Instrumentation L. S. Etbe The Perkin-Elmer Corporation Norwalk. Conn. 06859-0090
~men-TubulcrrColumn/: €vdution, w n t Statw, on3 Future Open-tubular (capillary) columns were invented almost 29 years ago. The past quarter of a century has been characterized hy a slow, steady evolution, with continuous improvements of this wonderful tool. Although the invention of these columns can he attributed to a single person, their continuous improvement is the result ofcontributions from scores of chromatographers around the world. The story of the evolution of open-tubular columns is also the story of the achievements of all of these scientists. However, it is virtually impossible to give credit to all the individuals who contributed to this progress. Therefore, although noting the more important achievements, I will particularly emphasize work with which my colleagues and I have been more closely related. Discussion of a scientific evolution represents a chapter in the history of science. History is always interesting. I t is, however, even more useful if it not only discusses the past, hut relates it to the present and the future. Ohviously, the latter is subjective. Still, it is useful, particularly if it gives the reader ideas for possible improvements. I hope that I can achieve this.
mbeshnhes Open-tubular gas chromabgraphy can be traced back to a single person, Marcel Jules Eduard Golay (Figure 1). He is not a chemist but a physicist; actually, he likes to call himself an information scientist. Dr. Golay was 83 years old on May 3,1985; hut he still has not retired, and he is as active to0003-2700/85/A357-14 19SOl.5OlO 0 1985 ~ m a i c a nChemical Societv
day as he was 29 years ago. In the fall hf 1956, Golay was considering the separation process that takes place in a gas chromatographic column which, at that time, naturally meant a packed column. He thought about how uncontrolled it was having the sample molecules strolling randomly around the particles. The logi-
cal conclusion of this thinking process was to replace the unorganized packed column by a simple, empty tube with the liquid phase coated as a uniform film on its inside wall, with an open, unrestricted path in the middle. He immediately tried it, and on Nov. 15. 1956, he reported some favorable results (I). Figure 2 shows one of Colay’s
F
L
12-ti X 1.44-rnrn 1.d. open-tubular m i m . mated vim Carbowax 1500 polyelhyleneglycol. Micm ~ a c m n d u c l l v k ydetector: S a n h -hi galvanometer. Sample: Phillips 37 hVdrocarton m i m e . TOManalysis time was only a lev seconds
recordicg
also showed two chromatograms that
became the sensation of the meeting. The first chromatogram showed the full separation of the three xylene isomers on a partition column with an analysis time of about 1 h; the second illustrated the separation of C,hydrocarbon isomers in 9 min (see Figure 4). These two chromatograms represent the practical start of open-tubular column gas chromatography.
M
Flguro 3. Early chromatogram obtained by Golay (spring of 1957) 1 6 4 X 0.25mm id. wn-brbular mpm. maled wlth Carbowax 15W polyethyleneglycol. Micro mer-
malconductivity detector;oscillosmpe reedan. Fwks: 1 = air, 2 = acetone. 3 = carbon diwlfide. 4 = chlomforrn. 5 = rnenvlene chlwlde. Retention time ot 1861 psak: 15 s
Y pkneerr Other work immediately followed Golay's. In particular, I will mention here the activities of four pioneering groups: AI Zlatkis a t the University of Houston, Sandy Lipsky a t Yale University, Dennis Desty a t British Petroleum, and my colleaguesa t PerkinElmer. Both Zlatkis and Lipsky henefited from the small-volume version (5) of the argon ionization detector invented by Jim Lovelock. Figure 5 shows what is probably the first chromatogram obtained a t the University of Houston, dated Nov. 16,1958. It was signed by Zlatkis and Lovelock, as well as by M. C. Simmons (then with Shell), R. E. Johnson, and H. Lilly (both with Barber-Colman). Zlatkis and Lovelock submitted their fmt paper to ANA. LYTICAL CHEMISTRYon Dee. 2,1958, on the use of open-tubular columns for the analysis of C1-C5 alcohols, CSC, oaraffins...oh-xvlene. and the okfins-(6).
first chromatograms. In the next step Golay used an oscilloscope as the readout. Figure 3 is a photograph of one of these chromatograms (2).These two examples show that wide-bore chromatography columns and h i h speed analysis certainly do not represent new inventions. Golay's fmt paper on open-tubular columns was presented a t the 1957 Lansing Symposium (3),giving the first approximation of the theory. During this presentation he showed three chromatograms of a simple, three-component mixture run on a 1420 A
packed column and on two 0.25-mm i.d. columns of 100- and 300-ft lengths. The chromatograms were not very exciting, although the one obtained on the 300-ft column was probably the first ever to show more than 10,OOO theoretical plates. In subsequent months, Golay and h i co-workers improved both the theory and the practice of these columns. And, a t the 2nd International Symposium on Gas Chromatography, held in May 1958 in Amsterdam (4), Golay not only presented the complete theory of opentubular column chromatography but
ANALYTICAL CHEMISTRY, VOL. 57, NO. 13. NOVEMBER 1985
LiDskv immediatelv tackled one of the most difficult applications of gas chromatography: the separation of fatty-acid methyl esters. Hia paper, coauthored with Landowne and Lovelock, was submitted to ANALYTICAL CHEMISTRYon Feb. 8,1959 (7). One cannot speak about the pioneering period of open-tubular column gas chromatography without mentioning D. H. Desty of British Petroleum. He built hi first capillary GC immediately after the Amsterdam Symposium, using the new flame ionization detedor, which was also intro-
Plumber's helper. wihout wrenches. Rheodyne's newest valves make it unnecessary todisconnect the Dlumbina when vou want to sub,,om ,n,ec,or stiiute o n e i column ~ for another. You need only turn a pair of tandem valves to select any column from as many as five. Switchina columns frequently is becoming a generally-accepted practice for several reasons. Often, you must switch to a different tod*eclor column to make a different analysis. But, even when switching columns is not
&
I
I 1
IWI
-
essential, dedicating a separate column to each analysis eliminates column equilibration delays, reduces interferences,and prolongs column life. Rheodynek Model 7066 Tandem Column Selector connects any of up to five columns (or a bypass line) between the sample injector and the detector. Off-line columns are sealed at both ends, and no column need ever be exposed to a solvent intended for another. OurTechnical Notes4 tells all about column selection with Model 7066 and other valves. To receive a copy, along with product literature,contact Rheodyne, lnc., PO. Box 966. Cotati, California 94928. U.S.A. Phone (707) 664-9050.
