Waters Amide Column Technology For Food Analysis

Transcription

1 Waters Amide Column Technology For Food Analysis Euan Ross Business Development Manager Chemistry perations Europe 2012 Waters Corporation 1

2 verview verview of HILIC Retention mechanisms and characteristics Practical considerations Implementing the Approach: Water Soluble Vitamins What is the Amide Chemistry BEH/Xbridge Amide Carbohydrate Analysis Further BEH/Xbridge Amide Application examples 2012 Waters Corporation 2

3 What is a Polar Molecule? General chemistry definition: A molecule whose centers of positive and negative charges do not coincide The degree of polarity is measured by the dipole moment of the molecule Dipole moment is the product of the charge at either end of the dipole times the distance between the charges The unequal sharing of electrons within a bond results in a separation of positive and negative electric charge. Polarity is dependent on the electronegativity difference between molecular atoms and compound asymmetry 2012 Waters Corporation 3

4 What is HILIC? HILIC - Hydrophilic Interaction Chromatography Term coined in 1990 to distinguish from normal-phase* HILIC is a variation of normal-phase chromatography without the disadvantages of using solvents that are not miscible in water Reverse reversed-phase or aqueous normal-phase chromatography Stationary phase is a PLAR material Silica, hybrid, cyano, amino, diol The mobile phase is highly organic (> 80%) with a smaller amount of aqueous mobile phase Water (or the polar solvent(s)) is the strong, eluting solvent *Alpert, A. J. J.Chromatogr. 499 (1990) Waters Corporation 4

5 Benefits of HILIC Retention of highly polar analytes not retained by reversed-phase Less interference from non-polar matrix components Complementary selectivity to reversed-phase Polar metabolites/impurities/degradants retain more than parent compound Enhanced sensitivity in mass spectrometry High organic mobile phases (> 80% ACN) promotes enhanced ESI- MS response Direct injection of PPT supernatant without dilution Facilitates use of lower volume samples Improved sample throughput Direct injection of high organic extracts from PPT, LLE or SPE without the need for dilution or evaporation and reconstitution 2012 Waters Corporation 5

6 Traditional SPE Methods for Reversed-Phase Chromatography Traditional SPE methods often contain an elution step that consists of high organic content To make this extracted sample compatible with your mobile phase, you must first evaporate the high organic eluent then reconstitute in some portion of aqueous Evaporation and reconstitution are often the most lengthy steps in an SPE procedure* In HILIC, the high organic eluent can be directly injected on the column, thus eliminating the need for evaporation and increasing your throughput *Jernal, M., Teitz, D., uyang, Z., J.Chromatogr. B, 732 (1999) Waters Corporation 6

7 poor ESI-MS Response excellent When To Use HILIC When to Use HILIC: polar HILIC Reversed-phase Normal-phase non-polar Compound Index Need improved retention of hydrophilic or ionizable compounds Need improved MS response for polar or ionizable compounds Need improved sample throughput for assays using organic extraction 2012 Waters Corporation 7

8 Elution Strength in HILIC: Solvent Selectivity Water Strongest Polar Elution Solvents Methanol Ethanol Use a less polar solvent to Increase retention of polar analytes Isopropanol Primary Solvent Acetonitrile Weakest 2012 Waters Corporation 8

9 verview verview of HILIC Retention mechanisms and characteristics Practical considerations Implementing the Approach: Water Soluble Vitamins What is the Amide Chemistry BEH/Xbridge Amide Carbohydrate Analysis Further BEH/Xbridge Amide Application examples 2012 Waters Corporation 9

10 HILIC Retention Mechanisms are Complex Combination of partitioning, ion-exchange and hydrogen bonding Polar analyte partitions between bulk mobile phase and partially immobilized polar layer on material surface Secondary interactions between surface silanols and/or functional groups with the charged analyte leading to ion-exchange Hydrogen bonding between positively charged analyte and negatively charged surface silanols 2012 Waters Corporation 10

11 Stationary Phases for HILIC separations Hybrid HILIC Columns (ph range 1 8 for BEH HILIC ph range 2 11 for BEH Amide) ACQUITY UPLC BEH Amide XBridge TM Amide ACQUITY UPLC BEH HILIC XBridge TM HILIC Silica HILIC Columns (ph range 1 5) Atlantis HILIC Silica 2012 Waters Corporation 11

12 2 nd Generation Hybrid Particles: Ethylene Bridged Hybrid (BEH) Particles U.S. Patent No. 6,686,035 B2 Bridged Ethanes within a silica matrix Anal. Chem. 2003, 75, Waters Corporation 12

13 What is the BEH/Xbridge Amide Chemistry? Ligand type: Trifunctional Amide Particle size: 1.7 µm and 3.5 µm Ligand density: 6.3 µmol/m 2 Carbon load: 12% Endcap style: None ph range: Waters Corporation 13

