World Congress on Biosensors 2014

World Congress on Biosensors 2014
Biosensors 2014

Monday, 18 November 2013

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:

Laboratory controlled study of the uptake and release of vanadium by oysters (Crassostrea virginica)

17 November 2013, 20:10:18
Publication date: March 2014
Source:Microchemical Journal, Volume 113
Author(s): Joel C. Richert , Carey J. Hardaway , Joseph Sneddon
Preliminary investigation of the uptake and removal of vanadium by oysters in a controlled laboratory environment showed that this occurs although the extent was difficult to quantify due to losses attributed to possible precipitation and the oyster shells impacting on the results. Nevertheless results did indicate that oysters can be affected (uptake) but can also purge (remove) vanadium in solution.

Classification of edible vegetable oil using digital image and pattern recognition techniques

17 November 2013, 20:10:18
Publication date: March 2014
Source:Microchemical Journal, Volume 113
Author(s): Karla Danielle Tavares Melo Milanez , Márcio José Coelho Pontes
This work presents a simple and non-expensive method based on digital image and pattern recognition techniques for the classification of edible vegetable oils with respect to the type (soybean, canola, sunflower and corn) and the conservation state (expired and non-expired shelf life). For this purpose, vegetable oil sample images were obtained from a webcam and the frequency distribution of color indexes in the red–green–blue (RGB), hue (H), saturation (S), intensity (I), and grayscale channels were obtained. Linear discriminant analysis (LDA) was employed in order to build classification models on the basis of a reduced subset of variables. For the purpose of variable selection, two techniques were utilized, namely the successive projection algorithm (SPA) and stepwise (SW) formulation. For the study evolving the classification with respect to oil type, LDA/SPA and LDA/SW models achieved a correct classification rate (CCR) of 95% and 90% respectively. For the identification of expired and non-expired samples, LDA/SPA models were found to be the best method for classifying sunflower, soybean and canola oils, achieving a CCR in the overall data set of 97%, 94% and 93%, respectively, while the LDA/SW correctly classified at 100% for corn oil data. These results suggest that the proposed method is a promising alternative for the inspection of authenticity and the conservation state of edible vegetable oils. As advantages, the method does not use reagents to carry out the analysis and laborious procedures for chemical characterization of the samples are not required.

Determination of reduced glutathione, cystein and total thiols in pine pollen powder by in situ derivatization

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Xiao-Yong Zhang , Yu-Lian Piao , Sheng-Yun Cui , Yong-Ill Lee
Glutathione (GSH), cystein (CySH) and total thiols in pine pollen powder were determined by spectrometric, fluorometric and high performance liquid chromatographic (HPLC) assays utilizing 5,5′-dithio-bis(2-nitrobenzoic acid) (DTNB, Ellman's reagent) and o-phthaldehyde (OPA) as derivatizing agents. The pollen samples were extracted with phosphate buffer solutions (PBS) containing excess derivatizing agents concomitant with ultrasonic cell rupture. In this way, thiol groups in the samples could be effectively blocked by in situ formation of relatively stable derivatizing products just after the pollen cell ruptured, thereby effectively preventing thiol groups from oxidation during sample preparation and making it possible to perform sensitive and accurate detections. Using a precolumn derivatization method, DTNB, GSH and CySH, as well as other thiol compounds can be determined or estimated by the HPLC method. Total thiols in the samples were determined by the spectrometric method using DTNB as the derivatizing agent. GSH was also selectively determined by the fluorometric method using OPA as the derivatizing agent. The detection results indicated that abundant thiol compounds, such as GSH, CySH and thiol protein, existed in pine pollen powder with measured amounts of 0.50–0.53μmol∙g−1 of GSH, 0.41μmol∙g−1 of CySH and 4.15μmol∙g−1 of total thiols.

Flow injection hydride generation for on-atomizer trapping: Highly sensitive determination of cadmium by tungsten coil atomic absorption spectrometry

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Piaopiao Chen , Yujia Deng , Kuncheng Guo , Xiaoming Jiang , Chengbin Zheng , Xiandeng Hou
Here we report the use of the tungsten-coil atomizer of a portable atomic absorption spectrometer as an on-atomizer trapping device and atomizer for the determination of trace cadmium, with flow injection hydride generation for production of volatile cadmium species from sample solutions. By mixing acidic analyte solution with tetrahydroborate solution, volatile cadmium species is produced and separated from the solution, and then transported and impacted onto the surface of the atomizer with a heating current set at 2.3A. Subsequent atomic absorption measurement was accomplished with in situ atomization at 8.5A. Compared to conventional direct injection, the sensitivity and the limit of detection were improved by 58- and 66-fold, respectively, based on 5.0mL sampling volume. In addition, use of flow injection significantly improved sample throughput. The proposed method was used for the analysis of several real water samples with good spiked recoveries.

