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

Abstract

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.

Recent advances in the analysis of antibiotics by CE and CEC

“…Finally, the determination of tobramycin after its separation of kanamycin A and kanamycin B was performed by CZE in about 8 min with conductivity detection and using a fieldamplified sample stacking (FASS) method to enhance the sensitivity. An LOD of 50 ng/mL was reached [33].…”

“…The use of CZE with ECL detection enabled the determination of norfloxacin spiked in human urine without sample pretreatment [14], and conductivity detection was employed for the determination of tobramycin spiked in human serum using kanamycin B as IS. This method enabled the direct quantitation of the non-UV-absorbing species [33]. An enantioselective CE method based on CD-EKC with UV detection enabled the determination of pazufloxacin enantiomers (a fluoroquinolone antibiotic) in spiked human urine without clean-up procedure and an LOD of 7.0 mg/mL for both pazufloxacin enantiomers [12].…”

Optimization of separation of heavy metals by capillary electrophoresis with contactless conductivity detection

“…Hence, a preconcentration technique would be necessary to enhance the detection sensitivity. FASI was employed due to its easy manipulation of the composition and ionic strength of the running buffer as well as sample matrices coupled with simple injection procedures without further alteration of the existing instrumentation [8][9][10][11]. Variables like solvent plug composition, length of the solvent plug and sample injection time were investigated in order to obtain the sensitivity enhancement.…”

Quantification of plasma lactate concentrations using capillary electrophoresis with contactless conductivity detection

“…The low background conductivity of these zwitterionic substances makes this buffer suitable for conductivity detection. An equimolar amount of MES-His is commonly used in the concentration range between 5 to 50 mmol/L for CE with a pH value of 6.0 and it has been successfully employed for the determination of organic species in serum and urine with CE-C 4 D [33,35,36].…”

“…Pormsila et al described the quantification of uric acid [33]. Furthermore, the determination of non-UV-absorbing organic pharmaceuticals, such as fosfomycin [34], tobramycin [35], valproic acid [36] and g-hydroxybutyric acid [37] is also possible by CE with contactless conductivity detection (CE-C 4 D). While the determination of lactate in food samples by this method has been described [38,39], as well as the separation of the enantiomers [38,40] and its use as internal standard in the determination of formaldehyde [41], the application of CE-C 4 D for the determination of this species in clinical samples has to our knowledge not yet been reported.…”