MULTIDIMENSIONALE SCHEIDINGEN IN DE GAS- EN VLOEISTOF CHROMATOGRAFIE

Transcription

1 MULTIDIMENSINALE SCHEIDINGEN IN DE GAS- EN VLEISTF CHRMATGRAFIE Hans-Gerd Janssen and many others Unilever Foods R&D Vlaardingen, Vlaardingen, the Netherlands University of Amsterdam, Amsterdam, the Netherlands

2 PEPLE KNW US BY UR BRANDS

3 The analytical tool kit

4 The analytical tool kit Many problems can be solved using one tool. Tighten a screw. More complex repairs often require a combination. Drill a hole to turn in a screw. Very complex operations require the use of two tools at the same time: Painting

5 Principle of Comprehensive 2D Chromatography Normal Chromatography Heart-cut 2D Chromatography Comprehensive 2D Chromatography Multidimensional techniques

6 Edible fats and oils (main constituents) Main compounds - Triglycerides (approx. 90%) - Diglycerides (approx. 5%) - Monoglycerides (approx. 0-5%) - Free Fatty Acids (approx. 0-1%) C H 2 C R C H C R ' C H 2 C R " R= CCCCCCCC.. R = CCCC=CCC.. R = CC=CCCC=CC.. C H 3 ( C H 2 ) 1 4 C H - Phospholipids (approx. 0-2%) - Sterols (approx. 0-2%) - Wax esters (approx mg/kg) - Contaminants (ppm levels) H R 2 R 3 CH 3 (CH 2 ) 14 C (CH 2 ) 15 CH 3 H R 1 R 3 H H R 3 C H 2 C R C H C R ' C H 2 P R " H

7 Introduction glycidyl esters CH 2 H CH 2 C R CH CH 2 CH CH 2 glycidol (2,3-epoxy-1-propanol) glycidyl ester Formation ccurrence Toxicity chem. synthesis not a typical food contaminant probably carcinogenic to humans IARC:2A vegetable oil refining (deodorization) refined vegetable oils/fats (ppm levels)??? (hydrolysis to glycidol in GI tract demonstrated!) Present in edible oils at < 1 mg/kg

8 Sample preparation method: heart-cut NPLC isolation Normal phase TLC, SPE and LC are widely used for isolating specific compound-classes from edible oils and fats. Glycidyl ester are slightly less polar than triacylglycerides. Detector signal (UV) GE-C18:1 Saturated GEs GE-C18:2 GE-C18:3 TAG DAG MAG.. GE reference solution Spiked palm oil min = 8 ml Time [min.] The NPLC step provides an efficient isolation of the glycidyl-esters. Fractions are analysed by GC-MS (SIM) after evaporation/redissolution.

9 Stable oil/water emulsions require emulsifiers Sugar-ester emulsifiers (after silylation) Mayonnaise Margarines Dressings Non-polar tail, differing in length Polar head

10 Complementary nature of GC and LC I MW Mono FA ester Mono FA SPAN GC separation: Di Di FA SPANester Elution largely on MW (size) with some contribution of polarity Sugars Free sugars Fatty Acids Free FA Polarity Tri FA SPAN FA ester Tetra FA ester Tetra FA SPAN

11 Complementary nature of GC and LC II Polarity 35 NPLC separation: Weight [mg] MW Elution largely on polarity (size) with some contribution of size / shape Time [min]

12 Combination of LC and GC comprehensive ( ) LC fr. 50 LC fr GC time

13 Principle of GC GC

14 Comprehensive 2D Chromatography: Normal GC Vanilla flavour Approx. 15 compounds compose the flavour Retention time (minutes)

15 And now in the GC GC mode second dimension relative retention times (seconds) first dimension retention time (minutes)

16 3D-Representation of a GC GC separation (detail) reconstructed 1st dimension chromatogram iso propyl-benzene 1,2,4-trimethyl-benzene para + meta cymene 1,2,3-trimethyl-benzene 0.2 n-nonane iso butyl benzene tert butyl benzene indan saturates olefins st dimension retention time (minutes) mono-aromatics nd dimension retention times (s) 4 5

17 Nice, but also not without problems verloading of the 2 D will be difficult to avoid for samples containing trace- and high level components HS SPME of a green tea infusion. StabilWax-DA / BPX-35 30x250x x100x0.1

18 Separation of a peptide sample using comprehensive LC LC (GPC RPLC) verlap 2 nd dimension retention time verlap (min) peak height st dimension GPC fraction number D LC Time (min) 2 1 D SEC Time (min)

19 High peak capacity peptide separations: SEC RPLC 1. Initial studies used manual fraction collection / transfer. 2. Automated version based on stop-flow. Stop-flow communication Pump 1 Isocratic SEC column pump Injection loop Waste 6 1 Pump 2 Stop flow valve RP column Pump A Mixer Restrictor Pump B UV/MS F. Bedani, W.Th. Kok and H.-G. Janssen, J. Chromatogr A, 1133 (2006)

20 Comprehensive 2D Chromatography with intermediate conversion Comprehensive 2D Chromatography A, B, C, D, E, F, G, H, I, J, K The CHEMICAL modulator: stores, to separate different, but converts, related, compounds (refocusses), according to 2 dimensions. reinjects. P Q,R,S,T,U,V,W,X,Y,Z

21 Instrumentation for separation - modification - separation Auto injector LC column Fraction collector

22 Healthy frying oils Polymerisation during deep-frying High temperature GC with on-column injection allows us to study triglycerides. But a mass of 900 Da is really the limit. Response [mv] Liquid frying oils are healthy, but have you ever cleaned the pan? rganic GPC (THF) with RI di-triglycerides tri-triglycerides polymerised triglycerides mono-triglycerides Time [min]

23 Fatty acids in the polymerised triglycerides 18:2 / 18:3 region tri-acylglycerides = TAG = triglyceride 16:0 18:1 tr 18:2 trtr Chain length: No. double bonds: Positions: 9,11-All rientation: sn-position: 1,3 or 2 cis and trans

24 What are Comprehensive Multi-dimensional Chromatography systems? Normal Chromatography Heart-cut Chromatography Hyphenation - Comprehensive 2D Chromatography Comprehensive XC Comprehensive 3D Chromatography XC XC

25 Instrumentation for Comprehensive (off-line) LC GC GC Injection valve Mobile phase delivery Column 1 st dimension Sequential GC GC analysis 2 nd dimension FID 3 rd dimension (ToF)-MS 4 th dimension

26 GC GC ToF MS vs LC-GC GC ToF MS LC GC GC ToF MS GC GC ToF MS Petrochemical product

27 Conclusions - Many samples around us are complex. - Single chromatographic techniques cannot resolve complex samples. - Multidimensional methods offer: - more peaks, - selective zooming. - Hyphenated couplings are preferred if you know what to look for. - Comprehensive methods provide you with the best possible separation. - Comprehensive methods are often simper than heart-cut methods. - Mass Spectrometry adds another dimension.