Determination of tobramycin in human serum by capillary electrophoresis with contactless conductivity detection

Department of Chemistry, National University of Singapore, Republic of Singapore.
Electrophoresis (Impact Factor: 3.03). 05/2006; 27(10):1932-8. DOI: 10.1002/elps.200500819
Source: PubMed


A study on the determination of the antibiotic tobramycin by CE with capacitively coupled contactless conductivity detection is presented. This method enabled the direct quantification of the non-UV-absorbing species without incurring the disadvantages of the indirect approaches which would be needed for optical detection. The separation of tobramycin from inorganic cations present in serum samples was achieved by optimizing the composition of the acetic acid buffer. Field-amplified sample stacking was employed to enhance the sensitivity of the method and a detection limit of 50 microg/L (S/N = 3) was reached. The RSDs obtained for migration time and peak area using kanamycin B as internal standard were typically 0.12 and 4%, respectively. The newly developed method was validated by measuring the concentration of tobramycin in serum standards containing typical therapeutic concentrations of 2 and 10 mg/L. The recoveries were 96 and 97% for the two concentrations, respectively.

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    • "In general , the LC-C 4 D methods use strongly diluted mobile phases of simple composition, since one of the prerequisites of detectability in conductivity detection is a sufficiently low background conductivity. The suitability of this detector for the analysis of AMGs in combination with CE has been demonstrated by Law et al. [36] and El-Attug et al. [37] [38] [39]. Even though there have been numerous publications on assay and impurity profiling using CE, LC still persists as the leading separation technique, presumably because of its better repeatability, robustness and widespread use. "
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    ABSTRACT: The analysis of highly polar (often charged) compounds which lack a strong UV absorbing chromophore is really challenging. Despite the numerous analytical methods published, the demand for a simple, robust and cheap technique for their analysis still persists. Here, reversed phase (RP) liquid chromatography (LC) with capacitively coupled contactless conductivity detection (C(4)D) was explored for the first time as a possible method for separation and detection of various aminoglycoside (AMG) antibiotics which were taken as typical test compounds: tobramycin (TOB), spectinomycin, streptomycin, amikacin, kanamycin A and kanamycin B. C(4)D was performed using a commercially available as well as a laboratory made cell. As ion-pairing reagents (IPR) four perfluorinated carboxylic acids were used: pentafluoropropionic acid, heptafluorobutyric acid, nonafluoropentanoic acid (NFPA) and pentadecafluorooctanoic acid (PDFOA). 0.125mM NFPA-acetonitrile (ACN) (90:10) or 0.125mM PDFOA-ACN (70:30) as mobile phases were suitable to detect TOB with reasonable retention times. However, NFPA was preferred for practical reasons. Its applicable concentration range in the mobile phase was strongly restricted by loss of chromatographic performance at lower levels and excessive background conductivity at higher levels. Overall repeatability and robustness of the method were rather poor which was explained by the relatively low IPR levels. Selectivity between the tested AMGs was mainly influenced by the number of protonated amino groups per molecule making it impossible to separate compounds of equal net charges. Problems encountered with gradient elution, hydrophilic interaction liquid chromatography (HILIC) and separation at high pH without IPRs are also discussed. Copyright © 2014 Elsevier B.V. All rights reserved.
    Journal of Pharmaceutical and Biomedical Analysis 12/2014; 112. DOI:10.1016/j.jpba.2014.12.015 · 2.98 Impact Factor
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    • "The determination of tobramycin in human serum has been reported using CE with Capacitively Coupled Contactless Conductivity Detection (CE-C 4 D) [25] "
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    ABSTRACT: A method was validated and optimized to determine tobramycin (TOB) and its related substances. TOB is an aminoglycoside antibiotic which lacks a strong UV absorbing chromophore or fluorophore. Due to the physicochemical properties of TOB, capillary electrophoresis (CE) in combination with Capacitively Coupled Contactless Conductivity Detection (C(4)D) was chosen. The optimized separation method uses a background electrolyte (BGE) composed of 25 mM morpholinoethane-sulphonic acid (MES) adjusted to pH 6.4 by L-histidine (l-His). 0.3 mM cetyltrimethyl ammonium bromide (CTAB) was added as electroosmotic flow modifier in a concentration below the critical micellar concentration (CMC). Ammonium acetate 50 mg L(-1) was used as internal standard (IS). 30 kV was applied in reverse polarity (cathode at the injection capillary end) on a fused silica capillary (65/43 cm; 75 μm id). The optimized separation was obtained in less than 7 min with good linearity (R(2)=0.9995) for tobramycin. It shows a good precision expressed as RSD on relative peak areas equal to 0.2% and 0.7% for intraday and interday respectively. The LOD and LOQ are 0.4 and 1.3 mg L(-1) corresponding to 9 pg and 31 pg respectively.
    Journal of pharmaceutical and biomedical analysis 01/2012; 58(1):49-57. DOI:10.1016/j.jpba.2011.09.032 · 2.98 Impact Factor
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    ABSTRACT: Recent advances and key strategies in capillary electrophoresis and microchip CE with electrochemical detection (ECD) and electrochemiluminescence (ECL) detection are reviewed. This article consists of four main parts: CE-ECD; microchip CE-ECD; CE-ECL; and microchip CE-ECL. It is expected that ECD and ECL will become powerful tools for CE microchip systems and will lead to the creation of truly disposable devices. The focus is on papers published in the last two years (from 2005 to 2006).
    Journal of Separation Science 04/2007; 30(6):875-90. DOI:10.1002/jssc.200600472 · 2.74 Impact Factor
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