Analysis and validation of the phosphorylated metabolites of two anti‐human immunodeficiency virus nucleotides (stavudine and didanosine) by pressure‐assisted CE‐ESI‐MS/MS in cell extracts: Sensitivity enhancement by the use of perfluorinated acids and alcohols as coaxial sheath‐liquid make‐up constituents

Bezy, Vincent; Chaimbault, Patrick; Morin, Pascal; Unger, Steve; Bernard, Marie-Agnès; Agrofoglio, Luigi A.

doi:10.1002/elps.200500850

Cited by 19 publications

(19 citation statements)

References 41 publications

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“…On the other hand, I MS (curve B) presents a maximum at around 7 mL/min. For I MS , a similar evolution was found by Bezy et al [34], without discussion of a possible suction effect during injection. Within the frame of this study, I UV is only influenced by suction effect and I MS by both suction, ionization/desorption efficiency and dilution effects.…”

Section: Sl Flow Rate: Dilution Effect?supporting

confidence: 63%

New insight into suction and dilution effects in CE coupled to MS via an ESI interface. II – Dilution effect

et al. 2009

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The hyphenation of CE with MS is nowadays accepted as a powerful analytical approach. As far as ESI, the most common interface, is concerned, one challenge is to provide the most sensitive as well as quantitative information, which is quite a difficult task, as it is linked, among other factors, to suction and dilution effects. In the coaxial ESI configuration, it has been previously demonstrated that suction effect depends on many parameters inherent to the ESI interface geometry, the prevailing ones being the CE capillary protrusion from the interface needle, the sheath liquid (SL) and the overall BGE flow rates and velocity profile. In this paper, dilution effect is studied, as the CE electrolyte is mixed with SL at the interface. Considering peak intensity and efficiency, this effect was studied as a function of the various parameters of the interface (capillary protrusion from the SL tube, nebulizing gas, SL and CE electrolyte flow rates) or of the source (skimmer and ESI voltages, drying gas flow rate and temperature). It appears that the dilution effect seems slightly lower than what can be anticipated from the proportions of the liquid flow rates. This study also indicates that suction effect has to be considered first to better understand the dilution phenomenon, as suction effect leads to an increase in peak intensity, before a dilution effect appears.

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Section: Sl Flow Rate: Dilution Effect?supporting

confidence: 63%

New insight into suction and dilution effects in CE coupled to MS via an ESI interface. II – Dilution effect

et al. 2009

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“…MEKC was also beneficial compared to CZE because of the removal of the large overloaded signal of the reagent peak by the micelles, which hindered the data acquisition of product peaks in CZE. The sensitivity with fluorescence detection (LOQ = 12 ng/mL) is better than the reported CE-MS method (LOQ = 50 ng/mL) for ddATP [10]; however, the present method would allow intracellular quantitation of ddATP only in the pmol range.…”

Section: Sensitivity With Mekccontrasting

confidence: 47%

“…Although CITP allows reaching a gain in sensitivity of around 100, this alone is not sufficient for the present study [12]. Detection by mass spectral interfacing to CE was described before [10] (see above). Therefore, fluorescence detection which requires prior derivatization of the compounds was examined here.…”

Section: Introductionmentioning

confidence: 99%

“…This procedure thus involves an extra step and does not allow a direct quantitation of the various types of nucleotide phosphates [1]. A pressureassisted CE-ESI-MS/MS method was recently reported, which allowed direct separation of antiretroviral dideoxynucleosides and nucleotides among which they did separate ddI and ddATP [10]. However, the sensitivity reported (LOQ = 50 ng/mL) would allow quantitation only in the pmol range and is not sufficient for the quantitation of the fmol levels of intracellular ddATP.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of dideoxyadenosine triphosphate by CE with fluorescence detection. I. Derivatization through the phosphate group

2007

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A CZE method was developed, which separates 2',3'-dideoxyadenosine-5'-triphosphate (ddATP) from other metabolites and endogenous nucleotides at high concentrations (20-200 microg/mL) to allow UV detection. To enhance sensitivity, fluorescence detection which requires prior derivatization of compounds was examined. Precapillary derivatization of ddATP in the presence of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDAC) with dansyl ethylenediamine (dansyl EDA) was faster and stable compared to that of 4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-propionyl ethylenediamine (BODIPY FL EDA). Reaction conditions, reagent concentrations and detection parameters were optimized and highest derivatization efficiency was achieved in 0.1 M 1-methylimidazole buffer (pH 8.0) with 140 mM EDAC in 1-methylimidazole buffer and 30 mM dansyl EDA in DMF for 90 min at 60 degrees C. Dansyl EDA derivatives of ddATP, 2'-deoxyadenosine-5'-triphosphate (dATP) and ATP were comigrating with the CZE method; therefore, a MEKC method was developed and optimized for repeatable separations. Upon dansylation, sensitivity of ddATP with fluorescence detection (LOQ = 12 ng/mL) was 160 times higher than UV detection (LOQ = 1.9 microg/mL).

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“…Increasing assisted pressure from 0 to 0.5 psi induced an important decrease of run time (À33%) and an enhancement of peak efficiency. Consequently, the signalto-noise of fenamiphos peak was improved (125%) as already proven in a previous work [29]. Finally, the increase of assisted pressure affects the resolution (2.5 at 0 psi, 1.5 at 0.5 psi) and a medium applied pressure of 0.2 psi (R s 5 1.9) was selected.…”

Section: Assisted Pressurementioning

confidence: 81%

Simultaneous enantioselective determination of fenamiphos and its two metabolites in soil sample by CE

2009

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The enantioseparation of fenamiphos and its two main metabolites (fenamiphos sulfoxide and fenamiphos sulfone) were simultaneously achieved by CE by using a dual CD system. A mixture of 25 mM carboxymethyl-beta-CD and 10 mM hydroxypropyl-alpha-CD was added to the acetic acid/ammonia (ionic strength=50 mM, pH 5) buffer and was suitable for the baseline resolution of all stereoisomers of analytes. A further addition of 5% methanol to the BGE increased significantly the resolution between the diastereoisomers of fenamiphos sulfoxide. An overimposed pressure (0.2 psi) was applied during the analysis in order to have better peak efficiencies and small run time. The composition of the sample solvent was found to be a crucial parameter. An amount of 15% MeOH added to the sample was a good alternative to ensure the total solubility of fenamiphos and the baseline separation of fenamiphos sulfoxide enantiomers. The extraction of pesticides from soil samples was also investigated. A methanolic extraction allowed recovering 50-75% of pesticides, which were detected by CE at the parts per million concentration level (3-100 mg/kg) with a good precision (5.1-13.2% RSD). This method was applied to soil samples and was found to be suitable to monitor the enantiomeric degradation of fenamiphos in environmental samples.

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Cited by 19 publications

References 41 publications

New insight into suction and dilution effects in CE coupled to MS via an ESI interface. II – Dilution effect

New insight into suction and dilution effects in CE coupled to MS via an ESI interface. II – Dilution effect

Analysis of dideoxyadenosine triphosphate by CE with fluorescence detection. I. Derivatization through the phosphate group

Simultaneous enantioselective determination of fenamiphos and its two metabolites in soil sample by CE

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