Highlights
• DNA extraction is required for PFS botanical authentication studies.
• The adsorption effect of talc, silica and dyes on DNA extraction was evaluated.
• Food supplements and model mixtures of excipients were spiked with known amounts of maize DNA.
• Maize DNA (internal standard) recoveries were calculated based on real-time PCR results.
• Excipients in food supplements can hamper DNA extraction due to adsorption phenomena.