exposure chamber 49 of two hundred ppb of the hydrazine fuel in nitrogen carrier gas hydrazine fuel vapor flowing from the chamber 49 can be collected by bubbling the effluent vapor through a small tube 52 into a vessel 54 containing 0 1n sulfuric acid a measured amount of the collected sulfuric acid sample may be analyzed using standard spectrochemical techniques employing colorimetric reagents to determine the average concentration of the hydrazine fuel in the chamber 49 during the collection and dosimeter exposure periods for example hydraver 2 manufactured by hach company may be used as a colorimetric reagent for hydrazine a known quantity of reagent is added to a measured amount of acid solution to provide a solution that changes color upon exposure to hydrazine vapor the color developed may be compared for colorimetric match to solutions containing known quantities of hydrazine and the reagent to determine the concentration of hydrazine in the gas stream the reflectometer records the amplitude attenuation produced in the fiber optic sensor which is then calibrated to the amount of hydrazine exposure referring to fig3 through 8 the peak otdr signal calibration returns 23 from the dosimeter sensor 16 normalized to the average peak power of the laser pulse 21 versus the exposure time of the sensor 16 in the hydrazine fuel exposure chamber 49 is shown in fig6 through 8 return results are measured by the reflectometer 51 for reactive cladding sensors 16 of fig3 and distal end sensors of fig4 these results are respectively shown in fig7 and 8 using pma sol gel reactive cladding dosimeter sensors as shown in fig3 the.