Measurement of tissue disulfide groups by Alcian blue 8GX and atomic absorption spectrophotometry

The primary purpose of this study was to quantify tissue disulfides with Alcian blue 8GX using atomic absorption spectrophotometry (ASS) to measure the copper moiety of the Alcian blue. The secondary purpose was to determine whether aqueous or alcoholic formalin was a better fixative for this procedure. Sections of mouse renal cortex fixed in 10% neutral formalin (NBF) or in ethanol/formalin/acetic acid (AFA) were stained in 0.5% Alcian blue 8GX in 0.8 M MgCl2 with prior thiosulfation (+Th) or without prior thiosulfation (-Th). The relative contents in the tissues of the copper of Alcian blue, measured by AAS, may be summarized as follows: -Th NBF, 1.15 micrograms Cu/mg tissue; -Th AFA, 1.35 micrograms Cu/mg tissue; +Th NBF, 1.99 micrograms Cu/mg tissue; +Th AFA, 3.25 micrograms Cu/mg tissue. These data indicate that 1) disulfide may be measured by this procedure, and 2) AFA is the preferred fixative for measurement of both disulfides and native sulfates.