GC Revolution
By: By Jim Norgaard (BS & MS IIT, Chicago)




Gas Chromatography is a well established analytical technique that can identify many compounds. The disadvantages to the current test techniques are many. One disadvantage is the vast knowledge and training it takes to interpret and run these columns analysis. Gas Chromatographs historically were time consuming and unable to specifically identify the compounds in which the instrument was reacting to. Advances in this technology are emerging while the demand for reliable and easy to use detection equipment is becoming required in more and more situations.

Photovac’s P10 series of portable GCs are factory programmed with a GC method and compound library specific to select industries and/or application areas. Ease of use is facilitated by a simple user interface – a dedicated calibration key provides access to calibration, and pushing the start button begins sample introduction and analysis. With a GC as the underlying analytic technique, named compounds and their concentrations are quickly displayed to the operator on the instrument panel.

First Responders, technicians, and professionals who need to monitor or evaluate VOCs in the environment have had limited choices regarding gas measurement: they can use general survey type devices, often termed Total VOC instruments, which provide a reasonable assessment of total VOC concentrations; or, they can collect samples from the environment and take them to a laboratory or facility where more sophisticated instruments such as Gas Chromatographs can be used to provide a precise assessment of the VOC sample(s).

However, both approaches are unsatisfactory when there are situations where personal safety may be at immediate risk and/or environmental harm is imminent. These scenarios, faced by First Responders as well as technicians and professionals in several major industries, are governed by statutory or industry imposed rules regarding VOCs encountered and appropriate responses. PEL’s set by the EPA and OSHA for compounds such as acrylonitrile, 1,3-butadiene, benzene and phosphine are set at 1 ppm or lower – with industry imposed action levels often at a fraction of the official PEL.

There has been a demand for instruments that provide results quickly and accurately. The focus of the operator should be the job at hand, not their relative expertise with any particular analytical instrument.

Photovac and other prominent VOC instrument manufacturers provide a variety of TVOC instruments (PID or FID based) that are responsive and, with certain instruments, offer very low level (sub-PPM) detection capability. Capable as they may be, such instruments do not specifically identify the compounds they are reacting to. Notably, some instruments equipped with a pre-filter allow identification of a single compound, but cannot identify multiple compounds in one sample run.




TVOC instruments do offer one strong feature; they are easy to operate. For example, single button operation and large display areas on the instrument provide sufficient means and information to allow a user to accomplish measurements easily and without guesswork or reliance on Quick Reference Cards.

Gas Chromatography is a comparative technique whereby compounds, introduced into and separated by the instruments analytic column, are identified by matching their exit (elution) time from the column against library data stored in the instrument. The strength of the detection signal indicates the concentration level of the compound(s). Detection levels ranging from parts per million (PPM) to low parts per billion (PPB) levels are easily obtained with consistent accuracy and exceptional precision.

Signature compounds have been defined for a number of industries as well as for various environmental and law enforcement requirements in the US and in other countries. These groups of compounds are effective surrogates for a broader range of compounds. Such compounds are often the most highly regulated for reasons of environmental hazard or for health and safety (e.g., general toxicity and/or cancer risk). These collectively monitored compound groups may number as few as 2 to 4 or as many as 10 to 12 compounds of interest.

For example, petroleum refining operations focus on BTEX (benzene, toluene, ethyl benzene, and xylene) detection to monitor their general quality of operation. In certain areas of plant operations, the decision to replace carbon canisters used for filtering process air focuses on the “leakage” of as little as 0.5ppm of benzene. Decisions made on the basis of unreliable analysis techniques may expose a refinery to regulatory oversight and/or unnecessary expenses.

Similarly, environmental site cleanup organizations often set up perimeter monitoring equipment to detect BTEX as well as compounds such as 1,2,4-trimethylbenzene, and naphthalene. Ground disturbed during the cleanup activity may release these compounds into the air necessitating immediate remedial action to prevent health risks impacting the communities surrounding the cleanup site.

Chemical plants concentrate on the VABB compounds (vinyl acetate, acrylonitrile, 1,3-butadiene, and benzene) as they monitor their operations. Again, certain plant operations are governed by monitoring a single compound such as acrylonitrile or 1,3-butadiene which, like benzene, are known carcinogens and regulated to sub-PPM levels.

First responders approaching a clandestine drug lab may look for 2 particular compounds (typically phosphine and toluene) or as many as 12 particular compounds when assessing the risks and hazards of securing a clandestine drug lab operation. Statistics published by the CDC point out that the most common injury suffered by First Responders dealing with Clan labs is respiratory damage often attributed to poor site assessment and lack of PPE usage. Further, the clean up of clandestine drug lab sites is increasingly measured by the elimination of certain select compounds. This work is the subject of pending Federal Legislation (H.R. 798) that directs the EPA to determine which chemicals are present and detectable at Clandestine Drug labs, and evaluate the effectiveness of cleanup techniques. Thirteen states so far have adopted legislation and/or executive guidelines regarding procedures for and evaluation of site cleanup activity.

In response to these needs, Photovac, Inc., has drawn on its long and deep history involving portable Gas Chromatography. Over 20 years ago, Photovac introduced the AirScan portable air monitor, followed up by the 10A10, 10S series, and Voyager series of portable GCs. The newest addition to that line of instruments is the P10 series portable GCs. These instruments combine several important characteristics that enhance their utility, including: industry focused, limited compound set; use of Gas Chromatography as an analytical engine providing high levels of accuracy and precision; and, rapid analytical performance.

Analytic quality, accuracy and precision, particularly in the area of Gas Chromatography, typically required a great deal of operator training and skill. However, offsetting such requirements is a revolutionary change in the way a GC can be used. Photovac has introduced, with its new P10 series GCs, the simplicity of “point and shoot” operation. Photovac’s new instrument allows a user to utilize the analytical quality and precision of the GC with little more effort than pointing the probe at a source and pushing the “start” button. The instrument automatically collects a sample of air and reports the measured concentrations of the compounds on the display while the analysis is in progress. Within 1 to 3 minutes, the full analysis is displayed on the instrument readout allowing the operator to make informed critical judgments.

All analyses are automatically stored in the datalogger at the end of the analytical session. The instrument has sufficient internal memory to store a minimum of 100 analyses.

Whether conducting trustworthy routine monitoring, making fiscally responsible decisions regarding equipment maintenance, or assessing situations involving immediate personal risk, Photovac’s new “point and shoot” P10 series of portable GCs offer users a revolutionary new choice in VOC gas detection instrumentation.

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