Engelborghs Koen

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By AAS after wet digestion of the samples the results were 20% higher (for milk) and 41% higher (for meat) in comparison with dry coshing. Cow and ewe milk and pork, beef, and mutton were sampled in six regions of the country and were studied with regard to residual amounts of four trace elements. Highest appeared to be the content of zinc, and lowest--the(More)
A specific, highly sensitive and exact polarographic method of phenol determination in the air is developed. The conditions of sample taking are outlined, and the effect of polarographic solution pH on the height of step and semi-wave potential is verified. The suggested method is readily applicable simple for execution, and provides for a good(More)
A rapid, highly sensitive modified polarographic method for the determination of styrene microconcentrations in air -0,5-I mg/cm3 was elaborated, on the different electrolyte of propionic acid or in 10-20 times higher sensitivity than the methods known so far; the relative error determination +/- 2%. The method is selective for styrene - aliphatic, aromatic(More)
During the production of penicillin and streptomycin, substantially high concentrations of butyl alcohol and butylacetate are measured in the working environment atmosphere. The penicillin and streptomycin dust appears to be the chief unfavourable factor of the workplace in the drying, sorting and packing processes of the antibiotics. An unfavourable(More)
A rapid polarographic method for determination of formaldehyde microconcentrations in air has been developed. The method is highly sensitive - 0,5 cg/ml, which is 10 times higher than the sensitivity of the known methods now at use, with standard deviation less than 1.0. It is formaldehyde-selective - other saturated and unsaturated aldehydes, ketones,(More)
Using theoretical calculations and personal observations and researches, the authors succeeded in demonstrating that evaporation from lacquered surfaces, particularly in the early period of drying, is the primary source of working environment air pollution with toluene and styrol in the varnishing workshops of furniture factories. Three equations are(More)
A modified polarographic method is developed for determination of furfurol in the air of the work environment. The method is based on furfurol cathod reduction to furfurol alcohol on dropping mercury electrode on the background of 0.1 M solution of lithium hydroxide. The sensitivity of the method is considerably higher than that of the already known(More)
  • Michiels Wim, Engelborghs Koen, Roose Dirk, N Katholieke, Universiteit Leuven
  • 1998
In this paper we investigate the sensitivity of the stability of neutral functional diierential equations with respect to changes in the delays. This sensitivity is caused by the behaviour of the essential spectrum which, in turn, is determined by the roots of an exponential polynomial. In 1], Avellar and Hale considered the case of multiple xed and nonzero(More)