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Selected papers from the latest issue:
Cl/Cl isotope effects inRh NMR of [RhCln(H2O)6-n]complex anions in hydrochloric acid solution as a unique ‘NMR finger-print’ for unambiguous speciation
15 February 2012, 00:36:22
Publication year: 2012
Source: Analytica Chimica Acta, Available online 14 February 2012
Theodor E. Geswindt, Wilhelmus J. Gerber, D. Jacobus Brand, Klaus R Koch
A detailed analysis of theCl/Cl isotope effects observed in the 19.11 MHzRh NMR resonances of [RhCln(H2O)6-n]complexes (n = 3-6) in acidic solution at 292.1 K, shows that the ‘fine structure’ of eachRh resonance can be understood in terms of the uniqueisotopologueand in certain instances theisotopomerdistribution in each complex. TheseCl/Cl isotope effects in theRh NMR resonance of the [RhCl6]species manifest only as a result of the statistically expectedCl/Cl isotopologues, whereas for the aquated species such as for example [RhCl5(H2O)],cis-[RhCl4(H2O)2]as well as themer-[RhCl3(H2O)3] complexes, additional fine-structure due to the various possible isotopomers within each class of isotopologues, is visible. Of interest is the possibility of the direct identification of stereoisomerscis-[RhCl4(H2O)2],trans-[RhCl4(H2O)2],fac-[RhCl3(H2O)3] andmer-[RhCl3(H2O)3] based on theRh NMR line shape, other than on the basis of their very similar δ(Rh) chemical shift. TheRh NMR resonance structure thus serves as a novel and unique ‘NMR-fingerprint’ leading to the unambiguous assignment of [RhCln(H2O)6-n]complexes (n = 3-6), without reliance on accurate δ(Rh) chemical shifts.
Source: Analytica Chimica Acta, Available online 14 February 2012
Theodor E. Geswindt, Wilhelmus J. Gerber, D. Jacobus Brand, Klaus R Koch
A detailed analysis of theCl/Cl isotope effects observed in the 19.11 MHzRh NMR resonances of [RhCln(H2O)6-n]complexes (n = 3-6) in acidic solution at 292.1 K, shows that the ‘fine structure’ of eachRh resonance can be understood in terms of the uniqueisotopologueand in certain instances theisotopomerdistribution in each complex. TheseCl/Cl isotope effects in theRh NMR resonance of the [RhCl6]species manifest only as a result of the statistically expectedCl/Cl isotopologues, whereas for the aquated species such as for example [RhCl5(H2O)],cis-[RhCl4(H2O)2]as well as themer-[RhCl3(H2O)3] complexes, additional fine-structure due to the various possible isotopomers within each class of isotopologues, is visible. Of interest is the possibility of the direct identification of stereoisomerscis-[RhCl4(H2O)2],trans-[RhCl4(H2O)2],fac-[RhCl3(H2O)3] andmer-[RhCl3(H2O)3] based on theRh NMR line shape, other than on the basis of their very similar δ(Rh) chemical shift. TheRh NMR resonance structure thus serves as a novel and unique ‘NMR-fingerprint’ leading to the unambiguous assignment of [RhCln(H2O)6-n]complexes (n = 3-6), without reliance on accurate δ(Rh) chemical shifts.
