| Continuous on-line true titrations by feedback-based flow ratiometry. The principle of compensating errors | |
| | |
MedLine Citation:
|
PMID: 11028636 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
|
We introduce a new concept for continuous on-line titrations based on feedback-controlled flow ratiometry and the principle of compensating errors. The system has been thoroughly tested by applying it to acid-base neutralization titrations with indicator-based end point detection. In a typical case, the total flow (FT, consisting of the sample and the titrant flows) is held constant while the titrant (e.g., a standard base containing an indicator) flow FB varies linearly in response to a controller output voltage. The sample (e.g., an acidic solution to be titrated) flow FA constitutes the makeup and thus also varies (FA = FT - FB). The status of the indicator color in the mixed stream is monitored by an optical detector and used either for governing the controller output or for interpreting the results of the titration. Three methods (PID based control, fixed triangular wave control, and feedback-based triangular wave control implemented on a PC) were examined. In the last and the most successful approach, the titrant flow is initially ramped upward linearly. At the instant a change in the color is sensed by the detector, the titrant flow rate FH is higher than the true equivalence flow rate FE because of the lag time between the first compositional change and its detection. The sensing of the change in color causes the system output to immediately reverse its ramp direction such that the titrant flow now goes down linearly at the same rate. At the instant a change in color, in the opposite direction this time, is again sensed, the titrant flow rate FL is lower than FE by exactly the same amount that FH was higher than FE. This principle of compensating errors (FE = (FH + FL)/2) allows true titrations with excellent reproducibility and speed (0.6% RSD at 3 s/titration and 0.2% RSD at 10 s/titration) and titrant volume consumption as little as 12 microL/titration and solves an old conceptual problem in flow based titrations. |
| | |
Authors:
|
Tanaka; Dasgupta; Huang |
Related Documents
:
|
20494776 - Bead-flow pattern: quantitation of fluid movement during torsional and longitudinal pha... 1994406 - Quantification of vascular stenosis with color doppler flow imaging: in vitro investiga... 10361846 - Ultrasonographic diagnosis and color flow doppler sonography of internal jugular venous... 15807216 - A reduction in intraovarian arterial blood flow resistance after ovulation is necessary... 26946 - Oxygen transport in chicken embryos under hypothermal exposure. 8229246 - Increased cerebral perfusion after detachable balloon embolization of carotid cavernous... |
Publication Detail:
|
Type: JOURNAL ARTICLE |
Journal Detail:
|
Title: Analytical chemistry Volume: 72 ISSN: 1520-6882 ISO Abbreviation: Anal. Chem. Publication Date: 2000 Oct |
Date Detail:
|
Created Date: 2000-10-10 Completed Date: - Revised Date: - |
Medline Journal Info:
|
Nlm Unique ID: 0370536 Medline TA: Anal Chem Country: UNITED STATES |
Other Details:
|
Languages: Eng Pagination: 4713-20 Citation Subset: - |
Affiliation:
|
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock 79409-1061, USA. |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
|
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Probing trace phenols based on mediator-free alumina sol--gel-derived tyrosinase biosensor.
Next Document: Investigation of the molecular extraction process in single subpicoliter droplets using a near-infra...