14 Influence of Stationary Phase on Retention ACQUITY UPLC BEH HILIC 2.1 x 50 mm, 1.7 µm Unbonded hybrid with low silanol activity ACQUITY UPLC BEH Amide 2.1 x 50 mm, 1.7 µm Bonded hybrid Atlantis HILIC Silica 2.1 x 50 mm, 3 µm Unbonded silica with high silanol activity Minutes (1) acenaphthene (2) thymine (3) 5-fluoroorotic acid (4) adenine (5) cytosine; UV 254 nm 2012 Waters Corporation 14

15 verview verview of HILIC Retention mechanisms and characteristics Practical considerations Implementing the Approach: Water Soluble Vitamins What is the Amide Chemistry Hilic Amide Carbohydrate Analysis Further Application examples 2012 Waters Corporation 15

16 Before You Start: Common HILIC mobile phases Common buffers/additives* Ammonium formate, ammonium acetate Formic acid, ammonium hydroxide, acetic acid Phosphate salt buffers ARE NT recommended due to precipitation in the highly organic mobile phase (phosphoric acid is K) Recommended buffer concentration: 10 mm N-CLUMN Recommended additive concentration: 0.2% N-CLUMN *The actual ph of the mobile phase may be 1 ph unit closer to neutral due to the highly organic mobile phase Canals, I.; umada, F. Z.; Roses, M.; Bosch, E. J. Chromatogr. A. 911 (2001) Espinosa, S.; Bosch, E.; Roses, M. Anal. Chem. 72 (2000) Waters Corporation 16

17 Before You Start: Column Equilibration and Wash Solvents Instrument Wash Solvents Strong needle wash: 9:1 acetonitrile: water Weak needle wash/purge solvent: initial mobile phase conditions [excluding salt, additive or buffer] Brand new column Run 50 empty column volumes of 50:50 acetonitrile:water with 10 mm buffer or 0.2% additive solution Column equilibration Equilibrate with 20 empty column volumes of initial mobile phase conditions Gradient separations Re-equilibrate with 5 to 8 empty column volumes As with any column, insufficient equilibration can cause drifting retention times 2012 Waters Corporation 17

18 Before You Start: Influence of Sample Diluent Sample diluent strongly influences solubility and peak shape (just like reversed-phase) Sample diluent should be at least 75% acetonitrile or as close to initial mobile phase conditions as possible However, polar analytes often have low solubilities in organic solvents General purpose HILIC diluent 75:25 acetonitrile:methanol works for most polar analytes ffers a compromise between solubility and peak shape Adjust according to your analytes (add 0.2% formic acid to increase solubility) In some cases, 25% methanol may be too polar to use as an injection solvent 2012 Waters Corporation 18

19 verview verview of HILIC Retention mechanisms and characteristics Practical considerations Implementing the Approach: Water Soluble Vitamins What is the Amide Chemistry Hilic Amide Carbohydrate Analysis Further Application examples 2012 Waters Corporation 19

20 Implementing the Approach: Example 1, Water Soluble Vitamins N NH 2 H N CH 3 H H 3 C H N H H H N N H 3 C N NH H Nicotinamide Pyridoxal Riboflavin Nicotinic acid H 3 C N N NH 2 N + Thiamine S CH 3 Cl - H H H H Ascorbic acid H H 3 C H 2 N H 2 N H 2 N P - H 3 C NH H 3 C H 3 C H H H N N CH 3 Co + CH 3 N N H 3 C N N N CH 3 CH 3 NH 2 NH 2 CH 3 CH 3 NH 2 H 2 N N N H N N Folic Acid NH H H NH B Waters Corporation 20

21 Stationary Phase Selectivity at Low ph: Water-soluble Vitamins 1 BEH Amide ph All 3 columns yield different selectivity 1,6 4 5 BEH HILIC BEH Amide has greatest resolution of all peaks 3, , Minutes 7 Atlantis HILIC Silica Compounds 1. Nicotinamide 50 µg/ml 2. Pyridoxine 50 µg/ml 3. Riboflavin 30 µg/ml 4. Nicotinic acid 50 µg/ml 5. Thiamine 50 µg/ml 6. Ascorbic Acid 50 µg/ml 7. B12 50 µg/ml 8. Folic Acid 25 µg/ml 2012 Waters Corporation 21

22 Stationary Phase Selectivity at High ph: Water-soluble Vitamins 1 6 BEH Amide ph Large selectivity difference between the two BEH chemistries BEH HILIC BEH Amide has greatest resolution of all peaks Compounds 1. Nicotinamide 50 µg/ml 2. Pyridoxine 50 µg/ml 3. Riboflavin 30 µg/ml 4. Nicotinic acid 50 µg/ml 5. Thiamine 50 µg/ml 6. Ascorbic Acid 50 µg/ml 7. B12 50 µg/ml 8. Folic Acid 25 µg/ml Minutes 2012 Waters Corporation 22

