From Accident to Improvement: A Case Study of Nitric Acid Splashing into Eyes During a Teaching Lab

During a laboratory session involving the acidic digestion of a soil sample for flame atomic absorption spectroscopy, a student sustained a near-miss eye injury due to a concentrated nitric acid splash following the detachment of the syringe and filter. The incident occurred during filtration of the digested solution containing concentrated nitric acid through a 0.45 μm syringe filter using a 10 mL Luer slip syringe. This report presents a detailed analysis of the incident using cause-tree methodology to identify contributing factors. The root cause analysis revealed a combination of procedural gaps (lack of specified syringe size and filtration of concentrated solution), inadequate technique (excessive pressure on the plunger and improper positioning at the fume hood), and suboptimal use of protective equipment. Based on these findings, staff implemented corrective actions, including protocol modifications (dilution of the acid prior to filtration, specification of a 1 mL syringe), enhanced training on proper filtration techniques and fume hood use, and procurement of improved safety goggles. This case study highlights the importance of well-designed and detailed procedures, proper training, and appropriate use of protective equipment in preventing laboratory accidents.