Fabric phase sorptive extraction/GC‐MS method for rapid determination of broad polarity spectrum multi‐class emerging pollutants in various aqueous samples

A rapid extraction and cleanup method using selective fabric phase sorptive extraction combined with gas chromatography and mass spectrometry has been developed and validated for the determination of broad polarity spectrum emerging pollutants, ethyl paraben, butyl paraben, diethyl phthalate, dibutyl phthalate, lidocaine, prilocaine, triclosan, and bisphenol A in various aqueous samples. Some important parameters of fabric phase sorptive extraction such as extraction time, matrix pH, stirring speed, type and volume of desorption solvent were investigated and optimized. Calibration curves were obtained in the concentration range 0.05–500 ng/mL. Under the optimum conditions, the limits of detection were in the range 0.009 –0.021 ng/mL. This method was validated by analyzing the compounds in spiked aqueous samples at different levels with recoveries of 93 to 99% and relative standard deviations of <6%. The developed method was applied for the determination of the emerging contaminants in tap water, municipal water, ground water, sewage water, and sludge water samples. The results demonstrate that fabric phase sorptive extraction has great potential in the preconcentration of trace analytes in complex matrix.     

Dynamic heterogeneities in a simple liquid over different time scales

The heterogeneous features of the supercooled state over different time regimes are explored in a self-consistent mode-coupling mode. The exponent a for the mean-square displacement approximately t(a), of a tagged particle is computed. The non-Gaussian parameter alpha(2)(t) shows a peak in the short time regime in addition to a second peak over longer times. The position of the short-time peak in alpha(2)(t) hardly shifts, while that of the other grows with density.     

Rate acceleration and diastereoselectivity in chelation-controlled indium-promoted Barbier allylation of pyridine-2- and quinoline-2-imines in aqueous solvents

The imines generated in situ from 2-pyridinecarboxaldehyde/2-quinolinecarboxaldehyde and aryl amines undergo indium-mediated Barbier allylation in aqueous media to provide homoallylic amines. Crotyl and cinnamyl bromides lead to diastereoselective allylation with d.r. up to 98:2.     

Preparation and characterization of diphenyllead(IV) and triphenyllead(IV) complexes with N-protected amino-acids and the dipeptides

The diphenyllead(IV) derivatives of N-benzoyl-(glycine, DL -alanine); N-formyl and N-acetyl-L -phenylalanine; N-monochloroacetyl-L -phenylalanine; N-benzoyl-(glycylglycine, DL -alanylglycine), and N-formyl- N-acetyl- and N-monochloroacetyl-(L -phenylalanylglycine) have been prepared in 1:2 molar ratio by reaction of diphenyllead dichloride with the appropriate amino-acid or dipeptide. Corresponding triphenyllead(IV) derivatives have been prepared in 1:1 molar ratio by reaction of triphenyllead chloride with the thallium(I) salts of the amino-acid or the dipeptide. These complexes have been characterized by elemental analysis, IR and ¹H NMR spectral studies. A polymeric hexacoordinated octahedral structure for diphenyllead(IV), and a five-coordinated distorted trigonalbipyramidal chain-type structure for triphenyllead(IV), complexes is confirmed by IR spectra. The carboxylate group acts in a bidentate manner, not as in diorgano and triorganotin(IV) complexes with these acids, where it is monodentate. The available bonding sites such as amide and peptide carbonyl (CO) and amide and peptide nitrogen atoms are not involved in bonding with lead (IV) and thus are available for bonding with the biological systems. The presence of different N-protecting groups does not affect the coordination sites around lead(IV). The triphenyllead(IV) compounds are relatively more stable than the diphenyllead(IV) compounds.     