23 Mobile Phase ph Selectivity: Water-soluble Vitamins 1 6 ph 9 BEH Amide Selectivity difference between ph 3 and ph Adequate resolution for both conditions Minutes 1 Greater sensitivity at ph ph 3 Compounds 1. Nicotinamide 50 µg/ml 2. Pyridoxine 50 µg/ml 3. Riboflavin 30 µg/ml 4. Nicotinic acid 50 µg/ml 5. Thiamine 50 µg/ml 6. Ascorbic Acid 50 µg/ml 7. B12 50 µg/ml 8. Folic Acid 25 µg/ml Minutes 2012 Waters Corporation 23

24 Final Method: Water-soluble Vitamins 1 6 Compounds 1. Nicotinamide 2. Pyridoxine 3. Riboflavin 4. Nicotinic acid 5. Thiamine 6. Ascorbic Acid 7. B12 8. Folic Acid Minutes 2012 Waters Corporation 24

25 Summary For HILIC retention and selectivity: ACN is used the primary [weak] solvent in HILIC Water, methanol, ethanol or isopropanol are strong [elution] solvents Stationary phase charge and bonded phase can impact retention and selectivity Analytes in their charged form exhibit greater retention [acids at high ph, bases at low ph] Practical considerations: At least 10 mm buffer or 0.2% additive is recommended in mobile phase A and B Sample diluent should contain at least 75% acetonitrile for solubility and peak shape Weak needle wash must be in a high organic solution [90 95% ACN] 2012 Waters Corporation 25

26 verview verview of HILIC Retention mechanisms and characteristics Practical considerations Implementing the Approach: Water Soluble Vitamins What is the Amide Chemistry Hilic Amide Carbohydrate Analysis Further Application examples 2012 Waters Corporation 26

27 Typical Chromatographic Analysis Amino or polyamine columns RI detection is commonly used Carbohydrates have very weak UV absorbances Typical Problems Encountered Salt interferences Anomer mutarotation Schiff Base formation Loss of reducing sugars at elevated temperatures Shortened column lifetime Not compatible with gradient separations 2012 Waters Corporation 27

28 Sample Preparation Very simple sample preparation Liquid Samples Dilute with 50:50 ACN/H 2 Filter using 0.45µm PVDF syringe filter (if necessary) Solid Samples Weigh out sample (~3g) into 50mL centrifuge tube Add 25mL of 50:50 ACN/H 2 and homogenize (mechanically) Centrifuge at 3200rpm for 30 minutes Collect supernatant and filter using 0.45µm PVDF syringe filter Depending on sample, additional sample dilutions may be necessary 2012 Waters Corporation 28

29 Carbohydrate Methods Gradient Conditions Isocratic Conditions: 75% ACN (with 0.2% TEA) at 35 C For food sugars and other mono- and disaccharides Gradient Conditions: 80-50% ACN (with 0.2% TEA) at 35 C For larger polysaccharides Alternative Methods: Use Acetone instead of ACN (77% Acetone) at 85 C o Reduced mobile phase cost Use NH 4 H instead of TEA as the mobile phase modifier o More compatible with Mass Spec 2012 Waters Corporation 29

30 LSU Stability Testing in ACN BEH Amide 2.1 x 150mm Column 75% ACN with 0.2% TEA, 0.29mL/min at 35 C Initial After 100 Honey inj. After 100 Molasses inj. After 100 Cereal inj Minutes 1) Fructose, 2) Glucose, 3) Sucrose, 4) Maltose, 5) Lactose (1mg/mL each) 2012 Waters Corporation 30

31 Salt Interferences ELSD using 75% ACN at 1.4mL/min, 35 C 4.6 x 150mm Columns, 10µL injection Food Sugars with *Salts on: Aminopropyl Column * 1 * * 2 3 Polyamine Column 4, * 4 5 Polymeric Amino Column Minutes 1) Fructose, 2) Glucose, 3) Sucrose, 4) Maltose, 5) Lactose (each 1mg/mL), * Salt Interferences 2012 Waters Corporation 31

32 Salt Interferences ELSD using 75% ACN at 1.4mL/min, 35 C 4.6 x 150mm Columns, 10µL injection BEH Amide With 0.1% TEA Mobile Phase Modifier Low Salt Retention = No Salt Interference * * Food Sugars with Salts Minutes 1) Fructose, 2) Glucose, 3) Sucrose, 4) Maltose, 5) Lactose (each 1mg/mL), * Salt Interferences 2012 Waters Corporation 32

