This dissertation focused on the development of a novel nanomaterial-based electrochemical sensors for pharmaceutical and environmental applications. The research is divided into two parts. In the first part, a low-cost and disposable sensor for the simultaneous determination of coenzyme Q10 (CoQ10) and α-lipoic acid (ALA) using manganese (IV) oxide-modified screen-printed graphene (MnO2/SPGE) electrode was developed. The incorporated MnO2 in the SPGE can greatly enhance the detection performance towards the oxidation of CoQ10 and ALA. The cyclic voltammetry (CV) and square-wave anodic stripping voltammetry (SWASV) were employed to investigate the electrochemical behavior of the developed sensor and also to perform the quantitative analysis of the analytes. This developed sensor provides an inexpensive and disposable sensor for the detection of CoQ10 and ALA. Furthermore, the nanomaterial-based electrochemical sensor exhibits the potential to integrate with other analytical methods for improving the analytical performance. The detail was demonstrated in part 2. In this part, the gold nanoparticle-modified screen-printed carbon electrode (AuNP/SPCE) integrated with ultra-high performance liquid chromatography (UHPLC) was developed for the detection of dithiocarbamate herbicides. Based on the obtained results, AuNPs play a catalytic activity towards the oxidation of dithiocarbamate compounds. The amperometric detection was performed after separation using UHPLC technique. The experimental parameters of both researches were optimized to obtain the best condition. The sensitivity, selectivity and analytical performance of both proposed sensors were discussed. Under the optimal conditions, the proposed sensors showed an acceptable range of accuracy and precision with low limits of detection in the micro-gram levels. Finally, the proposed sensors were successfully applied to detect target analytes in pharmaceutical, fruit, and vegetable samples. These developed systems exhibit the high potential to be useful methodologies for practical applications
