The chemical analysis of urine is performed using a dipstick, which is a small strip of plastic with a series of individual test pads attached. Each test pad measures a different chemical component of the urine and changes color to indicate the amount of that substance in the urine.he chemical analysis of urine is performed using a dipstick, which is a small strip of plastic with a series of individual test pads attached. Each test pad measures a different chemical component of the urine and changes color to indicate the amount of that substance in the urine.