Determination of tetraethyllead and tetramethyllead using high performance liquid chromatography and electrochemical detection

Summary A new method for the separation of tetramethyllead (TML) and tetraethyllead (TEL) was developed using high-performance liquid chromatography. The electrochemical detection was examined with different electrodes. Amperometric and pulse-amperometric techniques were investigated and the optimal working potential for each electrode was determined. Linearity for the glassy carbon electrode was observed between 350 ng and 30 g; the detection limit is 310 ng (TML) resp. 340 ng (TEL). In case of the mercury gold electrode the linearity range was 300 g–3 g and the detection limit 1.5 m (TML) resp. 1.7 g (TEL).     

Human prostate specific antigen (hPSA) purification and establishment of hPSA radioimmunoassay

Human prostate specific antigen (hPSA) RIA was developed with hPSA and anti-PSA prepared in our laboratory. Its standard curve was linear with a sensitivity of 0.5 g/L. Serum PSA levels of 130 normal males ranged from 0 to 3.5 g/L (1.15±0.93 g/L), which are consistent with the results of other conventional RIA. The recovery, intra- and inter-assay coefficients of variation conform to the demands of RIA, and the results of 41 samples obtained by both the PSA RIA and PSA RIA of DPC were well correlated (=0.990). PSA level of 23 patients with prostatic carcinoma was 10400 g/L.     

Zur Bestimmung N-substituierter Aniline mit Natriumchlorit

Zusammenfassung Es wird eine photometrische Bestimmungsmethode beschrieben für Anilin (40–720 g/ml), Monoäthylanilin (90–1650 g/ml) und Diäthylanilin (100–1600 g/ml) mit Natriumchlorit in äthanolisch-wäßrigen Lösungen, sowie für Diäthylanilin (85–1140 g/ml) und Dimethylanilin (30–330 g/ml) neben den primären und sekundären Aminen in essigsaurer Lösung mit demselben Reagens. Das Verfahren liefert gute Ergebnisse.

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Summary A photometric procedure is described for the determination of aniline (40–720 g/ml), monoethylaniline (90–1650 g/ml), and diethylaniline (100–1600 g/ml) with sodium chlorite in aqueous ethanolic solutions and of diethylaniline (85–1140 g/ml) and dimethylamline (30 to 330 g/ml) in presence of the primary and secondary amines in acetic acid solution using the same reagent. Good results have been obtained,

     

Semiquantitative estimation of the mycotoxins citrinin, Ochratoxin A, Aflatoxin M1 and penicillic acid on thin-layer chromatograms with a grey scale

Summary Spots of citrinin, ochratoxin A, aflatoxin M₁ and penicillic acid on thin-layer chromatograms can be semi-quantitatively estimated by using a grey scale, commonly used in photo laboratories. The detection limits are 0.01 g for citrinin, 0.006 g for ochratoxin A, 0.002 g for aflatoxin M₁ and 0.01 g for penicillic acid. Standard curves for these mycotoxins are given.

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Halbquantitative Bestimmung der Mycotoxine Citrinin, Ochratoxin A, Aflatoxin M₁ und Penicillinsäure auf Dünnschicht-Chromatogrammen mit Hilfe eines Graukeils

Zusammenfassung Mit Hilfe eines in Photolabors gebräuchlichen Graukeils können dünnschicht-chromatographische Flecke der obengenannten Mycotoxine halbquantitativ bestimmt werden. Die Nachweisgrenzen betragen 0,01 g für Citrinin, 0,006 g für Ochratoxin A, 0,002 g für Aflatoxin M₁ und 0,01 g für Penicillinsäure. Eichkurven werden angegeben.

     

The relative importance of temperature and isotope effects on the dipole oscillator strength distribution of H2

Summary The calculation of the effects of temperature and isotopic composition on the energy weighted moments of the dipole oscillator strength distribution of H₂ in the random phase approximation to the polarization propagator are reported. It is seen that the effect of isotopic composition is small, while that of temperature is of an order accessible to experiment. We find that all the mean excitation energiesI , for =–1, 0, 1, decrease with temperature as does the dipole oscillator strength momentS() for >0, while the opposite is true for <0. These effects are interpreted in terms of the bond length dependence of the excitation energies.     

Microwave Spectrum and Dipole Moment of 1,3‐dioxolane in the Hindered‐Pseudorotation States v = 0, 1, 2, and 3

The microwave spectrum of 1,3dioxolane (C₃H₆O₂) in the ground and first three excited states of hindered pseudorotation was studied. The transitions corresponding to the _b, _c, and _a components of the dipole moment were identified. The spectrum was analyzed using numerical diagonalization of the effective rotational Hamiltonian for four interacting states of hindered pseudorotation. The rotational constants, centrifugal distortion constants, the constants of interaction between general rotation and hindered pseudorotation, and the distances between the quasidegenerate vibrational levels ₀₁ = 64840.5, ₁₂ = 122231.7 and ₂₃ = 119732.7 MHz are determined. From the Stark effect of microwave transitions, the dipole moment components (in Debye units) in the hinderedpseudorotation states v = 0, 1, 2, and 3 are determined: 0|_b|0 = 1|_b|1 = 1.22, 2|_b|2 = 1.20, 3|_b|3 = 1.21, 0|_c|1 = 0.77, 2|_c3 = 0.66, and 1|_a|2 = 0.19.     

Size spectra for trace elements in urban aerosol particles by instrumental neutron activation analysis

Size-fractionated aerosol samples collected with micro-orifice impactors at Camden, NJ, a heavily industrialized urban area, and at two sites near Washington, DC, were analyzed for elemental constituents determined instrumentally from short-lived neutron activation products. A least-squares peak-fitting method was used with impactor calibration data to determine log-normal distribution parameters, i.e., mass median aerodynamic diameter (MMAD) and geometric standard deviation (_g) for particles bearing S, V, Br, and I. For these elements, MMADs ranged from 0.24 to 0.65 m; 0.23 to 0.53 m; 0.22 to 0.61 m, and 0.20 to 0.48 m, respectively.     

Flame atomic absorption spectrometric determination of cadmium and copper in biological reference materials using on-line sorbent extraction preconcentration

Summary Cadmium and copper at the g/g to ng/g level in plant and animal tissue reference materials, and at the g/l level in urine were determined by flame atomic absorption spectrometry using on-line sorbent extraction preconcentration based on flow injection techniques. Bonded silica reversed phase sorbent with octadecyl functional groups (RP-C 18), packed in a 100 l column, was used to collect the diethylammonium-N,N-diethyldithiocarbamate (DDTC) complex formed on-line in the sample digests at low pH. Methanol was used to elute the analyte chelates directly into the nebulizer-burner system of the spectrometer. Small air segments introduced before and after elution prevented the eluent from mixing with the sample solution and increased the sensitivity. A sampling frequency of 85/h could be obtained with a sample loading time of 30 s at a flow rate of 4.0 ml/min. The enrichment factor for both elements was 20 and the enhancement factors, including the effect of the organic solvent and with the flow spoiler removed, were 126 and 114 for cadmium and copper, respectively. The detection limits (3) were 0.15 g/l for cadmium and 0.2 g/l for copper. The precision was 2.3% and 1.4% r.s.d. for 10 g/l Cd and 45 g/l Cu, respectively (n=11). Results for the determination of cadmium and copper in various biological reference materials were typically in good agreement with certified values. Low recoveries were observed, however, for cadmium in samples containing high levels of copper and/or iron, such as bovine liver.On leave from Flow Injection Analysis Research Center, Institute of Applied Ecology, Academia Sinica, Shenyang, China