Errant use of gas chromatography for area monitoring of ethylene oxide in SPD departments

In recent months, we have seen certain people touting systems using gas chromatography (provided with a photo-ionization detector) for area monitoring of ethylene oxide in Supply, Processing, and Distribution (SPD) departments. [Sometimes SPD stands for Sterile Processing Department or Sterile Processing and Distribution.] Such systems, despite their expense, were reasonably popular 20-25 years ago. However,…

When is a part-per-billion (ppb) NOT a part-per-billion (ppb)?

As if it weren’t bad enough that clueless environmental authorities try to impose their ignorance on the field by using so-called “metric” units of gas concentration, another trap may be lurking for you. Everyone around the world agrees that a part-per-million (ppm) equals 10-6. Unfortunately, since everyone around the world does not agree with what…

Understanding Danger

The dictionary defines “danger” as “the state of being exposed to harm : liability to injury, pain, or loss.” Typically, gas detection is deployed in areas that contain potential danger. This danger may result from some sort of upset condition, as in a leak—representing an immediate toxic or explosive risk—or it could be more insidious,…

Surrogate Calibration

The term “surrogate calibration” refers to a practice in instrument calibration whereby a standard different from the entity to be measured is utilized. For example, thermal flowmeters are based on convective heat transfer effects, and can be calibrated at ambient conditions on a specific gas, and then be used at process conditions to make accurate…

Can the detector be calibrated at one concentration to cover the entire range? Since the response is linear, I think the answer is yes. Please confirm. Thanks.

The answer to your question is YES. You are correct in noting that the response of our instruments is linear. More than that, electrochemical voltametric sensors (such as we use) are inherently linear, with no electronic compensation required. However, for optimum accuracy in most applications, it is best to calibrate the instruments at a concentration…