Emerging issues on degradation by-products deriving from personal care products and pharmaceuticals during disinfection processes of water used in swimming pools

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Paola Bottoni , Lucia Bonadonna , Mattea Chirico , Sergio Caroli , Gyula Záray
The use of disinfection substances in the sanitation and disinfection processes of artificial water used for sports amenities and swimming pools has recently raised some serious concerns. Recreational Water Illnesses (RWIs) can put at serious risk the health of bathers and swimmers due to adverse effects caused by the use of disinfection chemicals, such as chlorine, chloramine, ozone and UV radiation, as well as their by-products. Remarkable documented evidence is available on the impact of Disinfection By-Products (DBPs), such as chloroform and other trihalomethanes, haloacetic acids and chlorophenols, deriving from the oxidation of common organic pollutants dissolved in raw, drinking, waste and artificial waters. Appropriate countermeasures, aimed at avoiding bathers' exposures to these chemicals, have been developed and adopted in public and private structures, also through important scientific contributions and technical provisions issued by the WHO and some national health authorities. On the other hand, it has been demonstrated that high reactive disinfection agents may transform other undesirable chemicals released by bathers, namely pharmaceuticals, sunscreens and other Pharmaceuticals and Personal Care Products (PPCPs) into chlorinated and oxidized compounds and nitrosamine precursors. The first symptoms of potentially adverse health effects on human subjects of these largely unknown by-products should be adequately taken into consideration and investigated.

Single-step procedure for trace element determination in synovial fluid by dynamic reaction cell-inductively coupled plasma mass spectrometry

17 November 2013, 20:10:1
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Franco Moyano , Ernesto Verni , Héctor Tamashiro , Silvia Digenaro , Luis D. Martinez , Raúl A. Gil
A fast and single-step procedure for the dissolution of human synovial fluid in formic acid and further determination by dynamic reaction cell-inductively coupled plasma mass spectrometry (DRC-ICPMS) with a high-efficiency sample introduction system was developed. The samples were collected, treated and analyzed in the same screw-capped tubes. In order to overcome the effect of considerable carbon content, the sample introduction, nebulization and ICP operating conditions were carefully optimized. Furthermore, DRC technology with CH4 as reaction gas was used for the elimination of spectral interferences due to polyatomic ions. The effect of the sample matrix was evaluated and mitigated through comparison of direct calibration against aqueous standards, direct calibration in formic acid media and analyte addition calibration. The recommended procedure involved low dilution and low detection limits (from 0.003μgL−1 for U to 13.3μgL−1 for Ti) with adequate precision (from 0.6% for Co to 6.6% for Ti). The proposed method was successfully applied to determine 16 trace elements in concentrations from 0.03μgL−1 (Cd) to 88.2μgL−1 (Cu) in human synovial fluid samples.

Modeling of second-order spectrophotometric data generated by a pH-gradient flow injection technique for the determination of doxorubicin in human plasma

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Mirta R. Alcaráz , Agustina V. Schenone , María J. Culzoni , Héctor C. Goicoechea
In this paper, the development of a pH-gradient flow-injection method with diode-array spectrophotometric detection combined with extended multivariate curve resolution–alternating least-squares (MCR–ALS) to quantitate doxorubicin in the presence of rifampicin in plasma samples is presented. Quantitation of doxorubicin was based on acid–base and spectral differences between its species and those for the interference. Overlapped profiles among the analyte and the interference were mathematically solved by data modeling with the well-known extended MCR–ALS algorithm. The method, which involves a simple sample pretreatment consisting in the addition of trichloroacetic acid followed by centrifugation, was applied to resolve validation mixtures composed of human plasma spiked with doxorubicin. Acceptable analytical figures of merit were obtained, i.e. recoveries from 96 to 107%, coefficients of variation between 0.2% and 7.8%, and limits of detection and quantification of 0.77 and 2.32μgL−1, respectively.

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Effects of UV-dechloramination of swimming pool water on the formation of disinfection by-products: A lab-scale study

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Nicolas Cimetiere , Joseph De Laat
UV dechloramination has become a very popular process for reducing the concentration of chloramines in public swimming pool water. As the effects of this process on the formation of disinfection by-products (DBPs) remain a controversial issue, a bench-scale study has been undertaken to examine the impact of UV dechloramination on the formation of various DBPs. Four pool water samples were exposed to UV radiation at 254nm in the presence of free chlorine ([Cl2]0 =3mgL−1) and then chlorinated in the dark for 24h ([Cl2]0 =3mgL−1). High UV doses (up to 47kJm−2) were used to simulate cumulative UV doses received by real pool waters. The data showed that UV irradiation led to a 90% photodecay of free chlorine for UV doses ranging from 13 to 20kJm−2, to the formation of chlorate ion (0.05–0.11mol of chlorate/mole of free chlorine decomposed) and to a significant increase in the chlorine demand of pool water during the post-chlorination step. UV exposure followed by post-chlorination did not significantly affect the formation of haloacetic acids, led to a small increase in the concentrations of adsorbable organic halogen (AOX) and of chloral hydrate and markedly increased the formation of trihalomethanes (chloroform, bromodichloromethane, chlorodibromomethane), dichloroacetonitrile, 1,1,1-trichloropropanone and chloropicrin.

