In the program from the 2020 ASME International Fall Engine Conference you'll find a joint paper by the University of Oxford and Cambustion entitled "The Influence of Cycle-to-Cycle Hydrocarbon Emissions on Cyclic NO:NO2 Ratio From a HSDI Diesel Engine" (ICEF2020-2904). Buried in there is a mention that the NO₂ concentration was measured with "a Cambustion prototype fast response LIF instrument" (LIF = Laser Induced Fluorescence). Well, I'm pleased to be able to announce that we will shortly be releasing a commercial version of such an instrument, along with an update to our fast NO analyser.
You'll probably know that nitrogen dioxide is usually measured by Chemiluminescence Detection (CLD), after firstly reducing the NO2 into NO by some form of so called "NOx converter". The CLD then responds to the resultant NO (by reacting it with ozone and detecting the near infrared luminescence generated by the reaction). This is indeed how our current generation of fast response CLD, the CLD500, measures NO2. The necessary residence time of the conversion process however does slow the response time of the CLD500 for NO2 to 8 ms, compared with the 2 ms NO response time, and if NO2 needs to be differentiated from NO, two sample heads are needed.
Laser Induced Fluorescence is a well established technique in analytical chemistry, with no known cross sensitivities. NO2 is irradiated with a laser at one frequency, and emission of light at other frequencies (similar to those detected in CLD) is detected. A few years ago we built a prototype system, based on an adapted CLD500, and this was the system used in the paper given this week at ICEF. In the meantime, we've been working on a production system, based on our new "600 series" analyser platform, which debuted with our FID600 fast hydrocarbon analyser last year.
We've also updated our fast CLD offering for NO — in the form of the CLD600. You can have CLD and LIF detection on a single sample head — so you don't need two sample lines to differentiate NO and NO2 any more. In fact, given the modular nature of the 600 series platform, you can also have a FID hydrocarbon detector in the same head too, and indeed one or more sample heads on the same system.
The NO and NO2 time response is 2 ms.
As with the FID600, the CLD600 and LIF600 have improved sample pressure tolerance, a web browser based user interface, 4 kHz digital data logging, and a wide variety of data output options.
You can download a preliminary brochure here.