A spectrophotometer includes an electronics compartment having disposed within, at least one light source, and at least one optical detector. A testing compartment has disposed within, an optical block having at least one fluid connection port, and a first light pipe optically coupled between the at least one light source and the optical block. A second light pipe is optically coupled between the optical block and the at least one optical detector. The testing compartment is adapted to perform spectrophotometry of a fluid sample disposed within a sample container in the optical block, and the electronics compartment is electrically isolated from the testing compartment. A spectrophotometer for use in an explosive atmosphere and a method of measuring a presence or concentration of an organic or inorganic compound in a fluid in an explosive atmosphere are also described.