Progress in Boronic Acid-Based Fluorescent Glucose Sensors

Effective management of diabetes relies on the frequent monitoring of blood glucose concentrations. The current approach of blood sampling and glucose concentration determination in vitro) presents many problems. Therefore, there is a drive for the development of non-invasive and continuous monitoring of glucose concentrations. The use of implanted glucose fluorescent sensors represents a promising approach. Due to its strong interaction with diol moieties, the boronic acid group often plays a critical role in the design of such glucose sensors. This paper reviews the progress in this area during the last ten years.     

Mixed micelles of benzyldimethyltetradecylammonium chloride with tetradecyltrimethylammonium and tetradecyltriphenylphosphonium bromides: a head group contribution

Mixed micelle formation by tetradecyltrimethylammonium (TTAB) and tetradecyltriphenylphosphonium bromides (TTPB) with benzyldimethyltetradecylammonium chloride (BTDACl) was studied with the help of conductivity and Kraft point measurements. The BTDACl + TTAB mixtures showed synergistic interactions whereas those of BTDACl + TTPB indicated weak antagonistic behavior. From Kraft temperature measurements, the enthalpy of fusion (H(1)(0)) from solid hydrated BTDACl to the liquid state in the presence of TTAB or TTPB was computed. It was found that DeltaH(1)(0) was much more positive for BTDACl + TTPB than for BTDACl + TTAB mixtures.     

Head-group-modification-controlled mixing behavior of binary cationic surfactants: conductometric,viscometric, and NMR studies

The mixed-micelle formation by hexadecyltrimethylammonium bromide (HTAB) with hexadecyltriphenylphosphonium bromide (HTPB) and hexadecyltributylphosphonium bromide (HTBB), and by hexadecylpyridinium bromide (HPyBr) with HTPB and HTBB has been studied with the help of conductivity, viscometry, and NMR studies. The conductivity studies showed close-to-ideal mixing in all cases with weak synergistic interactions. The relative viscosity is more sensitive than the conductivity and demonstrated that the micellization of HTAB, HPyBr, HTPB, and HTBB proceeded through the appearance of a minimum, whereas their mixtures showed a strong maximum in each case. NMR measurements suggested that bulky head groups of HTPB and HTBB induce significant steric hindrance in the mixed state upon mixing with HTAB and HPyBr. The appearance of the maximum shown by the relative viscosity in the mixed-micellization process is due to steric compulsions, which may also lead to some structural transitions.     

Remarkable effect of amide substituents on molecular organisation of silver selective pyridine-diamide-diester receptors

The structures of Ag selective 1 show that methyl and benzyl substituent at amide nitrogen in 1c and 1d induce optimal molecular organisation and electron rich character in the parent, electron deficient, water coordinated macrocycle 1 a. Whereas bulky benzyl substituent and longer spacer cause much molecular disorganisation in 1f.     

Preparation of metal bromoacetates from other salts by Solvolytic reactions in fused monobromoacetic acid

Solvolytic reactions between monobromoacetic acid and metal oxides, carbonates, oxalates, formates, sulphites, nitrates, nitrites and chlorides form monobromoacetates. In the case of transition metals, a molecule of solvent is also attached to the solvolysed products. The solvolysed products have been investigated by IR, magnetic susceptibility and molar conductance measurements. Lewis bases form adducts with these products. The solvolytic reactions have been explained on the bases of autoionization of monobromoacetic acid reported earlier¹ as, 2CH₂BrCOOH ? CH₂BrCOOH₂⁺+ CH₂BrCOO^?.     

Spectrophotometric determination of beryllium with carminic acid

Summary A new reagent has been proposed for the determination of beryllium. The method is based on the reaction between beryllium and carminic acid, forming a Be-carminic acid complex at pH 4. The absorption is measured at 580 nm. The molar absorptivity is 2.25×10³ mol^–1 cm^–1. Beer's law is obeyed from 0.4 ppm to 1.6 ppm of beryllium. The effects of pH, reagent concentration and interferences from foreign ions have been studied. The method has been applied to the determination of beryllium in polluted water and blood samples.

---

Spektralphotometrische Bestimmung von Beryllium mit CarminsÄure