Sample * In Many Styles and Sizes
Acid Digestion Bombs, Teflon lined. for treatina inoraanic sampies in HF, HCI and' other strong min-
Figure 4. Chromatogram shown by Golay a1the 1958 Amsterdam Symposium (4) 150-fl X 0.25i.d. OpMubular column. waled wim dldecyl phthalate. Column te-ratwe: 40 'C. Canier gas (He] flow rate: 0.96 mLImin. Micro thermaccMdunivilydets*w. Sample: mixhlre of i s m r i c Cshydrocarbons. cM.tesy of ButtemWhs, Im.
eral acids. or lor ~
~
digesting organic samples in strong alkalisor oxidizing acids at temperatures well above normalboiling points. Available infive different styles for various applications. Oxygen Combustion Bombs for breakingdown any solid or liquid combustible sample quickly and completely by oxygen combustionin a sealed bomb, for immediate conversionto soluble orms an complete recoveryof all elements.
duced in 1958 (8). H i s first report (9) was presented at the Symposium on Gas Chromatography, held in Leipzig, Oct. 9-11,1958. In subsequent years, Desty and his eo-workers have reported on a large number of investigations covering almost every aspect of opentubular column GC. Probably his most impressive chromatogram was presented at the 1961Lansing Symposium; it was obtained on a column d-
most 300 m long with an i.d. of 0.15 mm, showing the total analysis of a Ponca crude sample. In the proceedings of the symposium (IO)only part of the chromatogram was included, as the whole chromatogram had the length of a full recorder chart roll. A t Perkin-Elmer, Dick Condon had already been involved in open-tubular column work, even prior to t h e 1958 Amsterdam Symposium. H e had a
General Purpose Bombs in sizes from 21 mlto 2 gallons for a wide range of laboratory applications.
OurlS-page BulletinllOO details these bombs and their many uni ue applications. Write or plone for your copy.
I"
PARR INSTRUMENT COMPANY 211 Fifty-thirdStreet Moline, Illinois61265 Phone: 3091762-7716 TWX. 910-225-1753
Flgure 5. One of the first chromatograms, obtained Nov. 16, 1958, at the University of tiouston
I I;IHC.LL
1422A
7 0 4 VN
150-11X 0.25mm i.d. open-tubular column. waled wim wualane. Micro arwn lonlzetlmMe&. Sam ple: hybocarbon m i m e . SigMtwes (kflto right): A. Zlalkls. J. E. Lovelock. M. C. Slmmonds. R. E. Johns ~ H..Lilly
ntALhn atnvibr
~AI(L)
ANALYTICAL CHEMISTRY. VOL. 57. NO. 13. NOVEMBER 1985
Evaluating E Analysis Tec Consider Energy Dispersive X-ray Fluorescence . .
Analysk Range: simultaneous non-destructiie . analysii of elements from No through U in minutes Dynamic Range: ppm to 100%without dilution Sample Fonn: solids powder$ liquids and thin films Automation single button, unattended operation IBM K / A T with softkey selected, : compamble to an automated AA
Y
...
-~,j
,
T
Flgure 8. Chromatogam of a mixture of C2-Cs alkanes, alkenes. and alkynes, shown by Condon in his paper presented at the 1959 Plttsbwgh Conference ( 1 7 ) OpeMubular wlumns: 204fl X 0 . 2 h m Ld., wet& w i h dimemyl suWo!am, and 100- f l X 0.25-mn 1.d.. coated vim polypopybre glycol. wnnBcted In series. Column ternpamure: 33 ‘C. Carler sus (Ha)11w rate: 0.5 mL/min. Flame imkation Wectw
Flgure 7. Chromatogram of pc,,-.mint iii’s paper presented in 1962 [ 1 4 )
oil from Yakima Valley, Wash. (from Aver-
150-fl X 0 . 2 h m 1.d. open-tubular w l m , -mi with U w n 011 5WP-2000 pohlpropylsn, glywl. Tern perature: poeramned. as given. Canler gas (He)flow rate: 1.4 mllrnin. Flame ImiTatlmdetector. Peaks: 1 = aginens. 2 = Bpinsns. 3 = -1ypmi. 4 = menlhaa. 5 = rrnmohran. 6 = menmy1 atam. 7 = menumi
Flgure 8. Chromatogram of a fatty-acid methyl ester mixture (from the publication of Ettre, Averill. and Kabot. 1962 [ 131)
-
200-fl X 0.50mm id. 0pewMular wlumn, wled w i h butanedl01succinsm. Temperam: 196 OC. Carrier gaa (He) flow rate: 10 nXlmin. Flame imiTatimdetecta. Peeks mnespand to tha memVl esters: 1 = capylste.2 = capate.3 = b a t e . 4 = nm$tate5 plrnWe. 6 = stemte.7 =-.E = lhde ale. 9 = llnolenale
1424A
ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
major presentation at the 1959 Pittsburgh Conference, which was soon published (11). This paper contained a large number of impresaive cbromatograms showing, among others, the separation of C& hydrocarbons (Figure 6 ) and aromatics including the xylene isomers. He also used the new flame ionization detector. Warren Averill joined Perkin-Elmer in 1960 and, for a decade, he was probably the one who knew best how to coat a stainless-steel capillary tube. Figure 7 shows one of his chromatograms of peppermint oil; this was shown during his paper presented at the Annual Meeting of the Institute of Food Technologists, in Miami Beach, Fla., on June 11,1962 (12). Another field that we at PerkinElmer became very much involved in was the analysis of fatty-acid methyl esters on open-tubular columns coated with polyester phases. Figure 8 shows one chromatogram from 1962 (13). Note that it was obtained on a 0.50-mmi.d. column. widely used at that time. There is now renewed interest in such columns, and many consider them an entirely new invention, which, obviously, they are not.
Tubematerial Early columna were made both of plastic and glass tubing, and, by 1960, glass capillary drawing machines had already been described (14,15).In spite of this, however, metal columns were used almost exclusively at that time. The main reason for this was that methods for the preparation of a stable coating on the inside of a glass capillary tube had not yet been developed. This situation was well summarized in the discussions at the 1961 Lansing Symposium, particularly by Halbz. He stated that they could use a copper tube coated with squalane more than eight hours per day for more than seven months, whereas a squalane-coatedglaas open-tubular column Lasted no longer than two to three days: “On glass coated with squalane, you can see with your eyes after two days that your film is not in one piece” (26). Of the metal tubes, stainless steel became the most widely used. Naturally, such eolumns also had their problems, mainly because of an uneven inside surface and the activity of the material. To overcome these problems, in 1961 Averill proposed the use of special additives to the liquid phase, which would block the active sites (17).This technique was generally accepted for the coating of stainless-steel tubing. In the 1960s our knowledge about glass slowly increased, and techniques were developed to modify the inside tube wall, making it amenable to coat-
LJ-
‘he ACCUSPEC #ZO is the estabshed basic tool for high temperaure infrared studies. Designed to lperate with both dispersive and :T-IR spectrometers, the #20 irovides the facilities for infrared nalysis of samples at temperatures Iup to +7OO0C in controlled tmospheres. Current user applicaions include catalyst research, hermal stability.gas-solid reactions, tc. The #20 is essential for all esearch laboratories using infrared nalysis. C!