Highlights
► DirectRh NMR (19.11 MHz) spectroscopic method of speciation of [RhCln(H2O)6-n]in HCl ►Cl/Cl isotope effects inRh NMR of [RhCln(H2O)6-n]anions Isotopologue and Isotopomer inducedRh NMR ‘finger-print’ for unambiguous identification ►Rh NMR identification ofstereoisomerswithout a need for accurate chemical shifts.Dipstick based immunochemiluminescence biosensor for the analysis of vitamin B12in energy drinks: A novel approach
15 February 2012, 00:36:22
Publication year: 2012
Source: Analytica Chimica Acta, Available online 13 February 2012
L.S. Selvakumar, M.S. Thakur
In this article, we describe a dipstick based immunochemiluminescence (immuno-CL) biosensor for the detection of vitamin B12in energy drinks. The method is a direct competitive type format involving the immobilization of vitamin B12antibody on nitrocellulose membrane (NC) followed by treatment with vitamin B12and vitamin B12-alkaline phosphatase conjugate to facilitate the competitive binding. The dipstick was further treated with substrate disodium 2-chloro-5-(4-methoxyspiro {1,2-dioxetane-3,2¢-(5¢-chloro)tricyclo[3.3.1.13,7]decan}-4-yl)-1-phenyl phosphate (CDP-Star) to generate chemiluminescence (CL). The number of photons generated was inversely proportional to the vitamin B12concentration. After systematic optimization, the limit of detection was 1 ng mL. The coefficient of variation was below 0.2% for both intra- and interassay precision. Vitamin B12was extracted from energy drinks with recovery ranged from 90 to 99.4%. Two different energy drinks samples were analyzed, and a good correlation was observed when the data were compared with a reference enzyme linked immuno sorbent assay (ELISA) method. The developed method is suitable for an accurate, sensitive, and high-throughput screening of vitamin B12in energy drinks samples. The dipstick technique based on immuno-CL is suitable for the detection of several analyte in food and environmental samples.
Source: Analytica Chimica Acta, Available online 13 February 2012
L.S. Selvakumar, M.S. Thakur
In this article, we describe a dipstick based immunochemiluminescence (immuno-CL) biosensor for the detection of vitamin B12in energy drinks. The method is a direct competitive type format involving the immobilization of vitamin B12antibody on nitrocellulose membrane (NC) followed by treatment with vitamin B12and vitamin B12-alkaline phosphatase conjugate to facilitate the competitive binding. The dipstick was further treated with substrate disodium 2-chloro-5-(4-methoxyspiro {1,2-dioxetane-3,2¢-(5¢-chloro)tricyclo[3.3.1.13,7]decan}-4-yl)-1-phenyl phosphate (CDP-Star) to generate chemiluminescence (CL). The number of photons generated was inversely proportional to the vitamin B12concentration. After systematic optimization, the limit of detection was 1 ng mL. The coefficient of variation was below 0.2% for both intra- and interassay precision. Vitamin B12was extracted from energy drinks with recovery ranged from 90 to 99.4%. Two different energy drinks samples were analyzed, and a good correlation was observed when the data were compared with a reference enzyme linked immuno sorbent assay (ELISA) method. The developed method is suitable for an accurate, sensitive, and high-throughput screening of vitamin B12in energy drinks samples. The dipstick technique based on immuno-CL is suitable for the detection of several analyte in food and environmental samples.
Highlights
► Dipstick based immunochemiluminescence biosensor proposed for vitamin B12analysis. ► The limit of detection of vitamin B12is 1 ng mLand applied in energy drinks. ► Chemiluminescence generated was inversely proportional to vitamin B12concentration. ► Chemiluminescence analytical procedure was compared with ELISA. ► Alkaline phosphatase was stable chemiluminescent enzyme than Horse Radish Peroxidase.Novel Methods for the Quantification of(2E)-Hexadecenal by Liquid Chromatography with Detection by either ESI Q-TOF Tandem Mass Spectrometry or Fluorescence Measurement
15 February 2012, 00:36:22
Publication year: 2012
Source: Analytica Chimica Acta, Available online 13 February 2012
Anja Lüth, Corinna Neuber, Burkhard Kleuser
Sphingosine-1-phosphate lyase (SPL) is the only known enzyme that irreversibly cleaves sphingosine-1-phosphate (S1P) into phosphoethanolamine and(2E)-hexadecenal during the final step of sphingolipid catabolism. Because S1P is involved in a wide range of physiological and diseased processes, determining the activity of the degrading enzyme is of great interest. Therefore, we developed two procedures based on liquid chromatography (LC) for analysing(2E)-hexadecenal, which is one of the two S1P degradation products. After separation, two different quantification methods were performed, tandem mass spectrometry (MS) and fluorescence detection. However,(2E)-hexadecenal as a long-chain aldehyde is not ionisable by Electrospray Ionisation (ESI) for MS quantification and has an insufficient number of corresponding double bonds for fluorescence detection. Therefore, we investigated 2-diphenylacetyl-1,3-indandione-1-hydrazone (DAIH) as a derivatisation reagent. DAIH transforms the aldehyde into an ionisable and fluorescent analogue for quantitative analysis. Our conditions were optimised to obtain the outstanding limit of detection (LOD) of 1 fmol per sample (30 μL) for LC-MS/MS and 0.75 pmol per sample (200 μL) for LC determination with fluorescence detection. We developed an extraction procedure to separate and concentrate(2E)-hexadecenal from biological samples for these measurements. To confirm our new methods, we analysed the(2E)-hexadecenal level of different cell lines and human plasma for the first time ever. Furthermore, we treated HT-29 cells with different concentrations of 4-deoxypyridoxine (DOP), which competitively inhibits pyridoxal-5-phosphate (P5P), an essential cofactor for SPL activity, and observed a significant decrease in(2E)-hexadecenal relative to the untreated cells.
