Selective preconcentration of Lanthanum(III) by Coriolus versicolor immobilised on Amberlite XAD-4 and its determination by ICP-OES

Coriolus versicolor, a wood fungus, was immobilised on Amberlite XAD-4 and used as solid-phase biosorbent for preconcentrations of rare earth elements. La(III), Th(IV), U(IV) and Ce(III) were subjected to solid-phase extraction procedure. We observed that La(III) was selectively preconcentrated, while other ions remained in solution at pH 6.0. 5.0 mL of 1.0 mol L^?1 HCl was used to elaute La(III) from column. 250 mg of C. versicolor loaded on 1000 mg of XAD-4 was optimised as solid-phase matrix. Concentrations of ions in solutions were determined by inductively coupled plasma– optical emission spectrometry (ICP-OES). The calibration plot after preconcentration was linear in the range from 1.0 to 50.0 ng mL^?1 for La(III). Limit of detection was found as 0.27 ng mL^?1 for La(III) by SPE method. Relative standard deviation was found lower than 6.7% for 1.0 ng mL^?1 of La(III) solution (n = 10). The sensitivity of ICP-OES was improved by a factor of 46.8. The applicability of the method was validated through the analysis of certified reference samples of tea (NCS ZC-73014) and spinach (NCS ZC-73013).     

A new internal quality control chart based on biological variation

The instruments and analytical methods currently used in clinical laboratories today have better precision and stability than those used in the past. With the development of chemical and immunological methods and instrumentation technology, test precision has increased. However, the application of the Westgard multirule procedure to control sera in the Levey-Jennings chart may not be useful or cost-effective. We devised a new test-specific decision limit for accepting or rejecting runs based on the data of within-subject biological variation and prepared a control chart. We then applied these new limits and control chart to a group of tests performed in our laboratory. With the exception of the tests for albumin, total protein, and calcium, for which desirable performance standards could not be attained with the current technology and methodology, the application of these control limits was cost-effective and convenient. It is estimated that the value of healthy within-subject biological variations is constant, irrespective of the methodology, the area in which the study has been performed, and the number of subjects included in the study. We believe that control limits based on biological variation are reliable and cost-effective, and may be useful in modern and accredited laboratories.     

Synthesis, interface (Au/M2Pc2/p-Si), electrochemical and electrocatalytic properties of novel ball-type phthalocyanines

The phthalodinitrile derivative (3) was prepared by the reaction of 4,4'-(octahydro-4,7-methano-5H-inden-5-ylidene)bisphenol (1) and 4-nitrophthalonitrile (2) with dry DMF as the solvent in the presence of the base K(2)CO(3) by the method of nucleophilic substitution of an activated nitro group in an aromatic ring. The template reaction of 3 with the corresponding metal salts gave the novel bi-nuclear ball-type metallophthalocyanines, MPcs {M = Co (4), Cu (5), Zn (6)}. Newly synthesized compounds were characterized by elemental analysis, UV-vis, FT-IR (ATR), MALDI-TOF mass and (1)H-NMR spectroscopy techniques. The electronic spectra exhibit an intense π→π* transition of characteristic Q and B bands of the Pc core. The dielectric properties and interface between the spin coated films of 4-6 and a p-type silicon substrate have been studied by fabricating metal-insulator-semiconductor capacitors. The results indicated that the frequency dependence of the dielectric permittivity, ε'(ω), exhibits non-Debye type relaxation for all the temperatures investigated. The ac conductivity results indicated that the conduction mechanism can be explained by a hopping model at low temperatures (<430 K) and a free band conduction mechanism at high temperatures (≥430 K). The density of interface state calculations on these novel compounds showed that the combination of Au/4/p-Si is a promising structure with a high dielectric constant and a low interface trap density suitable for metal-oxide-semiconductor devices. The electrochemical properties of the Pc complexes were examined by cyclic voltammetry, differential voltammetry and controlled potential coulometry on platinum in non-aqueous media. The complexes showed ring-based and/or metal-based mixed-valence behaviours as a result of the remarkable interaction between the two Pc rings and/or metal centres. The mixed-valence splitting values for the complexes suggested that the mixed valence species are considerably stable. The Vulcan XC-72(VC)/Nafion(Nf)/4 modified glassy carbon electrode showed much a higher catalytic performance towards oxygen reduction than those of VC/Nf/5 and VC/Nf/6 modified ones.     

Towards standardization of external quality assessment schemes by using bias values based on biological variation

The precision and trueness of current instruments and methods in clinical laboratories is much better than in the past. However, the z-score and other comparison variables that are currently used in external quality assessment programs are based on relative data. Thus, they may change from program to program and also change over time within the same program and consequently may not be useful or cost-effective. We therefore devised a test-specific decision limit for accepting or rejecting test results based on a combination of the data of within- and between-subject biological variations. We then applied these limits to a group of tests performed in our laboratory and compared our results with those of external quality assessment programs. In addition, we combined external and internal quality control data on the same graph and prepared a two-dimensional graph for different levels of control sera. Inspection of all results of control sera on this new graph was more useful for decision making. We concluded that the z-score is not reliable for comparisons of test results in external quality assessment. As a substitute for this currently accepted practice, we assert that control limits based on biological variation are more reliable, and can be useful in the evaluation of both external and internal quality assessments and their combination on this new graph.