The UV-visible spectrophotometric method has been described the study of raw carbon nanotubes (R-MWCNTs) and functionalized multiwall carbon nanotubes (F-MWCNTs) for the control of bacterial growth by using validated analytical techniques. The absorption spectra of functionalized carbon nanotubes (F-MWCNTs) and raw carbon nanotubes (R-MWCNTs) show maximum absorbance at lambda (max) 600 nm. The linear relationship was found between absorbance and concentration of R-MWCNTs and F-MWCNTs in the range of 0.25-2.0 mu g mL(-1). The linear regression equation was evaluated by statistical treatment of calibration data and gives the value of correlation coefficient for F-MWCNTs (0.9999) and R-MWCNTs (0.9993), which indicate excellent linearity. The Optical and regression characteristics of the proposed method were found apparent molar absorptivity, limits of detection (LOD), and limit of quantitation (LOQ) for R-MWCNTs and F-MWCNTs (5.75 x 10(2): 8.25 x 10(2) L mol(-1) cm(-1)), (0.052: 0.018 mu g mL(-1)), and (0.055: 0.158 mu g mL(-1)), respectively. The validity of the proposed method was checked by precision, accuracy, linearity, limits of detection (LOD), and limit of quantitation (LOQ). The RSD (%) and quantitative recoveries (%) were obtained (0.026-0.0086) and (100.34 and 100.71) for R-MWCNTs: for F-MWCNTs by UV-visible spectrophotometric, respectively.