The classical first year chemistry definition of “pH” refers back to Danish biochemist Søren Sørenson, who originated the term, alluding to the “potential of hydrogen ion.” Specifically, pH is the negative logarithm of the molar concentration of the hydrogen ion (H+) in the particular solution. This is usually expressed as a formula… pH = -log[H+]…
Interscan started the real analytics movement in the field of gas detection, to demonstrate that at least one company is serious about assuring the best possible analytical accuracy in every measurement our instruments make. After all, the very term “gas detector,” which is far more common than “gas analyzer,” immediately reminds one of detector tubes,…
Our AccuSafe sensor units can often be installed close to the point source of the toxic gas sample, or in the area where workers might be exposed. Still, it is sometimes necessary to transport sample from some distance to the analyzer (or sensor unit). There is no inherent problem in doing this, unless the sample…
The term “sample conditioning” simply means the preparation of the gas sample containing your analyte to render it suitable for introduction into your gas analyzer. This is usually less of a consideration in ambient air monitoring applications than in source monitoring applications. When sampling from a source such as an industrial process, utility stack, or…
Ethylene Oxide (EO or EtO) Ethylene oxide is the most widely used low temperature sterilant, and it is still the dominant process used by the medical device industry, owing to its effectiveness and compatibility with most materials. First employed as a fumigant in the 1920s, it was developed as a sterilant in the 1940s by…
Back in the 1970s, many multi-point systems were being deployed, for monitoring carbon monoxide in parking garages and vehicular tunnels. Since long and otherwise exposed sample tubing runs needed to be installed, copper tubing was used. Because CO is not very reactive, and copper tubing is both flexible and robust, this was a preferred choice.…
There has long been interest in measuring the amount of carboxyhemoglobin in the blood of workers who might be exposed to carbon monoxide. CO-induced hypoxia is a real consequence. However, such measurements—when done in the conventional manner—are invasive and cumbersome. It was first demonstrated in 1948, by Torgny Sjöstrand, that COHb saturation could be estimated…
How about a little peak into the secret life of plants? Fruit ripening is a form of senescence and signifies the final stage in fruit development. Ripening, of course, eventually leads to spoilage, so there are important commercial reasons to increase and control post-harvest longevity. Complicating matters, post-harvest longevity varies naturally. Strawberries, for example, last…
We introduce this subject matter in our Gas Detection Applications Primer. OSHA has promulgated PELs (Permissible Exposure Limits) for many substances, and—unlike the ACGIH TLV®s—these have the force of law behind them. In general, the PELs are 8-hour time weighted averages, but ceiling limits have been established for some chemicals. 29 CFR 1910.1000 Table Z-1…
Especially when doing low range work, it is important to make sure that your instrument is properly zeroed. Ideally, zeroing should be performed with a certified zero gas. However, mostly since it adds another step to the calibration process, this practice has somewhat fallen out of favor. The alternative to a zero gas requires that…