Column Selection for Phenolic Acids and Amino-Phenolic Acids in Grain Samples

Record: 700

Category: Column Selection
Product: C18M 4D C18U 2D
Sample: phenolic acids 

Question

I need a column to separate phenolic acids (ferulic, p-coumaric, vanillic, cinnamic, etc.) from grains, and I would also like to analyze phenolic acids containing amines (such as 5-aminosalicylic acid). What column would you recommend?

Answer

Phenolic acids and related aromatic plant metabolites are most commonly analyzed using reversed-phase HPLC with C18 chemistry. A C18 column operated with an acidified aqueous/organic gradient (water with acetonitrile and/or methanol) is generally the most appropriate starting point for separating phenolic acids such as ferulic, p-coumaric, vanillic, and cinnamic acids from grain extracts, with UV detection typically used.

Shodex offers two suitable C18 options for this application space: Silica C18M 4D and C18U 2D, which differ in base material and operating characteristics.

Silica C18M 4D is a monomeric, fully end-capped ODS column based on high-purity silica and fulfills USP-NF L1 requirements. It is well suited for conventional reversed-phase analysis of phenolic acids under standard acidic mobile-phase conditions and is commonly used for plant-derived aromatic compounds when moderate pH ranges are sufficient.

C18U 2D is based on organic/inorganic hybrid silica particles and also fulfills USP-NF L1 requirements. It offers improved mechanical stability and alkali durability, with a usable pH range from 1 to 12 and compatibility with 100% aqueous mobile phases. These characteristics make C18U 2D particularly useful when method robustness, extended pH flexibility, or LC-MS compatibility is required.

For phenolic acids containing amine functionality, such as 5-aminosalicylic acid, retention and peak shape on C18 columns depend on mobile-phase composition and pH due to ionization effects. In many cases, acceptable separation can still be achieved on either C18M 4D or C18U 2D by optimizing gradient conditions and acid modifiers, with C18U 2D offering greater flexibility when pH adjustment is necessary.

Recommended Applications:

• Analysis of Chlorogenic Acid in Coffee (C18U-2D)
  Demonstrates reversed-phase C18U separation of a phenolic acid in a complex food matrix.
• Analysis of Chlorogenic Acid (C18M-4D)
  Shows effective reversed-phase separation of a phenolic acid derivative using C18 chemistry.

Additional Comments

Download or Print PDF