Chemiluminescence immunoassay for the detection and quantification of methyltestosterone residues in muscle tissue

Chemiluminescence as a detection method for immunoassay has successfully been applied to the measurement of methyltestosterone (MT) residues in muscle tissue. The sample is digested enzymatically, extracted with diethyl ether and purified on a Lipidex-5000 column. An optional clean-up utilized disposable C18 columns. As the luminescent label the N-(4-aminobutyl)-N-ethylisoluminol conjugate of MT was used. The antiserum was raised in a rabbit against MT-3-carboxymethyloxime-bovine serum albumin. The detection limit of the assay was 14 +/- 7 pg (n = 13), with a limit of quantification in muscle tissue of 0.125 ppb.     

Further solvent-free reactions of ferrocenylaldehydes: Synthesis of 1,1′-ferrocenyldiimines and ferrocenylacrylonitriles

Grinding of 1,1′-ferrocenedicarboxaldehyde with a 2.2 molar equivalent of an aromatic amine in a solvent-free environment provided excellent yields of 1,1′-ferrocenyldiimines. After mixing the aldehyde and amines, a gum or melt formed which eventually solidified to the product. An analytically pure sample of the product was obtained by cold recrystallization. Grinding of ferrocenecarboxaldehyde and 4-substituted phenylacetonitriles under solvent-free conditions provided good yields of the corresponding ferrocenylacrylonitriles. The yield in this reaction was very low when the substituent group para to the acetonitrile group was electron-donating.     

The purity of laboratory chemicals with regard to measurement uncertainty

The purity P of laboratory chemicals is often declared in the form P > or = xy% (e.g., P > or = 97%). With a randomly chosen set of 40 compounds we found that their purity is generally closer to 100% than to the lower limit. The distribution of the purity data as found in the laboratory depends on the analytical technique used. Whereas purities determined by chromatography do not exceed 100% (because the sum of all observed peak areas is set to 100%), the purities obtained by titration can exceed 100% (because the functionality of the compound is measured). Therefore, the data for these two groups need to be dealt with in different ways. For purities based on titration we propose to use a rectangular distribution with a range from Pmin to 101%, an expected purity value which is the mean and a standard uncertainty of the purity u(P) of 29% of the range. Purities determined by chromatography can be described with a triangular distribution (ramp function). One leg of the triangle represents the range from Pmin to 100% and the right-angle is located at 100%. The expected value is the median and the uncertainty u(P) is 24% of the range. These proposals match the experimental data well.     

Evidence of the Zn vacancy acting as the dominant acceptor in n-type ZnO

We have used positron annihilation spectroscopy to determine the nature and the concentrations of the open volume defects in as-grown and electron irradiated (E(el)=2 MeV, fluence 6 x 10(17) cm(-2)) ZnO samples. The Zn vacancies are identified at concentrations of [V(Zn)] approximately 2 x 10(15) cm(-3) in the as-grown material and [V(Zn)] approximately 2 x 10(16) cm(-3) in the irradiated ZnO. These concentrations are in very good agreement with the total acceptor density determined by temperature dependent Hall experiments. Thus, the Zn vacancies are dominant acceptors in both as-grown and irradiated ZnO.     

An Approach for Microprobe Measurement and Modeling for Millimeter-Wave Application

This paper describes a simple method to check the performance of microprobe. The two-port S-parameters of the microprobe are determined by one-port S-parameters measurement using HP 8510XF Network Analyzer. Based on the measurement, an equivalent circuit model for the microprobe is presented and good agreement between the measurement results and modeling results is obtained.     

Electron and hole conductivity in CuInS2

Single crystals of CuInS₂ have been grown from the melt and annealed in In or S to produce good n- or p-type conductivity, respectively. Two donor levels, one shallow and one deep (0.35 eV), and one acceptor level at 0.15 eV are identified. The hole-mobility data are best fitted with an effective mass $\text{m}{}_{\mathrm{<mtext>p</mtext>}}\text{1?1.3m}{}_{\mathrm{e}}$, which can be explained by simple, two band $\text{k}$. $\text{p}$ theory if the valence band has appreciable d character. Above 300°K, the hole mobility falls rapidly, evidently due to multiband conduction and/or interband scattering between the nondegenerate and degenerate valence bands. The conduction band mobility appears to be dominated, in many samples, by large concentrations ( >10¹⁸cm^?3) of native donors and acceptors, which are closely compensated.     

A comparison of chemiluminescence immunoassay and radioimmunoassay for the detection of nortestosterone residues in meat samples

A chemiluminescence immunoassay, with a nantiserum raised against 19-nortestorone-3- carboxymethyloxime/bovine serum albumin and the N-(4-aminobutyl)-N-ethylisoluminol conjugate of 19-nortestosterone as tracer is compared to a radioimmunoassay, with an antiserum against 19-nortestosterone-17-hemisuccinate/bovine serum albumin and 19-(6,7-³H) nor testosterone as the radioactive label. Both methods have a similar sensitivity but the limit of quantification is much lower for radioimmunoassay (0.08 μg kg^-1) than for chemiluminescence immunoassay (0.6 μg kg^-1). A more practical appraoch, the limit of decision, is defined which is determined by the analytical results obtained from certified blank reference samples. This concept gives a good qualitative agreement between the two immunoassay techniques and the number of false positive and negative results, as ascertaind by GC/MS, is minimized; this is shown for assays of 38 meat samples.