World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Friday, 22 June 2012

Just Published: Spectrochimica Acta Part B: Atomic Spectroscopy


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:
Spectrochimica Acta Part B: Atomic Spectroscopy
http://rss.sciencedirect.com/publication/science/5287
Selected papers from the latest issue:

Sensitive determination of bismuth by flame atomic absorption spectrometry using atom trapping in a slotted quartz tube and revolatilization with organic solvent pulse

22 June 2012, 09:39:19
Publication year: 2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
Ersin Kılınç, Sezgin Bakırdere, Fırat Aydın, O. Yavuz Ataman
Sensitivity of flame atomic absorption spectrometry (FAAS) for Bi determination wasimproved by slotted quartz tube (SQT) that was used also for atom trapping (AT). The trapped analyte was released by aspirating a small volume of organic solvent after a reasonable analyte collection time. Sensitivity was improved by 2.9 times by SQT-FAAS and 256 times by SQT-AT-FAAS with respect to FAAS. Optimum trapping period was found to be 6.0min (36.0mL of solution). Limit of detection (LOD) for SQT-AT-FAAS was found to be 1.6ngmL-1. %RSD was calculated as 4.0% for five replicate measurements of 7.5ngmL-1 Bi by SQT-AT-FAAS. Accuracy of the method developed was checked by analyzing a standard reference material of simulated fresh water (NIST 1643e) and result found was in good agreement with the certified one. The method can be applied in any laboratory equipped with a flame AA spectrometer. The consumption of time and sample volume is fairly low and application is simple and easy.

Potential of accuracy profile for method validation in ICP spectrochemistry

22 June 2012, 09:39:19
Publication year: 2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
J.M. Mermet, G. Granier
Method validation is usually performed over a range of concentrations for which analytical criteria must be verified. One important criterion in quantitative analysis is accuracy, i.e. the contribution of both trueness and precision. The study of accuracy over this range is called an accuracy profile and provides experimental tolerance intervals. Comparison with acceptability limits fixed by the end user defines a validity domain. This work describes the computation involved in the building of the tolerance intervals, particularly for the intermediate precision with within-laboratory experiments and for the reproducibility with interlaboratory studies. Computation is based on ISO 5725–4 and on previously published work. Moreover, the bias uncertainty is also computed to verify the bias contribution to accuracy. The various types of accuracy profile behaviour are exemplified with results obtained by using ICP-MS and ICP-AES. This procedure allows the analyst to define unambiguously a validity domain for a given accuracy. However, because the experiments are time-consuming, the accuracy profile method is mainly dedicated to method validation.

Highlights

► An analytical method is defined by its accuracy, i.e. both trueness and precision ► The accuracy as a function of an analyte concentration is an accuracy profile ► Profile basic concepts are explained for trueness and intermediate precision ► Profile-based tolerance intervals have to be compared with acceptability limits ► Typical accuracy profiles are given for both ICP-AES and ICP-MS techniques

A logical way through the limits of quantitation in ICP spectrochemistry

22 June 2012, 09:39:19
Publication year: 2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
J.M. Mermet, G. Granier, P. Fichet
The limit of quantitation (LOQ) is a crucial parameter in quantitative analysis. Besides the classical “10 s B approach”, other concepts have been previously described based on the limitation resulting from the calibration procedure, namely from the prediction bands and the uncertainty calibration. Because of the difficulty of obtaining a reliable value of the blank standard deviation, this approach was replaced by the study of the %RSD of the net signal as a function of the concentration. Recently described, the so-called accuracy profile method, accuracy being the contribution of both the trueness and the precision, allows the analyst to define a validity domain, the lowest point acting as a limit of quantitation. The aim of this work was to determine these various limits of quantitation, including that from the accuracy profile, to compare them, and to study the parameters that can influence their values. It was concluded that the LOQ deduced from the accuracy profile is a realistic one. Its value is mainly influenced by the calibration procedure, particularly when a weighting procedure is used. A 1/y weighting factor, y being the analyte line intensity, seems to be an efficient compromise for calibration.

