FOCUS
Eluent, Effluent, Eluate, and Eluite Chromatographic nomenclature can be, well, interesting Quickly now. Without getting out your copy of R. C. Denney's Dictionary of Chromatography, do you know the correct definitions of eluent, eluate, and effluent? If you do, go to the head of the class, because many analytical chemists do not understand the correct definitions of these commonly used chromatographic terms. Our own confusion about these terms led us to question ANALYTICAL C H E M -
ISTRY'S Associate Editor for chromatography, Georges Guiochon of Georgetown University, about their meaning. According to Guiochon, eluent (some times spelled eluant) is the solvent or solvent mixture used in elution chromatography and is synonymous with mobile phase. Eluate is the mixture of solute and solvent exiting the column. Effluent is the stream flowing out of a chromatographic column. "In practice, effluent could be synonymous with eluate," Guiochon explained. "However, effluent is the stream, whether there is a separation taking place or not. The eluate exists only during the course of a separation." A more precise term for the chromatographic solute or analyte is eluite, a term coined by Csaba Horvâth of Yale University around 1980. Eluite, which was designed to sound like the words analyte and solute, refers to a sample component that is being eluted. "Solute is a very broad term," said Horvâth. "Anything in solution—you don't have to be doing chromatography—is still a solute, right? This term eluite immediately tells you that now you're talking about a substance subject to an elution process in a chromatography column." Horvâth sees other problems with the term solute. For example, in adsorption chromatography (as opposed to partition chromatography) the eluite does not dissolve in the stationary phase during the elution process but is rather adsorbed to it. In such a case, the term solute is not precise.
When asked why he feels the new term is needed, Horvâth explained that "the word eluite makes it much more precise and convenient to talk from the physical chemical or theoretical point of view about a sample component undergoing the chromatography process. When you talk about this thing it seems to be much clearer. Because the
WW There are an enormous number of terms introduced in chromatography papers, but only a fraction of those make it in the language at l a r g e . · · alternative would be either analyte or solute. Analyte applies only when you do a chromatographic analysis. But if I do a physicochemical investigation by using chromatography I don't do an analysis and I don't have analytes. I don't have solutes either. The solute can be anything. I mean, I dissolve a lot of other compounds in my eluent. Salts and additives are also used. Why would I call only one a solute? I felt that more precisely we could call it an eluite." Eluite is still a rare term. "I don't know how many other people are using it," said Horvâth. "It usually takes quite a bit of time for such a word to catch on." Horvâth was somewhat more successful when he invented the term isocratic some years ago. After introducing the word for the first time in a lecture, he walked outside the meeting room to the exhibit area, where an instrument salesman was already trumpeting his company's chromatograph as having been specially designed for isocratic chromatography. "He heard the word in the lecture and immediately turned it into a sales pitch," recalled Horvâth. "I was really amazed. Indeed, weeks later people used it. If the time is right, the word is right, and there is a need for it, then it can be adopted very quickly." The discussion of eluite brings earli-
er controversies to mind. "In the old time," Horvâth explained, "chromatogram was a physical entity, the compounds separated in the column. When Giddings started to write his papers on chromatography, I remember he used the term chromatogram for the physical reality, not for this recording of the concentration profiles on a piece of paper. "When Kovâts wrote his paper on the Kovâts index," Horvâth said, "he spent the introductory part of it saying that in gas chromatography what we have is really not a chromatogram in the definition of the previous generation, that it should be called eluogram, because it is as a result of elution that the stuff comes out of the column. Eluogram didn't make it either." "There are an enormous number of terms introduced in chromatography papers," said Horvâth, "but only a fraction of those make it in the language at large. You can coin a new word, but if people don't like it for one reason or another, they don't take it." Stu Borman
ALMA Meets at Pitt The University of Pittsburgh was the site of this year's annual meeting of the Analytical Laboratory Managers Association (ALMA), and what a site it is. The university, with its spectacular Cathedral of Learning and many other examples of fine architecture, is an inspiring location for a scientific meeting. With most of the ALMA sessions held in the beautifully renovated William Pitt Union in a room that resembles Versaille's Hall of Mirrors and with luncheon served in the enclosed courtyard of the Frick Fine Arts Museum, this year's ALMA meeting was indeed a class act. One major advantage of the relatively small scale of ALMA meetings—an attendance of about 100 is typical—is the opportunity afforded for freewheeling discussions among members
ANALYTICAL CHEMISTRY, VOL. 59, NO. 2, JANUARY 15, 1987 · 99 A
