Chemical and statistical considerations in the determination of partition coefficients of weakly ionizable drugs and poisons

Opong-Mensah, Kofi; Woller, Thomas W.; Obaseki, Andrew O.; Porter, William R.

doi:10.1016/0731-7085(84)80041-2

Cited by 12 publications

(11 citation statements)

References 24 publications

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“…S rel is defined as S D divided by the highest recovery of the two analytes over which the S rel is calculated resulting in Eq. (10).…”

Section: Extraction Selectivitymentioning

confidence: 95%

“…Therefore, to model the pH dependency of the analytical recovery of the extraction system, the method should be functional both qualitatively and quantitatively. Conventional methods of modelling the extraction behaviour are based on determining absolute analytical recoveries at a certain pH [10,12,20,21]. Unless detailed precautions are taken, the determination of absolute analytical recovery is very susceptible to systematic error due to non-quantitative liquid handling.…”

Section: Introductionmentioning

confidence: 99%

“…Although possible, the formation of ion-pairs with counter ions from the sample is assumed to be negligible [1,[8][9][10].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reconsideration of sample pH adjustment in bioanalytical liquid–liquid extraction of ionisable compounds

Hendriks¹,

Uges

Franke

2007

Journal of Chromatography B

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“…S rel is defined as S D divided by the highest recovery of the two analytes over which the S rel is calculated resulting in Eq. (10).…”

Section: Extraction Selectivitymentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reconsideration of sample pH adjustment in bioanalytical liquid–liquid extraction of ionisable compounds

Hendriks¹,

Uges

Franke

2007

Journal of Chromatography B

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“…They estimated the ratio of cyclic tautomers to the open chain form equal to * 20:1. My laboratory measured the ionization of warfarin spectrophotometrically in 30 mM zwitterionic buffers saturated with n-octanol at 25°C and found pK a = 5.15 ± 0.04 and log 10 P n-octanol/ water = 2.82 ± 0.06 [110]. Walter and Kurz cited a literature value for the ionization of warfarin (pK a = 5.00) but measured log 10 D n-octanol/pH 7.0 = 1.46 [111].…”

Section: Chemical Implicationsmentioning

confidence: 99%

“…Box plot of experimentally measured[106][107][108][109][110][111][112][113][114][115][116] and computationally predicted[105] values for the pK a of warfarin. Box plots are a simplified way of depicting statistical distributions that aid in the identification of suspect values.…”

mentioning

confidence: 99%

Warfarin: history, tautomerism and activity

Porter

2010

J Comput Aided Mol Des

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The anticoagulant drug warfarin, normally administered as the racemate, can exist in solution in potentially as many as 40 topologically distinct tautomeric forms. Only 11 of these forms for each enantiomer can be distinguished by selected computational software commonly used to estimate octanol-water partition coefficients and/or ionization constants. The history of studies on warfarin tautomerism is reviewed, along with the implications of tautomerism to its biological properties (activity, protein binding and metabolism) and chemical properties (log P, log D, pK (a)). Experimental approaches to assessing warfarin tautomerism and computational results for different tautomeric forms are presented.

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Flow Injection Analysis of Mixtures of Dopamine, Adrenaline and Ephedrine in Human Biofluids Using Stabilized after Storage in Air Lipid Membranes with a Novel Incorporated Resorcin[4]arene Receptor

et al. 2005

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This work describes a technique for the rapid, selective and sensitive electrochemical flow injection analysis of mixtures of the stimulating compounds adrenaline, dopamine, and ephedrine using stabilized after storage in air bilayer lipid membranes (BLMs) with incorporated resorcin[4]arene receptor. Injections of the stimulating compounds were made into flowing streams of a carrier electrolyte solution and a transient current signal, with duration of seconds, reproducibly appeared in less than two min after exposure of the lipid membranes to the compounds. The magnitude of this signal was linearly related to the concentration of the compound, which could be determined at micromolar levels. Repetitive cycles of injection of stimulating compounds have shown no signal degradation during each cycle (30 sequential injections). The time of appearance of the transient response was different for each stimulating compound and increased in the order of adrenaline, dopamine and ephedrine. The difference in time of response has allowed selective detection and analysis of these compounds in mixtures. The investigation of the effect of potent interferences included a wide range of compounds usually found in human biofluids, as well as proteins and lipids. The results showed that only proteins (most common in lipid film based biosensors) pose a problem that can be eliminated by modulation of the carrier solution to flow rates that do not allow adsorption of these compounds in the lipid films. The technique was applied in human urine samples.

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Chemical and statistical considerations in the determination of partition coefficients of weakly ionizable drugs and poisons

Cited by 12 publications

References 24 publications

Reconsideration of sample pH adjustment in bioanalytical liquid–liquid extraction of ionisable compounds

Reconsideration of sample pH adjustment in bioanalytical liquid–liquid extraction of ionisable compounds

Warfarin: history, tautomerism and activity

Flow Injection Analysis of Mixtures of Dopamine, Adrenaline and Ephedrine in Human Biofluids Using Stabilized after Storage in Air Lipid Membranes with a Novel Incorporated Resorcin[4]arene Receptor

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