| dc.contributor.author | Singh, Hameraj. | en_US |
| dc.date.accessioned | 2014-10-21T12:35:03Z | |
| dc.date.available | 1995 | |
| dc.date.issued | 1995 | en_US |
| dc.identifier.other | AAINN05231 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55045 | |
| dc.description | Novel operational modes, fundamental characteristics and correlations of three common chromatographic detectors: the electron capture detector (ECD), the flame photometric detector (FPD), and the flame ionisation detector (FID) are reported. | en_US |
| dc.description | Conventional ECDs are driven by unipolar polarisation sources. Following the discovery that a.c. constant-frequency polarisation yields better sensitivities and comparable linear ranges, studies of other bipolar polarisation regimes were conducted. The results indicate that it is possible to operate bipolar constant-current ECDs with response by a decrease of frequency as compared to conventional systems that respond by an increase of pulser frequency. In addition, the bipolar pulsed (constant frequency) ECD is very sensitive and produces a calibration curve that is entirely linear, from the 5 attomoles/second $\alpha$-hexachloro-cyclohexane detection limit to the limit established by the extent of the standing current. | en_US |
| dc.description | Filters are commonly employed to reduce detector noise, but the nature of chromatographic noise has never been fully investigated. The effect of three types of filters (two digital and one analog) on the noise from the ECD, FPD and FID, as well as the nature of the noise were therefore investigated. The results show that chromatographic noise is mainly white noise (of a fundamental nature, reducing with filter time constant in square-root fashion and giving a constant noise "power" spectrum) that is converted into low frequency noise by the filter, thus the nature and sophistication of the filter are not very important. These results were supported by simulations, and equations were developed for the calculation of fundamental detector noise. | en_US |
| dc.description | Detector response ratios are widely employed, especially for probing peak identity and purity. Since integration is a common procedure in chromatography, an integral response ratio algorithm for automatic response ratio determination was developed. The integral method proved superior to the existing slope ratio method; and seems promising, particularly for sequential detection where the shape and retention time of peaks may vary from detector to detector. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1995. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Chemistry, Analytical. | en_US |
| dc.title | Chromatographic detectors: Novel operational modes, characteristics and correlations. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
