**4. Detection of phytochemicals in essential oils in** *Cymbopogon* **species—lemongrass**

An understanding of the chemical components in plants is important for the discovery of beneficial phytochemicals useful in the synthesis of therapeutic agents and other useful chemical compounds. Higher plants are crucial sources of bioactive compounds essential for the maintenance of human health. *C. citratus* contains many pharmacologically active essential oils, flavonoids, phenolic compounds, and other bioactive constituents [6]. The methods of extraction of these essential oils include the following:


*Phytochemical Contents of Essential Oils from* Cymbopogon *Species: A Tropical Medicinal Plant DOI: http://dx.doi.org/10.5772/intechopen.105396*

OPLC is particularly attractive for separating antimicrobial components from various matrices [58]. Gas chromatography is often combined with a flame ionization detector or an electron capture detector. This technique can quantify and determine the presence of materials present at low concentrations [59]. The gas chromatography section divides sample's compounds into pure chemical pulses based on their vaporization.

8.*Immunoassays*: This method uses monoclonal antibodies to identify pharmaceuticals and natural low-molecular-weight bioactive substances. Monoclonal antibodies are produced by hybridoma technology. They are becoming increasingly relevant in the study of bioactive compounds. They have been shown to have high specificity and sensitivity. MAb-based enzyme-linked immunosorbent assays (ELISA) have been shown to be more sensitive than traditional HPLC procedures in many cases [56].
