When the fraction of interest reached the six-port valve, it was
switched (Figure 2). The helium pushed the solution through the
sorbent. Analytes were retained, and solvent was vented to waste
through the ST tubing. Introduction of liquid into the GC column
did not occur because the transfer capillary (CT) had been
introduced farther into the liner than the GC column. The liquid
coming through CT was pushed by the helium in the direction
opposite to that of the GC column.
Once the transfer step was completed, the six-port valve was
switched and valve V1 was opened (Figure 3). The LC eluate was
sent to waste. The solution remaining in the transfer capillary CT
was also sent to waste, pushed out by helium. If some solvent
should remain in the CT capillary, solvent vapor would be
produced when the oven temperature was raised for the GC
analysis to be carried out. Such vapor would then enter the GC
column. To prevent this problem, the solvent solution should be
completely eliminated from the CT capillary before the GC
analysis.
Temperature and helium flows were kept constant for 0.25 min
after transfer, to eliminate the remaining solvent. After this purge
time, the on-off valves were switched as shown in Figure 4.
Subsequently, the thermal desorption of the trapped analytes was
achieved by quickly increasing the TOTAD interface temperature
to 250°C. This temperature was maintained for 5 min. The solutes
were then transferred to the capillary column, and the GC analysis
was carried out. Once the GC analysis was completed, the onoff valves were switched as shown in Figure 1. The interface was
cleaned by maintaining the helium stream for 5 min at 325°C,
and finally it was cooled to 80°C so that the process could begin
again.
(c) Timing.In Table 2 a timetable for the case of atrazine is
given as an example to illustrate the operation mode during the
process.
GC Analysis.Gas chromatographic separations were carried
out on a Quadrex (Weybridge, U.K.) fused-silica column (30 m
×0.32 mm i.d.) coated with 5% phenyl methyl silicone (film
thickness 0.25 µm). The column temperature was maintained at
40°C for 3 min and was then programmed to 200°Cat20°/min
When the fraction of interest reached the six-port valve, it was
switched (Figure 2). The helium pushed the solution through the
sorbent. Analytes were retained, and solvent was vented to waste
through the ST tubing. Introduction of liquid into the GC column
did not occur because the transfer capillary (CT) had been
introduced farther into the liner than the GC column. The liquid
coming through CT was pushed by the helium in the direction
opposite to that of the GC column.
Once the transfer step was completed, the six-port valve was
switched and valve V1 was opened (Figure 3). The LC eluate was
sent to waste. The solution remaining in the transfer capillary CT
was also sent to waste, pushed out by helium. If some solvent
should remain in the CT capillary, solvent vapor would be
produced when the oven temperature was raised for the GC
analysis to be carried out. Such vapor would then enter the GC
column. To prevent this problem, the solvent solution should be
completely eliminated from the CT capillary before the GC
analysis.
Temperature and helium flows were kept constant for 0.25 min
after transfer, to eliminate the remaining solvent. After this purge
time, the on-off valves were switched as shown in Figure 4.
Subsequently, the thermal desorption of the trapped analytes was
achieved by quickly increasing the TOTAD interface temperature
to 250°C. This temperature was maintained for 5 min. The solutes
were then transferred to the capillary column, and the GC analysis
was carried out. Once the GC analysis was completed, the onoff valves were switched as shown in Figure 1. The interface was
cleaned by maintaining the helium stream for 5 min at 325°C,
and finally it was cooled to 80°C so that the process could begin
again.
(c) Timing.In Table 2 a timetable for the case of atrazine is
given as an example to illustrate the operation mode during the
process.
GC Analysis.Gas chromatographic separations were carried
out on a Quadrex (Weybridge, U.K.) fused-silica column (30 m
×0.32 mm i.d.) coated with 5% phenyl methyl silicone (film
thickness 0.25 µm). The column temperature was maintained at
40°C for 3 min and was then programmed to 200°Cat20°/min
การแปล กรุณารอสักครู่..