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HPLC Application Sheet
AminoGlycoside: Tobramycin by LCMS
Note: Aminoglycoside drugs are difficult to retain on conventional HPLC columns because of their highly polar
characteristics. Ion pair reagents have to be used in order to induce retention, but they interfere with MS
detection. UV detection requires derivatization of the drug.
No ion pair agents were used in the above.

Click here to view printable Application Sheet
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Method Conditions
| Column |
Cogent UDC Cholesterol, 4µm, 100A |
| Catalog No. |
69069-7.5P |
| Dimensions |
4.6 x 75 mm |
| Mobile Phase |
60:40 acetonitrile/DI water + 0.5% formic acid
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| Temperature |
Ambient |
| pH |
2.90 |
| Flow rate |
0.5 mL/minute |
| Injection Volume |
1 µL |
| Samples |
Uracil (m/z 113), Tobramycin (m/z 468),
1 mg/L of each dissolved in DI water |
| Detection |
Mass Spec: Atmospheric Pressure Chemical Ionization in positive mode: APCI+ Single Ion Monitoring |
Discussion
Tobramycin is a drug used for treatment in patients with cystic fibrosis and other diseases caused by gram-negative
bacteria. It has a very narrow therapeutic range, so monitoring of the drug in patients' serum is crucial to avoid
devastating side effects. A simple, isocratic method for analyzing Tobramycin is presented:
No derivatization and no ion pair reagents are used in the method.
Symmetrical peak shape and reasonable retention make this method an excellent choice for an assay of this drug.
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