Analytical procedure for the determination of As, Cd, Cu, Ni, Co and Cr in marine biota samples using solid sampling high-resolution continuum source atomic absorption spectrometry (HR CS AAS) and accelerated fast temperature programmes has been developed. Calibration technique based on the use of solid certified reference materials similar to the nature of the analysed sample and statistics of regression analysis were applied. A validation approach in line with the requirements of ISO 17025 standard and Eurachem guidelines was followed. Accordingly, blanks, selectivity, calibration, linearity, working range, trueness, repeatability and reproducibility, limits of detection and quantification and expanded uncertainty for all investigated elements were assessed. The major contributors to the combined uncertainty of the analyte mass fractions were found to be the homogeneity of the samples and the microbalance precision. Traceability to the SI system of units of the obtained with the proposed analytical procedure results was also demonstrated. The potential of the proposed analytical procedure based on solid sampling HR CS AAS technique was demonstrated by direct analysis of marine reference biota samples. Overall, the use of solid sampling HR CS AAS permits obtaining significant advantages for the determination of selected trace elements in marine biota samples, such as straightforward calibration, a high sample throughput, sufficient precision, a suitable limit of detection and reduced risk of analyte loss and contamination. 相似文献
Four dithiooxalato (Dto) bridged one-dimensional Ni(ll) and Ni(ll)Cu(ll) complexes (Me6[14]dieneN4)Ni2(Dto)2) (1), (Me6[14]dieneN4)CuNi(Dto)2 (2), (Me6[14]aneN4)Ni2(Dto)2 (3), and (Me6[14]aneN4)CuNi(Dto)2(4), were synthesized. These complexes have been characterized by elemental analysis, IR, UV and ESR spectra. The crystal structure of complex 3 was determined. It crystallizes in the monoclinic system, space group C2/c with a = 2.2425(4) nm, b = 1.0088(2) nm, c=1.4665(3) nm, β= 125.32(3)° ;Z=4; R = 0.076, Rw = 0.079. In the complex, Ni(1) coordinates four sulphur atoms of two Dto ligands in plane square environment. Ni(2) lies in the center of mac-rocyclic ligand. For Dto ligand, two sulphur atoms coordinate Ni(1), and O(1) coordinates Ni(2) and forms weak coordination bond. O(2) is linked to N(2) of macrocyclic ligand through hydrogen bond. 相似文献
The reactions of 18-crown-6 with Na2[M(SCN)4] (M= Pd,Pt) were studied and the complex 1 [{Na(18-C-6)}2(H2O)]n[Pd(SCN)4]n and complex 2 [{Na(18-C-6)}2(H2O)]n[Pt(SCN)4]n were characterized by ele-mental analysis, IR and X-ray diffraction analysis. The complexes belong to monoclinic, space group P21/n with cell dimensions, 1:a=1.05734(7),b=1.42250(10),c=1.47762(10) nm,β=107.5330(10)°,V=2.1192(2)nm3,Z=2,Dcalcd=1.460g·cm-3,F(000)=964,R1=0.0406,wR2=0.1264 and 2:a=1.05985(19),b=1.4237(3),c=1.4744(3) nm,β=107. 096(3)°, V=2.1264(7)nm3,Z=2,Dcalcd=1.690g·cm-3,F(000)=1028,R1=0.0292,wR2=0.0859. In the solid state, the complexes 1 and 2 show an one-dimensional chain of [{Na(18-C-6)}2(H2O)]2+ complex cations and [M(SCN)4]2- (M=Pd,Pt) complex anions bridged by Na-N in-teractions. 相似文献
We consider particles in d, d2, interacting via attractive pair and repulsive four-body potentials of the Kac type. Perturbing about mean-field theory, valid when the interaction range becomes infinite, we prove rigorously the existence of a liquid–gas phase transition when the interaction range is finite but long compared to the interparticle spacing for a range of temperature. 相似文献
A ``-rule" is a sequence of pairwise disjoint sets , each of cardinality and subsets . A subset (a ``real') follows a rule if for infinitely many , .
Two obvious cardinal invariants arise from this definition: the least number of reals needed to follow all -rules, , and the least number of -rules with no real that follows all of them, .
Call a bounded rule if is a -rule for some . Let be the least cardinality of a set of bounded rules with no real following all rules in the set.
We prove the following: and for all . However, in the Laver model, .
An application of is in Section 3: we show that below one can find proper extensions of dense independent families which preserve a pre-assigned group of automorphisms. The original motivation for discovering rules was an attempt to construct a maximal homogeneous family over . The consistency of such a family is still open.
Some previous results of the author towards a classification of homogeneous metric continua are improved. The disjoint arcs property is fully revealed in this context. In particular, closed -manifolds, , are characterized as those homogeneous continua which do not have the disjoint arcs property.