Document 6RXwM0jmqzMrj4nBG65paqbvm

I To: OSHA File Interoffice Communication From: Dote: Subject: Randy Istre April 12,1990 Detected Areas in Blank Wafers VISTA In determining the 95% confidence limit for EDC, several added steps were taken because of detectedi areas appearing in blank Organic Vapor Monitor Wafers which have the same retention time as EDC. Ten blank monitor wafers were tested. An average wafer blank area of 1360 was determined for EDC. This determination was ihade by measuring peak heights of other peaks ( in millimeters) and dividing these lengths into their own areas. The average of these, (82) was multiplied by the peak height for EDC in each monitor blank chromatograph to get ten corrected areas for EDC. The average of these is 1360. Randy Istre Lab Analyst Ik cc: PLF VVV 000017857 r To: OSHA File IntwcHka Communication From: Date: Subject: Randy istre April 12,1990 Detected Areas in Blank Wafers VISTA In determining the 95% confidence limit for EDC, several added steps were taken because of detected areas appearing in blank Organic Vapor Monitor Wafers which have the same retention time as EDC. Ten blank monitor wafers were tested. An average wafer blank area of 1360 was determined for EDC. This determination was made by measuring peak heights of other peaks ( in millimeters) and dividing these lengths into their own areas. The average of these, (82) was multiplied by the peak height for EDC in each monitor blank chromatograph to get ten corrected areas for EDC. The average of these is 1360. Randy Istre Lab Analyst lk cc: PLF rc VVV 000017857