13272 - Analysis of Drugs (B)

Learning outcomes

The goal of this course is to prepare students to plan and execute instrumental (HPLC, GC, TLC, UV-Vis, Fluorometry, IR, Polarimetry, Refractive index, etc.) and chemical (reactivity of drug functional groups) analytical methodologies for drug analysis (identification and determination of drugs in pharmaceutical formulations and complex matrices)

Course contents

Physical chemical properties of drugs: physical state, colour, odour. Solubility: determination of solubility parameter; solvents; intermolecular forces: hydrogen bonding, Van der Waals and ionic interactions; structure solubility relationship and pKa of weak acid and weak base. Liquid state: boiling point at reduced pressure, extraction under reduced pressure, Rault law, liquid/vapour diagram. Solid state: crystal and amorphous drugs, melting point variables. Crystallisation. State diagrams, eutectic mixtures, solid solutions. Polymorphism.

Sample treatment Solvent extraction: liquid/solid extraction, liquid/liquid extraction, partition coefficient, single and multiple extraction steps. Extraction yield: pH, temperature, salts addition. Application to pharmaceutical formulations.

Physical chemical constants determination Refractive index determination by Abbe refractometer: quali-quantitative analyses of liquid drugs. Specific optical rotatory power: polarimetric determination. Density. Determination of relative density by picnometer. Melting point of crystal drugs and boiling point of liquid drugs.

Chromatographic techniques in drug analysis General concepts and principal classification of chromatographic techniques: gas chromatography and liquid chromatography. Instrumentation. UPLC (ultra pressure liquid chromatography) theory and applications. Theory of chromatographic separations, thermodynamic relationship: retention time, efficiency, selectivity, capacity factor, resolution. Van Deemter equation: rate theory.

Separation modes in liquid chromatography: liquid/liquid partitioning, liquid/solid adsorption. Thin layer chromatography (TLC), high pressure liquid chromatography (HPLC), gas chromatography ( GC). HPLC direct and reversed phase, solvent selection for liquid chromatography. Gradient and isocratic elution. Ion-pair , ion exchange and size exclusion chromatography. HPLC detectors for drug identification and quantification (UV-Vis, Photodiode array, fluorescence, refractive index, electrochemical detectors). GC detectors [Flame ionisation (FID), thermal conductivity, electron-capture detector]. Characteristics and criteria of choice. Quali-quantitative analysis by chromatographic techniques. Internal standard method, external standard method, peaks normalisation, trace analysis .

Method validation in drug analysis: linearity, accuracy, precision, reproducibility, detection and quantification limits (LOD, LOQ).

Spectrophotometric analysis of drugs: Qualitative analysis: UV spectra and drug chemical structure; maximum absorption wavelength and extinction coefficient, absorbance ratio; simple and conjugated chromophores, solvent and pH effect. Quantitative analysis Lambert Beer law, wavelength selection for quantitative analysis, selectivity, sensitivity, calibration curve construction. Derivative spectrophotometry: analysis of binary mixture of drugs (salicilic acid and acetyl salicilic acid)

Fluorometry Excitation and emission spectra for drug analysis. Quali-quantitative analyses of drugs . Chemical fluorescence derivatisation of drugs.

Infrared spectroscopy: application to drug analyses, identification of functional groups

Quali-quantitative elemental analysis Determination of the elements (C,H,N,O,S)of organic drugs

Identification of drugs by chemical reactivity of functional groups: alkenes, alcohols, phenols, ketones, aldehydes, acids, esters, amines, amides, nitro-derivatives and sulfur compounds.

Analytical profile of drug categories : alkaloids, amino acids, steroids, sugars, glycosides, barbiturates, xantines, penicillins, phenotiazines, benzodiazepines.

Readings/Bibliography

1. V.Cavrini, V.Andrisano Analisi farmaceutica. Metodi di riconoscimento e di separazione. Esculapio
2. Farmacopea Ufficiale della Repubblica Italiana, XI Edizione
3. Skoog West Chimica Analitica, SES.
4. K.A. Connors, Reaction Mechanism in Organic Analytical Chemistry, Wiley.
5. Colin F. Poole The essence of Chromatography, Elsevier

Teaching methods

Theorical lessons and laboratory practice

Assessment methods

Laboratory proof and oral examination

Teaching tools

Slides, Laboratory practise

Office hours

See the website of Vincenza Andrisano