LIQUID-CHROMATOGRAPHY WITH PHOTODIODE-ARRAY SPECTROPHOTOMETRIC DETECTION IN THE FORENSIC SCIENCES

Liquid chromatography (LC) is used in forensic laboratories for numerous applications including examination of drugs and poisons, plastics and polymers, oils, hydrocarbons, cosmetics, inks, dyes and pigments. LC with photodiode array detection (PDA) is a hybrid technique which can provide complete UV-visible spectral information on a given peak in a chromatogram, enabling determinations of peak purity to be made, and identification of unknown peaks to be assigned by library searches of spectral information in combination with retention behavior. These are valuable features normally associated with gas chromatography-mass spectrometry. The additional information available on each peak makes LC-PDA a particularly attractive technique for the forensic laboratory where higher levels of certainty are often demanded in test results. This paper reviews some of those applications for LC-PDA in the forensic sciences, including drug screening, drug and pharmaceutical analysis, differentiation of inks, identification of pesticides, fungi, quality control testing and profiling of cosmetics, street drugs and profiling of other complex mixtures. The practical and technical limitations of the technique are explored and its place in the hierarchy of methods available in forensic laboratories is evaluated.