Assessment of Quality Management Practices in Nigerian Petroleum Product Laboratories: A Case Study of Downstream Facilities in Lagos

The accuracy and reliability of petroleum product quality testing in downstream laboratories in Lagos State, South West Nigeria, have direct implications for consumer protection, regulatory compliance, and trade certification in the largest petroleum products market in West Africa. This study assesses the quality management systems of ten petroleum product testing laboratories in Lagos, including regulatory agency laboratories and independent commercial laboratories, against the ISO/IEC 17025:2017 requirements for testing and calibration laboratories. Assessment was conducted using a structured audit tool covering management system documentation, technical competence, measurement traceability, proficiency testing participation, inter-laboratory comparison performance, and equipment calibration records. Proficiency testing participation was voluntary and inconsistent, with only four laboratories having participated in at least one petroleum product proficiency testing round in the previous two years. Measurement uncertainty budgets were absent from 70% of test report templates reviewed. Equipment calibration was traceable to national standards for density and viscosity instruments but not for Karl Fischer titrators and flash point testers at six laboratories. Inter-laboratory comparison data from the Standards Organisation of Nigeria indicated that z-scores for octane number measurement exceeded acceptable limits at three laboratories. The study recommends mandatory accreditation under NAFDAC and SON co-regulation, increased frequency of national proficiency testing schemes, and targeted training on measurement uncertainty estimation for laboratory personnel. Keywords: petroleum laboratory, ISO 17025, quality management, proficiency testing, Lagos State