Citric acid as a safe alternative to oxalic acid in the Gomori reticulin technique: a comparative study

The use of oxalic acid is common in metallic impregnation techniques, where it serves as a reducing and bleaching agent for potassium permanganate. Given that oxalic acid is harmful to health, its replacement with another reagent is advantageous for healthcare professionals handling it in laboratory settings. Considering that citric acid can also reduce potassium permanganate, the aim of this study was to determine whether oxalic acid in the Gomori reticulin technique could be replaced by citric acid, a compound substantially less hazardous to health. To this end, 1%, 5%, and 10% citric acid solutions were tested on porcine liver and kidney samples, and the intensity of reticulin fiber staining, contrast, and overall morphological preservation were assessed in comparison with 1% oxalic acid. The results showed no statistically significant differences between the positive control (oxalic acid) and the citric acid protocols, with the 5% citric acid concentration proving most favorable in terms of required incubation time and the evaluated morphological parameters. It was therefore concluded that citric acid can be used as a bleaching agent for potassium permanganate in the Gomori technique, effectively replacing oxalic acid.