Highlights

► An analytical method is defined by its accuracy, i.e. both trueness and precision ► A limit of quantitation should be based on an accuracy criterion and not on precision ► The accuracy as a function of an analyte concentration is an accuracy profile ► Profile-based tolerance intervals define a validity domain ► The lowest concentration of this domain corresponds to a limit of quantitation

Quantitative real-time monitoring of multi-elements in airborne particulates by direct introduction into an inductively coupled plasma mass spectrometer

22 June 2012, 09:39:19
Publication year: 2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
Yoshinari Suzuki, Hikaru Sato, Katsuhiro Hiyoshi, Naoki Furuta
A new calibration system for real-time determination of trace elements in airborne particulates was developed. Airborne particulates were directly introduced into an inductively coupled plasma mass spectrometer, and the concentrations of 15 trace elements were determined by means of an external calibration method. External standard solutions were nebulized by an ultrasonic nebulizer (USN) coupled with a desolvation system, and the resulting aerosol was introduced into the plasma. The efficiency of sample introduction via the USN was calculated by two methods: (1) the introduction of a Cr standard solution via the USN was compared with introduction of a Cr(CO)6 standard gas via a standard gas generator and (2) the aerosol generated by the USN was trapped on filters and then analyzed. The Cr introduction efficiencies obtained by the two methods were the same, and the introduction efficiencies of the other elements were equal to the introduction efficiency of Cr. Our results indicated that our calibration method for introduction efficiency worked well for the 15 elements (Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Mo, Sn, Sb, Ba, Tl and Pb). The real-time data and the filter-collection data agreed well for elements with low-melting oxides (V, Co, As, Mo, Sb, Tl, and Pb). In contrast, the real-time data were smaller than the filter-collection data for elements with high-melting oxides (Ti, Cr, Mn, Ni, Cu, Zn, Sn, and Ba). This result implies that the oxides of these 8 elements were not completely fused, vaporized, atomized, and ionized in the initial radiation zone of the inductively coupled plasma. However, quantitative real-time monitoring can be realized after correction for the element recovery which can be calculated from the ratio of real-time data/filter-collection data.

Highlights

► APs were directly introduced into ICP-MS and real-time analysis was performed. ► The real-time data were calibrated by a multi-element standard solution from USN. ► During real-time analysis, APs simultaneously collected on a filter were analyzed. ► Element recovery was calculated by the real-time data/the filter-collection data. ► Quantitative real-time data could be realized by correcting the element recovery.

Comparison of Inductively Coupled Plasma Mass Spectrometry and Colorimetric Determination of Total and Extractable Phosphorus in Soils

22 June 2012, 09:39:19
Publication year: 2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
Krasimir Ivanov, Penka Zaprjanova, Milena Petkova, Violeta Stefanova, Veselin Kmetov, Deyana Georgieva, Violina Angelova
The most widely used method for determination of total phosphorus in soils is perchloric acid digestion, followed by a colorimetric assay to measure the concentration of P in solution. The first part of this study compares an alternative digestion method, using aqua regia (ISO 11466 and EPA Method 3052), with perchloric acid digestion procedure, and also compares inductively coupled plasma mass spectroscopy (ICP-MS) with colorimetry for the measurement of P on the basis of five internationally certified standard soils and 20 real-life soils with widely different extractability of phosphorus. The phosphorus concentration was determined by means of the reduced phosphomolybdenum blue and ICP-MS. The relationship between methods has been examined statistically. Good agreement of the results from colorimetry and ICP-MS was established for all certified soils. The microwave-assisted digestion with aqua regia was comparable, both in precision and accuracy, with the hot plate aqua regia method. The phosphorus concentration found with the HF+HClO4 digestion method was in good agreement with the certified mean values while the superiority in extracting phosphorus, when compared to other methods, was obvious. Soil testing for plant-available phosphorus in Bulgaria and many European countries is most commonly conducted using acid Ca-lactate extraction (Egner-Riehm test) and alkaline sodium bicarbonate extraction (BDS ISO 11263:2002), based on Olsen test, followed by a colorimetric assay to measure the concentration of P in solution. The second part of this study reports the differences between Egner-Riehm test and BDS ISO 11263:2002 measured colorimetrically and by ICP-MS. Fifty soils were selected from South Bulgaria to represent a wide range of soil properties. It was established that ICP-MS consistently yielded significantly higher P concentrations than the colorimetric method in both extraction tests, and the relative differences were greatest in soils with lower P concentrations.

