Injection cycle time

To reduce matrix effect, it is important to obtain cleaner extract and use adequate separation. In the presence of late-eluting components that cause matrix effect, adjustment of retention time, run injection cycle time, and/or postinjection column washing should be used to eliminate or reduce their impact. 

Total Time Injection — Injection Cycle Time for Run( A/d... 

The sheer number of samples, their diversity, and a lack of suitable standards for quantitation can at first seem an insurmountable challenge. Since method development for individual samples is not feasible due to time and economic factors, a broadly applicable generic method must be developed, without sacrificing information content. Also, an inject-to-inject cycle time of... 

Figure 5 Schematic of traditional sequential mode injection to injection cycle time (injection overhead) operation of an LC system.

Eight different lime and lemon flavor formulations were provided by a commercial flavor company (Table I). Six replicas of each flavor were analyzed using 7.5 uL aliquots. The aliquots were placed in 10 mL vials which were crimped and equilibrated for 15 minutes at 60 °C before static headspace sampling. The headspace parameters were 15 min incubation, 65 °C syringe, 0.75 min flushing of syringe after injection, cycle time of 4 min. Two mL were filled and injected at a 250 uL/s. There is no column for a separation prior to the mass selective detector (MSD), the entire headspace of each sample is introduced into the MSD. 

Figure 42 shows stacked injections. In this case, as a result of using stacked injections, the single 8 min injection time observed in Figure 40 is reduced to a 4.5 min injection cycle time allowing for the purification of two targets to be completed in only 47 minutes. An optimized SFC method took approximately 1 h to develop. Optimized SFC method conditions were determined to be 10 mL/min on a 2-ethylpyridine 1 cm x 25 cm column using isocratic methanol cosolvent 40/60, methanol/COi conditions. The outlet pressure was set at 140 bar and the column temperature set at 35 C. Ten injections were stacked over 47 minutes. 

Using the proportionahties in Equation 16C.7, we can graph the effects of changing viscosity and shear rate on the heat build up and this is shown in Figure 16C.5. Using the example from the previous section, we decreased an injection cycle time by... 

By analyzing rapid tooling molds based on FE thermal analysis, optimal cooling and injection cycle times can be calculated in advance, thus enabling tool-life and accuracy of rapid tooling to be optimized. 

Because cycle time to inject, flow, set, open, eject, and close is finite, and the face area or platen size is limited, the effective mol ding area is increased by increasing the number of mold cavities so that the number of finished pieces per cycle may be multipHed many times. 

Modification of BPA-PC for adaptation to the conditions of production of CD and CD-ROM disks, and of substrate disks for WORM and EOD was necessary. BPA-PC standard quaHties for extmsion and injection mol ding have, depending on molecular weight, melt flow indexes (MEI), (according to ISO 1130/ASTM 1238 in g/10 min at 300°C/1.2 kg, between less than 3 g/10 min (viscous types) up to 17 g/10 min. For CDs and optical data storage disks, however, MEI values exceeding 30 g/10 min, and for exceptionally short cycle times (5—7 s) even >60 g/lOmin are demanded at an injection mass temperature of 300°C (see Table 5). 

The prevacuum technique, as its name implies, eliminates air by creating a vacuum. This procedure faciUtates steam penetration and permits more rapid steam penetration. Consequendy this results in shorter cycle times. Prevacuum cycles employ either a vacuum pump/steam (or air) ejector combination to reduce air residuals in the chamber or rely on the pulse-vacuum technique of alternating steam injection and evacuation until the air residuals have been removed. Pulse-vacuum techniques are generally more economical vacuum pumps or vacuum-pump—condenser combinations may be employed. The vacuum pumps used in these systems are water-seal or water-ring types, because of the problems created by mixing oil and steam. Prevacuum cycles are used for fabric loads and wrapped or unwrapped instmments (see Vacuum technology). 

When only a few solutes are separated, they may occupy only a small portion of the total column volume at any given instant. In such cases, the productivity is improved by cyclic feed injections, timed so that the most strongly retained component from an injection elutes just before the least strongly retained component from the following injection (see Fig. 16-57). For a mixture of two components with k > 1, when the same resolution is maintained between bands of the same injections and bands of successive injections, the cycle time tc and the plate number requirement are ... 

Both thermoplastics and thermosets can be formed by compression moulding (Fig. 24.5). The polymer, or mixture of resin and hardener, is heated and compressed between dies. The method is well suited to the forming of thermosets (casings for appliances, for instance) and of composites with a thermosetting matrix (car bumpers, for example). Since a thermoset can be removed while it is still hot, the cycle time is as short as 10 seconds for small components, 10 minutes for large tliick-walled mouldings. Pressures are lower than for injection mouldings, so the capital cost of the equipment is much less. 

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