HEAVY!
I 4
Figure B. Chromatogram of a “pure” rrbulyl acetate sample on a wlde-bore column (from the publication of Jentrsch and Wvermann, 1962 [28]) 100- X I-mn i.d. opan-tubular w l w n . coated with polypo@ne glywl. Temperawe: 80 OC. Carrier gas (He) tlw rate: 37.3 M m l n . Flame ionirah detecta. Packed wlumn injector: 1-pL sample. The large p a k indicatedwith an arrow wneswnds m &butyl acetate: rest repesem lmpvllles In mS sample
The new ACCUSPEC #2000 prorides an exceptional range of !xperimental parameters for :T-IR. Within the #2000, the ample can be subjeEted to tempzritures from -170 C to +700 C ind pressures from high vacuum to !OOOpsig. Three optical modes are ivailable for sample analysis so that !yen the most difficult samples can ,e readily analysed in either transnission or reflectance modes. The iew #2OOOis a mustfor researchers Qorking on materials research, eaction mechanisms and high rmperaturelhigh pressure topics.
ACCUSPEC USA:
3375 Park Avenue Wantagh, NY 11793 Tel: (516) 783-9380
EUROPE: Sandyford Estate Foxrock, Dublin 18 Tel: (Dublin) 953221 TLX: 24474
-
~~
ing. In particular, Crob, Liherti. and Novotny and Tesarik pioneered in this field. From their methods, etching with gaseous HCI or HF (first described by Novotny and Tesarik) became the most widely accepted method. In addition, detailed investigations by scores of scientists in both Europe and the United States were carried out before glass replaced stainless steel as the most widely used column material (for a summary of this evolution, see References 18-20). This transition did not u k e place until the early 1970s. The introduction of fused silica as the column tube material in 1979 represented another breakthrough in the continuous improvement of open-tubular columns. The first report was presented by Dandeneau and Zerenner at the 1979 Hindelang Symposium (21);since then considerable work has been carried out in this field (for a summary, see Reference 22). Today, fused silica has replaced nearly all other column materials. Colurmdiametuandk@h In the early period of open-tubular column CC, column diameter depended mainly on the availability of suit. able metal tubing. The 0.25-mm (0.010-in.)i.d. tubing became the most
CIRCLE 1 ON READER SERVlCE CARD
1426A
ANALYTICAL CHEMISTRY, VOL. 57, NO. 13. NOVEMBER 1985
popular and remained so,even after the introduction of glass columns. Depending on the drawing machine, the actual internal diameter of the most frequently used tubing varied between 0.20 and 0.27 mm. As already mentioned, 0.50-mm (0.020-in.) i.d. columns had also been widely used practically since the beginning of open-tubular column GC. In addition to these columns, the utility of tuhing with even wider diameters was also investigated in the 1960s.For example, in 1964 Teranishi and Mon (23)described the use of 0.76-mm (0.030-in.) i.d. columns, which they used in C C N S applications. In the early 1960s Kovets had widely used 1.8-2-mm i.d. columns in the investigation of essential oils (24,W). Kovits even used these columns with thermal-conductivity detectors. In the early 19608, we were also very much interested in larger diameter open-tubular columns. Jentzsch and HBvermann, my German colleagues, extensively investigated the possihility of 1-mm i.d. columns (26-28); Figure 9 shows one of their chromatograms. In fact, such columns have been marketed for a number of years under the name of “macro Colay columns.” At Perkiu-Elmer we investigated the performance of 1.55-mm i.d.
Announcing the Varian VXR Series, the ultimate in research NMR
I
Now "second-best" isn't even close.
1
Unparalleled experimental flexibility for viifually all NMR techniques, including imaging spectroscop)!CPIMAS and wideline solids, and high performance liquids.
2
Patented zeresusceptibility probes that offer the highest guaranteed sensitivity on a wide range of nuclei, including the industry's only broadband switchable probe,
3
Advanc6d RF architecture that sets a new standard , in precision and stability for the most demanding experiments. including water suppression and multiple quantum spectroscop)!
4 5
6
A new modular design provides the flexibility to customizeyour instrument to meet your current and future needs.
Multiple operating modesfrom fully automated to complete manual control of all spectrometer functions.
A data system and software that even the competition recognizes as the best in the industy
Operating frwuencies to 500 MHz includng both narrow and wide bore magnets, and horizontal bore magnets up to 33 cm.
7
Varian-the first name in NMR for applications from materials science to biotechnology.
Varian's continuing commitment to excellence and to your success extends beyond delivering the best instrument.We support you with the worlds largest staff of NMR applications and service specialists. VXR systems are available now worldwide for demonstrationand immediate delivery. For more information call (800)231-5772 In Canada, call 416-457-4130 In Europe, call Zug. Switzerland. at (042)44-11-22, Darrnstadt, Germany. at (06151)7030. In Japan, call 3-204-1211
varian ~
ANOTHER
INSTRUMENT
~
Vartan lnstmrnent Group, 220 Hurnboldt Court, Sunnyvale. CA 94089 In Canada: 332 Guelph Street Georaetwn, Ontario L7G 485 In Europe: Steinhauserstre. CH-6300 Zug. Switzerland
CIRCLE 222 ON READER SERVlCE CARD
ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
1127 A
I
THE DEFINITIVE STANDARDS FOR CHLORINATED AND BROMINATED
DIBENZODIOXINS PREPAREDBY
CAMBRIDGE ISOTOPE LABORATORIES, INC. and
RADIAN edk d o o R A T I
N
AVAILABLE BROMODIBENZODIOXINS ISOTOPE LABELED STANDARDS FOR G U M S UNLABELED CHEMICAL STANDARDS FOR GC AND HPLC
BROMODIBENZOFURANS 0
ISOTOPE LABELED STANDARDS FOR GC/MS
0
UNLABELED CHEMICAL STANDARDS FOR GC AND HPLC
PLEASE CALL OR WRITE FOR OUR COMPLETE CATALOG 0N:
DIBENZODIOX1N/ DIBENZOFURANS POLLUTANTS/RESIDUES PESTICIDES/PCBs
Contact:
CAMBRIDGE ISOTOPE LABORATORIES 20 Commerce Way Woburn, MA 01801 USA 1-800-322-1 174 (617) 938-0067 (in Mass.) Telex 951935
