Reversed-Phase Separation of a Standard PAH Mixture on an Adamantyl Surface. Liquid Crystal Institute* Kent State University Kent, OH 44242

Size: px

Start display at page:

Download "Reversed-Phase Separation of a Standard PAH Mixture on an Adamantyl Surface. Liquid Crystal Institute* Kent State University Kent, OH 44242"

Rebecca Wilcox
5 years ago
Views:

1 i,- 00E OFFICE OF NAVAL RESEARCH 00 CONTRACT NO. N K ) TECHNICAL REPORT NO. 11 Reversed-Phase Separation of a Standard PAH Mixture on an Adamantyl Surface by S. S. Yang and R. K. Gilpin Liquid Crystal Institute* Kent State University Kent, OH *Subcontractor to Liquid Crystalline Polymer Research Center University of Connecticut Storrs, CT Prepared for Publication in Journal of Chromatography July 20, 1988 REPRODUCTION IN UiHOLE OR IN PART IS PERMITTED FOR ANY PURPOSE O THE UNITED STATES GOVERNMENT. THIS DOCUMENT HAS BEEN APPROVED FOR PUBLIC RELEASE AND SALE; ITS DISTRIBUTION IS UNLIMITED. DTIC SEL ECTE0 AUG 0 '21988

2 REPOR, DOCUMIENTATION PAGE Unc s s i aed None A 1d 0ec Sv~F 7% A2.~ 8'. B 1 C N.7 A.1, a v1 ycf EP? i Approved for Public Release, ~ (.,S~i ~Dist A~ 4i, ribut ion Unlimited 4 PE~kCAM.NC CRCA%,v2A?.Cd AECAT N..V8010) S %ON10-N~ CAAO1N RL,,o~r NMW(S) Technical Report No '4AMI Of PtAbCAMA.G CAr.ANJAT,CN 160 OF$-(I SYM60O. 74 %AMI Of VONOO~iNG CfCANIIATION University of Connecticut Office of Naval Research k &004iss Kay.I $fact. Ji'd Z'.P Ceo) 7b &OCR(S%Cry Sejec 4^0 IICe df 800 North Quincy Avenue Storrs, CT Arlington, VA NAM(4 Of fkdnojncispcc N so CU.CE $rwsof. 9 PSOC,AEMWv inst'rum1n1 OJNTJJAT0FN tk%1..%etf ORCANIZATION (if appli(eao Id ONR N K k AO0A&SS (C,ly State. *a ZiP CW#,) '0 SOUACd OF FUP4NAG NUjMBERS 800 North Quincy Avenue PRCA PRiECT TASK 1AK,, Arlington, VA L16(NTN ON CESCqN Reversed-Phase Separation of a Standard PAH Mixture on an Adamantyl Surface 12 PERSONAL AIJTMOR(S) S. S. Yang and R. K. Gilpin (Unclassified) Prepared for publication in J. of Chromatography Research carried out at Kenit State university (Sbotanr (LCPRC Publication No. (OSAri CO0O S %6SL.SEC7 TEAMS CCACqA..e CA. i. 1 r.c~ A fi de d d by 010(i A.ber) FILo GR0 S1.4 GMO%.P High Performance Liquid Chromatography (HPLC) Polycyclic Aromatic Hydrocarbons (PAR) an important technique for the analysis of polycyclic aromatic hydrocarbons (PAH). In carrying out the chromatographic separations, octadecyl (C 18 ) phases often are used because of their excellent selectivity towards PAH. Recently, Sander and Wise have studied and attempted to classify the various parameters which influence solute retention for this class of compounds. Surface coverage and solute shape have been found to be major factors which influence retention behavior. The elutioni order for polycyclic aromatic hydrocarbons which differ in planarity may reverse dep'qnding on structural differences in the C,phase being used. As a result of their studies. Sander and WXse have proposed that selected PHAS solutes (e.g., benzo[a] pyrene - BaP, phenanthrof 3, 4-clphenanthrene-PhPh, and 1,2i3,4:S,6:7,8-tetrabenzonaphthalene - TEN.) can be used to classify 00 FORM MAlt$ SAFA Od.t.9A MaDObvW#0 wa' t&?44viteo. SECWATY CLASSI1e(AfrOF Of 1041S 0AG( An GIAer OddOAs are ab~oote Unclasified

3 Block!9. (continued from front) Recently we have reported an unique stationary phase synthesized by exhaustively modifying porous silica with bulky rigid molecules of adamantane. This surface has been shown to produce good peak shapes for basic solutes even under less than favorable chromatographic conditions. In the current work the selectivity of the adamantyl surface has been studied. In carrying out the evaluation, the polycyclic aromatic hydrocarbon mixture recommended by Sander and Wise has been used.

