Rapid enantiomeric separation of polychlorinated biphenyls by electrokinetic chromatography using mixtures of neutral and charged cyclodextrin derivatives

Jou nal o Ch oma og aphy A, 910 (2001) 157–164 www.else ie .com/loca e/ch oma Rapid enan iome ic sepa a ion o polychlo ina ed biphenyls by elec okine ic ch oma og aphy using mix u es o neu al and cha ged cyclodex in de i a i es * ´´ C. Ga cıa-Ruiz, Y. Ma ın-Biosca, A.L. C ego, M.L. Ma ina ´´ ´ ´ Depa amen o de Quımica Analı ica , Facul ad de Quımica , Uni e sidad de Alcala , C a . Mad id–Ba celona Km . 33.600, ´ 28871 Alcala de Hena es ( Mad id ), Spain Recei ed 14 July 2000; ecei ed in e ised o m 19 Oc obe 2000; accep ed 20 No embe 2000 Abs ac Elec okine ic ch oma og aphy wi h cyclodex in de i a i es (CD-EKC) was used o achie e he apid enan iome ic sepa a ion o chi al polychlo ina ed biphenyls (PCBs). Thi een o he 19 chi al PCBs s able a oom empe a u e we e indi idually sepa a ed in o hei wo enan iome s by using 2-mo pholinoe hanesul onic acid (MES) bu e (pH 6.5) con aining ca boxyme hyla ed g-cyclodex in (CM-g-CD) as pseudos a iona y phase mixed wi h b-cyclodex in (b-CD) o pe me hyla ed b-cyclodex in (PM-b-CD). U ea was also added o inc ease he solubili y o PCBs and cyclodex ins in he aqueous sepa a ion bu e . Se e al expe imen al pa ame e s such as he na u e, concen a ion, and pH o he bu e , na u e and concen a ion o he cyclodex in de i a i es used, and he addi ion o di e en addi i es we e s udied in o de o imp o e he enan iome ic sepa a ion. In addi ion, he e ec o some ins umen al pa ame e s such as sepa a ion empe a u e and applied ol age was also in es iga ed. PCBs we e enan iome ically sepa a ed in less han 12 min by using a 50 mM MES bu e (pH 6.5) con aining 20 mMCM-g-CD, 10 mMb-CD o 20 mMPM-b-CD, and 2 Mu ea a a empe a u e o 458C and an applied ol age o 20 kV. 2001 Else ie Science B.V. All igh s ese ed. Keywo ds : Enan iome sepa a ion; Bu e composi ion; Polychlo ina ed biphenyls; Cyclodex ins 1. In oduc ion o e , al hough biologically ac i e chi al compounds a e in oduced in o he en i onmen as acema es, Polychlo ina ed biphenyls (PCBs) ep esen an hei up ake and me abolism by an o ganism may be impo an class o p io i y pollu an s due o hei selec i e o enan iome s [3,4]. The e o e, i is e y pe sis ence, oxici y and bioaccumula ion [1,2]. The impo an o de elop analy ical me hods enabling he enan iome ic sepa a ion o chi al PCBs is o special enan iome ic sepa a ion o chi al PCBs. ele ance because each enan iome may ha e di e - Gas ch oma og aphy (GC), usually employed o en oxici y, ac i i y o me abolic pa hways. Mo e- sepa a e PCB congene s, has also been employed o pe o m he sepa a ion o chi al PCBs [5–11]. Ne e heless, he cha ac e is ics o capilla y elec o- *Co esponding au ho . Tel.: 134-91-8854-935; ax: 134-91- pho esis (CE) echniques (high sepa a ion e iciency 8854-971. E-mail add ess : [email p o ec ed] (M.L. Ma ina). and lexibili