THE I N D U S T R I A L C H Y M I S T
THE NUMBERS RACKET B. J.Luberof, P h B . Years ago, analytical chemistry was part of industrial chemistry as evidenced by the publication of The Analytical Edition of IHEC. Now the magazines are separate and I’m afraid the fields are too. This is strange since everything an industrial man does, goes through the analytical lab a t some time. I t has to, because business is a pretty quantitative thing. Yet industrial men who can see right through a P and L statement or a heat and material balance have been known to fall all over themselves when given an analytical report sheet. Part of the reason is that analytical men and other technical men don’t talk to each other anymore. All fields have become more complex and have developed new jargon to cover their new complexity. But if people are to work together toward a common goal ( a requirement of industrial problem solving), then they have to have discourse on a mutually understandable level. For example, one young analytical chap had been struggling with methods development for a project that had been flying blind for want of analyses. Finally, one day he came sailing through the lab obviously drunk on success. T H E problem was solved! He proudly reported that the yield was 16.00%.
Well, his problem was solved. T H E problem was dead. Had he recognized T H E problem, had one of the process men explained it to him, or had he asked, he would have known that what was needed was an approximate number NOW-not four figures of failure weeks later. It’s pretty hard to convince analysts that * l O ~ o precision (one day we’ll have to explore what this means, or ought to mean) is all that’s needed at a particular stage of T H E problem. Their training puts high value on the hundredths figpe. And how often have engineers used a number which was carefully reported to two significant figures as though it had four. Then, when things don’t work out, who gets hung? The analytical lab. Is it any wonder that they ensure their paychecks by playing it safe with four figures. It’s funny how ingrained this attitude is. Tell an analyst that his result is “way out” and he reruns, looking for a 1% error. I got this treatment once when a pesticide assay had been reported to me as low by a factor of two. The problem was that an aliquot factor had gotten lost. (I’ve been wary ever since of results that seem to be off by an integral factor.) Then, there is the quantitative analysis that’s qualitatively wrong. There is no K2O in an NPK fertilizer; but everybody knows what a K2O assay means. I wonder how many people know the meaning of
“acidity calculated as HCI.” You could make this assay look totally different merely by reporting acidity as H2S04 or as weight per cent protons. Then, there is the clear, aqueous, acid solution with 3% Fe2Os. These are not trivial. Such analyses have often been misinterpreted because of lack of discourse between analyst and project men. There is a sneaky, modern qualitative/quantitative confusor too : the gas chromatograph peak with the same retention time as benzene that isn’t benzene. It’s very common for a n engineer to ask for a benzene determination, have the sample run by G.C., see a peak where benzene should be, and proceed to calculate
DR. L U B E R O F F has been working at the interface between chemistry and engineering since receiving his Ph.D. from Columbia in 1953. He has been associated with American Cyanamid and StauJer Chemical Co., and is presently Manager of Process Research for The Lummus Company, Bloomjeld, N . J . H i s publications which appear in the scientific and patent literature, both here and abroad, number several dozen. They are characterized by the diversity o f j e l d s they cover: from pesticide residue analysis through homogeneous catalysis to full process pow sheets. VOL. 6 1
NO. 8
AUGUST 1969
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T H E INDUSTRIAL CHYMIST
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the benzene concentration. Ask the same engineer if a material with a n 80.1 “C. boiling point is benzene and he’ll laugh at you. This is one of the big risks in G . C . I t performs a onetailed test. If benzene is there, it will see it; if (‘benzene’’ is seen, it may not be there. If you want to know how to get around this one, talk to your analytical lab. They’ll tell you how to handle this and a lot of other sneaky problems. Finally, there’s the method that doesn’t work. I t was taken from a reliable journal, run on four samples, and it didn’t work. Did anybody try it on a known sample? Unless you’ve been scorched a few times, the answer is “Of course not, why take time to run knowns?” Why, indeed? Not only to verify your reagents, your instruments, and your techniques, but also to check for interferences in your samples, recovery in your matrix. And these knowns should be run exactly like unknowns. In looking for an active ingredient, one makes a calibration curve of some response us. amount of active material present in the instrument, Then one takes the unknown, runs it through half a dozen steps to isolate the active ingredient, and checks response against the calibration. Finished? Not by a long shot. All this tells you is the amount of active ingredient in the instrument, not in the samfile. What one must do is to run a known amount of active material all the way through the isolation procedure, preferably in the presence of all the background materials, and then plot the response curve. Invariably, the method will look less sensitive and less precise-but it will be right. In one pesticide residue analysis, the calibration was made by spiking fruit-stand produce with pesticide. In this way, analytical recovery after grinding and multiple extractions was found to be 20%. Fortunately, it was always 20y0, and the federal agencies accepted the method. CHEMISTRY
lndustrial Chemists & Engineers YOU CAN ATTEND 3 IMPORTANT SYMPOSIA.. . RIGHT AT YOUR OWN DESK Informative papers from three “state-of-the-art” symposia sponsored by the ACS Division of Industrial and Engineering Chemistryare nowavailable to you as attractive, hard-cover books. Co-sponsored by the ACS monthly magazine, INDUSTRIAL AND ENGINEERING CHEMISTRY, these annual summer symposia are designed to bring practicing industrial chemists and chemical engineers up-to-date on broad subjects often encountered in their day-to-day work.
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(1) Chemistry and Physics of Interfaces June 1964 Symposium-Sydney Ross, Chairman.
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Attractive Forces at Interfaces Adsorption and Thermodynamics at the Liquid-Liquid interface , Surface Actlve Agents-Their Behavior and Industrial Use .Zeta Potential Measurement.. Structure of Macromolecules on liquid-Solid Interfaces,. ImmerSurface Sensitive sional Wetting of Solid Surfaces Mechanical Properties 177 pages (9 x 12) with index. Cloth bound. 17.50.
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