21. This leads to a colour change, which can be measured using a spectrophotometer . 22. He established Dobson ozone spectrophotometer stations in India. 23. Atomic absorption spectrophotometer , nitrogen analyzer, ion meter etc . are available here. 24. Historically, spectrophotometers use a monochromator containing a diffraction grating to produce the analytical spectrum. 25. Flame photometry is crude but cheap compared to spectrophotometer ( which uses a monochromator ). 26. He calibrated an instrument called the Dobson Ozone Spectrophotometer which provided data on atmospheric ozone. 27. In comparison, in 1943, the GE Hardy Spectrophotometer cost $ 6, 400. 28. They are therefore used as a calibration standard for optical spectrophotometers , and are available commercially. 29. Consequently, the use of Raman spectroscopy dwindled when commercial spectrophotometers became available in the 1940s. 30. To measure the sample, the transparent side must be placed toward the light in spectrophotometer .
