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A common path Mach-Zehnder interferometer is fabricated using planer polymer waveguide having MoS2 as an adlayer for chlorpyrifos detection. The dispersion characteristic and cutoff condition of proposed waveguide is obtained theoretically and hence the cutoff film thickness is optimised to get TE0 and TM0 propagating modes. Variation between the phase shift of propagating modes with the concentration of pure chlorpyrifos and its real commercial sample are obtained. A good linear variation between phase shift and concentration of chlorpyriphos is obtained in our fabricated waveguide for all considered temperatures. The obtained maximum sensitivity, minimum limit of detection and limit of quantification of chlorpyrifos is 5.66 degree/µM, 1.57µM and 5.24µM respectively, at 450C. The capability of the fabricated sensor to generate distinct response for pure and real sample of chlorpyrifos at different concentration and temperature were confirmed by principal component analysis. Since the response of sensor is better for real sample at lower temperature, therefore it is recommended that the concentration of chlorpyrifos in real sample should be measure at low temperature.