System and method that will synchronize data acquisition and modulation in a comprehensive two (multi) dimensional chromatography (separation) system to enable quantitative data analysis

#The present invention relates to comprehensive two-dimensional gas chromatography (2DGC or GCxGC). In particular, the invention relates to 2DGC or GCxGC that achieves a reproducible chromatogram.

#Two-dimensional gas chromatography is the result of combining two separation columns in gas chromatography. The effluent from the first column is periodically injected/transferred into the second column which separates the components of the effluent by a different criteria than that of the first column. Peak crowding/overlapping limits the usefulness of traditional chromatography. One way of handling the problem of peak crowding is overlapping comprehensive two-dimensional gas chromatography. In this set-up, the effluent from the first column is injected into the second column in a series of pulses by a modulator located between the columns. The modulator periodically stops and starts the movement of the effluent from the first column into the second column. The effluent from the second column is fed to a detector for data acquisition of the constituents of the effluent.

#Comprehensive two dimensional gas chromatographic separation is based on a modulation system to define the start and end of the second dimension separation. The second dimensional separation can be defined by the modulation period of the modulator that gated the effluent flow between the first dimensional and the second dimensional separation. The modulation unit is operated independently of GC data acquisition in the traditional Comprehensive two-dimensional gas chromatography (2DGC or GCxGC) system. This causes (1) the starting time of the second dimensional separation independent of the starting time of first dimensional separation that varies from run to run even if experiment conditions are exactly the same; (2) the peak fractions that are sliced into the second dimension separation are not exactly the same shape/intensity which will create many post data processing problems.

#FIG. 1 shows a schematic drawing of the GCxGC unit of the present invention.

#FIG. 2 shows how the interrupt and reset pulse sequence synchronizes the GC start with data acquisition.

#FIG. 3 shows that for the data of Table 2 the modulation process is not synchronized with data acquisition, the variation of the retention time will make the same compound appear not in the same position (in the second dimension) in the GCxGC chromatogram.

#Comprehensive two-dimensional gas chromatography (GCxGC) has demonstrated that two-dimensional separation can be applied to complex mixtures. There are two major advantages of GCxGC technique when compared to single dimensional GC: increased resolution that is approximately 10 times greater and sensitivity higher by approximately 50 times. In order to implement this new powerful separation instrument as a routine analytical tool, it is very important to automate the multi-steps for unattended operation. In addition, because of its increased resolving power, the interface of GCxGC to such elemental selective detectors as sulfur is very important in solving complex composition problems.

#The present invention is an improved comprehensive two-dimensional gas chromatography that is automated, that is, allows unattended operation. In addition to the unattended operation of the instrument, the chromatogram can now be reproduced with greater precision which allows improved control of the quantitative analysis step.

#The GCxGC schematic in FIG. 1 illustrates the functional diagram of the different units and their role in the automatic operation. This automation development include: (1) the use of liquid nitrogen level control and automatic liquid nitrogen refill system; (2) addition of an autosampler; (3) improved instrument control and data acquisition software; and (4) introduced pulse generator with external trigging option to synchronize the modulation with GC event.