1. GC/Computer Interfacing Using LabVIEW Courtney Arnott April 22, 2002 CHEM 250

2. Dedication  Bryan Alphin Bente (SBC Class of 1969)  Rachel Snider

3. LabVIEW  Graphical programming language (G)  Data acquisition  Instrument control  VI Front panel Block diagram 1. “LabVIEW User Manual,” p.1-1 and 1-2. National Instruments, 1992.

4. Goals  Interface GC with computer  Create data acquisition program  Display, report, integrate peaks

5. A-to-D Converter  Converts voltage signal to logic state  Two types Staircase Successive- approximation 2. Skoog, Holler, and Nieman. Principles of Instrumental Analysis, Fifth Edition. Saunders College Publishing: Philadelphia, 1998.

6. Integrating GC and Computer  Sends voltage signal from GC to A-D converter  Max signal = 1V

7. Testing the Connection  Used wires and voltmeter  Ran with computer interface and plotter simultaneously  Adjusted connection to achieve + voltage

8. Front Panel

9. Block Diagram

10. Sub-VIs  Separate VI used for one particular function  Make main program more organized  Can be used in other programs  Three Sub-VIs Peak Limit Table

11. Sub-VI: Peak  Y-values, Peak Min (set by user)  Finds peak amplitudes and locations

12. Sub-VI: Limit  Filters out solvent front  All y values over 0.65 are discarded from array  Corresponding x values removed

13. Sub-VI: Table  Integrates peaks  Formats locations, amplitudes, and areas into table

14. Program Results  Collects data and finds peak  Programmed to ignore solvent front  Displays peaks in table format  User information inputs

15. Future Program Goals  Fix integrate procedure  Export data to file  Publish reports