Determination of Compliance with Exposure Limits for Mixtures of Volatile Organic Compounds with a Field Portable GC/MS Kirk F. Meekin, Staff Member/Industrial Hygienist, ESH-5 (Industrial Hygiene & Safety Group); Mark D. Jankowski, Staff Member/Industrial Hygienist, WFM (Waste Facility Management Group); Johnny R. Randall, Senior Software Engineer, IIM (Integrated Information Management Group) IT Corporation Los Alamos N A T I O N A L L A B O R A T O R Y
Waste drum sampling with the Hapsite.
Introduction When monitoring a mixture of volatile organic compounds (VOCs), it becomes important to know whether or not exposure to the compounds will exceed the exposure limit for the mixture. We used the TLV for mixtures formula to determine compliance with the exposure limit. When results are available in near real time, as they are with Inficon s Hapsite, (a field portable gas chromatograph/mass spectrometer), and workers are waiting for instruction based on the analysis results, it is even more important to quickly determine compliance with the exposure limit for the VOC mixture. We used the TLV for mixtures formula in a spreadsheet linked to the data file generated by Inficon s Hapsite software to determine compliance with the exposure limit for a VOC mixture. The following figures and captions describe the steps and concepts involved in generating the Industrial Hygiene Concentration Report.
Figure 1. Total Ion Chromatogram (TIC) for 124tcb data file.
Figure 2. To generate the report for the data file select CAL-Quant from the reports menu in the Hapsite's Method program.
Figure 3. Select the file from which you would like to generate a report (124tcb.txt in this case).
Figure 4. The CAL-QUANT report in text file format.
Figure 5. From a previously opened blank spreadsheet, select Import Text File from the Get External Data option on the Data menu (this function is not available on versions of Excel before 2000).
Figure 6. Select the file from which you want to import data (124tcb.txt in this case).
Figure 7. Step 1 of the text import wizard.
Figure 8. Step 2 of the text import wizard.
Figure 9. Step 3 of the text import wizard.
Figure 10. Step 4 of the text import wizard.
Figure 11. Do 'Save As', change file name to 'calc' and the format to '.xls'. The file name does not have to be 'calc', but it has to be a file name that is built into the algorithm used on the Industrial Hygiene Concentration Report spreadsheet.
Figure 12. The original CAL-QUANT report data now in.xls format with Sheet 1 in the tab at the bottom of the sheet (without changing the sheet designation from the original file name, the algorithm won't work).
Figure 13. The Industrial Hygiene Concentration Report (previously opened) with results based on data from the calc.xls spreadsheet. The data is captured from the calc.xls spreadsheet and the percent exposure limit calculations are performed as soon as the calc.xls spreadsheet is saved.
Figure 14. Algorithm used on the Indutrial Hygiene Concentration Report to capture the concentration data from the calc.xls spreadsheet and report any non-numerical characters that may appear in the concentration field as zero.
Figure 15. Formula used to calculate percent exposure limit.
Results By following the steps outlined in this poster, we were able to determine in less than a minute whether or not the exposure limit for the mixture of VOCs in our calibration library had been exceeded.
Future work We would like to add more VOCs with similar toxicological effects to our calibration library. We also would like to streamline the process further by using visual basic to develop a macro that would automate many of the steps required to get the Cal-Quant report generated by Inficon s Hapsite software into a format that the Industrial Hygiene Concentration Report can use to calculate the final result.
Acknowledgements We would like to thank the following individuals for their support that made this work possible. - Dina Sassone, ESH-5, Industrial Hygiene Field Services Team Leader. Dina assisted with the initial procurement of the instrument. Dina also helped make it possible to hire Mark in June of 1999. - Robert Miller, Inficon, Inc. Robert provide us with the initial training needed to operate the Hapsite, ongoing technical support as needed, and the suggestion to use a macro to automate the process described in this poster. - Dennis McLain, Group Leader, Waste Facility Management Group. Dennis provided financial support for the continuing operation of the Hapsite, and allowed us to devote the time necessary to work on this project - Stacey Perez, ESH-DO, ESH Publications and Design Team. Stacey helped with the design and layout of the poster.
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