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Dec 19 2011

Pique the Geek 20111218: The Science of NCIS

The popular TeeVee show NCIS purports to use science to solve most of the difficult bits of its cases, almost always murders.  Since this is about a TeeVee show, I was torn betwixt posting this piece here or on Popular Culture, but chose here because it will get a little geeky.

Before I continue, let me tell you that I like the program very much, not so much for the science but for excellent script writing and character development.  I think that it is important to recognize a well crafted program.  Since most viewers are not technically proficient, the science is not a problem for them.

But it is for me.  I am reminded of another popular TeeVee show from years, the Jack Klugman one called Quincy, M. E., that relied heavily on fictionalized scientific methods.  I had a boss at one time who coined a phrase that I shall reveal later.

The principal scientific characters in NCIS are Abby, the Goth forensic scientist/firearms specialist/computer expert; “Ducky”, the medical examiner/psychological profiler (played by the brilliant character actor David McCallum, and The Man from U.N.C.L.E. was my favorite TeeVee show when I was a kid); and McGee, the young agent who is even a better computer expert than Abby.

The first thing that I find incredible is that these scientific analyses and the resulting conclusions are so damned FAST!  I know my way around advanced chemical instrumentation, and also know that even in the most advanced laboratories it can literally take DAYS, not minutes just to prepare a sample for analysis.  Then all of the controls and duplicates have to be prepared as well, and analyzed in the same analytical run to be valid.  On NCIS, one sample is all that is ever mentioned, and Abby throws it into “Major Mass Spectrometer” and gets an answer in minutes.

Another thing about Abby’s laboratory is that she seems only to have the mass spectrometer (by the way, the one on the show appears to be an Agilent (formerly Hewlett-Packard until they spun off their instrument division, stupidly) gas chromatograph/mass spectrometer and a polarizing light stereo microscope.  I can assure you that those two instruments are woefully inadequate to do the analyses that she reports.

To the kind of work that Abby does would require several technicians to do sample preparation (Abby HATES assistants) and several other key kinds of analytical instrumentation.  In particular, to do firearms residue analyses, unless old and only qualitative analyses, at least an X-ray fluorescence spectrometer (XRF) would be required, and most state of the art forensics laboratories have an electron microscope that does that in addition to many more things.

Also missing is a Fourier transform infrared spectrometer (FTIR).  Since she is so good about matching fibre evidence, one of those is essential for identifying the dyes used.  A polarizing light microscope is useful, but only IR data are conclusive.  There is also a notable lack of a ultraviolet/visible spectrophotometer (UV/VIS) that is extremely useful in identifying dyes as well as other kinds of materials.

There is another thing that bothers me about Abby’s mass spectrometer.  Her “Major Mass Spectrometer” is only GCMS, but can identify molecules that could not possibly pass through a gas chromatograph.  These are typically heavy molecules, the prime example of which is sugar.  If one attempts to quantitate sugar by GCMS, it is useless because the sugar just chars in the injection port.  One episode that comes to mind is where Major Mass Spectrometer found sagitoxin in a cadaver.

That material is very complex, and can not stand the kind of temperature required for a GC to run.  To find something like that, a liquid chromatograph/mass spectrometer (LCMS) is required.  If a GCMS is complex, and they are, but advances have made them easy enough for skilled technicians to operate and maintain.  That is not so much the case for LCMS, but for materials that are not volatile they are essential.  I promise you that Abby does not have one in her crowded laboratory, because they are big, and need at least one technician to keep them going.

Well, enough about Abby.  Pauley Perrette plays the character well, and her bubbly character is cool.  Besides, most of the time the actress gets the words right.  Not always, but enough to be credible to lay people who watch the show.

Now there is Ducky, who NEVER misses anything whilst doing an autopsy.  And he does them fast!  In three minutes he has cut out all of the organs, weighed them, and writes a report.  Well, it seems that way.  He and his assistant can reconstruct the cause of death for bodies who died decades ago, with only skeletal remains.  I find that to be a bit fantastic.

Real autopsies take weeks, although the initial bits can be done in a few hours.  However, when the fluids are sent for analyses, weeks are added, and for DNA, more weeks.  But wait!  He sends them to Abby, who can do weeks of work in an hour!  I will never talk badly about David McCallum, because he is an actor extraordinaire, and has earned his spot on TeeVee.  He has been acting before I was born, to wit 1947 when he started, and still gives a good performance.

Then there is McGee, played by Sean Murray.  His character is a computer geek who is struggling to be a good special agent.  He has the ability to hack into any database, regardless of the encryption or level of classification.  Right.  YOU try, regardless of how good you are, to hack into the DoD protected sites and not being detected and if you do, you had better have your other hand on a telephone to a high powered attorney, because you will be caught before you get into it.  Hell, I made a poorly considered comment last week about being sad and the deputy was at my door to check up on me before I knew it.  I had to assure him that I was OK, AND give him a cupcake before he went away!

I have no doubt that given the proper equipment and enough time that MOST, but not all, of the things that these folks might be able to do are possible.  But the time constraints are completely in conflict with reality.  As I said, if it takes a few days just to get a sample prepared (and that is not from just dragging feet), it is not possible to get a result in a couple of hours.

