Tobramycin is an important aminoglycoside antibiotic used in ophthalmic and intravenous treatments to treat bacterial infections by blocking protein synthesis.[1] Determinations of tobramycin, kanamycin and other aminoglycoside antibiotics have been previously demonstrated by HPAE-IPAD since 2004.[2–6] This document updates Thermo Scientific™ Application Note 61 using a highpressure-capable Dionex Integrion HPIC system equipped with updated EG technology and an electrochemical detector.

In this technical note, we describe a procedure to screen sample matrices for their effect on peak area, peak height, and retention time. We demonstrate this procedure by testing ethanol for possible interferences in AAA-Direct. However, the method described here can also be used to evaluate any matrix component analyzed by chromatography with electrochemical detection. In this technical note, we use the term test sample (TS) to describe the specific test compound evaluated for possible interferences.

In this application, three detectors were employed and compared. An IonPac CS18 column coupled to IPAD to detect biogenic amines in beer and wine samples prior to storage. As relatively little information exists on the accumulation of biogenic amines in alcoholic beverages during storage, refrigerated samples were analyzed using suppressed conductivity detection coupled to IPAD. UV detection was used to confirm the presence of tyramine in some alcoholic beverages. Detectors were also compared in terms of linearity, detection limits, precision, and recovery of biogenic amines spiked in samples.

In this update, the procedures described in AN 183 are used to determine biogenic amine levels in kiwi fruit, spinach, and chocolate. Application Note 183 (AN 183) describes the use of the IonPac CS18, a weak acid cation-exchange column, with suppressed conductivity, integrated pulsed amperometric detection (IPAD), and UV for the detection of underivatized biogenic amines in meat and cheese. The CS18 allows separation of biogenic amines without the use of highly-concentrated acidic eluents or organic solvents while still providing resolution of closely eluting peaks.

This update describes how tobramycin and its typical impurities can be determined in manufacturing process matrices using the same HPAE-IPAD method described in AN 61. The same method is used to assay tobramycin that is intentionally degraded, demonstrating its suitability as a stability indicating method. An ICS-6000 can be used for this application.