 The forensic chemistry unit handles over 5,000 narcotics cases per year, which requires the analysis of tens of thousands of items. The unit processes over 800 blood alcohol cases each year, used to determine if a DUI has been committed. The forensic chemistry unit also performs an analysis for ignitable liquids in arson investigations to assist the Denver Police and fire departments. As part of its state-of-the-art laboratory, the forensic chemistry unit has gas generators to produce all the gases used by its instruments. The generators produce hydrogen as a carrier gas and fuel gas, nitrogen as a carrier gas, and ultra-purified zero air used in flame ionization detectors and to purge water from some instrumentation. Here, vials of blood are being prepared for headspace analysis, used in suspected DUI cases. Alcohol in the blood samples is analyzed by heating the blood to force the volatile alcohol into the air at the top of the vial. To start the process, samples are placed into a heated headspace autosampler. This machine takes the vials and places them into an oven. When they reach the proper temperature, a sample is collected from the headspace and injected into an instrument called a gas chromatograph. The alcohol value of the blood sample can then be determined. A common instrument used to analyze controlled substances is the four-year transform infrared spectrophotometer. It takes approximately 30 seconds to perform this analysis, which produces a structural identification of relatively pure organic compounds. Controlled substances are verified using a series of color tests to indicate the possible presence of different narcotics. The orange color here indicates the sample contains an amphetamine-like compound, possibly methamphetamine. The next sample remains pink after testing, indicating it does not contain cocaine. And the third sample turns a dark blue color, which means there is a secondary amine present. The result of these three tests show the sample is likely methamphetamine. In addition to narcotics testing, the forensic chemistry unit also analyzes for ignitable liquid in arson debris cases. The sample being prepared here will be heated in an oven along with a carbon tab. The small tab, which is placed on the lid of the testing container, will absorb any volatile compounds that are driven off the material inside. Those compounds are then extracted from the carbon tab using a solvent. They can be analyzed using an instrument called a gas chromatograph mass spectrometer, which is also used in controlled substance analysis.