PID vs FID-Fixed GC 301

Dr. Jack DriscollPID Analyzers, LLC

Sandwich, MA 02563www.hnu.com

The Beginning 1 In 1984, researchers found a correlation between low (ppm) levels of

ethylene oxide (ETO) and cancer. In 1984, the permissible exposure limit (PEL) for ETO was 50 ppm. OSHA proposed an interim standard of 1 ppmand was working on a final standard of 1 ppm. ETO is used as an intermediate in the manufacture of a number of chemicals including ethylene glocol. It is also used to sterilize plastics in hospitals and pharmaceutical companies.

2 No portable instruments were available for this compound at the 1 ppmlevel. The FID does not have the sensitivity and the PID has a low response to ETO so there is a high background as a result of other VOC’s present. Electrochemical sensors are not specific enough-perfume will set them off

3. What can be done? Use a GC301 or GC312 with a PID.

The Solution 4. What can be done to reduce the ambient levels of ETO to reduce to a

safe level? Monitor the areas and alarm if the level is unsafe. Replace gaskets in the sterilizer & make sure no ETO is leaking into the area

5. The solution- early detection of leaks.

6. Monitoring solution GC301 with PID for monitoring ETO. This instrument is capable of detecting 0.1-20 ppm ETO.

7. The GC FID was not feasible since it could not detect < 10 ppm of ETO. In addition, it required H2 which the hospitals did not want in that area so FID was not an option

7. OSHA recommended GC PID for monitoring ETO

The PIDAdvantages of the PID GC301 PID (> 1,100 sold) 1. Fast response time- 60 sec

analysis time 2. More sensitive than the

FID (20 times better response for ETO)- 301C meets OSHA PEL requirements

3. Easy to use is a major requirement since hospitals do not have electronics techs available as a general rule

What are the recentimprovements?

More compact size- 19” rack mount PC rather than uP USB port for control/upgrading Color VGA display with touch screen Software Easy to change or modify program Detectors- new & improved More outputs Easier to expand features More digital I/O

9/2/2011 PID Analyzers, LLC

9/2/2011 PID Analyzers, LLC

GC Signal Schematic

PCRS232

Keyboard

Digital I/O- valvesDigital I/O Alarms

Diagnostics

DAC to 4-20 mA

ADC 16 bit

Display

Time clock, data calc & storage on hard drive

Detector

AMP

301-C GC Fluidics9/2/2011 PID Analyzers, LLC

9/2/2011 PID Analyzers, LLC Calibration

ETO MP &Chromatogram RunsETO MP Runs ETO chromatogram

ETO Specs

The Whole Story 1. This story happened in the mid 1980’s, and the solution was similar to

the VCM problem. Reduce the levels by monitoring and fix all the leaks early.

2. The PID had a number of advantages over the FID including sensitivity, ease of use, customers did not want to use H2 and wanted a simple instrument to operate

3. We have improved the PID sensitivity through redesign of the electronics, the PID and the chromatography. The new 301C can detect < 10 ppb of ETO, a 100 fold improvement over the results in the mid 80’3 to early 90’s.

4. The Model 301 has a number of unique features: PC based, internet & network connectivity, sample ahead MP (reduce analysis times), advanced diagnostics, …

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