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Selected papers from the latest issue:
Characterization of interactions between organotin compounds and human serum albumin by capillary electrophoresis coupled with inductively coupled plasma mass spectrometry
19 February 2012, 00:53:36
Publication year: 2012
Source: Talanta, Available online 17 February 2012
Jing Sun, Bin He, Qian Liu, Ting Ruan, Guibin Jiang
Thermodynamic data such as the binding constants are vital parameters describing interactions between exotic trace compounds and biomolecules in biochemical property modeling. In this study, the stability constants of organometallic compound and protein complexes were studied by using capillary electrophoresis coupled with inductively coupled plasma mass spectrometry (CE-ICP-MS), considering its low detection limits and low sample demand. Four organotin compounds (trimethyltin (TMT), tripropyltin (TPrT), tributyltin (TBT), triphenyltin (TPhT)) and human serum albumin (HSA) were used as model organometallic compounds and protein, respectively. Affinity capillary electrophoresis (ACE) and nonequilibrium capillary electrophoresis assays of equilibrium mixtures (NECEEM) were performed and compared by using ICP-MS as the detector to determine the binding constants of organotin compounds and HSA in 1:1 molar ratio assumption. Constant measurements of the two methods were both simple, however, ACE assays were more accurate and more appropriate for the constant determination of the organotin-HSA complexes, considering the errors of the NECEEM method. A good precision of the binding constants (logKb) using the ACE method was proved by different mathematical calculations, and the values were 6.13 ± 0.51 (TMT), 5.72 ± 0.38 (TPrT), 5.68 ± 0.34 (TBT), 6.05 ± 0.38 (TPhT) respectively for each of the organotin-HSA complexes, showing non-covalent interaction between organotin compounds and HSA. Meanwhile, this study also confirms the suitability of CE-ICP-MS method for further studies on organometallic complexation.
Source: Talanta, Available online 17 February 2012
Jing Sun, Bin He, Qian Liu, Ting Ruan, Guibin Jiang
Thermodynamic data such as the binding constants are vital parameters describing interactions between exotic trace compounds and biomolecules in biochemical property modeling. In this study, the stability constants of organometallic compound and protein complexes were studied by using capillary electrophoresis coupled with inductively coupled plasma mass spectrometry (CE-ICP-MS), considering its low detection limits and low sample demand. Four organotin compounds (trimethyltin (TMT), tripropyltin (TPrT), tributyltin (TBT), triphenyltin (TPhT)) and human serum albumin (HSA) were used as model organometallic compounds and protein, respectively. Affinity capillary electrophoresis (ACE) and nonequilibrium capillary electrophoresis assays of equilibrium mixtures (NECEEM) were performed and compared by using ICP-MS as the detector to determine the binding constants of organotin compounds and HSA in 1:1 molar ratio assumption. Constant measurements of the two methods were both simple, however, ACE assays were more accurate and more appropriate for the constant determination of the organotin-HSA complexes, considering the errors of the NECEEM method. A good precision of the binding constants (logKb) using the ACE method was proved by different mathematical calculations, and the values were 6.13 ± 0.51 (TMT), 5.72 ± 0.38 (TPrT), 5.68 ± 0.34 (TBT), 6.05 ± 0.38 (TPhT) respectively for each of the organotin-HSA complexes, showing non-covalent interaction between organotin compounds and HSA. Meanwhile, this study also confirms the suitability of CE-ICP-MS method for further studies on organometallic complexation.
Highlights
► Kbof organotin-HSA complexes were determined by ACE-ICP-MS and NECEEM-ICP-MS. ► LogKbvalues between organotin compounds and HSA were in the range of 5.68-6.13. ► The interactions between tin compounds and HSA were non-covalent and reversible.The discrimination between phospholipids of diverse structure and phosphacoumarins of various hidrophobicity through fluorescent response of Tb-doped silica nanoparticles decorated by cationic surfactant
19 February 2012, 00:53:36
Publication year: 2012
Source: Talanta, Available online 17 February 2012
Olga D. Bochkova, Asiya R. Mustafina, Alsu R. Mukhametshina, Vladimir A. Burilov, Andrey V. Nemtarev, ...
The work represents colloids of silica nanoparticles displaying fluoresecent response on biorelevant compounds exemplified by phosphacoumarins and phospholipids. The luminescent properties of the colloids arise from Tb(III) complexes doped into silica nanoparticles (SNs). The noncovalent decoration of SNs by dicationic surfactant with further interfacial binding of dye anions enables to develop colloids programmed to display a substrate induced fluorescent response. The latter results from the quenching of Tb(III) centered luminescence by dye anions through dynamic mechanism and subsequent displacement of quenching anions by the non-quenching substrates from the interface of SNs. Both negative charge and hydrophobicity of substrates are the key factors affecting the selectivity of the substrate induced fluorescent response. The peculiar effects of zwitter-ionic and anionic phospholipids on the fluorescent response have been revealed. The applicability of the fluorescent procedure in the sensing of impurities in commercial phosphatidylcholine is also introduced
Source: Talanta, Available online 17 February 2012
Olga D. Bochkova, Asiya R. Mustafina, Alsu R. Mukhametshina, Vladimir A. Burilov, Andrey V. Nemtarev, ...
