U.S. EPA Ground Level Ozone Targets Released

U.S. EPA Ground Level Ozone Targets Released

New US EPA Ground Level Ozone Targets Released

If you’ve ever purchased high-end audio equipment, you’ve most likely seen several columns of specification with a long lineup of numerical values. IN some cases, bigger is better, in others, smaller numbers mean improved quality. Along with total audio bandwidth, one of the most important values is the Signal to Noise Ratio (SNR). SNR, as is implicit in its name, evaluates an amplified broadcast signal or recorded snore signal against the background noise that the equipment itself creates. In this case, the bigger the SNR, the reduced amount of distortion, and thus the greater the sound output is to a live performance. SNRs have always been necessary to measure instrumentation output as well. Currently, with growing demand on the detection limits of gas chromatography and mass spectrometry, getting rid of response noise has become more vital than it ever has been before. Now is the time to attempt to reduce or eliminate the sources of this noise wherever possible.

In past weeks, the U.S. EPA released its new ground level ozone target of 70 parts per million (ppm). Reaching this threshold limit will call for a significant increase in atmospheric testing for volatile organic compounds (VOC) in several areas that had not previously required monitoring. Depending on the demographic area, air sampling for sixty or more contaminants will be administered , with special highly-accurate multi-component mixtures of these volatile chemicals used to determine a baseline. Two different mixtures are available, with the concentrations of these components falling into two ranges, either a high range around 1 ppm or a lower range mixture of components at 100 parts per billion (ppb).

As you might imagine, carrier gases now become an essential component of any plan to boost SNR. And because these gases are not supplied by the instrument provider, they can frequently be critiqued the most when questions surface. Where once “commodity type” specialty gas grades like “Zero,” “Pre-Purified,” or “Ultra-High Purity,” could be acceptable for component detection as low as 500-1000 ppm, Continuous Emmissions Monitoring (CEM) now requires something better. In this case, better means certified lower levels of impurities, with analytical certification of their actual concentration, along with proper cylinder preparation to reduce wall off-gassing, and to minimize atmospheric contamination while under vacuum. Discharging of these gases also necessitates the right pressure pressure reduction device , again lowering contamination of the system through routine cleaning and assembly, and the proper choice of materials that will not react with the sample stream.

So what to do? Insist on carrier gases that reduce distortion and provide as flat a baseline as is practical for the application. If analytical requirements mandate accuracy below 10 parts per million, utilize the best available carrier gases. Look for secondary purification as part of the packaging process, either by absorption media or cryogenic distillation. Inquire about cylinder preparation, as the gas is only as good as the container its held in. Also ask about record keeping and the accuracy of the reference standards, again because a low level oxygen impurity report means nothing if the instrument isn’t properly calibrated, or the calibration gas has no traceability to a defined standard.

Gases such as PurityPlus® Grade 6.0 Helium and Ultra Zero Air, with full certificates of analysis, can feasibly satisfy the needs of an increasingly precise world. Try them, you’ll be well satisfied.

Please feel free to contact PurityPlus directly or find a local provider for all of your specialty gas and advanced specialty gas equipment needs.

October 14, 2015

Rich Mansmann