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Figure 4. Average phosphate chain lengths of the calcium polyphosphate matrices are shown for all 3 parameters (24-hour-gelled, five-hour-gelled, and non-gelled disks) and amorphous calcium polyphosphate, as calculated from the 31P NMR spectra by a peak area method (see text). No differences were seen between the cefuroxime-loaded matrices and their blank counterparts for any parameter, before or after the elution study. The gelling process changed the average phosphate chain length, such that a longer gelling time caused more phosphate chain lysis. All of the disks after the seven-day elution study revealed pyrophosphates (2 phosphates bonded together) in the calcium polyphosphate matrices, another indication of matrix degradation throughout the elution process (n = 1).