Preconcentration of toxic elements in artificial saliva extract of different smokeless tobacco products by dual-cloud point extraction

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Sadaf Sadia Arain , Tasneem Gul Kazi , Jamshed Bashir Arain , Hassan Imran Afridi , Kapil Dev Brahman , Naeemullah
Smokeless tobacco (SLT) has been associated with oral cancer. In present study, the total and artificial saliva extracted toxic elements (TEs), arsenic (As), cadmium (Cd), nickel (Ni) and lead (Pb) were estimated in SLT products (gutkha, green and brown snuff). Dual-cloud point extraction has been used for the preconcentration of As, Cd, Ni and Pb in artificial saliva extract, using complexing reagent, ammonium pyrrolidinedithiocarbamate. The dual-cloud point extraction procedure was based on forming complexes of elemental ions with complexing reagent and subsequent entrapping of the complexes in nonionic surfactant. Then the surfactant rich phase containing the complexes was treated with nitric acid, and detected ions were back extracted again into aqueous phase at the second cloud point extraction stage, and finally determined by electrothermal atomic absorption spectrometry. The validity of methodology was tested by simultaneously analyzing certified reference material and spike recovery test. The experimental enhancement factors of As, Cd, Ni and Pb were found to be 52, 58, 48 and 44, respectively. The concentration of As, Cd, Ni and Pb in artificial saliva extracts corresponds to 18–24, 45–75, 30–55, and 20–30%, respectively, of the total contents of TE in different types of SLT products (gutkha, brown and green snuff). It was estimated that 10g intake of SLT products (gutkha, brown and green snuff) could contribute 2.2–13, 21–69, 3.4–48 and 10–75% of the provisional maximum tolerable daily intake of As, Cd, Ni and Pb, respectively for adults ~60kg.

Determination of aluminum in botanical samples by adsorptive cathodic stripping voltammetry as Al-8-hydroxyquinoline complex

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): Lídia B. Santos , Maisa T.F. de Souza , Alexandre T. Paulino , Edivaldo E. Garcia , Eurica M. Nogami , Juliana C. Garcia , Nilson E. de Souza
A fast and sensitive new procedure for the determination of total aluminum by adsorptive cathodic stripping voltammetry (AdCSV) in plant samples consumed for dietary and/or medicinal purposes was described. The Al(III)-8-hydroxyquinoline (Al-8HQ) complex was adsorbed on a hanging mercury dropping electrode (HMDE) at 0.300V versus Ag/AgCl electrode during a 30s accumulation time. An electrochemical cell containing 0.024molL−1 ammonia–ammonium acetate buffer (pH6.80) as supporting electrolyte and 7.43mgL−1 8-hydroxyquinoline (8-HQ) as ligand for aluminum were employed. A linear response was observed over the 8.54×10−8 to 2.35×10−7 molL−1 range with a limit of detection (LOD) of 8.54×10−8 molL−1 and a relative standard deviation (RSD; n=3) of 1.86% for 8.54×10−8 molL−1 aluminum solution. Aluminum contents in green tea (Camellia sinensis), carqueja (Baccharis genistelloides), cascara sagrada (Rhamnus purshiana) and senna (Cassia acutifolia) were 502.5±14.1, 195.6±21.0, 309.1±11.7, 205.6±16.1μg aluminum per g of dry tea, respectively. The accuracy of the developed method was evaluated by flame atomic absorption spectrometry (FAAS) and all of the results were similar. It indicates that AdCSV could be efficiently applied in the determination of aluminum as 8-HQ complex in real food samples.

Arsenic metabolites in human serum and urine after seafood (Anemonia sulcata) consumption and bioaccessibility assessment using liquid chromatography coupled to inorganic and organic mass spectrometry