Source: Analytica Chimica Acta, Available online 13 February 2012
Anja Lüth, Corinna Neuber, Burkhard Kleuser
Sphingosine-1-phosphate lyase (SPL) is the only known enzyme that irreversibly cleaves sphingosine-1-phosphate (S1P) into phosphoethanolamine and(2E)-hexadecenal during the final step of sphingolipid catabolism. Because S1P is involved in a wide range of physiological and diseased processes, determining the activity of the degrading enzyme is of great interest. Therefore, we developed two procedures based on liquid chromatography (LC) for analysing(2E)-hexadecenal, which is one of the two S1P degradation products. After separation, two different quantification methods were performed, tandem mass spectrometry (MS) and fluorescence detection. However,(2E)-hexadecenal as a long-chain aldehyde is not ionisable by Electrospray Ionisation (ESI) for MS quantification and has an insufficient number of corresponding double bonds for fluorescence detection. Therefore, we investigated 2-diphenylacetyl-1,3-indandione-1-hydrazone (DAIH) as a derivatisation reagent. DAIH transforms the aldehyde into an ionisable and fluorescent analogue for quantitative analysis. Our conditions were optimised to obtain the outstanding limit of detection (LOD) of 1 fmol per sample (30 μL) for LC-MS/MS and 0.75 pmol per sample (200 μL) for LC determination with fluorescence detection. We developed an extraction procedure to separate and concentrate(2E)-hexadecenal from biological samples for these measurements. To confirm our new methods, we analysed the(2E)-hexadecenal level of different cell lines and human plasma for the first time ever. Furthermore, we treated HT-29 cells with different concentrations of 4-deoxypyridoxine (DOP), which competitively inhibits pyridoxal-5-phosphate (P5P), an essential cofactor for SPL activity, and observed a significant decrease in(2E)-hexadecenal relative to the untreated cells.
Highlights
► very sensitive tandem-MS method for(2E)-hexadecenal ► easily practicable HPLC/fluorescence detection method for(2E)-hexadecenal ► HPLC/fluorescen for the first time in the present sphingolipid research ► Derivatization with DAIH to generate a comfortable analyzable azine ► Determination of(2E)-hexadecenal level in biological samples for the first time everAssessment of a Geochemical Extraction Procedure to determine the Solid Phase Fractionation and Bioaccessibility of Potentially Harmful Elements is Soils: A case study using the NIST 2710 reference soil
15 February 2012, 00:36:22
Publication year: 2012
Source: Analytica Chimica Acta, Available online 13 February 2012
Joanna Wragg, Mark Cave
Three mineral acid sequential extraction regimes (HNO3only, HNO3followed by HCl and aqua regia) were applied to the NIST 2710 contaminated reference soil. The major and trace element chemical analysis data from the extractions were subjected to a chemometric self-modelling mixture modelling procedure which identified that 12 distinct physico-chemical components were extracted. The fractionation of As, Cd, Ni and Pb between these components were determined. Tentative assignments of the mineralogical sources of the components were made. The human ingestion bioaccessible fraction of As, Cd and Pb were determined using thein vitroBARGE UBM bioaccessibility test and were found to be 51.6%, 68.0% and 68.4% respectively. The relationship between the lability of the physico-chemical components and the bioaccessible fraction of the soils was investigated and the bioaccessible fractions were assigned to specific components. The extraction scheme using aqua regia was found to be the most suitable as it was the only one which extracted the iron sulphide phase in the soil.
