tailieunhanh - HPLC A Praactical User'S Guide Part 11

Tham khảo tài liệu 'hplc a praactical user's guide part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | TWO-DIMENSIONAL HPLC SYSTEMS 197 with large through pores completely filling the tube. The monolith column formed is then treated with a silylation reagent to form a bonded phase within the silica pores. Commercial columns such as the Chromolith SpeedRodTM run with efficiency of a 2-3-mm particulate column but can be run at flow rates of 6-8mL min without exceeding approximately 2 500 psi back-pressure greatly decreasing run times. These columns offer the potential for creating a hybrid-silica monolith which can be run on existing HPLC systems at high flow rates that are temperature and pH resistant. By their very nature these columns would be void free and the only column killers that they would suffer from would be particulates and bound organics. They probably could be reverse flushed for particulate wash out and bound materials could be washed off with strong solvents. MICRO-PARALLEL HPLC SYSTEMS A variation of the microfluidics HPLC-on-a chip mentioned in Chapter 15 is the polymeric BrioTM cartridge system. A replaceable 8- or 24-channel BrioTM cartridge contains side-by-side 30-cm X . column channels packed with standard HPLC stationary phase. The cartridge is run loaded into an autosampler-equipped VeloceTM gradient chromatography system. A BrioTM cartridge inserted into the VeloceTM system makes the same HPLC separations in all channels with simultaneous UV and or FL detection. As a quality control or cost-per-test instrument the 100-run cartridge allows accelerated assessment of compound purity stability and other physiochemical properties. Running this many 15 sec sample separations on a single instrument can rapidly reduce a laboratory s sample load. TWO-DIMENSIONAL HPLC SYSTEMS Much of the pressure to develop automated sequential HPLC separations has come from the necessity to separate complex biological mixtures especially protein mixtures. Traditionally complex mixtures of proteins have been separated using two-dimensional gel .