The Hewlett Packard HP 5890 Series II Gas Chromatograph (GC) System Split/Splitless Programmable Pressure Injector with Manual Pneumatics, FID and TCD. This Gas Chromatograph is a chemical analysis instrument used for separating chemicals in a complex sample. Different chemical constituents of a sample pass in a gas stream (carrier gas, mobile phase), the chemicals exit the end of the column and are detected and identified electronically. The function of the stationary phase in the column is to separate different components, causing each one to exit the column at a different time (retention time). Other parameters that can be used to alter the order or time of retention are the carrier gas flow rate, and the temperature
This GC includes a Split/Splitless Programmable Pressure Injector, which introduces a sample into a heated small chamber via a syringe through a septum. The carrier gas then either sweeps the entirety (splittless mode) or a portion(split mode) of the sample into the column. In split mode, a part of the sample/carrier gas mixture in the injection chamber is exhausted through the split vent. Split injection is preferred when working with samples with high analyte concentrations (>0.1%) whereas splitless injection is best suited for trace analysis with low amounts of analytes (<0.01%). In splitless mode the split valve opens after a pre-set amount of time to purge heavier elements that would otherwise contaminate the system. This pre-set (splitless) time should be optimized, the shorter time (e.g., 0.2 min) ensures less tailing but loss in response, the longer time (2 min) increases tailing but also signal.