in commercial food in Siena Province (Tuscany, Italy) in the period 2001–2010

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Silvano Focardi
In this paper, the presence and amount of mercury and polychlorobiphenyls (PCBs) were determined in more than 1000 food items collected monthly in the period 2001–2010 in commercial food shops in Siena (Tuscany, Italy), in order to assess risk to humans due to food consumption. The overall results clearly show a strong difference in concentration of the two contaminants between foods from the terrestrial trophic web and those from the marine trophic web. Particular attention was paid to study the Mediterranean swordfish (Xiphias gladius) and bluefin tuna (Thunnus thynnus) because anthropic impact on these species is great due to their topmost position in trophic webs; thus it is very important to know their health status and evaluate their toxicity for humans. Many samples of bluefin tuna and swordfish show mercury levels higher than 0.5mg/kg f.w., which is the maximum level set by the European Commission (EC, Regulation n. 1881/2006) for most fish species. Taking into account the important nutritional contribution that fish makes to the diet, it is advisable that women of childbearing age, pregnant and breastfeeding women as well as young children select fish from a wide range of species, without giving undue preference to large predatory fish such as swordfish and tuna. In any case, it is interesting to note a significant decrease in levels of both mercury and PCBs in bluefin tuna and swordfish found in the Sienese market over the course of the past ten years.

Highlights

► The study was carried out on samples of several food items collected in Siena (Tuscany, Italy). ► We have analyzed mercury and polychlorobiphenyls (PCBs). ► The results show high levels of these two contaminants in food from marine origin. ► The results show a decrease in these two contaminants in food in last ten years. ► Pregnant and breastfeeding women must select fish from a wide range of species.

Effect of the cooking procedure on the arsenic speciation in the bioavailable (dialyzable) fraction from seaweed

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Cristina García Sartal, María del Carmen Barciela-Alonso, Pilar Bermejo-Barrera
Seafood, including edible seaweed, contains high levels of arsenic. The intake of seaweed is a route to arsenic exposure. Due to the different toxic behaviors among arsenic species, speciation studies are a matter of vital importance to evaluate possible health risks for consumers. Most seaweeds are ingested after a heat treatment and these thermal procedures could lead to a change in arsenic speciation. In this work an arsenic speciation study of four edible seaweeds (Kombu, Wakame, Nori and Sea Lettuce) after cooking has been performed by anion-exchange HPLC connected to an ICP-MS for arsenical detection. Speciation studies were also carried out in the cooking waters of those samples. Powdered cooked seaweed was subjected to an in-vitro digestion procedure by using Piperazine-NN-bis (2-ethane-sulfonic acid) disodium (PIPES), as a buffer solution at a pH of 7.0 and dialysis membranes of 10kDa molecular weight cut off (MWCO). Dialyzable fractions were analyzed to identify the arsenic species that become bioavailable for human body functions. Total arsenic concentrations were found between 5.3 and 79.1μgg−1, 3.6–36.7μgg−1 and 1.8–54.3μgg−1 for raw and cooked seaweed, and cooking water, respectively. Total arsenic bioavailability percentages were 20%, 29%, 18% and 11% for cooked Kombu, Nori, Wakame and Sea lettuce, respectively. Results suggest that the heat treatment and the acidic environment and enzymes used in the in-vitro gastrointestinal digestion are not sufficient to produce a change in the arsenic species of the four seaweeds studied. Arsenic species are comparable in each seaweed before and after being cooked, their cooking water and dialysate. Arsenosugars were the main arsenic species found. As(III) species and arsenobetaine (AB) were only found in the Sea Lettuce sample. Glycerol sugar and sulfonate sugar were the most bioavailable species for cooked Kombu and Wakame. Phosphate sugar showed to be in highest proportion in the dialyzable fraction of Nori. AB and glycerol sugar became more bioavailable in the Sea Lettuce sample.