4 Reversed-Phase Separation of a Standard PAH mixture on an Adamantyl Surface S. S. Yang and R. K. Gilpin* Department of Chemistry Kent State University Kent, OH * author to whom correspondence should be addressed Ir IteI IE'I 3.l wfriiii

5 INTRODUCTION -Reversed phase high performance liquid chromatography (HPLC) is an important technique for the analysis of polycyclic aromatic hydrocarbons (PAH). In carrying out the chromatographic separations, octadecyl (C 1 8 ) phases often are used because of their excellent selectivity towards PAH. Recently, Sander and Wise have studied and attempted to classify the various parameters (i) c:' Influence solute retention for this class of compounds. Surface coverage and solute shape have been found to be major factors which influence retention behavior. The elution order for polycyclic aromatic hydrocarbons which differ in planarity may reverse depending on structural-differences in the C 1 8 phase being used. As a result of their studies, Sander and Wise have proposed that selected PAH solutes (e.g., benzola]pyrene - BaP, phenanthro[3,4-c]phenanthrene - PhPh, and 1,2:3,4:5,6:7,8-tetrabenzonaphthalene - TEN.) can be used to classify phases in terms of their selectivity. -Recently we have reported an unique stationary phase synthesized by exhaustively modifying porous silica with :T. bulky rigid molecules of adamantane. This surface has been shown to produce good peak shapes for basic solutes even under less than favorable chromatographic conditions't4. In the current work the selectivity of the adamantyl surface has, been studied. In carrying out the evaluation, the polycyclic.

6 2 aromatic hydrocarbon mixture recommended by Sander and Wise has been used.

7 3 EXPERIMENTAL SECTION Reagent: Adamantylethyltrichlorosilane was purchased from Petrarch System Inc. (Levittown, PA) and was used as received. LiChrosorb SilOO (dp - lopm) was obtained from E. Merck (Darmstadt, West Germany). HPLC grade acetonitrile was purchased from Aldrich Chemical Co. (Milwaukee, WI). Water was purified using a Milli-Q water system (Millipore Co., El Paso, TX). A test mixture containing Bap, PhPh, and TBN in acetonitrile was supplied by the National Bureau of Standards (NBS)(Gaithersburg, MD) Preparation of adamantyl phase: Adamantylethyltrichlorosilane was used to chemically modify silica as previously described (4). Subsequently, this material was packed into a 4.6 mm i.d. X 150 mm stainless steel column using a dynamic packing procedure (5). Chromatography: Chromatographic experiments were carried out using a LC/9560 ternary gradient liquid chromatograph (IBM Instruments Inc.) equipped with a UV detector. The column was evaluated using a mobile phase of acetonitrile/water (v/v, 85:15) at a flow rate 2 ml/min.

8 4 RESULT AND DISCUSSION A representative separation of the NBS test mixture on the adamantyl phase is shown in figure 1. Capacity factors (k') of each PAH compound and selectivity values (a) are summerized in table 1. For comparison purposes, data obtained from chromatograms, supplied with the test mixture (6) also are listed for several different C 1 8 phases. The elution order of the PAH compounds (BaP < PhPh < TBN) is similar to a commercial monomeric C 1 8 phase (e.g., Beckman Ultrasphere ODS phase). Likewise, selectivities, a(tbn/bap) = 2.10, a(fhph/bap) = 1.47, are closest to this same commercial column. However, the k' data are about 1/3 that obtained from the Beckman column. Presumably based on the above data a number of other solutes may be expected to behave similarly and the adamantyl surface will be applicable to separations now being carried out on C18 columns with similar selectivity. In a more general sense, this probably should not hold true based on geometrical considerations and the proposed "slot" model (2) for PAH solutes. Because of its ball-like structure the adamantyl molecule effectively shields unreacted silanols even for small basic solutes such as aniline (3). Since the surface structure is rigid compared to conventional linear n-alkyl phases, it should not only be useful for carrying out

9 numerous applications but also should provide an important tool for testing interaction/interfacial models.

