Analytic Sample Preparation MethodsSpecimen HandlingChemistry Techniques, AnalyticalSpectrometry, Mass, Matrix-Assisted Laser Desorption-IonizationSensitivity and SpecificityReproducibility of ResultsPolymerase Chain ReactionUnited StatesFood, PreservedCookingBisacodylHistocytological Preparation TechniquesLongitudinal StudiesDrug CompoundingChemical FractionationMicrowavesReference StandardsCohort StudiesTandem Mass SpectrometryChromatography, High Pressure LiquidParticle SizeMass SpectrometryCross-Sectional StudiesSolid Phase Extraction