Low voltage scanning electron microscopy of uncoated kidney stones

Some organic kidney stone components are easily damaged by a 10-30 kV electron beam used in conventional scanning electron microscopy. To avoid beam damage and reduce charging, it is desirable to study kidney stones by low voltage (1-5 kV) scanning electron microscopy (LVSEM) even though image resolution will suffer and X-ray microanalysis will not be available. If one is proficient in crystal morphology one can analyze gold-coated kidney stones by LVSEM without much difficulty. Stone components examined include calcium oxalate monohydrate, calcium oxalate dihydrate, struvite, calcium apatite, brushite, whitlockite, cystine, uric acid, uric acid dihydrate and ammonium acid urate. For all these components with the exception of the very small whitlockite and ammonium acid urate crystals, uncoated kidney stones can be examined with a 1 kV electron beam.