y) make his echnique compe i i e wi h 0021-9673/01/$ – see on ma e 2001 Else ie Science B.V. All igh s ese ed. PII: S0021-9673(00)01176-6 ´ 158 C . Ga cıa-Ruiz e al . /J . Ch oma og . A 910 (2001) 157 – 164 GC in he ield o he enan iome ic sepa a ions [12]. plied ol age was also s udied in o de o imp o e P io o his wo k, a mode o CE, cyclodex in- he esolu ion ob ained be ween he enan iome s o modi ied micella elec okine ic ch oma og aphy chi al PCBs. (CD-MEKC) has been employed o he enan io- me ic sepa a ion o chi al PCBs [13–16]. In ac , 12 PCBs (IUPAC numbe s 45, 84, 88, 91, 95, 132, 136, 2. Expe imen al 139, 149, 171, 183 and 196) we e sepa a ed each one in o i s wo enan iome s using sodium dodecyl sul a e (SDS) in 2-(N-cyclohexylamino)e hane- 2.1. Reagen s sul onic acid (CHES) bu e (pH 10) con aining 2 M u ea and g-cyclodex in (g-CD) [13] o mix u es o All eagen s employed we e o analy ical g ade. b- and g-CD as chi al modi ie s [14]. On he o he CHES was pu chased om Sigma (S . Louis, MO, hand, chi al sepa a ions o PCBs 131, 135, 144, and USA); 2-mo pholinoe hanesul onic acid (MES), so- 175 along wi h o he se en chi al PCBs desc ibed dium dihyd ogenphospha e dihyd a e, bu anol be o e we e ob ained using a bo a e bu e (pH 9) (BuOH), dime hyl o mamide (DMF), and sodium con aining also SDS and g-CD, bu wi h a highe hyd oxide we e supplied by Me ck (Da ms ad , concen a ion o u ea (5 M) [15]. The abo e-men- Ge many); ammonium ace a e, b-CD, g-CD, and ioned g oup o 15 PCBs we e also enan iome ically u ea we e om Fluka (Buchs, Swi ze land); ca - sepa a ed by CD-MEKC using a mixed micella boxyme hyla ed g-cyclodex in [CM-g-CD, deg ee o sys em bile sal –SDS wi h g-CD [16]. Finally, he subs i u ion (D.S.)|3], ca boxyme hyla ed b-cyclo- possibili ies o using bile sal s alone as chi al dex in (CM-b-CD, D.S.|3), and pe me hyla ed b- su ac an in MEKC o achie e he enan iome ic cyclodex in (PM-b-CD, D.S.|12–13) we e ob ained sepa a ion o chi al PCBs we e in es iga ed [17]. om Cyclolab (Budapes , Hunga y); me hanol I micelles a e no added o he elec oly e solu- (MeOH) was om Lab Scan (Dublin, I eland).Wa e ion, he sepa a ion o elec ically neu al compounds used o p epa e solu ions was pu i ied h ough a (such as PCBs) can also be achie ed by CE using Milli-Q sys em om Millipo e (Bed o d, MA, USA). cha ged cyclodex ins alone o mixed wi h neu al All solu ions we e il e ed p io use h ough 0.45-mm CDs. In his ype o elec okine ic ch oma og aphy po e size disposable nylon il e s om Scien i ic (EKC), named cyclodex in elec okine ic ch oma- Resou ces (Ea on own, NJ, USA). og aphy (CD-EKC), he cha ged cyclodex in ac s The 19 PCBs s udied we e supplied by D . as pseudos a iona y phase [12,18]. As in o he modes Eh ens o e Re e ence Ma e ials (Augsbu g, Ge - o CE, he enan ioselec i i y o his chi al pseudo- many). Table 1 shows he basic s uc u es and s a iona y phase can be modi ied using a ious chi al IUPAC numbe s o he compounds