Desenvolvimento de um detector piezelétrico para cromatógrafo a gás interfaceado a microcomputador
A piezoelectric detector based on a commercial quartz crystal of 3.57MHz is shown. A PTFE cell attached to the GC-column outlet holds the polymer-coated crystal, whose terminals were removed. Two TTL oscillators (reference and sensor) are used and the beating of their frequencies is monitored throug...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Sociedade Brasileira de Química
1999-01-01
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| Series: | Química Nova |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40421999000100020 |
| Summary: | A piezoelectric detector based on a commercial quartz crystal of 3.57MHz is shown. A PTFE cell attached to the GC-column outlet holds the polymer-coated crystal, whose terminals were removed. Two TTL oscillators (reference and sensor) are used and the beating of their frequencies is monitored through a home-made counter card inserted in a microcomputer. The original thermal conductivity detector was also interfaced, but through a 12-bit analog-to-digital converter. In spite of the well-known fact that QCM has low sensitivity at high temperatures, results show significant peak deformation for low temperatures. In addition, the phenomenon is also dependent on the chemical composition of the absorbent film besides instantaneous partial pressure and chemical composition of the analyte. |
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| ISSN: | 0100-4042 1678-7064 |