Shift in pH of biological fluids during storage and processing: effect on bioanalysis

Fura, Aberra; Harper, Timothy W.; Zhang, Hongjian; Fung, Lawrence K.; Shyu, Wen Chyi

doi:10.1016/s0731-7085(03)00159-6

Cited by 92 publications

(66 citation statements)

References 8 publications

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“…It was subsequently reported that there is a difference in pH between fresh plasma and stored plasma (Fura et al, 2003). This was attributed to rapid CO 2 loss during plasma collection, storage, and incubation, causing an increase in pH.…”

Section: Introductionmentioning

confidence: 99%

“…In attempts to address this issue, Wan and Rehngren (2006) determined that stronger buffers were required to minimize pH shifts, whereas others advocated the use of a 10% CO 2 atmosphere (Fura et al, 2003;Musteata et al, 2006;Kochansky et al, 2008) or initial purging of plasma with CO 2 followed by ultracentrifugation for determination of fup (Nilsson and Schmidt, 2001). There is further discussion in the literature, supporting the use of either stronger buffer or incubation in a CO 2 atmosphere (Banker and Clark, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Control and Measurement of Plasma pH in Equilibrium Dialysis: Influence on Drug Plasma Protein Binding

Curran¹,

Claxton²,

Hutchison³

et al. 2010

Drug Metab Dispos

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ABSTRACT:Past publications have highlighted the influence of postdialysis plasma pH on the measured fraction unbound in plasma (fup). There is disparity in the industry as to which of two main methods is more suitable for controlling postdialysis plasma pH: the use of either a stronger buffer or a CO 2 atmosphere for the incubation. In the current study, it has been found that 10% CO 2 could be too high for the buffering capacities of both 100 mM sodium phosphate (pH 7.40 decreased to pH 6.90 after a 6-h incubation) and plasma (decreased below pH 7.40 after a 6-h incubation). To provide appropriate control over the postdialysis plasma pH, for a range of species, it is proposed that a standard phosphate buffer strength (100 mM) and pH (7.40) in combination with a 5% CO 2 atmosphere be used for equilibrium dialysis. Furthermore, statistically significant differences in fup values obtained with a pH difference of less than 0.32 pH unit have been demonstrated. An acceptance range for postdialysis plasma pH in routine in vitro fup screening assays of pH 7.40 ؎ 0.10 is recommended.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Control and Measurement of Plasma pH in Equilibrium Dialysis: Influence on Drug Plasma Protein Binding

Curran¹,

Claxton²,

Hutchison³

et al. 2010

Drug Metab Dispos

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show abstract

“…La stabilité des composés peut également être modifiée par les changements de pH (14). Par exemple, les composés à fonctions esters, amides, carbamates, urée, béta-lactame, lactones, hydantoines, glucuronides acylés, etc sont susceptibles d'être dégradés (10). Le pH de l'échantillon biologique peut être stabilisé à 7,4-7,5 par addition de tampon citrate ou phosphate (10).…”

Section: Méthodes D'analyseunclassified

“…Par exemple, les composés à fonctions esters, amides, carbamates, urée, béta-lactame, lactones, hydantoines, glucuronides acylés, etc sont susceptibles d'être dégradés (10). Le pH de l'échantillon biologique peut être stabilisé à 7,4-7,5 par addition de tampon citrate ou phosphate (10). Par conséquent, le maintien d'un pH stable est essentiel lorsqu'il s'agit de caractériser et de quantifier des composés qui sont eux mêmes sensibles au pH ou qui génè-rent des metabolites thermosensibles.…”

Section: Méthodes D'analyseunclassified

Traitements de l'échantillon biologique avant l'analyse chromatographique. Applications à la pharmacocinétique et à la toxicologie

Nicolas¹,

Robert²,

Kelly³

et al. 2004

Ann Toxicol Anal

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“…A estabilidade dos fármacos em fluidos biológicos depende de suas propriedades químicas, da matriz biológica, do material e tempo de acondicionamento (FDA, 2001;Resolução-RE nº 899, Anvisa, 2003;Fura et al, 2003). A estabilidade determinada para um tipo de matriz e material de acondicionamento é específica e não pode ser extrapolada para outros materiais (FDA, 2001;Resolução-RE nº 899, Anvisa, 2003).…”