used h oughou addi i es [19,20], wi h se e al ypes o cyclodex in his s udy acco ding o Ballschmi e and Zell nomen- de i a i es (neu al and cha ged) he mos used in cla u e [23]. he las ew yea s [21,22]. The pu pose o his wo k was o s udy he possibili ies o CD-EKC wi h a cha ged cyclodex in 2.2. Appa a us as chi al pseudos a iona y phase alone o mixed wi h 3D a neu al cyclodex in as chi al addi i e o achie e A HP CE sys em (Hewle -Packa d, Waldb onn, he enan iome ic sepa a ion o a g oup o chi al Ge many) equipped wi h an on-column diode a ay PCBs. The in luence o he na u e, concen a ion and de ec ion (DAD) sys em and HP 3D-CE Chems a ion pH o he bu e , as well as he na u e and con- so wa e was used. Sepa a ions we e pe o med on cen a ion o he cyclodex in de i a i es used and uncoa ed used-silica capilla ies o inne diame e he addi ion o se e al o ganic addi i es (me hanol, (I.D.) 50 mm and ou e diame e (O.D.) 375 mm, bu anol, and u ea) on he enan iome ic sepa a ion o pu chased om Composi e Me al Se ices (Wo ces- PCBs was in es iga ed. The e ec o o he ex- e , UK). Capilla ies had a o al leng h o 58.5 cm pe imen al pa ame e s such as empe a u e and ap- and a leng h o 50 cm o he de ec o . Capilla y ´ C . Ga cıa-Ruiz e al . /J . Ch oma og . A 910 (2001) 157 – 164 159 Table 1 Sample solu ions we e p epa ed by dissol ing Basic s uc u e, sys ema ic names and IUPAC numbe s (acco ding each PCB in DMF o achie e a inal concen a ion o o Ballschmi e and Zell nomencla u e [23]) o he chi al PCBs 200 ppm app oxima ely. s udied Be o e i s use, a new capilla y was insed wi h 1 MNaOH o 30 min, ollowed by a 30-min inse wi h wa e . Be ween in oduc ion o samples, he capilla y was condi ioned wi h wa e o 2 min, 0.1 MNaOH o 2 min, wa e o 2 min and sepa a ion PCB name IUPAC numbe bu e o 2 min. Injec ions we e made by p essu e ( om 50 mba o 1.2 s o 20 mba o 1 s). Fo 2,29,3,6-Te achlo obiphenyl 45 2,29,3,39,6-Pen achlo obiphenyl 84 sepa a ion, ol ages be ween 15 and 25 kVwe e used 2,29,3,4,6-Pen achlo obiphenyl 88 and he de ec ion ook place a 230 nm. A he end o 2,29,3,49,6-Pen achlo obiphenyl 91 he day he capilla y was insed wi h wa e o 2 2,29,3,59,6-Pen achlo obiphenyl 95 min, 0.1 MNaOH o 2 min and wa e o 2 min, 2,29,3,39,4,6-Hexachlo obiphenyl 131 hen s o ed in wa e . The condi ioning me hod was 2,29,3,39,49,6-Hexachlo obiphenyl 132 2,29,3,39,59,6-Hexachlo obiphenyl 135 used o ob ain good peak shapes and ep oducible 2,29,3,39,6,69-Hexachlo obiphenyl 136 e en ion da a. 2,29,3,4,49,6-Hexachlo obiphenyl 139 2,29,3,4,59,6-Hexachlo obiphenyl 144 2,29,3,49,59,6-Hexachlo obiphenyl 149 3. Resul s and discussion 2,29,3,39,4,49,6-Hep achlo obiphenyl 171 2,29,3,39,4,5,69-Hep achlo obiphenyl 174 2,29,3,39,4,59,6-Hep achlo obiphenyl 175 All chi al PCBs s able a ambien empe a u e (19) 2,29,3,39,4,6,69-Hep achlo obiphenyl 176 we e injec ed in o a CE sys em using cha ged CD 2,29,3,4,49,59,6-Hep achlo obiphenyl 183 de i a i es alone o