1 / 21

Analysis of short chain aliphatic carboxylic acids in aqueous environment by HPLC

Analysis of short chain aliphatic carboxylic acids in aqueous environment by HPLC. Annie Coenen , Jim Dohmen Jos Hellenbrand , Ynze Mengerink Ron Peters and Sjoerd van der Wal. Most industrial aqueous fluids contain short chain carboxylic acids at ppm levels e.g.

conley
Download Presentation

Analysis of short chain aliphatic carboxylic acids in aqueous environment by HPLC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Analysis of short chain aliphatic carboxylic acids in aqueous environment by HPLC Annie Coenen, Jim Dohmen Jos Hellenbrand, Ynze Mengerink Ron Peters and Sjoerd van der Wal

  2. Most industrial aqueous fluids contain short chain carboxylic acids at ppm levels e.g. - plant process fluids - aqueous extracts of organic solvents - processed drinking water

  3. Water in “bricks” Stale taste correlated with: Technique - aldehydes at ppt levels GC-MS - ketones at ppt levels GC-MS - carboxylic acids ppb’s LC

  4. Trace analysis • The most direct method is preferred Reversed phase HPLC, UV at 200 nm

  5. HPICE + suppressed conductivity

  6. API-ES, Neg, Scan, 50 120 120 100 100 HMB glutaric malic glycolic oxalic succinic malonic lactic 80 80 60 60 40 40 20 20 0 0 2 2 4 4 6 6 8 8 10 10 12 12 14 14 RP-HPLC-ES-MS min min

  7. Second choice: pre-column derivatization Benefits - detectability - increase in S/N - higher selectivity - more retention

  8. Strategy to derivatize carboxylic acids

  9. Derivatization by BHBT

  10. Program 10 l 1.5 M EDC in water + 10 l sample + 10 l 20% pyridine in methanol + 10 l 30 mM BHBT in DMSO Mix in reaction vial Inject 0 l at end of previous gradient Draw 2 l from reaction vial Draw 8 l water React 5’at 40oC inject Derivatization protocol BHBT

  11. Derivatization of BHBT

  12. Short chain acids by BHBT

  13. Process fluid (BHBT-deriv.)

  14. C1 C2 C3 iC4 C4 C5 C6 C7 iC8 C9 100 80 60 40 20 0 2 4 6 8 10 12 14 16 Time(min.) Removal of reagent peak: C1- to C9-acid Using C18 amide column

  15. Derivatization by NPH

  16. Derivatization by NPH • Protocol • 40 l 40 mM NPH in 50% aq. Ethanol • 80 l 250 mM EDC + 1.5% pyridine aq. • 400 l sample* • vortex 0.5’ • React 15’at 60oC • Vortex 0.5’ • Inject 40 l * Often samples are pre-diluted to 50% ACN

  17. NPH: - Robust HPLC system - Little reagent interference

  18. Comparison of methods

  19. Specific detection of NPH-derivatives ABSORBANCE ACID ALDEHYDE 6 KETONE 4 22 0 nm 360 400 440 480

  20. Specific detection of NPH-derivatives mAU C3-ald 16 14 12 C3-ketone 10 C4-ald 8 C4 6 iC4 C4-ketone C6 C5 4 2 0 min 2.5 5 7.5 10 12.5 15 17.5 20 22.5 C4 iC4 mAU C5 C6 4 2 0 -2 -4 -6 -8 min 2.5 5 7.5 10 12.5 15 17.5 20 22.5

  21. NPH: - Additional MS detection

More Related