Phytochemical Analysis and Determination of the Chemical Composition of Larvicidal Extracts of Black Pepper (Piper nigrum L.) Waste: An Undergraduate Chemistry Experiment

A laboratory experiment was developed to introduce undergraduate chemistry students to the chemical characterization of agroindustrial waste extracts by gas chromatography-mass spectrometry (GC-MS). The students prepared hexane and dichloromethane extracts from black pepper (Piper nigrum L.) waste. GC-MS analysis revealed the possible presence of sesquiterpenes and piperine, compounds commonly found in P. nigrum fruits. During postlab discussion, the students were encouraged to search for information about the biological properties of the putatively identified compounds. Most students found that piperine shows larvicidal activity. Thus, an experiment was conducted by a postgraduate research group to investigate the larvicidal potential of P. nigrum waste extracts. From the results, the students concluded that the hexane extract had higher larvicidal activity than the dichloromethane extract. We also provided students with the opportunity to identify piperine using (+)-APCI FT-ICR MS spectra. The proposed experiment helped students to learn and practice GC-MS and stimulated them to search the scientific literature for solutions to environmental problems.