Highlights

► ICP-MS and colourimetry are compared for the measurement of total and extractable P. ► ICP-MS analysis registers greater extractable P than colorimetric methods. ► ICP-MS analysis cannot be directly correlated with colorimetric analysis for P.

Comparison between the characteristics of the plasmas generated by laser on solid and molten steels

22 June 2012, 09:39:19
Publication year: 2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
Hiroyuki Kondo
Plasma characteristics, excitation temperatures of atomic iron and electron densities, were compared between the laser-induced plasmas generated on solid steel at room temperature and molten steel. The excitation temperatures of iron atom were determined by Boltzmann plot using neutral iron atomic emission lines in the wavelength range of 386 to 400nm. Electron densities were estimated by measured linewidths of AlI394.4nm. Excitation temperature of iron decreased from 10800K at 10μs to 7300K at 80μs of delays for solid steel. Significant difference in the excitation temperatures of iron atom wasn't exhibited between the plasmas generated on solid and molten steels. The linewidths observed with molten steel were narrower than those observed with solid steel in most of neutral atomic lines of iron and aluminum. Electron density in the plasma produced on molten steel was estimated to be (0.99±0.15)×1017 cm-3, which was 46% of electron density in the plasma on solid steel at the same observation delay of 10μs from the laser pulse. The optical depths were obtained by evaluating the broadening due to self-absorption in the resonance line, FeI385.99nm. The iron atom density in the plasma induced on molten steel has been found to be 1.3 times that in the plasma induced on solid steel.

Highlights

► Little difference in plasma temperatures between solid and molten steels ► Narrower linewidths for molten steel than solid steel plasmas ► Resonant line of iron showed broader width for molten steel than solid steel ► Electron density for molten steel was 46% of that for solid steel. ► Atomic density in plasma for molten steel was 1.3 times that for solid steel

In situ investigation of the surface silvering of late Roman coins by combined use of high energy broad-beam and low energy micro-beam X-ray fluorescence techniques

22 June 2012, 09:39:19
Publication year: 2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
F.P. Romano, S. Garraffo, L. Pappalardo, F. Rizzo
The compositional analysis of archaeological metals performed with the X-ray Fluorescence technique (XRF) provides information on the ancient technology. One of the most interesting case-study concerns the techniques used by Romans for silvering the surface of coins. Different metallurgical processes have been suggested in previous studies. Recently the investigation has been addressed to the mercury-silvering and to its possible use in the mass-production of coins minted during the late period (after 294AD). In the present paper the non-destructive investigation of the silvering process used for manufacturing the Roman nummi – the important typology of coin introduced by Diocletian in his monetary reform - is approached by the combined use of the standard X-Ray Fluorescence (XRF) and the low energy micro-X-Ray Fluorescence (LE-μXRF) portable methods. The research was focused on the systematic determination of the mercury presence in a large number of samples and on its correlation with silver in the surface of the coins. 1041 Roman nummi belonging to the Misurata Treasure were analyzed in situ, at the Lepits Magna Museum (El Khomes, Lybia). The treasure, composed of about 108 thousand silvered coins, gives the unique opportunity to study the Roman coinage in a wide interval of time (about 40years in the period 294–333AD) and in almost all the imperial mints operating in the Roman world.

