The seasonal changes in the concentration of polycyclic aromatic hydrocarbons in precipitation and aerosol near Lake Balaton, Hungary.

The concentration of polycyclic aromatic hydrocarbons (PAHs) in atmospheric precipitation and aerosol samples was monitored in a rural site by Lake Balaton, Hungary to examine the seasonal variation. The seasonal mean concentration of individual 3-6-ring PAHs in precipitation varied from 1 to 54 ng l-1 and from 3 to 350 ng l-1 in summer and winter, respectively. In the atmospheric aerosol samples the seasonal mean concentration of PAHs varied from 4 to 880 pg m-3, from 4 to 300 pg m-3, from 11 to 1050 pg m-3 and from 36 to 5000 pg m-3 in spring, summer, autumn and winter, respectively. Wet (412 micrograms m-2 year-1) and aerosol (190-300 micrograms m2 year-1) deposition rates were also estimated indicating that the two processes are of comparable importance in the removal of 3-6-ring PAHs from the atmosphere.

Sample preparation of atmospheric aerosol for the determination of carbonyl compounds.

Sample preparation including sonication and solid phase extraction has been developed for the determination of carbonyl compounds in atmospheric aerosol. Aerosol samples were sonicated in acidified acetonitrile containing 2,4-dinitrophenylhydrazine (DNPH) to form hydrazone derivatives of aldehydes and ketones. Water was added to the extract to increase its polarity. Then the solution was passed through an octadecyl or phenyl solid phase extraction cartridge. The concentrated hydrazone derivatives were eluted with tetrahydrofuran, the eluate was evaporated to dryness then dissolved in acetonitrile/water mixture and finally analysed by RP-HPLC with UV detection at 360 nm. The absolute detection limits of the individual carbonyl compounds range from 0.4 to 5.8 ng.

Semi-preparative high-performance reversed-phase displacement chromatography of insulins.

A reversed-phase displacement chromatographic method has been developed for the purification of bovine and porcine insulin samples. Up to 500 mg of raw insulin could be purified on a Nucleosil C8 analytical column using a methanol-containing phosphate buffer carrier and a cetrimide-containing displacer. A proinsulin contamination level as low as 100 ppm in the collected fractions could be achieved.