A simple and sensitive method with a fast sample preparation procedure is proposed for the determination of mercury species in plasma/serum. The method combines online high-performance liquid chromatography separation, Hg cold-vapor formation and inductively coupled plasma mass spectrometry detection. Prior to analysis, plasma (250 μL) was accurately pipetted into 15 mL conical tubes. Then, an extractant solution containing mercaptoethanol, L-cysteine and HCl was added to the samples following sonication for 10 min. Quantitative mercury extraction was achieved with the proposed procedure. Separation of mercury species was accomplished in less than 8 min on a C8 reverse phase column with a mobile phase containing 3% v/v methanol + 97% v/v (0.5% v/v 2-mercaptoethanol + 0.05% v/v formic acid). The method detection limits were found to be 12 ng L−1, 5 ng L−1 and 4 ng L−1 for inorganic mercury, ethylmercury and methylmercury, respectively. Method accuracy is traceable to Standard Reference Material (SRM) 966 Toxic Metals in Bovine Blood from NIST. Additional validation was provided by the analysis of a secondary reference serum sample from the INSQ-Canada. Finally, the method was successfully applied for the speciation of mercury in plasma samples collected from volunteers exposed to methylmercury through fish consumption. For the first time to our knowledge, levels of different species of Hg in plasma samples from riverside populations exposed to MeHg were determined. 相似文献
The N‐acyl thiourea complexes bis[N,N‐diethyl‐N′‐(p‐nitrobenzoyl)‐thioureato]copper(II) ( 1a,1b ) and bis(N,N‐diphenyl‐N′‐benzoylthioureato)copper(II) ( 2a,2b ) crystallize in each case in two modifications. X‐ray structural analysis shows that 1a and 1b are cis‐trans isomers. This is very unusual for N‐acyl thioureato complexes because with exception of one platinum(II) complex up to now only cis complexes have been found. In contrast X‐ray structural analysis of both forms 2a and 2b of the other complex shows no cis‐trans pair. Both modifications are cis complexes. In solution both isomers of the copper(II) complexes are observable by EPR spectroscopy. 相似文献
From blue to red: While four π‐conjugated nitrophenolates absorb within a relatively narrow region in solution, they cover the entire visible spectrum when isolated in vacuo (see picture). The work combines gas‐ and solution‐phase spectroscopy and provides the first benchmark of theoretical excitation energies for nitrophenolates.
The determinant of the n×n matrix associated with the finite-difference operator μδ2r+1 is obtained explicitly for all n and all integral r?0. An interesting combinatorial identity results. 相似文献
A direct correlation between aromaticity and the thermodynamic stability in the tautomeric equilibrium of 3,3′-(1,4-phenylene)bis(pentane-2,4-dione) is studied using experimental methods and theoretical approaches. According to the results, the most abundant tautomer corresponds to the bis-β-keto-enol tautomer when conditions such as temperature, solvent polarity, and pH are deliberately changed. Theoretical results of aromaticity analysis showed good concordance with the experimental results, using rigorous computations such as induced magnetic field (Bind) and free of in-plane component NICS (FIPC-NICS). 相似文献
Complexes [Ru(η6−C10H14)(Cl2)(HdmoPTA)](OSO2CF3) ( 1 ), [Ru(η6−C10H14)(Cl2)(dmoPTA)] ( 2 ) and [Ru(η6−C10H14)(Cl2)-μ-dmoPTA-1κP:2κ2N,N’-MCl2] (M=Zn ( 3 ), Co ( 4 ), Ni ( 5 ), dmoPTA=3,7-dimethyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane) have been synthesized and characterized by elemental analysis and spectroscopic techniques. The crystal structures of 1 , 3 and 5 were obtained by single-crystal X-ray diffraction. The antiproliferative activity of the complexes was evaluated against colon cancer cell line Caco-2/TC7 by using the MTT protocol. The monometallic ruthenium complexes 1 and 2 were found to be inactive, but the bimetallic complexes 3 , 4 and 5 display an increased activity (IC50 3 : 9.07±0.27, 4 : 5.40±0.19, 5 : 7.15±0.30 μM) compared to cisplatin (IC50=45.6±8.08 μM). Importantly, no reduction in normal cell viability was observed in the presence of the complexes. Experiments targeted to obtain information on the possible action mechanism of the complexes, such as cell cycle, ROS and gene expression studies, were performed. The results showed that the complexes display different properties and action mechanism depending on the nature of metal, M, bonded to the CH3NdmoPTA atoms. 相似文献
We present zero and longitudinal field μ SR measurements of single crystal and polycrystalline specimens of the heavy fermion
compound CePt2Sn2. Above 1 K the behaviour of the two samples is indistinguishable; the muon 1/T_1 increases with decreasing temperature until
25 K when it plateaus. The 1/T_1 relaxation rate differs strongly for the two cases below \sim\,0.8\ K. At 0.1 K a rate of
about 20 μ s-1 is seen in the polycrystal while in the single crystal it is only about 5 μ s-1. Even more revealing is the fact that longitudinal field decoupling spectra at very low temperatures demonstrate an essentially
static spin system to be present in the polycrystalline material while the single crystal shows definite dynamic spin properties.
We conclude that, in the presence of the distortion, long range magnetic order occurs below 0.9 K while in tetragonal symmetry
long range order is suppressed (probably due to frustration) and spin fluctuations remain for T\rightarrow0.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献