columns (29).Because of their increased sample capacity, these wider diameter columns could be used with direct sample introduction (without any split) and even with standard thermal-conductivity detectors. In addition, because of the smaller capacity factors (due to the higher phase ratios), these columns were particularly suited for the rapid analysis of highboiling compounds. For example, Quiram could analyze n-cetyl alcohol in 8 min at 175 “C (i.e., 169 OC below its boiling point) using a 250-ft X 1.55-mm i.d. column and a flow rate as high as 800 mL/min (30).This result, of course, is not surprising; in fact, in 1960 Golay had pointed out (31)that the pipeline from Texas to Maine (which certainly does have a very high phase ratio) actually may be an excellent “open-tubular column” for highboiling compounds. Until now, I have surveyed only the development of columns with a wider diameter. The pioneering work on small-diameter (less than 0.2 mm) columns was carried out by Desty in 1960-61 (10,32). Until recently, very little work was done in this field, mainly because of the unavailability of such tubing and problems with the introduction of extremely small samples. However, over the past five years, there has been renewed interest in such columns. With regard to the length of opentubular columns, for more than two decades most were made of relatively long tubes-usually 100-300 ft. Some were even longer. The record in column length belongs to A1 Zlatkis; in 1959, he prepared and tested a onemile-long open-tubular column made of nylon tubing with an i.d. of 1.676 mm, and obtained an HETP of 1.61 mm (33). Shorter columns have also been used since the beginning of open-tubular column GC, although less frequently. I have already mentioned that Golay’s first columns were less than 20 f t long. Desty has also reported on short (1-10 m) columns (10,32). In 1964 Marco demonstrated the analysis of C ~ - C Ialcohols ~ on a 9-m X 0.50-mm i.d. column in less than 5 min (34).In our laboratories, Johansen carried out a detailed study in 1977 (35)that demonstrated some possibilities for short (10-15 m) open-tubular columns. They greatly reduced the analysis time while still providing adequate efficiency. Such short columns, especially those with 0.50-0.53-mm i.d., are of particular interest now as a replacement for packed columns in routine applications. Coating technique and liquld phases
Basically, two methods have been used to coat the inside wall of the col-
CIRCLE 32 ON READER SERVICE CARD
1428A * ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
umn tubing with liquid phase: the dynamic and the static method. In both cases, the liquid phase is in a solution. In the dynamic method, the solution is passed through the tube, wetting the inside surface; in the static method, the tube is completely filled with the liquid phase and the solvent is allowed to evaporate slowly. The dynamic method was first mentioned by Dijkstra and De Goey (36);the static method was first used by Golay ( 4 ) . Later, Bouche and Verzele (37) simplified the static method by using a vacuum to evaporate the solvent slowly from the filled column tube. Both the dynamic and static methods exist in many variations. Just as with packed columns, commonly available organic compounds, such as plasticizers, hydrocarbons, polyalcohols, and polyesters, were used at the beginning as the liquid phase for open-tubular columns. The basic problem with these, however, is their relatively low molecular weight (resulting in excessive bleeding) and the presence of impurities. Slowly, higher molecular weight polysiloxanes (silicones), made specifically for gas chromatography, replaced the older phases, thereby extending the usable upper temperature limit. However, an apparent contradiction soon became evident: To reduce bleeding and further extend the upper temperature limit, high-molecular-weight polymers were desired. On the other hand, the higher the molecular weight of the polymer, the poorer its solubility. The solution to this problem is to coat the column with a relatively low molecular weight substance and then repolymerize this prepolymer in the column, creating a high-molecularweight, cross-linked liquid phase. The final polymer coating can also be partially bonded to the Si-OH groups of the inside tube surface. Madani, in 1976 (38,39),was the first to prepare such columns, and he was soon followed by a number of other researchers including Blomberg, the Grobs, Lee, Lipsky, Sandra, and Schomburg. This development is still continuing. Film thickness
In the past, relatively little was done on controlled changes to the liquidphase film thickness. This was mainly for three reasons: 0 For a long time, the dynamic coating method was used most frequently. With this method, it is difficult to know the actual film thickness. Until the advent of immobilized, cross-linked stationary phases, films thicker than about 1pm were unstable: The excess phase was soon lost through bleeding. Metal columns had to be coated with a somewhat thicker film to re-
lwobalanceswith the same specifications are the same,rigM.? Wrong. The way a balance is designed and built determines how accurately it weighs-in the long run. bVhatyoucan'tseedoesmatter.
Y y w w a ~ ~ d o n e r i g h t y w ~ e ~ O d o ~ .
A&D balances are accurate - and careful attention to a host of details ensures they stay that way for a long, long time. We build in shock and overload protectlonto prevent damage. Electronics are 'burned-in' to discover defects before shipping. Important details other manufacturers often neglect.
A&D
Some people prefer to buy 'off-theshelP parts to build electronic balances. We make our own. As an electronics company from the beginning, we've developed SpKlallZed A/D conversion technology to build weighing equipment that lives up to the extremely high standards we set for all our products. It's the only way.
mclnufocturesevery major pari used in A&D
Call 800-232-5737 (toll-free in the US)or writc
I-
balances.
''Td out more
CIRCLE 3 ON READER SERVICE CARD ANALYTICAL CHEMISTRY, VOL. 57, NO. 13. NOVEMBER 1985
1419A
5,
1-2
CHROMATOGRAPHY SPECIALISTS SPECIFY ALLTECH 75
65
55 45 35 25 Programmed at a rate of 2 oClmin--lclsotherma14
25
Figure 10. Chromatogram of a Cr-G hydrocarbon mixture (alkanes, alkenes. cycloalkanes. and aromatics) on a SCOT column (from the publicationof Ettre. Purceii, and Billeb. 1966 1501) ~~. loo-n x o.5o.mm 1.d SCOT column, prepared wrn qqllllmliquid phare. phasa ra110: 67. F I l~nlm ~ ~
~
~
. ..
1 = mamana. 2 = emana. 3 = propane. 4 = popane. 5 = propans. c a n s a y of Msral Dakka. Inc.. New Y d . N.Y.
tion detscmr.~ h nrst s IIYB &s:
'ou're a specialist, and so are ye. It takes a specialist to keep ip with the changes and idvancements in the field, and I takes a specialist to pioneer hose changes. Alltech does ,oth. For 30 years, Alltech b s o c i a t e s , Inc./Applied icience Labs has been the eader in innovative :hrornatography products. Our ;as Chrom Q is an industry itandard; we pioneered the ise of Vespel ferrules; we leveloped t h e Microbore 4PLC column; and our new ION-PAKD GC columns are ast replacing Packed GC :olurnns in labs around the vorld; and on and on and on; )roduct after product, nnovation after innovation. t takes a specialist to inderstand what another ipecialist needs, both now, ind in the future. At Alltech, we 1 nderstand. 'or your free copy of our :atalog, please contact us at:
ALLTECH ASSOCIATES LPPLIED SCIENCE LAB3
2051 Waukegan Road Deerfield, II. 80015 TEL: 312-948-8800 CIRCLE 5
430,.
