FPIA has emerged as a viable technique for quantification of small molecules in mixtures, including: pesticides, mycotoxins in food, pharmaceutical compounds in wastewater, metabolites in urine and serum indicative of drug use (cannabinoids, amphetamines, barbiturates, cocaine, benzodiazepines, methadone, opiates, and PCP), and various small molecule toxins. As well as with the analysis of hormone-receptor interactions.