mixed wi h neu al CD de i a- 2,29,3,39,4,49,59,6-Oc achlo obiphenyl 196 i es in he sepa a ion bu e o pe o m hei en- 2,29,3,39,4,49,6,69-Oc achlo obiphenyl 197 an iosepa a ion by CD-EKC. The ype o bu e wi hou and wi h addi i es (me hanol, bu anol and empe a u e was a ied om 25 o 608C and UV u ea), and some ins umen al pa ame e s such as de ec ion was pe o med a 230 nm. sepa a ion empe a u e and applied ol age we e also Elec oly ic solu ions we e degassed in an ul- a ied. asonic ba h KM om Raypa (Ba celona, Spain). A 654 pH me e om Me ohm (He isau, Swi ze land) 3.1. CD-EKC using cha ged cyclodex ins alone was employed o adjus he pH o he sepa a ion bu e s. CM-g-CD and CM-b-CD we e used a concen- a ions anging om 5 o 50 mM( i e alues, 5, 10, 2.3. P ocedu e 20, 30, 50 mM) in he case o CM-g-CD and om 10 o 20 mM o CM-b-CD ( wo alues). Two pH Sepa a ion bu e s we e p epa ed by dissol ing he alues we e es ed using di e en bu e s: pH 9 app op ia e amoun o bu e , CD de i a i es, and using a 50 mMCHES bu e and pH 6.5 using 50 u ea in o wa e o achie e he desi ed concen a ion, mMammonium ace a e o 50 mMMES bu e s. adding in some cases adequa e aliquo s o liquid Concen a ions anging om 10 o 50 mMin CM-g- addi i es (me hanol o bu anol) p io o he addi ion CD we e also es ed a pH 6.5 (50 mMMES bu e ) o wa e . Finally, he pH was adjus ed o 6.5 wi h 1 using 1% and 5% me hanol, 1% n-bu anol o 2 M Mo 0.1 Msodium hyd oxide solu ion o MES u ea as addi i es. In all hese expe imen s an applied bu e , wi h 1 Mo 0.1 MNH solu ion o ol age o 20 kV and a empe a u e o 258C we e 3 ammonium ace a e bu e o wi h 1 Mhyd ochlo ic employed. Unde any o hese expe imen al con- acid o phospha e bu e p io o ob ain he inal di ions he chi al ecogni ion o PCBs was achie ed. olume. Howe e , since he use o CM-g-CD enabled he ´ 160 C . Ga cıa-Ruiz e al . /J . Ch oma og . A 910 (2001) 157 – 164 ob en ion o a peak o a highe numbe o PCBs di e en concen a ions o g-CD (20, 30, o 40 mM) (one single peak) han CM-b-CD, CM-g-CD was we e employed, none o he PCBs s udied we e chosen in o de o s udy he po en ial o using enan iome ically sepa a ed. These esul s show ha mix u es o his cha ged CD and neu al CDs o g-CD is no a good chi al addi i e in he CD-EKC pe o m he chi al sepa a ion o PCBs. A alue o sys em desc ibed. Howe e , when b-CD o PM-b- pH equal o 6.5 was also chosen because a pH 9 he CD we e used as chi al addi i es, se e al chi al elec oosmo ic low was much oo high and he PCBs we e enan iome ically sepa a ed using 20 mM elu ion window was e y small. In addi ion, MES o 30 mMCM-g-CD as pseudos a iona y phase (see bu e was p e e ed ins ead o ammonium ace a e Table 2). When b-CD was used up o 12 o he 19 bu e because he la e gene a ed highe cu en chi al PCBs (45, 88, 91, 95, 131, 132, 136, 139, 144, in ensi y alues han MES bu e . 