0 042 g l it was found that with dpf the use of the solution filter was required while for dmf the short wavelength cutoff of commercial quartz of greater than 2 mm thickness was adequate to minimize the degree of self photooxidation induced by emission lines other than 254 nm the construction of the crocheted ptfe reaction chamber for the post column photochemical reactor is as follows ptfe tubing small parts inc sst 30 having a 0 30 mm internal diameter was crocheted into a cylinder having a diameter slightly larger than the cylindrical filter device the reaction chamber used in this work is made from 5 to 20 meters of ptfe tubing and provides reaction times of 0 5 to 3 minutes for flow rates in the range 0 5 to 1 0 ml min crocheting the reactor tubing greatly reduces the degree of band broadening caused by this length of post column tubing the exterior of the reactor is wrapped with a light reflective foil preferably an aluminum foil to increase the photon flux it was found that baseline drift was substantially reduced by immersion of the exterior of the reactor in an ice bath the ice bath did not significantly affect peak heights or the extent of self photooxidation but reduced low frequency noise apparently by stabilizing the lamp temperature and thereby stabilizing the photon flux the effect of temperature stabilization of the effluent passing.