Labelled p-Coumaric Acid 4-O-Sulfate, the sulfate conjugate of p-Coumaric Acid. p-Coumaric Acid 4-O-Sulfate is one of the metabolites in human biological fluids after coffee consumption. p-Coumaric Acid 4-O-Sulfate is also a metabolite of 4-Nonylphenol (N650430).