149, 171 and 176) we e enan iome ically esol ed, while he use o PM-b-CD only enabled he enan io- 3.2. CD-EKC using mix u es o cha ged and sepa a ion o eigh chi al PCBs (45, 88, 91, 95, 131, neu al cyclodex ins 136, 144 and 197). Al hough he use o PM-b-CD enabled he enan iome ic sepa a ion o a lowe The use o di e en neu al cyclodex ins (g-CD, numbe o PCBs, his CD de i a i e allowed he b-CD o PM-b-CD) as chi al addi i es in he enan iosepa a ion o PCB 197 ha was no possible sepa a ion bu e con aining CM-g-CD was s udied using b-CD as chi al addi i e. Fu he mo e, i is he in o de o achie e he enan iome ic sepa a ion o i s ime ha PCB 197 is sepa a ed in o i s wo chi al PCBs (see Table 2). U ea (2 M) was also enan iome s by CE (see Fig. 1a), and al hough i was added because i was shown ha he shape o peaks only pa ially esol ed (R50.8), his PCB has only s imp o ed unde hese condi ions p obably due o a been pa ially sepa a ed by GC and high-pe o m- be e solubiliza ion o PCBs and CDs in he aqueous ance liquid ch oma og aphy (HPLC) bu in e y long bu e . When mix u es o 30 mMCM-g-CD wi h analysis imes [11,24]. In ac , he pa ial enan io - Table 2 Chi al PCBs enan iosepa a ed, om he 19 chi al PCBs s udied, using 50 mMMES bu e (pH 6.5) and 2 Mu ea wi h mix u es o a CM-g-CD, as pseudos a iona y phase, and se e al neu al CDs, as chi al addi i es Cha ged CD Neu al CD Tempe a u e Cu en in ensi y Chi al PCBs enan iome ically sepa a ed (pseudos a iona y phase) (chi al addi i e) (8C) (mA) 30 mMCM-g-CD 20 mMg-CD 25 115 None 30 mMg-CD 25 115 None 40 mMg-CD 25 115 None 30 mMCM-g-CD 40 mMb-CD 25/45 115/150 45, 95 20 mMCM-g-CD 40 mMb-CD 45 97 45, 95 30 mMb-CD 45 97 45, 95, 136 20 mMb-CD 25/45/60 70/97/120 45, 88, 91, 95, 136, 144, 149 10 mMb-CD 45 97 45, 88, 91, 95, 131, 132, 136, 139, 144, 149, 171, 176 5mMb-CD 45 97 45, 88, 91, 95, 131, 132, 136, 139, 144, 149, 171, 176 20 mMCM-g-CD 10 mMPM-b-CD 45 97 45, 88, 91, 95, 131, 136, 144 20 mMPM-b-CD 45 97 45, 88, 91, 95, 131, 136, 144, 197 40 mMPM-b-CD 45 97 45, 88, 95, 136 60 mMPM-b-CD 45 97 45, 88, 95, 136 30 mMCM-g-CD 20 mMPM-b-CD 45 150 45, 88, 91, 95, 131, 144, 197 a Cu en in ensi y is also included. Ins umen al condi ions: uncoa ed used-silica capilla y, 58.5 cm (50 cm o he de ec o )350 mm I.D.; injec ion, 20 mba , 1 s; applied ol age, 20 kV; and UV de ec ion a 230 nm. ´ C . Ga cıa-Ruiz e al . /J . Ch oma og . A 910 (2001) 157 – 164 161 MEKC [15,16], longe analysis imes (be ween 15 and 25 min) we e equi ed in con as o he esul desc ibed in his wo k (analysis ime less han 8 min) (see Fig. 1b). These chi al sepa a ions we e also epo ed by GC [8,9] bu in gene al e y long analysis imes we e equi ed (mo e han 1 h). On he o he hand, hese esul s do no ag ee wi h hose ob ained by CD-MEKC [13,14], in which g-CD was mo e e ec i e in he enan iome ic sepa a ion o chi al PCBs han b-CD due o he la ge size o he ca i y o g-CD compa ed o b-CD. This di e en beha io be ween CD-MEKC and CD-EKC could be due o he o ma ion o a e na y complex PCB– su ac an monome –CD (demons a ed o o he se e al solu es and su ac an s [25]), which does no ake place in CD-EKC. In addi ion, some au ho s belie e ha his e na y complex inside he g-CD ca i y may accoun o i s e ec i eness [26]. The enan iome ic esolu ions ob ained o chi al PCBs when he concen a ion o b-CD was a ied om 5 o 40 mMa e shown in Fig. 2a. I can be obse ed ha he bes enan io esolu ion co esponds o 10 mM o PCBs 45, 91, 95, 132, 144, 149 and 171, whe eas o PCBs 88, 131, 136, 139 and 176 he bes esolu ion was achie ed a 5 mMo b-CD. On he o he hand, he bes esul s ob ained o all he chi al PCBs enan iome ically sepa a ed wi h PM- b-CD we e achie ed a a concen a ion o 20 mM (see Fig. 2b). Using a cons an concen a ion o Fig. 1. Enan iome ic sepa a ion o PCBs 197, 144 and 131. b-CD o PM-b-CD, simila esul s we e ob ained Sepa a ion bu e : 50 mMMES (pH 6.5), 2 Mu ea, and 20 mMwhen 20 mMo 30 mMCM-g-CD was employed. CM-g-CD wi h (a) 20 mMPM-b-CD and (b) 10 mMb-CD. Then, a 20 mMconcen a ion o CM-g-CD was Injec ion by p essu e, 20 mba o 1 s. Capilla y, 58.5 cm (50 cm chosen in o de o dec ease he cu en in ensi y (up o he de ec o )350 mm I.D. Tempe a u e, 458C. Applied ol age, 20 kV (|97 mA); UV de ec ion a 230 nm. o 150 mA wi h 30 mMCM-g-CD). Fig. 2 also shows ha he enan iome ic esolu ions ob ained o esolu ion (R50.7) o PCB 197 has ecen ly been PCBs 45, 88, 91, 95, 131, 136 and 144 we e be e s pe o med using a chi al capilla y column (wi h wi h b-CD han wi h PM-b-CD and gene ally be e hyd oxyp opyl-pe me hyl i lu oace yl g-cyclodex- wi h 10 mM han wi h 5 mMo b-CD. in) by GC in an analysis ime close o 60 min [11]. The e ec o he empe a u e and he applied On he o he hand, he use o a PM-b-CD de i a ized ol age on he enan iosepa a ion o PCBs was also silica as chi al s a iona y phase in e e sed-phase s udied in his wo k. Tempe a u es o 25, 45 and HPLC has allowed one o pa ially esol e PCB 197 608C and applied ol ages o 15, 20 and 25 kV we e (R50.8) in abou 50 min [24]. These esul s seem o employed o he bes condi ions selec ed [50 mM s con i m ha PM-b-CD is a good chi al addi i e o MES bu e (pH 6.5), 2 Min u ea, 20 mMin he enan iosepa a ion o highly hyd ophobic com- CM-g-CD and 10 mMin b-CD]. An inc ease in he pounds such as oc achlo obiphenyl (PCB 197). In empe a u e o applied ol age did no p oduce a addi ion, al hough he chi al sepa a ions o PCBs 131 signi ican e ec on he enan io esolu ion excep o and 144 ha e p e iously been epo ed by CD- PCBs 95 and 136. Fo PCB 95 an inc emen in he ´ 162 C . Ga cıa-Ruiz e al . /J . Ch oma og . A 910 (2001) 157 – 164 Fig. 3. (a) Elec ophe og am co esponding o he chi al sepa- a ion o a mix u e o PCBs 176, 88, 91, 95 and 45 by CD-EKC using a 50 mMMES bu e (pH 6.5) con aining 2 Mu ea, 20 mM CM-g-CD, and 10 mMb-CD. (b) Elec ophe og am co e- sponding o he chi al sepa a ion o a mix u e o PCBs 131, 95, 45 Fig. 2. Enan iome ic esolu ion o chi al PCBs as a unc ion o (a) and 136 by CD-EKC using a 50 mMMES bu e (pH 6.5) b-CD concen a ion; (b) PM-b-CD concen