A graphene oxide/lysine (GO/lys) composite, synthesized using a very simple chemical method, has been used to modify a glassy carbon electrode for the voltammetric detection of diazepam.

Verbena officinalis L. (Vervain; family-Verbenaceae),a traditionally used and medicinally promising plant, has been reported to contain triterpenoids as major class of phytoconstituents. But no work has ever been carried out on V. officinalis to isolate major chemical constituent(s), and to standardize plant material on the basis of isolated constituent(s) using TLC densitometry.The chloroform extract of V. officinalisaerial parts was prepared by extracting properly identified plant in a Soxhlet apparatus.Preliminary phytochemical screening of chloroform extract showed presence of triterpenoids. Column chromatography of chloroform extract using solvent systems viz., hexane:chloroform, chloroform and chloroform:methanol in different concentrationsyielded five fractions (F 1 -F 5 ). Preliminary phytochemical screening of various fractions of chloroform extract revealed presence of triterpenoids in F 2 and F 3 fractions. Therefore, these fractions were further subjected to column chromatography. White colored crystals were obtained in SF 1 sub-fraction separated from F 2 and was designated as VOC-1. Structure of VOC-1 was elucidated by IR and NMRspectral studies and was characterized as ursolic acid. Further, ursolic acid was quantified in V. officinalisaerial parts by validated TLC densitometric method. The content of ursolic acid was found to be 0.1580% in V. officinalis aerial parts.The linearity range, correlation coefficient, intra-