Structural elucidation of a PDE-5 inhibitor detected as an adulterant in a health supplement. Journal of Pharmaceutical and Biomedical Analysis 48 (2008) 1070-1075

Isolation and identification of Thiohomosildenafil and Thiosildenafil in health supplements. Journal of Pharmaceutical and Biomedical Analysis 47 (2008) 279-284

Identification of Benzamidenafil, a new class of Phosphodiesterase-5 Inhibitor, as an adulterant in a dietary supplement. Journal of Pharmaceutical and Biomedical Analysis 47 (2008) 255-259

Isolation and identification of hydroxythiohomosildenafil in herbal dietary supplements sold as sexual performance enhancement products. Food Additives & Contaminants: Part A, 2008

Detection of sibutramine, its two metabolites and one analogue in a herbal product for weight loss by liquid chromatography triple quadrupole mass spectrometry and time-of-flight mass spectrometry, Rapid Communications in Mass Spectrometry 2007 (21) 614-618

Structural elucidation of a tadalafil analogue as an adulterant in a herbal product. Food additives and contaminants 2006 (23) 446

Simultaneous determination of synthetic phosphodiesterase-5 inhibitors found in a dietary supplement and premixed bulk powders for dietary supplements using high-performance liquid chromatography with diode array detection and liquid chromatography-electrospray ionization tandem mass spectrometry. Journal of Chromatography A 2006 (1104) 113

Structural identification of a new acetildenafil analogue detected in a premixed bulk powder. Food additives and Contaminants 2006 (23) 870

Detection of sildenafil analogues in herbal products for erectile dysfunction. Journal of Toxicology and Environmental Health 2006 (69) 1951

Electrospray tandem mass spectrometric investigations of tadalafil and its analogue. Rapid Communication in mass spectrometry 2006 (20) 3488

Screening for common adulterants (Western Drugs) in Chinese Proprietary Medicines (CPM). 2nd Annual HSA-NUS Joint Scientific Seminar, Singapore, 19 May 2004