a ion. O he con- con aining 2 Mu ea, 20 mMCM-g-CD, and 20 mMPM-b-CD. di ions as in Fig. 1. O he condi ions as in Fig. 1. empe a u e o ol age d i es o a dec ease in he CD-EKC in o all hei 10 enan iome s in less han 12 enan io esolu ion. In he case o PCB 136 he min, using 20 mMCM-g-CD as pseudos a iona y con a y e ec was obse ed, ha is, enan iome ic phase and 10 mMb-CD as chi al addi i e. Fig. 3b esolu ion inc eased when inc easing he empe a u e shows he enan iome ic sepa a ion o ou PCBs (45, o he applied ol age. On he o he hand, an inc ease 95, 131 and 136) in only 9 min, using 20 mM in he empe a u e o he applied ol age p oduced a CM-g-CD as pseudos a iona y phase and 20 mM dec ease in he analysis ime bu an inc ease in he PM-b-CD as chi al addi i e. In bo h sepa a ions he cu en in ensi y (da a no shown). The e o e, 458C analysis ime is smalle han ha ob ained by CD- and 20 kV we e chosen as good comp omise among MEKC (be ween 20 and 40 min) [13–16], bu a enan io esolu ion, analysis ime and cu en in ensi y. smalle numbe o PCBs can be sepa a ed simul- Unde hese condi ions, he simul aneous enan io- aneously because he sepa a ion window is wide me ic sepa a ion o mix u es o chi al PCBs we e when a CD-MEKC sys em is used. O he sepa a ions pe o med. o chi al PCBs (132, 139, 149 and 171) a e shown in Two examples o mul icomponen sepa a ions a e Fig. 4, being in all cases he analysis ime sig- shown in Fig. 3. In Fig. 3a a mix u e o up o i e ni ican ly smalle han ha ob ained wi h CD-MEKC PCBs (45, 88, 91, 95 and 176) was sepa a ed by [13–16]. ´ C . Ga cıa-Ruiz e al . /J . Ch oma og . A 910 (2001) 157 – 164 163 he enan iome ic sepa a ion o se e al PCBs. Up o 12 o he 19 chi al PCBs s able a oom empe a u e (45, 88, 91, 95, 131, 132, 136, 139, 144, 149, 171 and 176) we e enan io esol ed wi h b-CD, while eigh chi al PCBs (45, 88, 91, 95, 131, 136, 144 and 197) we e enan iome ically sepa a ed wi h PM-b- CD. This wo k p esen s o he i s ime he enan- io esolu ion o he PCB 197 by CE, and al hough i was only pa ially esol ed, simila esolu ions we e ob ained by GC o HPLC bu using e y longe analysis imes. In addi ion, al hough he chi al sepa a ions o he o he PCBs ha e been epo ed by CD-MEKC, longe analysis imes we e equi ed. The bes enan io esolu ions we e ob ained wi h concen a ions be ween 5 and 10 mMo b-CD and 20 mMo PM-b-CD. On he o he hand, in gene al, he enan io esolu ion o he chi al PCBs did no ha e a signi ican change when inc easing he empe a u e (up o608C) o he applied ol age (up o 25 kV), being 458C and 20 kV a good comp omise among enan io esolu ion, analysis ime, and cu en in ensi- y.Finally, mul icomponen mix u es o chi al PCBs we e enan iome ically sepa a ed by CD-EKC using 20 mMCM-g-CD as pseudos a iona y phase in a MES bu e (pH 6.5) wi h 2 Mu ea and b-CD o PM-b-CD as chi al addi i e. Fig. 4. Elec ophe og ams co esponding o he chi al sepa a ion Acknowledgemen s o PCBs 132, 149, 171 and 139 by CD-EKC using (a) 50 mM MES bu e (pH 6.5), 2 Mu ea, 20 mMCM-g-CD, and 10 mM b-CD and (b) 50 mMMES bu e (pH 6.5), 2 Mu ea, 20 mM´ The au ho s hank he Comunidad Au onoma de CM-g-CD, and 5 mMb-CD. O he condi ions as in Fig. 1. Mad id (Spain) o p ojec 07M/0049/1998. 