ON READER SERVICE CARD
ANALYTICAL CHEMISTRY, VOL.
z-nwmyc
.wlng .sure 11. Chromatogram of an oil of marjoram sample obtained in a GClMS system a SCOT column (from the investigations of Averill and Struck, 1966 see Reference 49) SC-tl X 0 . 5 h m 1.d. SCOT mlumn, prepared vlh 05138 polyphenyl emer liquid phase. phase ratio: 50. Temperatwe: pwamned,as given. Total (on cwrm recadlng
duce the activity of the inside tube surface. Thus, conscious variation of the liquid-phase film thickness was not plausible until the advent of glass columns. According to the theory of o p e n p bular columns, columns prepared with a thin film have a higher absolute efficiency. This was the primary reason why most of the glass columns were prepared with a relatively thin (about 0.2-pm) film. However, it had been understood for a long time that it is advantageous to select the film thickness according to the type of sample: This had been pointed out as early as 1961-63 by Jentzsch and H6vermann (27,a). In 1974 in our laboratories, Averill and March (40) illustrated the differences in the separation of early peaks in complex natural samples, such as gasolines and essential oils, when ', NO. 13. NOVEMBER 1985
changing the film thickness from 0.25 ,um to 0.50 pm; in fact, columns with a 0.50-pm film (in addition to 0.25pm f h columns) were commercially introduced at that time. Continuing these investigations, in 1979J o h n (41) published his pioneering study on the characteristics of 0.27-mm i.d. columnscoated with 1-pm fh. The introduction of immobilized phases finally permitted the preparation of open-tubular columns with film thicknesses well above 1pm. The first detailed reports on such columns, with film thicknesses up to 8 p m , were published in 1983 almost simultaneously by the Grobs (42). Sandra (43), and ourselves (44,45). Such columns, particularly with the simultaneous increase of the tube diameter, represent an exciting new field in the application of open-tubular columns. Although this discussion dealt only
RESEARCH-SENSITIVE FT-IR UNDER $4O,OOb
n
t
If you want an FT-IR spectrometer powerful enough for tomorrow's problems as 4 1 as today's, we built OUT new FTS 40 just for you. The F S 40 has the same sensitivity as OUT higher priced FTS spectrometers, allowing you to do GCiIR, microscopy, ATR, photoacoustic studies and other research level chniques, on difficult samples, over a range of 10,000 cm-' to 220 cm;' at a resolution f 0.5 cm-! And with its new desktop 3240 data system, the FTS 40 has the computing power for GCIIR, rapid searching of large Sadtler libraries, multi-component analysis and other applications far beyond the capabilities of other modestly priced spectrometers. Available with accessories and full support. Starting at $39,500, it's the best value in R-IR today. Please write for literature to Bio-Rad Digilab Divish 17 Putnam Avenue, --nhidge, MA 02139. Or call (800)225-1248, ext. 1'-
. .
with increasing the film thickness, it should also be mentioned that in some cases decreasing it may be desirable, particularly when analyzing very high boiling samples. For example, Adams and co-workers demonstrated in our laboratories, in 1977, the use of columns with a 0.05-pm-thick film for the analysis of amino acid derivatives (46). Porous-layer open-tubular (PLOT) columns
1. Wqh sample. Place in furnace 2. Set system balance to zero.
In his 1958 paper ( 4 ) ,Golay had already indicated the advantages of increasing the inside surface area to be coated; he elaborated on this in 1960 in more detail (31). The advantage of such columns is a decrease in the phase ratio of the column while keeping a very thin liquid-phase film. The inside surface area can be increased by building up a porous layer on the inside tube wall, either by chemical treatment or by deposition of porous particles from a suspension. The latter method was developed in 1962-63 by Horvbth (47,48),then at the University of Frankfurt, in the laboratory of Dr. Halbsz, by adopting Golay’s original static coating method. Because these columns were prepared by coating the inside tube wall with a porous support layer, they are commonly called support-coated open-tubular (SCOT) columns. In the latter half of the 1960s we continued Horvith’s work, extensively studying these columns and making them commercially available (for a summary, see Reference 49). Figures 10 and 11show typical chromatograms; the latter was obtained with a GCIMS system and represents a total ion current recording. SCOT columns were very popular for at least a decade because of their advantages: higher sample capacity, higher flow rates, the need for fewer plates for the separation of early peaks (cf., e.g., Figure lo), and very good efficiency. The only limitation of these columns was the residual activit y of the particles used in building up the porous layer. However, overall column performance was still good, comparable to that of metal columns used at that time. With the advent of highly sophisticated and efficient glass and fused-silica columns in the second half of the 1970s, the importance of SCOT columns diminished. The wider diameter thicker film columns developed recently seem to have completely replaced them. This may, however, not necessarily remain so, as the theoretical background of SCOT columns is sound. In fact, a comparison of a SCOT column and a smooth-walled column with the same inside gas volume and total liquid-phase volume should favor the SCOT column as-
CIRCLE 151 ON READER SERVICE CARD
1432A
ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
suming, naturally, th& proper inert particles are found for building up the porous layer. This certainly is not an insurmountable task. In addition to increasing the inside surface area of partition columns, POrous-layer open-tubular columns represent the only way to prepare opentubular adsorption columns. A number of researchers prepared such columns in the 1960s by creating the porous adsorbent layer either by chemical treatment or by the deposition of the porous adsorbent particles (see Reference 49). Figure 12 illustrates the performance of such a column, prepared by depositing bentonite particles on the inside wall of the column (51).At present there is renewed interest in adsorption-type POrous-layer open-tubular columns. lnstrumentatlonfor open-tubular columns
The subject of this paper is column development. However, columns do not exist in themselves; they are always part of a system, and one cannot split them apart. This is especially true for open-tubular columns; their small sample capacity and the low carrier gas flow rates used with these columns create special requirements for the system, particularly concerning the way in which samples are introduced. The problems associated with sample introduction were recognized practically since the beginning of open-tubular column GC. In fact, the first papers describing the application of open-tubular columns already dealt with the possibility of split sampling (6, 7,9,11,32). Split sampling refers to dividing the mixture of the sample vapor and the carrier gas into two highly unequal parts, the smaller one being conducted into the column. Although early split systems represented a simple tee design, their construction was soon refined, adopting the so-called concentric tube design. It is safe to say that by 1961-62, reliable split sample introduction systems were described and made commercially available (52-55). In addition, the two basic requirements of linear splitting were also soon recognized: that no sample loss should be encountered during evaporation, e.g., due to thermolysis, and that sample vapor and carrier gas must be homogeneously mixed prior to splitting. Later complaints about the apparent nonlinearity of split-type sample introduction can all be traced back to disregarding these two basic requirements. Naturally, in the past 20 years, split sample introduction systems have been significantly improved, and a number of other systems have been introduced permitting, for example, direct, on-column sample introduction
custom tailored for the petfect fit The N E R M A G R 10-10 C Series of quadrupole mass spectrometers, in addition t o being the most powerful and sensitive instruments in the field, have been especially designed for ultimate compatibility with LC interfacing. ..
