Scanning electron microscopy of uric acid crystals.

<p>After finishing the turbidimetrical assay, some of the solutions were filtered through a 45 µm filter, and uric acid crystals were observed by scanning electron microscopy. These images correspond to uric acid crystals formed at pH = 4.65, in the absence (A) and presence of 20 mg/L (B) and 40 mg/L (C) theobromine.