FOCUS about topics of interest. ALMA meetings bring academic, industrial, government, and contract lab managers together in a forum at which common problems can be discussed. Instrument company representatives also attend ALMA meetings to monitor the pulse of the market and to touch base with lab managers, many of whom have sign-off authority on major instrument purchases. ALMA members have so far steered clear of evaluating specific commercial instruments and vendor service policies at meeting sessions, although the concept has been considered. On a person-to-person level, however, t h e ALMA national meeting is certainly a place where comparisons are made and brand names are named. In an era in which scientific instrumentation at college and university campuses is frequently past its prime, a serious concern of academia-based ALMA members involves the "care and feeding" of instruments. One university instrument facility manager explained his dilemma as follows: "A lot of people envy me for having been so successful at getting new instrumentation into my group. But that success comes at the price of not being able to
maintain it properly. We have to hire qualified people, in many cases Ph.D.s, to maintain, operate, and provide analytical support for all this major instrumentation. But the university is finding it increasingly difficult to put these people on hard money [university payroll], and I'm forced to recover salaries through soft money [government grants]. The faculty says we can't request money for instrumentation use in our grants because what the grant agencies are then going to do is to delete a postdoc from the grant and put the savings into instrument maintenance. Money will be shifted within the grant, and the total sum will remain the same." Another conferee suggested t h a t granting agencies such as the National Science Foundation might be willing to support five-year service contracts along with new instrumentation purchase grants. Many others, however, seemed to feel that this would not be a cost-effective solution to the problem. As one lab manager put it, "For less money than it costs to buy service contracts for all my scientific instrumentation, I can run my entire group, which not only provides analytical services but already supports the instrumenta-
HIGHEST QUALITY FOR TOP PERFORMANCE AT LOWEST PRICES UNISEAL® Pressure Decomposition Vessels* The most versatile range on the world market. FOR : DECOMPOSITION · DIGESTION · SOLUBILIZATION · SELECTIVE EXTRACTION · LEACHING · HYDROLYSIS · DESTRUCTION OF ORGANIC MATTER ORGANIC AND INORGANIC SUBSTANCES
STANDARD UNITS Maximum Pressure 1,200 P S I / 8 5 A T M • 23 m l · 7 0 m l • 23ml · 70ml with controlled -torque closure
" T W O I N O N E " High Pressure Series ol six vessels** Maximum Pressure 5,250 PSI 350 ATM The new generation of Uniseal® High Pressure Decomposition Vessels for practically any quantity of specimen comes in six sizes: 5. 10. 25, 50, 70 and 110 ml which safely operate at pressures of up to 350 atm./5,250p.s.i. and temperatures of up to 180°C Uniseal® now markets the most comprehensive and versatile range of decomposition vessels.
«
Mb
ES
ill
w
ALL-IMPORTANT : UNISEAL'S SUPERIOR, SPECIALLY PROCESSED TEFLON C O M P O N E N T S ARE C H A R A C T E R I Z E D BY VERY H I G H D E N S I T Y , E N S U R I N G N O N - P O R O S I T Y , N O N - P E N E T R A T I O N , NON-SEEPAGE · N O L E A K A G E , NO V O L A T I L I Z A T I O N LOSSES · LONGEST O P E R A T I O N A L L I F E T I M E APPLICATIONS a
^PATENTED
* Agricultural Chemistry · Analytical Chemistry • Bio-Clinical Chemistry • Cement · Ceramics · Corrosion · Environmental Pollution · Food a Forensic Toxicology · Geochemistry · Glass Industry · Marine Research m Metallurgy · Mining · Pharmaceuticals · Plastics · Refractories
Ryan Scientific Post Office Box 6496 Columbia, SC 29260 (803) 782-3964 Telex: 9102405145 CIRCLE 140 ON READER SERVICE CARD 100 A · ANALYTICAL CHEMISTRY, VOL. 59, NO. 2, JANUARY 15, 1987
tion at a 95% up rate." Another attendee agreed that dependence on service contracts is less desirable than having knowledgeable staff on hand to respond to problems. "I don't think the service contract is the answer," he said. "I think you have to have an honest and respected discipline that corresponds to understanding the instrument. Unfortunately, the academic community doesn't respect that discipline at this point." In a later discussion on the recruitment and training of technical personnel, the relative merits of hiring chemists at different degree levels was a subject for lively debate. Hiring bachelorlevel chemists is certainly more costeffective, but questions remain about how to motivate them properly in light of the severely limited promotion opportunities for B.S. chemists in most companies. One proposed solution was to liberalize such limitations in recognition of the fact that an exceptional B.S. employee may be working at a de facto Ph.D. level after several years of intensive laboratory experience. In hiring new employees, the needs of the prospective employee must be matched to the needs of the organization. One lab manager recounted a recent choice he had to make between two excellent candidates. "They were both very enthusiastic," he said, "and it was a very difficult decision. Ours is a service laboratory, and I asked myself, Which individual would be better suited to that environment? As it turned out, I didn't hire the person who I thought was the better of the two because I didn't think he would have been happy. He was a real research type of person. If you're not in an R&D environment, you have to be careful who you hire. You have to suit the personality to the job, and that's always a very, very difficult thing to do." Another manager replied that he thought this was one area in which academia had failed. "Ninety percent of the people who come out of the university environment are going to do applications-oriented work," he said. "And the people who are their mentors in the university are doing them a disservice by not telling them that. They promote the full professorship as the epitome of human existence. That might be so for some people. We find it is best to be honest with new recruits, telling them that in a service lab like ours, the first priority is to deliver the product." Next year's ALMA meeting is scheduled to be held in Detroit, Mich. For more information about the organization, write ALMA, c/o R. F. Stalzer, P.O. Box 258, Montchanin, Del. 19710 (302-571-8216). Stu Rorman