The work represents colloids of silica nanoparticles displaying fluoresecent response on biorelevant compounds exemplified by phosphacoumarins and phospholipids. The luminescent properties of the colloids arise from Tb(III) complexes doped into silica nanoparticles (SNs). The noncovalent decoration of SNs by dicationic surfactant with further interfacial binding of dye anions enables to develop colloids programmed to display a substrate induced fluorescent response. The latter results from the quenching of Tb(III) centered luminescence by dye anions through dynamic mechanism and subsequent displacement of quenching anions by the non-quenching substrates from the interface of SNs. Both negative charge and hydrophobicity of substrates are the key factors affecting the selectivity of the substrate induced fluorescent response. The peculiar effects of zwitter-ionic and anionic phospholipids on the fluorescent response have been revealed. The applicability of the fluorescent procedure in the sensing of impurities in commercial phosphatidylcholine is also introduced
Highlights
► substrate responsive colloids based on silica coated Tb(III) complexes ► interfacial displacement of quenching anions by substrates induces fluorescent response of SNs ► the hydrophobicity of anionic substrates guides the selectivity of fluorescent response ► anionic phospholipids provide fluorescent response with detection limit being 0.008 g/L ► anionic impurities in phosphatidylcholine can be detected by fluorescent responseDetermination of carboxylic acids in water by gas chromatography-mass spectrometry after continuous extraction and derivatisation
19 February 2012, 00:53:36
Publication year: 2012
Source: Talanta, Available online 17 February 2012
Beatriz Jurado-Sánchez, Evaristo Ballesteros, Mercedes Gallego
This paper describes a new approach for the determination of monocarboxylic, dicarboxylic and tricarboxylic acids (35 compounds) in water. The analytes, in acid medium (pH ∼1.3), were sorbed on an 80 mg LiChrolut EN − Supelclean ENVI-18 (1:1) column and subsequently eluted with methanol. After evaporation of the extract to ∼10 μL, the analytes were spiked with 60 μL of the derivatising reagent and derivatised in a household microwave oven for 3 min. Among the reagents tested (BF3/1-butanol; acetyl chloride/1-butanol; isobutyl chloroformate/1-butanol; trimethylphenylammonium hydroxide,N,O-bis-(trimethylsilyl)acetamide,N,O-bis-(trimethylsilyl)trifluoroacetamide and trimethylchlorosilane), the best results in terms of reaction yield and stability of the derivatives were obtained with the mixture of 1% trimethylchlorosilane inN,O-bis-(trimethylsilyl)trifluoroacetamide. Microwave assisted derivatisation was used as an alternative heating approach for the rapid silylation of carboxylic acids. The proposed method proved to be a suitable analytical procedure for several types of carboxylic acids in water, with limits of detection within the range 0.6 − 15 ng L, precision values from 4.0 to 6.0% (as within-day relative standard deviation) and recoveries from 93 to 101% for all the target analytes.
Source: Talanta, Available online 17 February 2012
Beatriz Jurado-Sánchez, Evaristo Ballesteros, Mercedes Gallego
This paper describes a new approach for the determination of monocarboxylic, dicarboxylic and tricarboxylic acids (35 compounds) in water. The analytes, in acid medium (pH ∼1.3), were sorbed on an 80 mg LiChrolut EN − Supelclean ENVI-18 (1:1) column and subsequently eluted with methanol. After evaporation of the extract to ∼10 μL, the analytes were spiked with 60 μL of the derivatising reagent and derivatised in a household microwave oven for 3 min. Among the reagents tested (BF3/1-butanol; acetyl chloride/1-butanol; isobutyl chloroformate/1-butanol; trimethylphenylammonium hydroxide,N,O-bis-(trimethylsilyl)acetamide,N,O-bis-(trimethylsilyl)trifluoroacetamide and trimethylchlorosilane), the best results in terms of reaction yield and stability of the derivatives were obtained with the mixture of 1% trimethylchlorosilane inN,O-bis-(trimethylsilyl)trifluoroacetamide. Microwave assisted derivatisation was used as an alternative heating approach for the rapid silylation of carboxylic acids. The proposed method proved to be a suitable analytical procedure for several types of carboxylic acids in water, with limits of detection within the range 0.6 − 15 ng L, precision values from 4.0 to 6.0% (as within-day relative standard deviation) and recoveries from 93 to 101% for all the target analytes.
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