September 2016 SPSFAM Book

9/13/2016

Existing Methods (General)

▪ Gravimetric assays

▪ Vanillin colorimetric assay

▪ Bioassay directed fractionation ▪ Ytterbium precipitate ▪ DMAC based colorimetric assays ▪ BL-DMAC ▪ ICT BL-DMAC

▪ Acid Butanol colorimetric assay ▪ Bates-Smith colorimetric assay ▪ Thiolysis/Phloroglucinolysis ▪ Chromatography ▪ HPLC

▪ CPS BL-DMAC ▪ OSC DMAC

▪ Size exclusion

PAC Method Survey Study

Principal 

Standard

Blank

Pros vs. Cons

Method BL‐DMAC

A2 A2

solvent solvent solvent

Fast, high throughput; standard no ideal

ICT BL‐DMAC CPS BL‐DMAC

A2

DMAC react with terminal unit of PAC molecules to  form a colored compound detected at 640 nm

c‐PAC  is more accurate than A2; not commercially 

CPS DMAC c PAC ‐ 

c PACs ‐

solvent

available 

Good for cranberry products; not accepted outside  OSC

OSC‐DMAC 

RF

solvent

Vanillin react with PAC to form a colored compound detected at 500 nm

Vanillin

catechin

sample Time consuming; less sensitive; overestimated PACs

Easy to operate; overestimate PACs; water content  and ions affect results Easy to operate; Water content and metal ions  affect results; side reaction

Acid Butanol

solvent

c‐PACs

PACs molecules are cleaved and converted to  anthocyanidins detected at 550 nm

Bates‐Smith

sample

European Pharmacopoeia

A pharmacopeia method; for hawthorn berries 

RF

solvent

Degradation of PACs into monomers and then  analysed using HPLC 2‐8 mers are separated and quantified, polymers>10  are eluted together 

Total PACs and mean DP;  Thiol agent is not lab‐friendly; time consuming USDA accepted method; No response factor for A‐ type oligomers

Thiolysis

epicatechin

solvent

epicatechin A2, RF

HPLC

solvent

Gravimetry 

PACs are extracted, purified and weighted

NA

NA

Time consuming, easy to overload

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