Why the LUMA detector Matters

A few weeks ago, I wrote an article on “Why VUV Technology Matters”.? I had recently switched all process streams to these new instruments and was very impressed with the technology, I was compelled to share my thoughts.? The VGA is a game changing detector, however, where it comes up short is on pure chemicals.? Essentially, the signal can become saturated making it difficult to quantitate accurately.? There are things that can be done to help, such as varying sample size, but once you get this instrument going you will find that the workload increases, and you are not likely to interrupt it to tweak the sample size.

Cue the LUMA.

The LUMA is an equally powerful detector, if not more powerful.? Where the VGA, essentially automates the analysis of complex samples, leaving little need for chromatographic expertise, the LUMA is the Chromatographers detector.? VUV Analytics, Inc. answered the need for analyzing trace components in pure compounds, but what they came up with was something very special.

The most common detector is the Flame Ionization Detector, it is very sensitive and very linear, but it is blind to combustion products, Hydrogen, Water, Carbon Dioxide and other fixed gases.? A Thermal Conductivity Detector will be the next detector you can expect to find in a laboratory, as well as most online analyzers.? The TCD can see fixed gases and water but is not as sensitive.? These two detectors combined can handle most of the chromatographic needs, but neither of these detectors are selective.? A selective detector can see specific components such as sulfur or nitrogen, but is blind to other compounds, because of this selectivity, these detectors can be very sensitive.

The interesting thing about selective detectors is that often, something else is needed to support the analysis, for example, a Sulfur Chemiluminescence Detector, requires that a furnace be mounted to your GC, in addition, Oxygen, and a vacuum pump is needed.? The technology is unreliable at best, and I refuse to purchase one, opting rather to send sulfur speciation samples to third party labs, it just isn’t worth my time to maintain this beast.? I understand there may be some newer versions of the SCD that may work better, but my experience was so traumatic I’d rather not try.

The SCD is an extreme example of a selective detector, and I mention it here because to me, if there was ever a GC detector that needs to go away, in my opinion, the SCD would be it, admittedly, I would love to deliver the fatal blow.?

There is another analysis that seems unnecessarily complex. The Refinery Gas Analyzer uses several valves, detectors and columns and really can leave you vulnerable to erroneous data, due to the actual calibration range.? This instrument tends to become the catch all for any gas sample, and in my opinion, it is not robust enough to carry this burden.

So why does the LUMA detector matter?

The LUMA detector matters because it is a multi-selective detector, that is elegantly simple.? No moving parts, no complex hardware, just a column and the LUMA.? It may not have the spectral range of the VGA, but when looking for trace contaminants in pure compounds, the 12 spectral bands are plenty.? In addition, you can take this detector and replace any FID or TCD on your current GC right now and benefit from added sensitivity and selectivity.? Your current CDS most likely can capture the 12 bands of spectral data, as this type of detector is used for HPLC-UV, no development needed, take your favorite GC method and add the LUMA.? The LUMA is essentially a Universal-Selective detector, imagine what a skilled chromatographer can do with such a detector!

Here is what I did.? I am serious about my dislike for the SCD and the RGA, so I placed a TCD inline with the LUMA, to prepare a death blow to the SCD (think the fax machine scene in Office Space) and to have an alternative to the RGA.? What I learned over the past few months revealed how powerful this detector is.? Given the right column, you can speciate sulfur at sub ppm levels, as well as oxygenates, aromatics, hydrocarbons.? I did have to grow some new brain cells, I am not used to dealing with UV data, I expect most of you are in the same boat, but eventually it clicked.? I am just at the beginning of this journey, but from where I stand, I can see a GC lab without FID’s (apart from Simdis), SCD’s, RGA’s, not to mention the possibilities for online analyzers.? There is a disturbance in the FORCE, it is the LUMA!