Source: Analytica Chimica Acta, Available online 13 February 2012
Joanna Wragg, Mark Cave
Three mineral acid sequential extraction regimes (HNO3only, HNO3followed by HCl and aqua regia) were applied to the NIST 2710 contaminated reference soil. The major and trace element chemical analysis data from the extractions were subjected to a chemometric self-modelling mixture modelling procedure which identified that 12 distinct physico-chemical components were extracted. The fractionation of As, Cd, Ni and Pb between these components were determined. Tentative assignments of the mineralogical sources of the components were made. The human ingestion bioaccessible fraction of As, Cd and Pb were determined using thein vitroBARGE UBM bioaccessibility test and were found to be 51.6%, 68.0% and 68.4% respectively. The relationship between the lability of the physico-chemical components and the bioaccessible fraction of the soils was investigated and the bioaccessible fractions were assigned to specific components. The extraction scheme using aqua regia was found to be the most suitable as it was the only one which extracted the iron sulphide phase in the soil.
Highlights
► Three mineral acid extractions regimes were used. ► Self-modelling mixture resolution identified 12 distinct components. ► The human ingestion bioaccessible As, Cd and Pb fractions were measured. ► The bioaccessible fractions were assigned to specific physic-chemical components. ► The extraction scheme using a mixture of HCl and HNO3was found to work best.Chemiluminescence enzyme immunoassay using magnetic nanoparticles for detection of neuron specific enolase in human serum
15 February 2012, 00:36:22
Publication year: 2012
Source: Analytica Chimica Acta, Available online 13 February 2012
Xiaoling Fu, Meng Meng, Yu Zhang, Yongmei Yin, Xiangsheng Zhang, ...
To detect a biomarker for small cell lung carcinoma, neuron specific enolase (NSE), a sensitive and specific chemiluminescence enzyme immunoassay was developed. Fluorescein isothiocyanate (FITC) labeled NSE capture antibody connected with NSE and alkaline phosphatase (ALP) labeled NSE detection antibody in a sandwich-type detection manner. This immune complex was further reacted with anti-FITC coated magnetic beads. In a magnetic field, the complex was enriched, and the sensitivity was thus enhanced. The limit of detection (LOD) of this method was < 0.2 ng mL. The proposed immunoassay was highly selective, and not interfered by hook effect. The recovery was > 83.0% and the coefficient of variation was < 10.0%. Human sera from 120 patients were tested with the presented and traditional chemiluminescence enzyme immunoassay. An excellent linear relationship was obtained between two techniques. Overall, this immunoassay offers a promising alternative for NSE detection than traditional clinical examinations.
Source: Analytica Chimica Acta, Available online 13 February 2012
Xiaoling Fu, Meng Meng, Yu Zhang, Yongmei Yin, Xiangsheng Zhang, ...
To detect a biomarker for small cell lung carcinoma, neuron specific enolase (NSE), a sensitive and specific chemiluminescence enzyme immunoassay was developed. Fluorescein isothiocyanate (FITC) labeled NSE capture antibody connected with NSE and alkaline phosphatase (ALP) labeled NSE detection antibody in a sandwich-type detection manner. This immune complex was further reacted with anti-FITC coated magnetic beads. In a magnetic field, the complex was enriched, and the sensitivity was thus enhanced. The limit of detection (LOD) of this method was < 0.2 ng mL. The proposed immunoassay was highly selective, and not interfered by hook effect. The recovery was > 83.0% and the coefficient of variation was < 10.0%. Human sera from 120 patients were tested with the presented and traditional chemiluminescence enzyme immunoassay. An excellent linear relationship was obtained between two techniques. Overall, this immunoassay offers a promising alternative for NSE detection than traditional clinical examinations.
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