Highlights

► Custom-building of a high energy broad-beam and a low energy micro-beam XRF ► In situ analysis of the silvering methods in late Roman nummi with plated surfaces ► The broad-beam XRF was applied for the detection of mercury traces in the coin alloy ► The low energy micro-XRF was used to scan the surface patina of the coins ► The correlation between mercury and silver at the coin surface was evidenced

Elemental changes in hemolymph and urine of Rhodnius prolixus induced by in-vivo exposure to mercury: A study using synchrotron radiation total reflection X-ray fluorescence

22 June 2012, 09:39:19
Publication year: 2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
Andrea Mantuano, Arissa Pickler, Regina C. Barroso, André P. de Almeida, Delson Braz, Simone C. Cardoso, Marcelo S. Gonzalez, Marcela B. Figueiredo, Eloi S. Garcia, Patricia Azambuja
In recent years, the effects of pollution on the health of humans and other vertebrates were extensively studied. However, the effects on some invertebrates are comparatively unknown. Recent studies have demonstrated that toxic metals interfere with the reproduction, development and immune defenses of some terrestrial and marine invertebrates. Some environmental conditions including pollution produce chronic and acute effects on different animal's organs and systems. In this work, we investigated changes in the concentrations of Cl, K, Ca, Fe and Zn in Rhodnius prolixus as insect model. The elements were quantified using urine and hemolymph samples collected on different days after feeding the insects with blood containing HgCl2. The synchrotron radiation total reflection X-ray fluorescence measurements were carried at the X-ray fluorescence beamline facility in Brazilian Synchrotron Light Laboratory. The observation reveals that the calcium level was higher in the hemolymph than in urine. On the other hand, the urine collected from insects treated with HgCl2 showed higher level of Cl than hemolymph samples. Ca, Fe and Zn concentrations decrease drastically in urine samples collected after 2days of HgCl2 treatment. The regulation of triatomines excretion was discussed pointing out the importance of trace elements.

Highlights

► Changes in Cl, K, Ca, Fe and Zn contents in Rhodnius prolixus were evaluated. ► In triatomines these elements have not been previously described. ► Cl, Ca, Zn levels were lower than control in hemolymph after 5days of HgCl2 fed. ► Cl, Ca, Zn levels were higher than control in urine after 2days of HgCl2 fed.

Application of spectroscopic techniques to the study of illuminated manuscripts: A survey

22 June 2012, 09:39:19
Publication year: 2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
S. Pessanha, M. Manso, M.L. Carvalho
This work focused on the application of the most relevant spectroscopic techniques used for the characterization of illuminated manuscripts. The historical value of these unique and invaluable artworks, together with the increased awareness concerning the conservation of cultural heritage, prompted the application of analytical techniques to the study of these illuminations. This is essential for the understanding of the artist's working methods, which aids conservation-restoration. The characterization of the pigments may also help assign a probable date to the manuscript. For these purposes, the spectroscopic techniques used so far include those that provide information on the elemental content: X-ray fluorescence, total reflection X-ray fluorescence and scanning electron microscopy coupled with energy-dispersive spectroscopy and laser-induced breakdown spectroscopy. Complementary techniques, such as X-ray diffraction, Fourier transform infrared and Raman spectroscopy, reveal information regarding the compounds present in the samples. The techniques, suitability, technological evolution and development of high-performance detectors, as well as the possibility of microanalysis and the higher sensitivity of the equipment, will also be discussed. Furthermore, issues such as the necessity of sampling, the portability of the equipment and the overall advantages and disadvantages of different techniques will be analyzed.

Highlights

► The most used techniques for studying illuminated manuscripts are described and compared. ► For in situ, non-destructive analysis the most suitable technique is EDXRF. ► For quantitative analysis TXRF is more appropriate. ► Raman spectroscopy is mostly used for pigments identification. ► FTIR was used for the characterization of binders and parchment.


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