quadratic mean, , 1209 quadro- , 1209 quadrupole ion storage trap (Quistor), 1209 quadrupole mass analyser, 1210 quadrupole splitting in Mössbauer spectroscopy , 1210 qualitative analysis, 1210 qualitative elemental specificity in analysis , 1210 quality assurance, 1211 quality control, 1211 quality factor in nuclear analytical chemistry , 1211 quality of solvent in polymer chemistry , 1211 quantitative analysis, 1211 quantitative structure–activity relationship (QSAR) in drug design , 1212 quantitative structure–activity relationships (QSAR), 1212 quantity, 1212 quantity calculus, 1212 quantity of dimension one (dimensionless quantity), 1213 quantized internal energy, 1213 quantum counter, 1213 quantum efficiency, 1213 quantum mechanics/molecular mechanics , 1214 quantum of radiation , 1214 quantum yield, , 1214 quantum-mechanical tunnelling, 1215quarter-transition-time potential, 1215 quartet state, 1215 quartz–iodine lamp, 1215 quasi-classical trajectory (QCT) method, 1216 quasi-enantiomers, 1216 quasi-equilibrium, 1216 quasi-molecular ion in mass spectrometry , 1216 quasi-racemic compound, 1217 quasi-single-strand polymer, 1217 quaternary ammonium compounds, 1217 quaternary structure, 1217 quencher, 1218 quenching, 1218 quenching constant in photochemistry , 1218 quenching correction in photochemistry , 1218 quinarenes, 1219 quinhydrones, 1219 quinomethanes, 1220 quinomethides (quinone methides) [obsolete] , 1220 quinone diazides, 1220 quinones, 1220 quinonimines (quinone imines), 1221 quinonoximes, 1221 ρ-value (rho-value), 1221 ρσ-equation (rho-sigma equation), 1222