What is analytical chemistry?

We analytical chemists continue to have a variety of concerns about what we do, and those concerns vary with the context of where we do it. The argument stems from confusion over the worthiness of providing a service and whether that can ever fit our definition of science.

Peter Kissinger
We analytical chemists continue to have a variety ofconcerns about what we do, and those concerns vary with the context of where wedo it. The argument stems from confusion over the worthiness of providing aservice and whether that can ever fit our definition of science. Our professionis not alone in this regard. Physicians, lawyers, accountants and investmentbankers provide services for which they are well-compensated and held in highregard (in their own minds) by that pecuniary measure of service quality.
 
 
On the other hand, the last three professions are also theobjects of frequent derision. There are many lawyer jokes, but few analyticalchemistry jokes. The compensation in a field is proportional to the number ofjokes devoted to it. Please create some for analytical chemistry! 
 
The professorial class at medical, law and business schoolsis not particularly concerned that the professions underlying their teachingprovide essential services to society at large. After all, people who wearsuits deserve employment so that builders of sailboats and golf courses alsohave employment.
 
 
Definitions of analytical chemistry vary. "Analytical chemistryis what analytical chemists do" is commonly attributed to my mentor, the lateProf. Charles N. Reilley of the University of North Carolina (UNC) at ChapelHill. "Analytical chemistry is the strategy and tactics of chemicalmeasurements" is attributed to Prof. Larry R. Faulkner, who rose to leadershippositions at the University of Illinois and later led the University of Texas.
 
 
My own definition has centered on "getting quality dataabout chemical systems to support quality decisions," with the implication thatanalytical chemists can distinguish data sufficient for the purpose or not.Don't all chemists (scientists) do this? No, they do not. Too many simplyaccept what is delivered by an instrument print-out or what is sent to them byan in-house or contract research laboratory or academic core laboratory.
These are the days of digital displays and outputs onspreadsheets. These are the days where instruments are presumed to becalibrated, but are often not shown to be calibrated.  
 
The very best analytical chemists are attentive to theproblem addressed, the sample considered, and the basic science of themeasurement, the quality of the data and the appropriateness of the conclusiondrawn from it. These people are too rare. Data is regularly handed off toothers who lack appropriate skepticism about what it means. The only perfectnumbers are those from counting small numbers of things. Everything measuredhas a decimal point.
 
Let's combine the three definitions. Analytical chemistry iswhat analytical chemists do with strategies and tactics of chemicalmeasurements to get quality data to support quality decisions. But we must digdeeper. Strategy involves grasping the underlying principles of metrology anddeveloping entirely new ones as needed. Implied is the choice of an approach,including a tool that fits the requirements of the conclusion to be made.
 
 
Tactics involves sampling, calibration and validation to thepurpose. Quality data implies validation and understanding the selectivity,accuracy and precision of the information to be reported. The underlying basisof a measurement is a critical component of analytical chemistry. Academicanalytical chemists and scientists in the very best instrument companies wantto know how things work and what limitations result.
 
 
I recently attended talks at Purdue by Profs. Jim Jorgenson(UNC-Chapel Hill) on separations and Gary Hieftje (Indiana University) onspectroscopy in electrical discharges. Both speakers represented the very besttraditions of analytical chemistry—understanding the basic science behind thesignal responsible for the data reported. Both have had a large impact on theirrespective fields. You know it when you see it and it feels good. Analyticalchemists in this category enlighten us by deepening our understanding ofnature. That is what I call science, and it is not to be confused with anindustrial-quality control lab. Both are no doubt important, both suggestchallenging problems to be solved. One is not better than the other, but thedifferences should be clear. 
 
Nearly every experimental scientist and engineer focused onbiology, environment, pharmacy, food, agriculture, medicine, forensics,synthetic chemistry, materials and energy does analytical chemistry. It's thatimportant! Some suggest that because it is so popular, it must be both easy andunimportant. It is neither. It is very hard to get good numbers. Just try toget them twice. Too few of us seriously consider how an error is propagatedthrough a measurement scheme.
 
I have my favorites. I've seen five digits reported for amethod calibrated with a standard reported to be 95 percent pure, more or less.I see pH meters that read to three digits past the decimal point, when thecalibrators vary plenty in the second decimal place and were received in thelab three years ago. I see data reported for chromatographic methods faroutside the range of calibrators establishing the slope. I've seen glucosemeters reporting a few extra digits when the accuracy on a good day is no betterthan 15 percent over a rather limited range. 
 
 
Let's face it, we really don't yet understand all thecomplications of what goes on in the source of a mass spectrometer for acomplex mixture, when sample-to-sample, those things we are not determining varyin concentration by orders of magnitude in ways we cannot know. Why pretendthat we do understand?
 
 
Suspend belief in instrument outputs now and then. Becurious about tables of numbers. Don't trust. Verify. Go out there and get goodnumbers that we all can trust before we make a decision about how the universeworks, if Mr. Jones should go to jail or if the latest cancer drug should beapproved.
 
Do we think about how good the numbers really need to be tosupport a decision? While 7.385 ng seems better than 7.4 ng or 7 ng, would onereally be preferred over the other? Given a standard deviation of +/-1 ng, thelast of these pleases me most. The first looks better on a PowerPoint slide.That's fashion, not science. That's adding noise, not enlightenment.
 
 
Peter T. Kissinger is chairman emeritus of BASi, chairmanof Prosolia in Indianapolis and a professor of chemistry at Purdue University.


Peter Kissinger

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