The VESTEC THERMOSPRAY Interface has earned the reputation of being the industry standard for the LC/MS combination.
i
!
The custom tailored NERMAG mass spectrometers and the famous VESTEC THERMOSPRAY Interface add UD to ...
.
For more information, circle our number and visit us at:
;i ’ ,,
I EASTERN ANALYTICAL SYMPOSIUM 1 I
I
NMI YORK NOV.19-221985 BOOTH NO110
I
II I
‘I
l i
11
I
.
.-
I,.!? :
‘I&
i
.i
I!
I
- -. - ....._... - . . . ._.. .__
47.32.92.05 -Telex : RIBMAG 204 029 F ~
~~~
~~~~~~~~~~
DELSI Inc. 10 Kingsbridge Rood,
~~
~
Fairfield NJ 07006 - U.S.A. Tel. : (201) 227.76.90 -Telex : DELSINERMAG UD 314806
.
with or without previous sample evaporation (56). Thepresent Today, interest in capillary columns is exponentially increasing. This is best demonstrated by the 700 participants at the 6th International Symposium on Capillary Chromatography, which was held May 13-16,1985,at Riva del Garda, Italy. The importance of this large number of attendees is even more evident if we consider that a t the recent Biannual International Chromatography Symposium (Oct. 1-5,1984,Nknberg, F.R.G.), which encompassed all branches of chromatography, the total number of registrants was only about 1ooO. The present status of open-tubular Union Giken apparatus achieves a column GC can be characterized by dead time as short as 1A millisecond three trends. The first is the change- I for measurement of fast reactions. over from soda-lime or borosilicate G a s pressure is directly applied to glass to fused-silica tubing. This dethe surface of the reactants in each velopment is practically complete in reservoir, mixing and flow being the United States and, although it is somewhat slower in Europe, the direccontrolled from the end of the tion is clear. This is accompanied by system by a high-response stop two related events. The first is invalve. The RA-401 STOPPED creased use of well-defined crossFLOW SPECTROMETER is the linked phases and, the second, reliideal match for fast reactions. ance on a few highly specialized suppliers for high-quality fused-silica columns, replacing homemade glass columns based on individual and usually empirical technology. AU of these developments led to a vast improvement in the overall quality and performance of the columns used in practice and ensure better uniformity of their characteristics The second trend is characterized by the greater flexibility available in me R A 4 5 1 DATA PROCESSOR generthe selection of column variables. Presate% a simulated reaction curve from ent-day columns have diameters from the measured results and automatically 0.05 to 0.75 mm, film thicknesses from calculates the rate constant. about 0.2 r m up to 5 4 rm, and lengths from 10 m o r even shorter up to 100 m. The availability of such a wide range readily permits the selection of the optimum parameters for a given application. Finally, the third trend is found in the application of open-tubular columns. Until recently, they were primarily considered tools for the analya s 110 I." I,&"." sis of very complex samples, and chromatographers often tried to outdo The R A 4 1 5 RAPID SCAN ATTACH. themselves in "number counting," MENT monitors the change in absorp tion spectrum during the qeaction. seeking to separate the largest number of peaks in a given sample. This,naturally, did not mean that the eeaential advantage of the columns was not Other attachments are available foi clear-that, compared with packed T-jump, P-jump, fluorescence and columns, one can either obtain better flash photolysis. resolution in equal time or the same resolution in a much shorter time. C O n t r t m).rok*xpQrt4*ntforrrdama*:However, this rule was frequently ATAGO BUSAN CO..LTD. overshadowed by the illustration of 7-23 ~ h o ~ S h l m h r ( tMlmm-ku. l. very high absolute efficiencies. Most T o k h 105 dmpan Telex: 38451 "1% TAGOA TOKYO recently, analysts finally began to rePhon.: 03 4328741 alize that today's open-tubular col"11
CIRCLE 2 ON READER SERVICE CARD
1434A
ANALYTICAL CHEMISTRY. VOL. 57. NO. 13. NOVEMBER 1985
FyUre 12. Chromatogram of an aromatic hydrocarbon mixture on an adsorptlon-type PLOT column (fromthe publication of Ettre, Purcell, and Norem, 1965 [57]) 50-ll X 0.50-mm i.d. PLOT column prepared wlth Bentom 34, CelHe. and M 5 0 phenylslllwne oil. Temperature: 100 OC. Canier gas (He)flow rate: 4 mLlmln. Peaks: 1 = benzene. 2 = thiophene. 3 = toluene, 4 = enylbemene. 5 = pxylene. 6 = mxylene. 7 = +xylene, 8 = Isqxopylbnzene. 9 = rrpopylbenzene. 10 = hMbutyC benzene, 11 = set-butylbenzem. 12 = 41%-
propyl-l-memylbenzene,13 = M u t y C benzene. COvteSy Ot Weston PUbUShlW CO., Nils, Ill.
umns have obvious advantages, even in relatively simple applications usually solved with packed columns. Because of their h g b sample capacity and excellent resolution capability, the larger diameter, thicker film columns introduced in the past two years are particularly important in this respect. They posskss a degree of reproducibility not found in packed columns. They are flexible, inert, stable, and have a long lifetime. They do not have the inherent defects (rigid structure, active sites of the solid support, high inlet pressures, ete.) of the packed column. Thus, it seems obvious that they are ideal for a routine analytical laboratory. With this, we have arrived a t the future of the opentubular GC column. (continued o n p . 1436 A)
ANALYTICAL ELECTRO-ANALYSlS APPARATUS SHAKERBATH
RECIPROCATING SHAKERS
Cat No 6250 To provide immersed agitation at controlled temperatures Available in two sizes, table model or floor model, to meet a wide range of requirements. Variable speed, stroke, and temperature featured in all models
WARING CONTAINERS
Cat no. 1000 (w/o platinum) Apparatus tor determining copper, lead, antimony, cadmium, nickel, and zinc, by the electro-deposition process. Apparatus also available lor high speed determinationsand the separation of metals by the mercury cathode technique
BLENDER POWER UNITEXPLOSION PROOF
STIRRERS
\
\
+ ?I
&
Cat No 7225 (wlo agitator) The Eberbach Con.Torque stirrer with high torque output, is designed to stir highly viscous materials such as resins Hollow spindle concept utilized in Eberbach Stirrer line'assures additional gripping of agitator and facilitates changing containers. Available from 1170 thru 1/10 hp.