Section: Estudo De Estabilidadeunclassified

Análise enantiosseletiva da mirtazapina em plasma: comparação de métodos de preparação das amostras

Santana¹

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Figura 25. Efeito do pH da fase doadora na recuperação de 250 ng mL -1 de cada enantiômero da mirtazapina. Condições de extração: 25 ºC; 30 min; 7 cm de fibra; 700 µL de plasma e 3,1 mL de água MILLI-Q-PLUS ® ou tampão fosfato (Fase doadora); 22 µL de tolueno (Fase aceptora). As condições cromatográficas são apresentadas na seção 3.2.2. (n = 3 para cada experimento). 72Figura 26. Efeito da adição de diferentes volumes de NaOH 10 mol L -1 na recuperação de 250 ng mL -1 de cada enantiômero da mirtazapina. Condições de extração: 25 ºC; 30 min; 7 cm de fibra; 700 µL de plasma e 3,1 mL de água MILLI-Q-PLUS ® (Fase doadora); 22 µL de tolueno (Fase aceptora). As condições cromatográficas são apresentadas na seção 3.2.2. (n = 3 para cada experimento). 72Figura 27. Efeito da adição de cloreto de sódio na recuperação de 250 ng mL -1 de cada enantiômero da mirtazapina. Condições de extração: 25 ºC; 30 min; 7 cm de membrana; 700 µL de plasma, 150 µL de NaOH 10 mol L -1 e 3,1 mL de água MILLI-Q-PLUS ® (Fase doadora); 22 µL de tolueno (Fase aceptora). As condições cromatográficas são apresentadas na seção 3.2.2.. (n = 3 para cada experimento)._____________________________________________________ 74Figura 28. Perfil de múltiplas extrações na recuperação de 250 ng mL -1 de cada enantiômero da mirtazapina. Condições de extração: 25 ºC; 7 cm de membrana; 700 µL de plasma, 150 µL de NaOH 10 mol L -1 e 3,1 mL de água MILLI-Q-PLUS ® (Fase doadora); 22 µL de tolueno (Fase aceptora). As condições cromatográficas são apresentadas na seção 3.2.2.. (n = para cada experimento)._____________________________________________________ 75Figura 29. Efeito da temperatura na recuperação de 250 ng mL -1 de cada enantiômero da mirtazapina. Condições de extração: 30 min; 7 cm de membrana; 700 µL de plasma, 150 µL de NaOH 10 mol L -1 e 3,1 mL de água MILLI-Q-PLUS A A B B S S T T R R A A C C T T $EVWUDFW A AB BS ST TR RA AC CT TThe increased interest in enantioselective pharmacokinetic and pharmacodynamic properties of chiral drugs, aiming to establish the advantages in the production of estereochemically pure drugs, has led to the development of methods of analysis with low limits of quantification, selectivity and reproducibility, which are suitable to be used in kinetic disposition studies.On this basis, mirtazapine, a new antidepressant with estereoselective pharmacokinetic and pharmacodynamic properties but with few suitable methodologies for the separation and quantification of its enantiomers, was selected to evaluate two techniques of sample preparation.The procedure involved a classic liquid-liquid extraction and a new technique of liquid-phase microextraction using microporous polypropylene hollow fiber, both using toluene as extraction solvent. The analyses were carried out by high-performance liquid chromatography using chiral stationary phase and UV detection, at 292 nm. The chromatographic separation of (+)-(S)-e (-)-(R)-mirtazapine was performed on a Chiralpak AD column protected by a CN guard column, using hexane:ethanol (98:2, v/v) ...

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Shift in pH of biological fluids during storage and processing: effect on bioanalysis

Cited by 92 publications

References 8 publications

Control and Measurement of Plasma pH in Equilibrium Dialysis: Influence on Drug Plasma Protein Binding

Control and Measurement of Plasma pH in Equilibrium Dialysis: Influence on Drug Plasma Protein Binding

Traitements de l'échantillon biologique avant l'analyse chromatographique. Applications à la pharmacocinétique et à la toxicologie

Análise enantiosseletiva da mirtazapina em plasma: comparação de métodos de preparação das amostras

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