tailieunhanh - HPLC A Praactical User'S Guide Part 3

Tham khảo tài liệu 'hplc a praactical user's guide part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 30 RUNNING YOUR CHROMATOGRAPH Connect one end of your column blank to the tubing from the injector outlet the other end is connected to the line leading to the detector flow cell. We have one more fluid line to connect to complete our fluidics. A piece of tubing can be fitted to the detector flow cell outlet port to carry waste to a container. In some systems this line will be replaced with small-diameter Teflon tubing. In either case the line should end in a back-pressure regulator an adjustable flow resistance device designed to keep about 40-70psi back-pressure on the flow cell to prevent bubble formation that will interfere with the detector signal. Air present in the solvent is forced into solution during the pressurization in the pump. The column acts as a depressurizer. By the time our flow stream reaches the detector cell the only pressure in the system is provided by the outlet line. If this is too low bubbles can form in the flow cell and break loose resulting in sharp spikes in the baseline. The back-pressure regulator prevents this from happening. The final connections are electrical. A power cable needs to be connected to each pump. Check the manuals to see whether fuses need to be installed and do so if required. Finally connect the 0-10mV analog signal connectors on the back of the detector to the strip chart recorder. Connect red to red black to black. If a third ground wire is present in the cable connect it only at one end either the detector or the recorder end. Note The ground wire connects to the cable shield which is wrapped around the other two wires in the cable. If no ground is connected no shielding of the signal occurs. If both ends of a ground are connected the shield becomes an antenna worse than no shield at all. Now our system is ready to run. We will need to prepare solvent flush out each component then connect flush out and equilibrate the column before we are ready to make our first injection of standard. Solvent .