8
cat No. Cat No. Cat No. 8470 8580 8575 Glass. stainless steel. and aluminum containers available in capacities from 1000 ml to 3 ml Commercial one quart Blendor Power units to include an explosion proof power unit will accept all Eberbach containers Replacement blending assemblies and components available CIRCLE 51 ON READER SERVICE CARD
ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
1435A
increase precision in injection.
-
Rheodyne’s Tech Note 5 shows how you can maximize HPLC precision by using skillful sample injection techniques. The information is drawn from hundreds of closely controlled experiments using different types of sample injectors and different loading methods. The 6-page summary of results is written to help both the beginner and the experienced chromatographer. The experiments yielded some surprising answers to highly practical questions.One question: How much sample must you waste to fill a sample loop “completely”? (It’s more than you are likely to think.) Another question: When you are reading a syringe to judge the amount of sample be,ing loaded, how much sample can you inject without impairing accuracy? (It’sless than you may think.) Get the answers to these and other salient questions now.
Send for Tech Note #5. Contact Rheodyne, Inc., PO. Box 996, Cotati, California 94928, USA. Phone (707) 664-9050.
RwODYNE THE LC CONNECTION COMPANY
The future Until recently, these columns were mainly considered tools for the analysis of complex mixtures-in other words, for samples that could not be satisfactorily separated on a packed column. The newest developments in column technology finally have started to convert the chemists in routine analytical laboratories to using these columns, even for relatively simple applications. The advantages of the thicker film, wider diameter columns in most instances are so overwhelming that it does not seem far-fetched to predict that within the next few years they will replace the packed column in most routine applications. The new developments in open-tubular columns are, however, not restricted to these workhorse columns. There are also many advances in column technology for those who are analyzing complex mixtures. I am thinking particularly of the small-diameter columns providing very high absolute efficiencies. We shall certainly see a more widespread application of these columns. As I discussed earlier, apart from a few reports, very little was done in the past in the field of open-tubular adsorption columns. I believe that in the future this will also change. Many advances can also be predicted in the GC systems in which the columns are used. We certainly will have smaller, fully automated and dedicated instruments for open-tubular column use only, including the use of robotics for sample preparation. We will also see increasing use of open-tubular columns in hyphenated techniques such as GUMS and GC/FTIR. Prediction of the future is always difficult. However, I feel it is safe to say that we are finally at the threshold of the universal acceptance of open-tubular columns in every field. With this, 29 years after their invention, we are finally starting to fulfill the pioneers’ dreams. I have tried to survey almost 30 years of open-tubular column development. It represented a nostalgic journey for me, surveying the activities of a generation. For many of us, these activities became our whole life. It was exciting, and it was interesting. But even more important, it was fun! Based on the Chromatography Award Address, presented at the 189thNational Meeting of the American Chemical Society, Miami Beach, Fla., April 28-May 3,1985
References (I) Golay, M.J.E. “Progress Report of
Gas Chromatographic Experimental Work for September and October 1956”; Perkin-Elmer Corp., Norwalk, Conn., Nov. 15,1956. Re rinted on p. 3 of Ettre, L.S. “Open-TubuLr Columns in Gas Chromatography”; Plenum Press: New York, N.Y., 1965.
CIRCLE 182 ON READER SERVICE CARD 1436A ANALYTICAL CHEMISTRY, VOL. 57, NO. 13, NOVEMBER 1985
(2) See also Ettre, L.S. In “Applications
of Glass Capillary Gas Chromatography”; Jennings, W.G., Ed.; Marcel Dekker: New York, N.Y., 1981; pp. 1-47. (3) Golay, M.J.E. In “Gas Chromatography (1957 Lansing Symp.)”; Coates, V.J.; Noebels, H.J.; Fagerson, IS., Eds.; Academic Press: New York, N.Y., 1958; pp. 1-13. (4) Golay, M.J.E. In “Gas Chromatography 1958 (Amsterdam Symp.)”; Desty, D.H., Ed.; Butterworths: London, 1958; pp. 36-55. (5) Lovelock, J.E. Nature (London) 1958, 182,1663-64. (6) Zlatkis, A.; Lovelock, J.E. Anal. Chem. 1959,31,620-21.
(7) Lipsky, S.R.; Landowne, R.A.; Lovelock. J.E. Anal. Chem. 1959.31.852-56. (8) McWilliam, I.G.; Dewar, R.A. Nature
(London)1958,181,760. (9) Destv, D.H. Abh. Dtsch. Akad. Wiss. Berlin, Kl.Chem. Biol. 1959,9,176-84. (10) Desty, D.H.; Goldup, A.; Swanton, W.T. In “Gas Chromatography (1961
Lansing Symp.)”; Brenner, N.; Callen, J.E.; Weiss, M.D., Eds.; Academic Press: New York, N.Y., 1962; pp. 105-38. (11) Condon, R.D. “Design Considerations of a Gas Chromatography System Employing High Efficiency Golay Columns,” presented a t the 10th Pittsburgh Conf. Anal. Chem. Applied Spectroscopy, Pittsburgh, Pa., March 1959; Anal.
Chem. 1959,31,1717-22. (12) Cieplinski, E.W.; Averill, W. “Gas
Chromatographic Analysis of Essential Oils Using Golay Columns and a Flame Ionization Detector,” presented at the Annual Meeting of the Inst. of Food Technologists, Miami Beach, Fla., June 11,1962. GC Applications No. GC-AP002; Perkin-Elmer Corp.: Norwalk, Conn., 1962. (13) Ettre, L.S.; Averill, W.; Kabot, F.J. “Gas Chromatographic Analysis of Fatty Acids,” GC Applications No. GC-AP001; Perkin-Elmer Corp.: Norwalk, Conn., 1962. (14) Desty, D.H.; Haresnape, J.N.; Whyman, B.H.F. Anal. Chem. 1960,32, 302-4. (15) Kreyenbuhl, A. Bull. SOC.Chim. France 1960,2125-27.
(16) “Discussion on Capillary Columns.” In “Gas Chromatography (1961 Lansing Symp.)”; Brenner, N.; Callen, J.E.; Weiss, M.D., Eds.; Academic Press: New York, N.Y.,1962;p. 560. (17) Averill, W. In “Gas Chromatography (1961 Lansing Symp.)”; Brenner, N.; Callen, J.E.; Weiss, M.D., Eds.; Academic Press: New York, N.Y., 1962; pp. 1-6. (18) Novotny, M.; Zlatkis, A. Chromatogr.
