What is an internal standard (IS) and external standard method in quantitative chromatography? Give advantages of IS approach.

What is an internal standard (IS) and external standard method in quantitative chromatography? Give advantages of IS approach.

• A. An internal standard is a compound added to all samples and standards to correct for variability; advantages include improved accuracy and precision by compensating for injection and recovery variability and matrix effects.
• B. An external standard method uses a standard added to all samples and standards.
• C. Internal standard eliminates the need for calibration.
• D. External standard is more accurate.

Answer: (A)