4. Conclusions Re e ences The enan iome ic sepa a ion o chi al PCBs was ´´ ´ [1] M.J. Gonzalez, M.A. Fe nandez, L.M. He nandez, A ch. no possible by CD-EKC using an anionic cyclo- En i on. Con am. Toxicol. 20 (1991) 343. dex in alone (CM-b-CD o CM-g-CD) as chi al ˜´´ [2] G. Fon , J. Manes, J.C. Mol o, Y. Pico, J. Ch oma og . A 733 pseudos a iona y phase in a MES bu e (pH 6.5) (1996) 449. wi h 2 Mu ea. The addi ion o a neu al cyclodex in ¨¨ [3] J. Falle , H. Huhne uss, W.A. Konig, R. K ebbe , P. Ludwig, such as g-CD (concen a ions anging om 20 o 40 En i on. Sci. Technol. 25 (1991) 676. ¨ [4] H.R. Buse , M.D. Mulle , C. Rappe, En i on. Sci. Technol. mM) in a MES bu e (pH 6.5) wi h u ea (2 M)26 (1992) 1533. con aining CM-g-CD as pseudos a iona y phase did [5] A. Glausch, J. Hahn, V. Schu ig, Chemosphe e 30 (1995) no enable one o sepa a e enan iome ically any 2079. chi al PCB. Howe e , he employmen o o he [6] A. Glausch, G.P. Blanch, V. Schu ig, J. Ch oma og . A 723 neu al cyclodex ins (b-CD o PM-b-CD) enabled (1996) 399. ´ 164 C . Ga cıa-Ruiz e al . /J . Ch oma og . A 910 (2001) 157 – 164 ´ [7] G.P. Blanch, A. Glausch, V. Schu ig, R. Se ano, M.J. [16] A.L. C ego, M.A. Ga cıa, M.L. Ma ina, J. Mic ocol. Sep. 12 ´ Gonzalez, J. High Resolu . Ch oma og . 19 (1996) 393. (2000) 33. ´ [8] P. Haglund, K. Wilbe g, J. High Resolu . Ch oma og . 19 [17] A.L. C ego, M.J. Gonzalez, M.L. Ma ina, Elec opho esis 19 (1996) 373. (1998) 2113. [9] W. Ve e , U. Klobes, B. Luckas, G. Ho inge , J. Ch oma- [18] B. Chank e adze, J. Ch oma og . A 792 (1997) 269. ¨ og . A 769 (1997) 247. [19] G. Gubi z, M.G. Schmid, J. Ch oma og . A 792 (1997) 179. ´´ [10] L. Ramos, L.M. He nandez, M.J. Gonzalez, Anal. Chem. 71 [20] S. Fanali, J. Ch oma og . A 792 (1997) 227. (1999) 70. [21] M.J. Sepaniak, C.L. Coppe , K.W. Whi ake ,V.C. Anigbogu, [11] C.S. Wong, A.W. Ga ison, J. Ch oma og . A 866 (2000) Anal. Chem. 67 (1995) 2037. 213. [22] I.S. Lu ie, J. Ch oma og . A 792 (1997) 297. [12] B. Chank e adze, Capilla y Elec opho esis in Chi al Analy- [23] K. Ballschmi e , M. Zell, Z. F esenius, Anal. Chem. 302 sis, Wiley, Chiches e , 1997. (1980) 20. ´´ [13] M.L. Ma ina, I. Beni o, J.C. Dıez-Masa, M.J. Gonzalez, [24] P. Haglund, J. Ch oma og . A 724 (1996) 219. Ch oma og aphia 42 (1996) 269. [25] E. Sain -Aman, D. Se e, J. Colloid In e ace Sci. 138 ´´ [14] M.L. Ma ina, I. Beni o, J.C. Dıez-Masa, M.J. Gonzalez, J. (1990) 365. Ch oma og . A 752 (1996) 265. [26] S. Te abe, Y. Miyashi a, O. Shiba a, E.R. Ba nha , L.R. [15] J. G ainge , Z. Liu, K. Ma ano, J. Ba , D.G. Pa e son J ., Alexande , D.G. Pa e son, B.L. Ka ge , K. Hosoya, N. O ganohalogen Comp. 31 (1997) 286. Tanaka, J. Ch oma og . 516 (1990) 23.