Practical and theoretical consideration of flow-through microcalorimetry: determination of “thermal volume” and its flow rate dependence

O'Neill, M; Beezer, Anthony E.; Vine, George J.; Кемп, Р. Б.; Olomolaiye, D.; Volpe, Pedro L. O.; Oliveira, Denise Aparecida Gonçalves de

doi:10.1016/j.tca.2003.09.021

Cited by 18 publications

(13 citation statements)

References 11 publications

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“…The imidazole catalysed hydrolysis of triacetin (ICHT) [14] is suggested as a suitable reaction for the validation of batch or static calorimeters and the base catalysed hydrolysis of methyl para 4-hydroxy benzoate (BCHMP) [15] (methyl paraben) is suggested for the validation of calorimeters operating in the flow through mode. Results obtained from studies using the BCHMP test and reference reaction have been reported previously [15,19], these results have shown that the flow rate dependencey of thermal volume for each instrument is different and indeed for each experimental arrangement (e.g. sample and reference cell set-up).…”

Section: Flow-through Calorimetric Equationssupporting

confidence: 63%

“…sample and reference cell set-up). O'Neill et al report [15,19] that the observed value for V c can differ by as much as 15%, over a range of typical experimental flow rates, from the nominal physical (engineered volume). It was also reported that the heat measured by the calorimeter was not necessarily just that of the reacting solution within the calorimetric chamber.…”

Section: Flow-through Calorimetric Equationsmentioning

confidence: 99%

“…If this data is to be useful and comparable between different users and different laboratories it is necessary to have some method for validating calorimetric output, in terms of rate constant, k, and enthalpy, H. To this end chemical test and reference reactions have been developed and subjected to inter and intra laboratory trials, the results of which have been recently published [14,15]. These test and reference reactions also allow training of new personnel, troubleshooting for potential sources of instrumental error and investigation of experimental design [16][17][18][19][20]. Calorimetric data (Power, Js -1 , as a function of time, s), with the aid of the relevant equations, allows a number of parameters to be determined.…”

Section: Calorimetric Equations: Solution Phasementioning

confidence: 99%

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Recent Developments for the Analysis of Data Obtained from Isothermal Calorimetry

O'Neill¹

2005

CPB

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Isothermal calorimetry is rapidly becoming an indispensable tool for the quantitative determination of a variety of kinetic and thermodynamic parameters for a wide range of systems. In particular calorimetry is finding increased application to the investigation of stability and incompatibility of pharmaceutical materials. In order to draw meaningful conclusions and to predict behaviour in related systems it is necessary to have the means to calculate accurately parameters such as the rate constant and enthalpy. To this end several groups have been developing equations which describe calorimetric output in these terms. This paper will briefly outline some of these equations and discuss some of the limitations that currently exist in their application. A particular emphasis is placed on the recent developments relating to the application of these equations to flow calorimetric data. The main application of these equations is usually found in the pharmaceutical industry. Pharmaceutical formulations are usually extremely complex mixtures consisting of many different excipients as well as the active drug. Because of these large numbers of ingredients it is often observed that multiple chemical and physical process occur over the lifetime of the study. This complexity is then reflected in the calorimetric data rendering the application of the simple equations useless. Dealing with this complexity is a major issue amongst the calorimetric community and some of the recent advances in this field are also discussed.

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Section: Flow-through Calorimetric Equationssupporting

confidence: 63%

Section: Flow-through Calorimetric Equationsmentioning

confidence: 99%

Section: Calorimetric Equations: Solution Phasementioning

confidence: 99%

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Recent Developments for the Analysis of Data Obtained from Isothermal Calorimetry

O'Neill¹

2005

CPB

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“…[25,26] The thermal volume is dependent on the flow rate used in the measurements, and this volume can be determined by using a calibration reaction procedure (this will be further addressed in the Experimental Section). Finally, after dx i =dt are determined by online spectroscopic measurements, and all corresponding total heat flows q are determined by calorimetry, multivariate analysis is applied to solve Equation (6) to calculate the individual ith heat of reaction or reaction enthalpy D r H i .…”

Section: à1 ð4þmentioning

confidence: 99%

Combined Online Spectroscopic, Calorimetric, and Chemometric Analysis: Reaction Enthalpy Determinations in Single and Parallel Reactions