Highlights

► Qualitative arsenic speciation study in seaweeds ► Characterization of arsenic species in edible seaweeds after cooking ► Arsenic speciation study in dialysates of cooked seaweeds

ICP-AES determination of minor and major elements in Cornelian cherry (Cornus mas L.) after microwave assisted digestion

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Iva Juranović Cindrić, Michaela Zeiner, Martina Krpetić, Gerhard Stingeder
Inductively coupled plasma atomic emission spectrometry (ICP-AES) was used for the determination of minor and major elements present in Cornelian cherry (Cornus mas L.), as this fruit and its preservatives may be considered as important nutritional supplements. Prior to ICP-AES measurement, the samples were digested in a microwave assisted digestion system. The ICP-AES method was validated and optimized for the determination of selected elements in Cornelian cherry. The accuracy of the method as estimated through by spiking experiments was satisfactory, the recoveries obtained after microwave digestions in whole fruit (A), mesocarp (B) seed (C), and juice ranged from 84–123%, 74–115% 82–124%, and from 83–116% respectively. For microwave assisted digested Cornelian cherry samples of whole fruit (A), mesocarp (B) and seeds (C) the following limits of detection were obtained <2ng/g for Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Zn, Mg, and K, moderate 2–10ng/g for B, and Ca. The highest LODs were obtained only for Al in mesocarp (B) and seeds (C) compared with whole fruit (A). For microwave assisted digested Cornelian cherry juice the limits of detection were in the range 0.04–0.108μg/L. The precision of the method was evaluated using the standard deviation, RSD, of repeated determinations of the analytes and for all elements RSD ranged from 0.5 to 7% except for Na 12%. The intermediate precision (< 4.8%), the day-to-day reproducibility (< 6.8%), and the overall uncertainty of measurement (approx. 4–10%) for all elements analyzed demonstrated the good applicability of the chosen microwave assisted digestion procedure. Regarding potentially toxic elements, Cu and Pb are below 4μg/g in the whole berry, Cr and Cd were not even detected.The order of magnitude of the concentrations for the elements found in whole fruit (whole fruit, A) and seed (C) is found to be similar for most of the elements of interest, namely in μg/g: 2.52 and 6.0 B, 2074.4 and 3971.8 Ca, 2.4 and 2.4 Cu, 7.8 and 4.1 Fe, 4019 and 3288 K, 288 and 237 Mg, 1.65 and 3.1 Mn, 22.9 and 41 Na, 9.0 and 6.9 Ni, 2.9 and 3.3 Pb, 6.9 and 12.5 Sr, respectively. In Cornelian cherry juice the content of Al, Ba, Cd, Cr, Cu, Mn, Pb, and Sr were below the limits of detection (0.06, 0.07, 0.07, 0.006, 0.01, 0.042, 0.056, 0.04 and 0.009μg/L, respectively). The content of minor elements was 0.135 Fe, 0.163 Ni, 0.828 Zn and 1.47mg/L B. The concentrations of major elements were 11.3 Na, 51.7 Ca, 94.3Mg and 1326mg/LK.

Highlights

► Popularization of Cornelian cherry and the potential of European cultivars as a new promising fruit species. ► The elemental content of berries influences the quality of fruit, including organoleptic characteristics and stability. ► Metal concentrations were determined using ICP-AES. ► The knowledge of the mineral contents of berries is important from the toxicological point of view. ► This study is important confirms the importance of Cornelian cherry as nutritional supplement.

Determination of mercury in size fractionated road dust samples by flow injection-cold vapor-atomic absorption spectrometry

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Agustín Londonio, Fabián Fujiwara, Raúl Jiménez Rebagliati, Darío Gómez, Patricia Smichowski
An investigation was carried out to explore the effect of citric, hydrochloric, oxalic and tartaric acids on mercury vapor generation in a flow injection system in conjunction with atomic absorption spectrometry detection (CV-AAS) for its determination in road dust samples. Samples were collected in Buenos Aires (Argentina) during two months at 15 sites grouped in five zones with different urban characteristics and traffic profile. They were sieved in four fractions (with the following particle diameter (d): A: d <37μm, B: 37< d <50μm, C: 50< d <75μm, and D: 75< d <100μm) before Hg determination. The operating conditions (chemical and physical parameters) and the type and concentration of the acids studied (citric, hydrochloric, oxalic and tartaric) were assessed for the efficient generation of Hg. The interfering effect of metals and metalloids, present as minor and major concentrations in road dust, on Hg signal were evaluated using the four acids. Hydrochloric acid resulted to be the most convenient reaction medium in terms of sensitivity but a suitable control of interferences was not reached. For a complex matrix such as road dust, the best control of interferences was achieved when oxalic acid was tested, even when lower Hg signal was obtained in comparison with HCl. The detection limit (3σ criterion) turned out to be 0.3ngg−1. For checking accuracy, two certified reference materials were analyzed and results were in good agreement with certified values. Mercury concentrations in road dust ranged between 0.1μgg−1 and 4.6μgg−1 and the mean concentration value resulted to be 1.09μgg−1. In the four fractions, Hg concentrations (μgg−1) varied as follows: Fraction A (<0.0003–3.51); Fraction B (0.49–4.63); Fraction C (0.20–1.36) and Fraction D (0.16–1.88). The procedure is simple, rapid and robust.

