Pharmaceutical Analysis: Methods, Validation, and Quality Control
Core concepts
Analytical questions test method selection and validation parameters. Know the principles: UV-Vis (Beer–Lambert, chromophores, wavelength selection), HPLC (reversed-phase vs normal-phase, mobile-phase pH, ion pairing), GC (volatile/thermostable analytes), titration (acid-base, redox, complexometric), and spectroscopy (IR for functional groups, NMR for structure, MS for molecular mass/fragmentation).
Validation and quality
Memorize ICH validation parameters: accuracy, precision (repeatability, intermediate, reproducibility), specificity, detection limit, quantitation limit, linearity, range, and robustness. System suitability tests (resolution, tailing factor, theoretical plates, RSD) are common question targets. Understand calibration curves, internal vs external standards, and the difference between LOD (S/N ≈ 3) and LOQ (S/N ≈ 10).
Pharmacopoeial tests
Know that pharmacopoeial monographs include identification, assay, and limit tests (e.g., heavy metals, arsenic, chloride). Dissolution testing uses USP Apparatus I (basket) and II (paddle); content uniformity vs weight variation depends on dose and drug proportion.
Traps and rule of thumb
A frequent trap is confusing precision with accuracy, or asking which parameter detects degradation products (specificity/stability-indicating assay). Rule of thumb: if the question asks whether a method can measure the analyte in the presence of impurities, the answer is specificity. If it asks about repeatability, it is precision.