Determination of acid dissociation constants of triazole fungicides by pressure assisted capillary electrophoresis

Konášová, Renáta; Dytrtová, Jana Jaklová; Kašička, Václav

doi:10.1016/j.chroma.2015.07.005

Cited by 42 publications

(18 citation statements)

References 41 publications

(47 reference statements)

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“…The acid dissociation constant (Ka, or pKa in minus logarithm scale) is a fundamental parameter for physicochemical characterization of biologically and pharmacologically relevant compounds [1,2]. Capillary electrophoresis (CE) has been widely used for accurate determination of pKa of a great variety of polyprotic compounds [1][2][3][4]. It is an excellent alternative to potentiometric [2,5], ultraviolet-visible (UV/Vis) spectrophotometric [2,6] and NMR [2,7] determination because it is not limited by sample volume or purity, it can be fully automated and it allows a great versatility in the selection of the separation conditions.…”

Section: Introductionmentioning

confidence: 99%

“…It is an excellent alternative to potentiometric [2,5], ultraviolet-visible (UV/Vis) spectrophotometric [2,6] and NMR [2,7] determination because it is not limited by sample volume or purity, it can be fully automated and it allows a great versatility in the selection of the separation conditions. The CE determination of pKa is usually performed measuring the electrophoretic mobility (me) of the target compounds as a function of pH within an appropriate pH range in aqueous solutions [4], mixed hydro-organic [8] or nonaqueous media [9] using fused silica capillaries with UV detection [4,8,9]. During the last decade, different interesting alternatives have been proposed to increase the reproducibility and throughput of these typical procedures, such as application of multiplexed [10] and miniaturized instrumentation [11], coated capillaries [12,13], mass spectrometry detection [14,15] or internal standard-based methods [16].…”

Section: Introductionmentioning

confidence: 99%

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Determination of acidity constants and prediction of electrophoretic separation of amyloid beta peptides

Peró-Gascón

Benavente

Barbosa

et al. 2017

Journal of Chromatography A

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In this paper we describe a strategy to estimate by CE the acidity constants (pK) of complex polyprotic peptides from their building peptide fragments. CE has been used for the determination of the pKs of five short polyprotic peptides that cover all the sequence of amyloid beta (Aβ) peptides 1-40 and 1-42 (Aβ fragments 1-15, 10-20, 20-29, 25-35 and 33-42). First, the electrophoretic mobility (m) was measured as a function of pH of the background electrolyte (BGE) in the pH range 2-12 (bare fused silica capillary, I=25mM and T=25°C). Second, the ms were fitted to equations modelling the ionisable behaviour of the different fragments as a function of pH to determine their pKs. The accuracy of the pKs was demonstrated predicting the electrophoretic behaviour of the studied fragments using the classical semiempirical relationships between m and peptide charge-to-mass ratio (m vs. q/M, classical polymer model, q=charge and M=relative molecular mass). Separation selectivity in a mixture of the fragments as a function of pH was evaluated, taking into account the influence of the electroosmotic flow (EOF) at each pH value, and a method for the simple and rapid simulation of the electropherograms at the optimum separation pH was described. Finally, the pKs of the fragments were used to estimate the pKs of the Aβ peptides 1-40 and 1-42 (C and D 3.1, E 4.6 and Y 10.8 for acidic amino acids and N-D 8.6, H 6.0, K 10.6 and R 12.5 for basic amino acids), which were used to predict their behaviour and simulate their electropherograms with excellent results. However, as expected due to the very small differences on q/M values, separation resolution of their mixtures was poor over the whole pH range. The use of poly(vinyl alcohol) (PVA) coated capillaries allowed reducing the EOF and a slight improvement of resolution.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determination of acidity constants and prediction of electrophoretic separation of amyloid beta peptides

Peró-Gascón

Benavente

Barbosa

et al. 2017

Journal of Chromatography A

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“…Owing to the acid–base properties of the 1H‐1,2,4‐triazole group, the triazole ring is protonated at the N4 position in aqueous solution at pH lower than 2.4. As most agricultural soils have a pH in the range 4–8, triazoles remain in their neutral form . On the contrary, properties such as soil mobility and bioavailability are strongly influenced by the presence of other chemicals and the sorption by soil particles .…”

Section: Introductionmentioning

confidence: 99%

Complexation and stability of the fungicide penconazole in the presence of zinc and copper ions

Kovač

Jakl

Fanfrlík

et al. 2020

Rapid Comm Mass Spectrometry

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Rationale:For the risk assessment of penconazole in the environment and the evaluation of the possible consequences of its use, it is important to determine how its reactivity and degradation are influenced by metals commonly found in nature, such as copper and zinc. Methods:Changes in the reactivity of penconazole in the presence of zinc/copper ions were studied using electrospray ionisation mass spectrometry and density functional theory calculations.Results: Many penconazole complexes with copper and zinc ions were created; a comparison of the elements showed that a few complexes were formed analogously (doubly charged complexes with four penconazole molecules, singly charged complexes with chlorine as a counterion and singly charged complexes with deprotonated penconazole as a counterion). The metal complexes with different structures indicated different reactivity of penconazole with copper and zinc. Conclusions:The experimental and computational approaches have revealed different changes in the structure of penconazole. In the Zn(II) complex, penconazole deprotonated to stabilise the bond to Zn(II). In the Cu(II) complex, it loses one chlorine atom, creates an additional ring between the triazole ring and the phenyl ring, and/or creates a double bond in the short aliphatic chain.

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“…200 kJ mol −1 ) complexes . The pK a values of the majority of triazoles are below 2 . This predetermines that triazoles, namely Cyp (pK a = 1.73 ± 0.01), will be in the neutral form in most environmental systems.…”

Section: Introductionmentioning

confidence: 99%

Mimicking of cyproconazole behavior in the presence of Cu and Zn

Jakl

Fanfrlík

Dytrtová

2017

Rapid Comm Mass Spectrometry

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Determination of acid dissociation constants of triazole fungicides by pressure assisted capillary electrophoresis

Cited by 42 publications

References 41 publications

Determination of acidity constants and prediction of electrophoretic separation of amyloid beta peptides

Determination of acidity constants and prediction of electrophoretic separation of amyloid beta peptides

Complexation and stability of the fungicide penconazole in the presence of zinc and copper ions

Mimicking of cyproconazole behavior in the presence of Cu and Zn

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