Introduction

Quality Control procedures are vital in the production of fused silica GC columns. With a growing consumables market, production increases have a major impact on the QC operation. To make this QC process more efficient, Da Vinci Europe Laboratory Solution provides an automation solution to capillary column QC testing using robotics.

Production

GC columns are manufactured from extreme pure glass (fused silica). Base material is a very narrow 50-530µ capillary tube extracted at 2200°C from a 1.5 m hollow glass rod. The fragile glass capillary receives a 6 layer protective exterior polyimide coating which allows it to bend. Finally internal coating, cutting to specific lengths and coiling makes it a capillary GC column ready for its final QC check.

Workflow

Capillary GC column testing involves a lot of manual handling: the column must be positioned in the GC oven compartment and connected to the GC inlet and detector. These miniature fittings require careful installation since Hydrogen is used as carrier gas. Hydrogen leaks must be avoided. Each type of column (type of coating/packing, diameter, length) requires its own QC test procedure. The type of test mix and GC method parameters are entered for each column. Finally the GC analysis produces a QC report which is evaluated by the tester. If it passes, a certificate is enclosed in the GC column packaging and is ready for shipment.

Robotics

To automate the above QC test procedure, the first challenge was how a robot should handle a fragile object like a GC capillary column. Da Vinci Europe co-invented a column cassette in which two similar columns are installed by the tester. The columns ends are attached to specially designed gas-tight seals that mate with injector and detector receptacles in the GC oven. The robot can now firmly grip the cassette and accurately position it in the oven.

A book-shelf style 'hotel' is designed to store 40 cassettes in an 8 by 5 grid, resulting in a total test capacity of 80 columns. The hotel is loaded with cassettes by the operator from the rear; the robot takes the cassettes from the front. This allows safe loading and unloading the column hotel whilst the robot is operating.

The robot system includes an integrated GC with auto-sampler. Two modifications were made to the off-the-shelf GC; one was to accommodate a pneumatics cassette lift mechanism which facilitates the gas-tight connections between the GC and the test columns. Second, the GC oven door mechanism was modified to open and close automatically during column exchange.

Operation

Operators prepare the cassettes by installing the test columns and attaching a unique barcode. Da Vinci Europe developed special software GC sequencing application that allows the operator to setup a test series. Each entry describes the test procedure of the columns in a cassette. As a reference, the robot scans the cassette barcode and looks up the defined test parameters (test mix, GC method). The correct test parameters are then uploaded to the GC system. The cassette is installed in the GC and the test is started. Upon completion, the cassette is returned to its origin and a test report is printed.

Conclusion

After the installation of three capillary GC columns test robots, the number of manual test GC in the QC lab was drastically reduced. Automated test runs can now be executed overnight which improves QC test throughput significantly.

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