Determination of fosfomycin in pus by capillary zone electrophoresis
A method is described for the determination of fosfomycin in pus by capillary zone electrophoresis with reversed electroosmotic flow, and indirect UV absorbance detection. Sample pre-treatment is limited to removal of proteins and cell debris by adding the double volume of methanol, followed by vort...
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Published in | Journal of Chromatography A Vol. 1081; no. 1; pp. 55 - 59 |
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Main Authors | , , , , |
Format | Journal Article Conference Proceeding |
Language | English |
Published |
Amsterdam
Elsevier B.V
15.07.2005
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | A method is described for the determination of fosfomycin in pus by capillary zone electrophoresis with reversed electroosmotic flow, and indirect UV absorbance detection. Sample pre-treatment is limited to removal of proteins and cell debris by adding the double volume of methanol, followed by vortexing for few seconds, and centrifugation at 15,000
×
g for 2
min. The supernatant is directly injected into the instrument. Fosfomycin is separated from sample constituents with a background electrolyte at pH 7.25 (25
mM benzoate buffer with 0.5
mM hexadecyltrimethylammonium bromide added, adjusted to pH with tris(hydroxymethyl)-aminomethane (TRIS)). Separation is carried out in a capillary with 50
μm I.D., 64.5
cm total length, 56.0
cm to the detector, at 25
°C with −25
kV voltage applied. Due to the low absorbance of the analyte, indirect UV detection was performed at 254
nm using a bubble cell capillary. Sample was injected by pressure (450
mbar
s). Repeatability for fosfomycin in spiked pus (from 8 or 10 consecutive injections of three different series at concentrations of 100
μg/mL of the antibiotic) was between 2.4 and 8.2% relative standard deviation (RSD). Accuracy (expressed as recovery of fosfomycin determined by three independent analysis at 10, 100 and 300
μg/mL fosfomycin added to plain pus) was between 75 and 102%. Intermediate reproducibility (
n
=
9 at three different days) was between 2 and 12% RSD. Limit of detection and limit of quantitation were 4.5 and 15
μg/mL, respectively. The concentration of fosfomycin in pus of patients treated with the antibiotic ranged up to 240
μg/mL. The concentration of other anionic pus constituents identified beside chloride (acetate, succinate, lactate, phosphate) ranged between 20 and 7800
μg/mL. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0021-9673 |
DOI: | 10.1016/j.chroma.2005.01.085 |