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ENVIRONMENTAL ANALYSIS I. Solid Phase Extraction step-by-step method development.

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Presentation on theme: "ENVIRONMENTAL ANALYSIS I. Solid Phase Extraction step-by-step method development."— Presentation transcript:

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2 ENVIRONMENTAL ANALYSIS I. Solid Phase Extraction step-by-step method development

3 Goal of Six-Step Mode v Isolation v Purification v Trace enrichment

4 Six-Step Method Development v Compile known parameters ä Tech Support Form v Follow step-by-step guide v Fill in method development form

5 Technical Support Form

6 Pertinent Data v The analyte(s) v The matrix v The analytical method v Existing method(s)

7 The Analyte v Structure v pKa(s) v Concentration v Sample volume v Solubility v Stability

8 The Matrix v Type of matrix v pH and ionic strength v Interferences

9 The Analytical Method v Final technique v Compatible solvents v HPLC conditions

10 Existing Method v Liquid-liquid method v Current SPE method details v Data from current method

11 Method Development Example Pollution Unlimited 1224 Sunnyside Drive Elution, Alaska (907) (907) Dr. Anna Light

12 The Analyte

13 The Analyte (cont.)

14 The Matrix

15 The Analytical Method

16 Other Information

17 Following the Guide

18 The Form Sample name _________________ Analyte of Interest ________________ Sample size ____________________ Sorbent Bed Mass _______ Cartridge volume_____ Sorbent phases to try 1) _____ 2) _____ 3) _____ 4) _____ 1. Sample pretreatment ___________________________ 2. Condition column with ____ mL of _________ at ___ mL/min 3. Equilibrate column with ____ mL of _________ at ___ mL/min. 4. Load sample at ______ mL per minute. 5. Remove interference with ____ mL of _________ at ___ L/min. Drying step _____ minutes 6. Elute analyte with ____ mL of _________ at ___ mL/min. Remember to include soak step if possible!

19 Filling in the Form

20 Following the Guide

21 Sample Size Determination

22 Filling in the Form

23 Sorbent Capacity Hydrophobic phases: 1- 5% of Sorbent Mass Ion Exchangers 0.3 to 0.6 milli-equivalents per gram

24 Following the Guide

25 Select a Mechanism

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29 Following the Guide

30 Selecting a Sorbent

31 Filling in the Form

32 Following the Guide

33 A Reminder...

34 Sample Pretreatment

35 Filling in the Form

36 Following the Guide

37 Conditioning and Equilibration

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39 Filling in the Form

40 Following the Guide

41 Sample Loading Rate

42 Filling in the Form

43 Following the Guide

44 Removing Interferences

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46 Filling in the Form

47 Following the Guide

48 Drying Time

49 Filling in the Form

50 Following the Guide

51 Selecting an Elution Solvent

52 Elution Solvent Volume

53 The Completed Form

54 What if Low Recovery? v Losses during rinse step v Analyte breakthrough v Poor elution

55 Losses During Rinse Step Check rinse for presence of analyte

56 Analyte Breakthrough Stack ColumnsElute Separately

57 Analyte Breakthrough v Check pH and ionic strength at each step of extraction procedure v Select phase offering greater interaction

58 Impact of pH Analyte loaded at pH=2 Analyte loaded at pH=7

59 Selection of Bonded Phase Analyte well retained on C8 Analyte poorly retained on C2 Analyte well retained on C18(EC)

60 Poor Elution v Select stronger elution solvent ä pH, ionic strength, % organics v Select less retentive sorbent v Include a soak step

61 Solvent Strength Elution with 20% methanol in water Elution with 5% methanol in water Elution with 100% methanol.

62 Less Retentive Sorbent Analyte completely eluted from C8 Traces of analyte remain on C18(EC)

63 Soak Step The analyte is completely eluted from the column which was soaked for one minute with the elution solvent. Some analyte remains on the column that was not soaked in the elution solvent.


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