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): M. Contreras-Acuña , T. García-Barrera , M.A. García-Sevillano , J.L. Gómez-Ariza
The present paper reports for the first time the bioaccessibility of arsenic species in Anemonia sulcata and its metabolization in the human body after the ingestion of this seafood, a delicacy highly appreciated in the south of Spain. Speciation in tissue extracts and human fluids was carried out by anion/cation exchange chromatography with inductively coupled plasma mass spectrometry ((IC)-ICP-MS). Results obtained show that about 54% of the arsenic present in the anemones is lost after cooking, around 95% of total arsenic in cooked anemones is bioaccessible and 85% of the amount ingested is eliminated from the body by urine in 90h. The relative abundance of As in urine varies along the time, but after the first 10h follows the order arsenobetaine (AB)≈DMAV (dimethylarsinate)>arsenocholine (AsC)>tetra-methyl-arsonium (TETRA)>trimethyl-arsine oxide (TMAO)>MAV (monomethylarsonate)>iAsV >dimethylarsenoethanol (DMAE), while the major species in cooked anemones is AB followed by DMAV >dimethylmonothioarsinic acid (DMASV)>AsC>TETRA>TMAO>iAsV >glycerylphosphorylarsenocholine(GPAsC)>MAV >DMA. After 30min from the ingestion, DMAV is the most abundant in human serum, followed by AB, MAV and AsC. Finally, the use of organic mass spectrometry allowed the standardless identification of AsC, GPAsC, DMASV and DMAE.

Legionella spp. survival after different disinfection procedures: Comparison between conventional culture, qPCR and EMA–qPCR

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): A. Mansi , I. Amori , I. Marchesi , A.M. Marcelloni , A.R. Proietto , G. Ferranti , V. Magini , F. Valeriani , P. Borella
The development of rapid and sensitive methods for the detection and quantification of Legionella viable cells is essential for monitoring water quality and preventing legionellosis. The aim of this study was to verify the applicability of a quantitative PCR (qPCR) method used in combination with ethidium monoazide (EMA) to the quantification of Legionella spp. in samples collected from swimming pools, water recirculation systems and hot water systems in two fitness clubs. This molecular technique (EMA–qPCR) allows the amplification of target DNA from culturable and viable cells, but prevents the amplification of DNA from non-viable cells. The effectiveness of this new method able to detect alive legionellae was also compared with conventional qPCR and culture method. Our results confirm that EMA–qPCR allows to discriminate the non-viable cells from those viable and that it is particularly indicated for monitoring the effectiveness of thermal treatments for the Legionella contamination control in water environments, also providing information about the presence of Viable But Non-Culturable (VBNC) cells. Other Gram-negative bacteria typically associated with biofilm were identified in samples taken from swimming pools and balance tanks, suggesting that also the presence of biofilm should be monitored for a more general view of water contamination.

The molecular enrichment approach for the identification of microbiological indicators in recreational waters

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): F. Valeriani , S. Giampaoli , V. Romano Spica
The identification of rapid methods for the surveillance of recreational waters and aquatic environments is necessary to provide adequate levels of health safety and quality standards. Molecular techniques have been proposed in recent years as a valuable alternative to traditional microbiological cultural methods, having numerous advantages (speed, specificity and sensibility). We have previously described a method for the detection of Staphylococcus aureus in recreational waters by a molecular enrichment approach, based on a two steps PCR performed on 23S rDNA. The approach has been now expanded to other microbiological indicators, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli. This methodological extension to other prokaryotic genomes has required a partial primer re-design and protocol optimization, in order to improve the assay. The usage of native not recombinant Taq-polymerases for detection of E. coli eliminated the background probably due to traces of the bacterial genome in many commercially available reagents. The obtained results clearly underline the feasibility of a fast and integrated molecular approach to quantify the standard biological indicators for assessment of safety and quality in recreational waters.

Identification of starch and determination of its botanical source in ancient manuscripts by MEKC–DAD and LDA

17 November 2013, 20:10:18
Publication date: January 2014
Source:Microchemical Journal, Volume 112
Author(s): M.E. Castillo-Valdivia , A. López-Montes , T. Espejo , J.L. Vílchez , R. Blanc
A simple and rapid Micellar Electrokinetic Capillary Chromatography method with UV diode-array detection (MEKC–DAD) has been developed for the identification of the two starch polysaccharides, amylopectin and amylose, in ancient manuscripts. Moreover, a linear discriminant analysis (LDA) has been used in order to determine the botanical source of the starch (wheat, maize or rice). The reason to develop this method is that starch has been used throughout history in paper manufacture as glue and sizing agent. The LDA was applied to the amylopectin/amylose ratio using the area and height data recorded. The separation was performed in an extended path-length fused-silica capillary (‘bubble capillary’) of 36cm in length and 50μm i.d.. The running buffer was composed of 20mM sodium acetate, 1.2mM I2, 7.2mM KI, and 50mM sodium dodecyl sulphate (SDS) at pH6. The potential applied was 22kV in positive polarity, the temperature was 25°C, and the detection was performed at 560nm. Injection of the samples was performed at 20mbar for 2s. An artificial ageing test was carried out in the three types of starch in order to determine the effect of the temperature, relative humidity and irradiance on this compound. The procedure was performed in an ageing chamber according to the ISO 5630-3:1996 and 11341:2004 standards. The methods were applied to samples from manuscripts preserved in the Historic Archive of the University of Granada and the Royal Chancellery Archive of Granada (Spain). 

1 comment:

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