Measurements were carried out with a multichannel CCD spec-trophotometer (Ocean Optics, Dunedin, FL, USA; model USB2000).
Optical fibers were used to transport the radiation from a tungsten-halogen lamp (Ocean Optics Inc., model LS-1) to a 100-cm optical path flow cell (Ocean Optics; model LPC) and from the cell to the detector array.
Data acquisition was carried out with the software provided by the manufacturer.