Highlights

► We determined by the first time Hg on road dust samples collected in Buenos Aires. ► We compared four acid media for Hg vapor generation. ► The effect of each acid media on the control of interferences was assessed. ► The use of organic acids for Hg vapor generation is the most correct procedure from the environmental point of view. ► This work reports by the first time concentrations of Hg in Buenos Aires road dust as well as information on its origin.

Microanalytical investigation of nematodes

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Zoltán Sávoly, Péter Nagy, Károly Havancsák, Gyula Záray
The chemical characterization of individual free-living nematodes is a challenge due to their small size and correspondingly, their low dry mass (1–3μg). The concentrations of minor (S, P, Ca, K) and trace elements (Fe, Zn, Cu, Ni, and Mn) of individual specimens (Xiphinema Vuittenezi) were determined by total reflection X-ray fluorescence (TXRF) spectrometry following a two step sample preparation procedure. The mean concentrations of minor and trace elements changed in the range of 1–4 and 0.01–0.4ng/μg, respectively. The relative standard deviation varied between 9.4 and 25.3% which was influenced not only by the analytical procedure but also by the biological deviations among the eleven investigated specimens. The stress effect caused by CuSO4 treatment resulted in significant change in the nematodes only in their Zn content. In the lack of certified reference material, the TXRF method was checked by inductively coupled plasma mass spectrometry (ICP-MS) analyzing solutions of 100 digested nematodes. The carbon and nitrogen content of nematodes was also measured by total C/N analyzer and their ratio amounted to 4.78±0.31 which is lower than the values published for the bacterial or fungal feeding ones. The way of copper uptake was investigated by scanning electron microscopy (SEM). Nematode treated with copper-nitrate was pecked out at the mid-body using focused ion beam (FIB) technique. In order to preserve the cross-section to be investigated, platinum coating was applied prior to the FIB operation. Energy dispersive X-ray analysis was performed along the cross-section measuring the distribution of platinum, sulfur and copper. It has been found that the sulfur and copper distributions were fairly similar following the copper treatment, and these elements had the highest concentration in the cuticle.

Highlights

► Elemental analysis of individual plant parasitic nematodes by TXRF spectrometry. ► Determination of cross sectional distribution of elements by focused ion beam-SEM. ► Bulk analysis of 100 nematodes by ICP-MS following a microwave-assisted digestion.

Separation and preconcentration of trace amounts of Cr(III) ions on ion imprinted polymer for atomic absorption determinations in surface water and sewage samples

23 October 2012, 09:32:38
Publication year: 2012
Source:Microchemical Journal, Volume 105
Barbara Leśniewska, Beata Godlewska-Żyłkiewicz, Agnieszka Z. Wilczewska
A new type of Cr(III)-imprinted polymer was prepared from Cr(III)–pyrrolidinedithiocarbamate complex, acrylamide functional monomer and ethylene glycol methacrylate cross-linking agent. The polymer was employed as a selective solid phase extraction material for separation of trace amounts of Cr(III) ions under dynamic conditions. The effects of the conditioning of imprinted polymer, conditions of Cr(III) retention and elution were studied. It was found that Cr(III) ions can be retained on tested sorbent with high efficiency and repeatability (87%, RSD=3.2%) from a solution of pH 3.50–4.75. The quantitative elution of analyte was obtained with 0.2molL−1 nitric acid solution. The retention of Cr(VI) ions on the polymer in the studied pH range (1.0–7.0) was at the level of 10–15%. The selectivity of prepared sorbent towards Cr(III) ions was good in the presence of Cu(II) and Ni(II) ions and worse in the presence of Fe(III) ions at a concentration higher than 0.5μgmL−1. The detection limit for Cr(III) obtained by electrothermal atomic absorption spectrometry (ETAAS) after preconcentration of 40mL of sample on the polymer was 0.018ngmL−1. The developed separation method was successfully applied to the ETAAS determination of trace amounts of Cr(III) in tap and river water and municipal sewage.

Highlights

► New type of imprinted polymer was prepared for separation and enrichment of Cr(III) ions. ► The selectivity is characterized with retention values of 87% and 6–15% for Cr(III) and Cr(VI) ions, respectively. ► Applications to speciation analysis and for determination of Cr(III) ions in surface water and sewage samples are described.