“…A number of colour formation reactions utilizing different reagents have been employed for the visible spectrophotometric determination of LAN in pharmaceuticals [4,12,40,[44][45][46][47][48][49][50][51][52][53][54][55][56]. The reported methods are based on complexation and oxidative coupling [44], formation of a charge-transfer complex [4,45], redox followed by complexation or colour bleaching [46][47][48][49], bromination [50], ion-pair complexation reaction [51][52][53][54][55] and coupling with diazotized p-nitroaniline [56]. However, most of the reported visible spectrophotometric methods suffer from one or more disadvantages, such as poor sensitivity [4,44,45], a narrow range of determination [47][48][49][50], use of a heating step [44,48], and use of an extraction step [52][53][54][55], as shown in Table 1.…”