Thursday, July 7, 2011
New Features of the Model 301MP Area & Stack Monitor
We used a photoionization detector (PID) to analyze ppb levels of ethylene oxide (ETO). The range of the Model 301MP Area Monitor was extended so that the same analyzer can be used to measure both workplace exposure levels of ETO and stack levels. This 25 point sequencer has separate banks for the permissible exposure (PEL) and stack levels. The software was modified and a programmable sample ahead feature was implemented. This sample ahead feature provides a faster analysis time since the sampling is done during the analysis of the sample. As soon as the sample is injected, sample ahead can be started and the next sample will begin purging the sample line and the sample loop. With a 15 second inject time, the sample can be purged for 75 seconds before the new sample is injected which is adequate to clean the line from 2,000 ppm to < 1 ppm. When the high level bank points are sampled, the range is automatically switched from 0-20 to 0-2000 ppm. For the PEL sample bank, the range is switched to 0-20 ppm. The capillary column used for the analysis was an 0.53 mm thick film (7.5 micron). The detection limit for ETO was 5 ppb extending the range from 5 ppb to 2,000,000 ppb or 400,000:1. A photo of the 301C is shown below. For more info, visit our website at http://www.hnu.com.