Liquid Chromatography–Tandem Mass Spectrometry for Simultaneous Determination of Ticarcillin and Vancomycin in Presence of Degradation Products. Application to the Chemical Stability Monitoring of Ticarcillin- Vancomycin Solutions

Abstract

Acute bacterial conjunctivitis and their complications are commonly treated by 6 mg/mL ticarcillin and 50 mg/mL vancomycin eyes drops, formulated separately in hospitals. A rapid, selective and specific LC-tandem MS method has been developed and validated for simultaneous quantification of ticarcillin and vancomycinin solution and in presence of degradation products. Atlantis ® C18 Column T3 (250×4.6 mm I.D., 5 µm) and gradient mobile phase composed of 44 mM trifluoracetic acid/methanol allowed for good separation. Degradation products were separated on LC and detected with mass spectrometry in full scan mode. The method was suitable forthe stability study of ticarcillin-vancomycin pH 5.2 solutionsover an 8-day period storage at 5 ± 3°C and at room temperature (25 ± 2°C). The solutions remained stable up to 5 days at 5 ± 3°C. At room temperature, degradation of ticarcillin was accelerated in presence of vancomycin, while vancomycin stability was not further affected by ticarcillin. High-resolution mass spectrometry was used for the characterization of the degradation products.

Time-of-flight secondary ion mass spectrometry analyses of vancomycin

“…In order to establish a more accurate mass scale for PLGA and vancomycin, the spectra were recalibrated using known higher-mass species from the two chemicals. Mass resolutions for C 4 27), and C 3 H 4 O þ (56) were 4300, 6900, 4100, and 8800, respectively. The fidelity of the assignment is quantified by the deviation, in parts per million (ppm), of the peak from the assigned chemical formula D…”

“…32,33 Vancomycin has been investigated using LC-MS, in which the base peak is C 7 H 14 O 2 N þ , the vancosamine end group in the glycoside group of vancomycin, with C 13 H 25 O 7 N þ (307) corresponding to the glycoside group having a much smaller abundance. 27 In the LC-MS investigation, an abundant peak at m/z 725 is identified as [Mþ2H] 2þ . [27][28][29] MS, 27,29 in TOF-SIMS, it is much weaker than C 6 H 14 N þ .…”

“…Liquid chromatography-mass spectrometry (LC-MS) has been used to investigate vancomycin, with doubly charged and doubly protonated ions being the diagnostic ion for vancomycin. [27][28][29] However, this method lacks imaging and depth profiling capabilities. Despite the fact that vancomycin is an antibiotic that has been extensively studied, to our knowledge, there have been no TOF-SIMS studies on vancomycin and identification of diagnostic ions.…”

“…The weak peak of a positive ion at m/z 144 in Fig. 2(c) is also known to be C 7 H 14 O 2 N þ from LC-MS. 27,29 which is the vancosamine moiety as depicted in Fig. 4.…”

“…4. It is worth pointing out that in contrast to TOF-SIMS, C 7 H 14 O 2 N þ is a rather abundant peak in LC-MS. 27,29 We also tried identifying other peaks that are not as abundant as C 6 H 14 N þ and C 7 H 4 O 2 Cl À . For example, the negative ion at m/z 121 is assigned to C 7 H 5 O 2…”