That does not mean that NCIS is not a good show.  I really like the characters, and how they interact.  The bit about McGee and Abby having a fling for a while was interesting, especially when it was revealed that McGee and Abby slept in the coffin that she uses as a bed.  Unsaid, but strongly implied, was that they did more than SLEEP in the coffin.

They are likable characters, and the writers have done a good job of adding a bit of personal conflict betwixt each of them in their relations.  That is good writing, and I applaud the producers and writers for being able to keep it up for so long.  The stories are still fresh, and even keep me guessing now and then, but I have figured out the formula.  It is simply the age old one of diversion of attention.  The writers are very good at that device, and it is a very good one.

Now I suspect that you are either bored to tears or wondering why I mentioned Quincy, M. E. some time ago.  Here is why.  Some years ago I was the Laboratory Director at an environmental analysis laboratory, and one of the contracts that we had was to analyze tissue samples of fish, crawfish, and small mammals at a highly contaminated site in south Louisiana.  There were people who were hired to take the specimens, and they brought them to us.

Let us take a squirrel as an example.  First, you thaw it.  That takes time.  Then you puree it in nothing more elaborate than a Waring blender, with purified water.  Now you have raw squirrel soup.  There is nothing that you can do with than without further treatment.  This ends Day One.

The next day, you decant the liquid from the remains and extract the water with a solvent, normally dichloromethane.  That takes a day, because to give valid results, you take part of the water and extract it again for a double sample, in case results are not clear.  Then you take another part and spike it with chemicals that are known to be similar to the ones for which one is looking.  Then you take all of the glassware that was washed during the same cycle and do a blank, to assure that there is no carryover from past analyses.

But it is even more complicated.  The spike that I mentioned above is a matrix spike, meaning that actual samples are divided and spiked.  The recoveries of the materials at know levels tell about how well the extraction process worked.  Normally those are done in duplicate.

Then there is the blank spike, where everything except the actual sample is spiked, and all of the steps are taken with them as were done with the actual sample.  That takes into account any contamination of reagents and standards, because the results from a “good” analysis can be predicted with a high level of confidence.

Oh, then you have to calibrate the instrument for looking at the materials at hand.  Normally, that is done by analyzing known standard solutions of materials in pure solvents and making a calibration curve to establish the response of the instrument.  We like linear calibration curves, but nonlinear ones are acceptable if the cause(s) are known and can be accounted for properly.

Finally, a solvent blank is run at the front end and the real end of the series.  That just shows that the instrument is clean before an analytical run is done, because it is assumed that chromatographic grade solvents are as pure as they can be.  This is not always the case, and I shall tell you about it in a minute.

For most analyses, a GCMS run takes from 15 minutes to over an hour, depending on what you are trying to analyze and quantitate.  Some can take two hours, give or take.  Let us take one hour as a standard run.  Now do the maths:

Solvent blank:  1 hour

Blank spike 1: 1 hour

Matrix spike 1: 1 hour

Sample:  1 hour

Matrix spike 2:  1 hour

Blank spike 2:  1 hour

Solvent blank 2:  1 hour

Thus, it can take seven hours to analyze ONE sample because of the control samples that have to be run.  That is just when you are looking for things that you suspect that might be there.  When looking for unknown materials, it can take much longer, because you have to identify, at least to some point, the properties of the material(s) that you want to identify.

But it can be even worse.  If any of the control samples show up to be out of defined levels (and there are defined levels, in EPA protocols as defined in SW-846 and any number of forensic protocols), all of the results are invalid.  Then you have to start again, and hope to get it right.

I have had a few experiences when the analyses did not conform, and almost always it was traced to more than one person performing the extractions.  It was not because one was better than the other, but they just did things differently, and that threw off the results.  I made it policy that only one technician could process ALL of the samples for any given analysis and the failure rate went to zero.  I do not care how carefully you follow a recipe, if you and I cook a cake using the same directions it will be a little different, but if we cook MANY cakes, mine will be more similar to each others than yours will be to mine.

OK, finally Quincy.  If you remember the show, Sam was sort of like Abby in that he could get results fast.  My old boss, Peter Meehan, had to defend the lag time for our laboratory to the folks who had polluted the water and had us analyzing the animals there.  He had the good idea of taking a stuffed toy squirrel and a burnt out GC column, and trying to push the stuffed animal through a 0.1 mm column.

He went on to explain that the animal had to be processed in a complex manner, and that what they say on TeeVee was nothing but a Quincy Box, where the whole animal was dropped into the intake and a result came out of the back in ten minutes.

Anyhow, programs like NCIS sort of make science fun for the lay public, but does a disservice by making it seem easier and faster to get results than it really is.  It it still good fun, but hardly realistic.

Well, you have done it again.  You have wasted many more einsteins of perfectly good photons reading this bit of fiction!  And even though the people at the FOX “News” Channel realize that THEY are a large part of the reason that the political climate is so decisive when they read me say it, I always learn much more than I could possibly hope to teach by writing this series, so keep those questions, comments, corrections, and other feedback coming.  Tips and recs are also always welcome.  I shall stay around this evening as long as comments warrant, and return around the same time tomorrow for Review Time.

On Wednesday, My Little Town will recollect some of the Christmas traditions that my family followed when I was growing up, Friday we shall continue our series about the history of The Who in Popular Culture, and Sunday in this space we shall look at the pagan origins of many of our current Christmas celebrations.

Warmest regards,

Doc, aka Dr. David W. Smith

Crossposted at

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