Rev. 1971,14,1-44. (19) Alexander, G. Chromatographia 1980, 13,651-60. (20) Jennings, W. “Gas Chromatography with Glass Capillary Columns”; Academic Press: New York, N.Y., 1st ed. 1978, 2nd ed. 1980. (21) Dandeneau, R.D.; Zerenner, E.H. J.
High Resol. Chromatogr.lChromatogr. Commun. 1979,2,351-56.
(22) Jennings, W. “Comparisons of Fused
Silica and Other Glass Columns in Gas Chromatography”; Huthig Verlag: Heidelberg, 1981. (23) Teranishi, R.; Mon, T.R. Anal. Chem.
1964,36,1491-92. (24) Kugler, E.; Kovlts, E. Helu. Chim. Acta 1963,46,1480-1513. (25) Kovlts, E. Helv. Chim. Acta 1963,46, 2705-31. (26) Jentzsch, D.; Hovermann, W. “Die
Anwendung von Makro-Golay SBulen in der Gaschromatographie,” No. 19-GC; Bodenseewerk Perkin-Elmer & Co.: Ueberlingen, 1962. (27) Jentzsch, D.; Hovermann, W. In “Gas
In minutes. Not hours. Introducing Fast Affinity Chromatography, SOX faster than soft gels. Beckman's new Ultraffinitym-EPcolumn makes it all possible. With Fast AffinityChromatoaraohv (FACI, you can puriy large quaritiries of v i n i a ~ ya i y proiein .n a fcw m.ruies inslead of several hours -0: cvcn many days 111 ni3sr cases you I1 have analysis resulrs 50 io 200iinics las!cr ihar. withcmventiorialsoH gel columns Everything a soft gel does and more. Because ihe I;liralfiniry-EP cdumn allows a w.der rarge of Iiqard !c macrornolec:ile inicraciions you II be able in isd.i!e everyihing lrorn weady binding u even proreins IO srrongly bound molelies Y ~ caii immob!lize er.zy.mes wiih high aci:viry In shon y c u II gel capaSiliry you ncvcr had wiih soh 7e:s Easier to use.
Fasi hlfiniry Ctroma!cgrapny simplifies cach alfiniry srep !ron: cierivaiizanon ihrough load wasp.
These unique columns come pre-packed ;Ind ready to derivatize. Also they provide an excellent environment for biologically active molecules. Free booklet on Fast Affinity Chromatography, Write us to get your free copy of Bst Affinity Chromatography. This detailed booklet explains the complete methodology of FAC including stepby-step procedures for six practical applications. To bring Fast Affinity Chromatography into your lab,see your local Beckman representative today, If the Ultraffinity-EP column doesn't live up to the claims made here, return it within 30 days BECKMAN of purchase for your money back. Beckman Instruments, Inc.,Altex Scientific Operations, 1716 Fourth Street, Berkeley, CA 94710. (415) 527-5900. Offices in major cities worldwide.
3rd eluie Whars mo!c Ultraffinily-EPc o l u ~ n wers come the problems of ligand leakage and microbial degradation that are often associated with agarose and other affinity supports lPBl "cjklmn
Inr,lY/I/OI'. Oj., A\*%.*"**,,
CIRCLE 22 ON READER SERVICE CARD
r-
k4 1935-1985
(43) Sandra, P.: Temmerman, 1.; Verstappe, W. J . High R e d . Chromatogr.lChromatogr. Commun. 1983.6, 501-4. (44) Ettre. L.S. Chromatographin 1983, 17,553-59. (45) Ettre. L.S.; McClure. G.L.: Walters. J.D. Chromatographia 1983.17.560-69. (46) Adams. R.F.: Vandemark. F.L.: Schmidt, G.J. J . Chromatogr. Sci. 1977, 15,6348. (47) HorvBth. C. “Trennsiulen mit d8nnen porben Schichten fbr die Gaschromatographie.” Inaugural Dissertation, J.W. Goethe Universiut. Frankfurt am Main. 1963. (48) HslBsz, I.: HorvBth, C. Anal. Chem. 1963,35,499-505. (49) Ettre. L.S.; Purcell, J.E. In “Advances in Chromatography. Vol. Io”, Giddings, J.C.; Keller, R.A.. Fds.: Marcel Dekker: New York. N.Y., pp. 1-97. (50) Ettre, L.S.: Purcell. J.E.: Billeb, K. Sep. Sci. 1966.1,777-802. (51) Ettre, L.S.: Purcell, J.E.; Norem, S.D. J. Cas Chromatogr. 1965,3,18145. (52) Ettre, L.S.: Averill, W. A n d Chem. 1961,33.68044. (53) HalBsz, 1.; Schneider. W. Anal. Chem. 1961,33.97&82. (54) HalBsz. I.; Schneider. W. In “Gas Chromatography (1961 Lansing Symp.): Brenner, N.: Callen, J.E.: Weiss. M.D.. Eds.: Academic Press: New York. N.Y., 1962;pp. 287-3W. (55) Gill, H.A.: Averill, W. “Design Considerations and Performance of a Linear Programmed-Temperature Gas-Liquid Chromatograph for Golay and Packed Columns,” presented s t the 13th Pittsburgh Conf. Anal. Chem. Applied Spectroscopy. Pittsburgh. Pa., March 5, 1962; Reprint. Perkin-Elmer Corp.: Nowalk. Conn., 1962.
Manufactured By
ERMA INC. 2 - 4 - 5 Kajicho Chiyoda-Ku T o k y o 101, Japan
TELEX 2655671
lR6D PO Drawer H K w s t o n . MA 02364 617/565-5125 TELEX 881004
9
i
Leslie Ettre earned a degree i n chemical engineering and a technical doctorate from the Technical University of Budapest. In Europe, Ettre was active i n industrial research, research management, and academic teaching. After emigrating to t h e U.S. i n 1958, he joined t h e Perkin-Elmer Corporation, where h e has served as a n applications chemist, product specialist, and, in his present capacity, as senior staff scientist. His research interests include GC (trace analysis, detector response, selective detectors, retention indexes, and open-tubular columns),LC, and t h e history o f chromatography.
I H & U lnrroouces the n e w 7510lD Refractive Index Detection System t o enable you to achieve faster, easier, more reproducible results. T h e 7510/D marries t h e legendary ERMA RI Detector with the unique 3000 series in-line solvent degasser to eliminate drift and reduce baseline noise caused by gasses entering the mobile phase. Contact I R B D for details o n how the 75101D will improve the performance of your HPLC System.
ERMAIN J CIRCLE 49 ON READER SERVlCE CARD
1438A
(56) See: Sandra, P., Ed. “Sample Introduction in Capillary Gas Chromatography, Vols. I-II”; A. Hbthig V d a g : Heidelberg, 1985.
ANALYTICAL CHEMISTRY. VOL. 57, NO. 13, NOVEMBER 1985
