Solvent-free sampling with di-n-butylamine for monitoring of isocyanates in air

The solvent-free sampler for airborne isocyanates consisted of a polypropylene tube with an inner wall coated with a glass fibre filter, coupled in series with a 13 mm glass fibre filter. The filters were impregnated with reagent solution containing equimolar amounts of di-n-butylamine (DBA) and acetic acid. Air sampling was performed with an air flow of 0.2 l min(-1). The formed isocyanate-DBA derivatives were determined using liquid chromatography and tandem mass spectrometry. The sampler was investigated in regard to collection principle and extraction of the formed derivatives with good results. The possibility to store the sampler before sampling and to perform long-term sampling was demonstrated. Field extraction of the sampler was not necessary, as there was no difference between immediately extracted samples and stored ones (2 days). In comparative studies, the sampler was evaluated against a reference method, impinger-filter sampling with DBA as reagent. The ratios between the results obtained with the sampler and the reference in a test chamber at a relative humidity (RH) of 45% was in the range of 83-109% for isocyanates formed during thermal decomposition of PUR. At RH 95%, the range was 72-101% with the exception of isocyanic acid. In two field evaluations, the ratios for fast curing 2,4'- and 4,4'-methylene bisphenyl diisocyanate (MDI) was in the range 81-113% and for the 3-ring MDI the range was 54-70%. For the slower curing 1,6-hexamethylene diisocyanate (HDI) and HDI isocyanurate, the ratios were in the range 78-145%. In conclusion, the solvent-free sampler is a convenient alternative in most applications to the more cumbersome impinger-filter sampler.     

Immersed solid phase microextraction to measure chemical activity of lipophilic organic contaminants in fatty tissue samples

It is known that solid phase microextraction (SPME) fibers can be equilibrated directly within environmental matrices such as water, sediment and soil slurries. Here it is shown that this method can also be applied to biological tissue. SPME extraction of biological matrices reportedly causes lipophilic fouling of the fiber. However, we found no significant measurement bias when combining equilibrium sampling with fiber surface cleaning. The uptake of lipophilic organic pollutants from the tissue and into the SPME fiber coating was characterized by fast equilibrium partitioning without sample depletion and without impacting the sorptive properties of the fiber. The precision of the method when applied to hexachlorobenzene and several PCB congeners in harbor porpoise blubber was 15%, which includes the variation between SPME samplings, manual injections and the instrumental analysis. A good correlation (r(2)=0.95) was obtained between SPME measurements of PCB 153 in blubber and concentrations obtained via a traditional analytical approach. These results indicate that SPME is a promising technique for measuring chemical activity in biological tissue, which would make it a useful tool for studying chemical distribution in organisms as well as biodilution and biomagnification phenomena.     

Integrated catchment modeling for nutrient reduction: scenarios showing impacts, potential, and cost of measures

A hydrological-based model (HBV-NP) was applied to a catchment (1900 km2) in the southern part of Sweden. Careful characterization of the present load situation and the potential for improved treatment or reduced soil leaching were analyzed. Several scenarios were modeled to find strategies to reach the Swedish environmental goals of reducing anthropogenic nitrogen load by 30% and phosphorus load by 20%. It was stated that the goals could be reached by different approaches that would affect different polluters and social sectors. However, no single measure was enough by itself. Instead, a combination of measures was necessary to achieve the goals. The nitrogen goal was the most difficult to attain. In order to be cost-effective, these measures should be applied to areas contributing the most to the net loading of the sea. This strategy could reduce the costs by 70%-80% when compared with implementing the measures in the entire catchment. Integrated catchment models may thus be helpful tools for reducing costs in environmental control programs.