33 Reducing Sugar Anomers H H H H H H H H -D-Glucose H H H H Mutarotation H H H H H H H H H H H H H H H H H H H -D-Glucose H H Sucrose -Glucose -Glucose -Maltose -Maltose Isocratic: 75% ACN at 15 C Minutes 2012 Waters Corporation 33

34 Anomer Collapse 0.2% TEA in 75% ACN 35 C 75% ACN 0.2% TEA in 75% ACN 25 C 75% ACN Glucose Sucrose Maltose 0.2% TEA in 75% ACN 15 C 75% ACN Minutes 2012 Waters Corporation 34

35 Demonstration of Anomer Collapse -D-glucopyranose H H H H H H H H H H -D-glucopyranose H H H H H H H H H H % ACN with no modifier at 35 C % ACN with 0.2% TEA at 35 C % Acetone with 0.05% TEA at 90 C Minutes 1) Fructose, 2) Glucose, 3) Sucrose, 4) Maltose, 5) Lactose (each 1mg/mL) 2.1 x 150mm 0.29mL/min 2012 Waters Corporation 35

36 Commercial Food Samples on BEH Amide Column ELSD on ACQUITY UPLC using 0.15mL/min at 85 C Isocratic: 77% Acetone with 0.05% TEA 2.1 x 50mm Columns, 0.7µL injection Strawberry Smoothie Hot Cross Buns White Bread Tomato Ketchup Lamb Curry Meal Raisin Bran Cereal Energy Drink Food Sugars Minutes 1) Fructose, 2) Glucose, 3) Sucrose, 4) Maltose, 5) Lactose (1mg/mL each) 2012 Waters Corporation 36

37 Analysis of Beer Beer is made, in part, with malted barley. When the barley malt is first cooked in the brewing process, the resulting liquid contains maltose, other simple sugars and larger, more complex carbohydrates. During fermentation, yeast consumes the sugars, converting them to alcohol and natural carbonation. When finished, most beers contain little or no maltose or other simple sugars, but retain many of the larger polysaccharides 2012 Waters Corporation 37

38 Analysis of Beer BEH Amide, 1.7µm (JTC-22-03), 2.1 x 100mm 10 minute gradient 75-45% ACN with 0.2% TEA at 35 C 0.13mL/min, 1.3µL injection volume Samples: 50% in 50:50 ACN/H 2 Food Sugar Region Wheat Beer Pilsner Dark Ale Double Chocolate Stout Malto-tri, tetra, penta, hexa, hepta-ose Minutes 2012 Waters Corporation 38

39 Fucose Xylose Arabinose Glucose Maltose Lactose Maltotriose Maltopentaose Maltoheptaose Maltohexaose Maltotetraose Analysis of Beer BEH Amide, 1.7µm (JTC-22-03), 2.1 x 100mm 10 minute gradient 75-45% ACN with 0.2% TEA at 35 C 0.13mL/min, 1.3µL injection volume Samples: 100% Beer (No dilution or filtering) Double Chocolate Stout Gain Switching Food Sugar Standard Malto-tri, tetra, penta, hexa, hepta-ose Minutes 2012 Waters Corporation 39

40 Summary The BEH particle technology provides a stable and robust substrate for the trifunctional amide bonding, provides extended column lifetime under a wide variety of conditions (temperature & ph) Anomer peaks arising from reducing sugars can be collapsed into a single peak by using either high temperature or high ph mobile phases Low salt retention eliminates salt interferences from complex sample matrices Available in both HPLC (XBridge Amide, 3.5µm) and ACQUITY UPLC BEH Amide chemistries for easy method transfer Ideally suited for a wide variety of samples ELS detection allows gradient elution for analysis of more complex polysaccharides Lower mobile phase consumption for sub-2µm particles results in reduced cost and waste 2012 Waters Corporation 40

41 The ACQUITY BEH Method Selector Tool: ACQUITY UPLC BEH Amide Column

42 2012 Waters Corporation 42

43 Step 1 Select Column Dimensions 2012 Waters Corporation 43

44 Step 1 Select Column Dimensions 2012 Waters Corporation 44

45 Step 2 Determine the Sample Type 2012 Waters Corporation 45

46 Step 3 Select Detector 2012 Waters Corporation 46

47 Step 4 Select Temperature 2012 Waters Corporation 47

48 2012 Waters Corporation 48

49 verview verview of HILIC Retention mechanisms and characteristics Practical considerations Implementing the Approach: Water Soluble Vitamins What is the Amide Chemistry Hilic Amide Carbohydrate Analysis Further Application examples 2012 Waters Corporation 49

50 Quality Control checks Incoming raw materials Stevia related compounds Waters Corporation 50

51 Ascorbic acid and Isoascorbic acid 2012 Waters Corporation 51

52 Water Soluble Vitamins 2012 Waters Corporation 52

53 Thank You? 2012 Waters Corporation 53