RESUMEN
We constructed a circular multireflection (CMR) cell, allowing multireflection around the center of the cell. This is caused by a skewed adjustment of the entering beam (equivalent to a simple parallel shift/offset), avoiding the center of the cell, thus leading to multiple reflections. The experimental setup with a cell with an inner diameter of 6 cm showed up to 17.5 beam passes on polished aluminum and attained path lengths up to 105 cm, demonstrated by Fourier transform infrared measurements of CO(2) gas between 2283 and 2400 cm(-1). The circular concept, i.e., the centering of the reflections, is useful for absorption spectroscopy on trace gases and aerosols. The optical alignment of the cell can completely be performed from outside the experimental setup, e.g., an aerosol flow reactor or a vacuum system. The variation of the path length is easily possible by adjusting the position of the cell with respect to the entering light beam.
RESUMEN
A quantitative analysis of the technical octabromo diphenylether mixture DE-79 is performed by (1)H NMR, avoiding any separation technique. The mass fractions are 36% BDE183, 19% BDE197, 13.1% BDE207, 9.1% BDE196, 7.3% BDE153, 6.2% BDE203, 2.2% BDE180, 1.6% BDE171, 1.2% BDE154 and 0.7% BDE206, considering an additional mass fraction of 1.3% BDE209 determined by HPLC analysis with a diode array detector (DAD). HPLC chromatograms of the BDEs in commercial decaBDE, octaBDE DE-79 and pentaBDE DE-71 and UV spectra of the components of DE-79 are presented. The photolysis of the octaBDE mixture DE-79, dissolved in tetrahydrofuran, by simulated sunlight is monitored by HPLC-DAD and observed to proceed mainly via debromination. Polybrominated dibenzofurans are identified from their UV spectra as significant intermediates.