10 REFERENCES (1) L. C. Sander and S. A. Wise, Anal. Chem., 56(1984)504. (2) L. C. Sander and S. A. Wise, Advances in Chromatography, (J. C. Gidding, ed.) Marcel Dekker, Inc., New York, 1986, vol.25, pp 139. (3) S. S. Yang and R. K. Gilpin, Anal. Chen., 59(1987)2750. (4) R. K. Gilpin and J. A. Sqaires, J. Chromatogr. Sci., 19(1981)195. (5) R. K. Gilpin and W. R. Sisco, J. Chromatogr., 194(1980)285. (6) L. C. Sander and S. A. Wise, J. High Resolut. Chromatogr. Commun., in press.

11 7 Table 1. Comparison of PAH retention & column selectivity Column* capacity factor (k')# selectivity (a) Bap PhPh TBN PhPh/BaP TBN/BAP A i A0 B C D E F >86 C G * Columns: A = adamnatyl, B = Beckman Ultrasphere ODS, C = Whatman Partisphere C18, D = Whatman Partisil ODS-2, E = Vydac TP low load custom synthesis, F = Vydac 201TP, G = Vydac TP high load custom synthesis. #. Solutes: BaP = benzo[alpyrene, PhPh = phenanthro[3,4-c]phenanthrene, TBN = 1,2:3,4:5,6:7,8-tetrabenzonaphthalene. k' data except column A are from ref.(6).

12 8 Figure Caption Figure 1: Chromatogram of the NBS test mixture. Column: adamantyl (4.6 mm i.d. X 150 mm). Mobile phase: acetinitrile-water, 85/15, v/v. Flow rate: 2 ml/min.

13 469 0i 2nm.)

14 ACKNOWLjEDGEMENT Support from DARPA0oNR contract NO01lI86-KO??Z is acknowledged.. f-ki

15 T E C H N I C A _L R E _ P O RT I R P I B 8 -o U ]D-ONST T L IO T _ G E N 1 /1113t/ 71/2 No. Copies No. Copies Office of Naval Research 2 Dr. David Young Attn: Code 1113 Code N. Quincy Street NORDA Arlington, Virginia NSTL, Mississippi Dr. Bernard Ocuda I Naval Weapons Center Naval Weapons Support Center Attn: Dr. Ron Atkins Code 50C Chemistry Division Crane, Indiana China Lake, California Scientific Advisor Naval Civil Enginreering Laboratory 1 Commandant of the Marine Corps Attn: Dr. R. W. Drisko, Code L52 Code RD-i Port Huere-e, California Washington, D.C U.S. Army Research Office Defense Technical Information Center 12 Attn: CRD-AA-IP Building 5, Careron Station high P.O. Box Alexandria, Virginia quality Research Triangle Park, NC Mr. John Bo. ;e OTNSROC I Materials Branch Attn: Dr. H. Sir;er-an Naval Ship Ergineering Center Applied Che-istry Division Philadelphia, Pernsylvanla Annapolis, Oaryla-d Naval Ocean Systems Center Or. William Tolles Attn: Dr. S. Yaramoto Superintendent Marine Sciences Division Chemistry Division. Code 6100 San Diego, California Naval Research Laboratory Washington, D.C

Ulm 1.00 &L6 MICROCOPY RESOLUTION4 TEST CHART. 4-_IU44k 1URE-AU OF STANOARM-19WA - -W ~ -. EW W W.~ %

Ulm 1.00 &L6 MICROCOPY RESOLUTION4 TEST CHART. 4-_IU44k 1URE-AU OF STANOARM-19WA - -W ~ -. EW W W.~ % ND-R193 591 A ROTATIONAL ISOMERIC STATE MODEL FOR THE POLYCARBONATE 1/'1 OF 22' - BIS (4-H.. (U) MASSACHUSETTS INST OF TECH CAMIRIDGE DEPT OF CHEMICAL ENOINEE.. A HtITNII( ET AL. UNCLASSIFIED MEu"M. 31