2009

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Calorimetry and signal processing: Vibrational spectroscopies, heat-flow microcalorimetry, and multivariate analysis are combined to decouple the reaction enthalpies of parallel reactions [picture: see text]. This methodology allows the evaluation of reaction enthalpy from complex systems without recourse to conventional kinetic modeling. Simultaneous in situ/online spectroscopy and heat-flow measurements as well as multivariate analyses are performed, apparently for the first time, to determine heats of reaction for single and parallel reactions. Two different vibrational spectroscopy techniques, namely Raman and FTIR spectroscopy, are used in conjunction with flow-through TAM III microcalorimetry. With respect to the spectroscopic analysis, the reaction spectra are first analyzed to determine the pure-component spectra and the corresponding concentrations without recourse to external calibration. With respect to the calorimetric analysis, a soft modeling approach is employed to determine the heats of reaction without recourse to any conventional kinetic models. This combined approach is implemented to determine the extents of reaction as well as the corresponding heats of reaction at 298.15 K and 0.1 MPa for a) the hydrolysis of acetic anhydride (single reaction) and b) the hydrolysis of methyl paraben and ethyl paraben in alkaline solution (both single and parallel reactions). In the latter case, the heat-flow contributions from the two simultaneous reactions are successfully decoupled. Taken together, these results demonstrate proof of concept for the present approach. The newly developed methodology appears to be quite general and particularly useful for investigating complex reaction systems. This is particularly true for multiple simultaneous reactions and reactions where the detailed kinetic expressions are not available, or cannot be easily determined. The use of extents of reaction is also very helpful where there is high variability in reaction rates, that is, due to the presence of impurities, changes in catalyst activity, or concentrations, temperature, and pH.

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“…This was confirmed by our experimental finding that varying the pump rate between 30 and 120 cm 3 /h had negligible effects. Using the alkaline hydrolysis of methyl paraben for the chemical calibration (O'Neill et al, 2003(O'Neill et al, , 2004, the thermal sensitive volume was determined to be 0.51 cm 3 . All measurements were performed in the 3,000 mW calorimetric range.…”

Section: Flow Through Calorimeter Working In a ''Measuring Loop'' (Ml)mentioning

confidence: 99%

Control of continuous polyhydroxybutyrate synthesis using calorimetry and flow cytometry

Maskow

Müller

Lösche

et al. 2006

Biotech & Bioengineering

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The substrate-carbon flow can be controlled in continuous bioreactor cultures by the medium composition, for example, by the C/N ratio. The carbon distribution is optimal when a maximum fraction flows into the desired product and the residual is just sufficient to compensate for the dilution of the microbial catalyst. Undershooting of the latter condition is reflected immediately by changes in the Gibbs energy dissipation and cellular states. Two calorimetric measurement principles were applied to optimize the continuous synthesis of polyhydroxybutyrate (PHB) by Variovorax paradoxus DSM4065 during growth with constantly increasing supply rates of fructose or toxic phenol. Firstly, the changed slope of the heat production rate in a complete heat balanced bioreactor (CHB) indicated optimum carbon channeling into PHB. The extent of the alteration depended directly on the toxic properties of the substrate. Secondly, a flow through calorimeter was connected with the bioreactor as a "measurement loop." The optimum substrate carbon distribution was indicated by a sudden change in the heat production rate independent of substrate toxicity. The sudden change was explained mathematically and exploited for the long-term control of phenol conversion into PHB. LASER flow cytometry measurements distinguished between subpopulations with completely different PHB-content. Populations grown on fructose preserved a constant ratio of two subpopulations with double and quadruple sets of DNA. Cells grown on phenol comprised a third subpopulation with a single DNA set. Rising phenol concentrations caused this subpopulation to increase. It may thus be considered as an indicator of chemostress.

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Practical and theoretical consideration of flow-through microcalorimetry: determination of “thermal volume” and its flow rate dependence

Cited by 18 publications

References 11 publications

Recent Developments for the Analysis of Data Obtained from Isothermal Calorimetry

Recent Developments for the Analysis of Data Obtained from Isothermal Calorimetry

Combined Online Spectroscopic, Calorimetric, and Chemometric Analysis: Reaction Enthalpy Determinations in Single and Parallel Reactions

Control of continuous polyhydroxybutyrate synthesis using calorimetry and flow cytometry

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