QUALITY ANALYSIS OF SELECTED PHYSICOCHEMICAL PROPERTIES OF PREMIUM MOTOR SPIRIT (PMS) COMMERCIALLY AVAILABLE IN BENIN CITY.

Premium Motor Spirit (PMS), commonly known as petrol, is the most widely used fuel in Nigeria, and Benin City in particular. It plays a vital role in transportation, power generation, and other daily activities. However, the quality of PMS available to consumers has often been questioned due to issues of adulteration, contamination, and poor handling. These problems can affect engine performance, increase fuel consumption, and contribute to environmental pollution. This study focused on the analysis of selected physicochemical properties of Premium Motor Spirit (PMS) obtained from four Local Government Areas in Benin City, namely Oredo, Ikpoba- Okha, Egor, and Ovia North East. The aim was to evaluate the quality of PMS distributed within these areas and compare the results against the standard specifications provided by the American Society for Testing and Materials (ASTM). Parameters such as density, Reid vapour pressure (RVP), octane rating, boiling point, colour, and basic sediment and water (BSW) were determined following ASTM approved methods. The distillation results showed initial Boiling Points (IBP) ranging from 32 - 35°C with three samples slightly below the ASTM specification of 35°C, while Final Boiling Points (179 - 190°C) and recovery (98 - 99%) were within accepted limits. Density values measured at 15°C ranged from 0.741 - 0.746g/cm3 , falling within the ASTM specification range of 0.720 - 0.780g/cm3 , indicating compliance in terms of volatility and combustion efficiency. Colour determination revealed a consistent Plain Yellow appearance across all samples, in agreement with ASTM D1500 standards, reflecting proper refining and the absence of contaminants such as water, rust or heavy hydrocarbons. The BSW values for all the four LGAs were less than 0.05% by volume, which is well within ASTM tolerable limits, confirming negligible water or sediment contamination. The RVP values ranged from 57.22651 - 58.60546kpa, falling within the ASTM range of 45 - 60kpa. Lastly, the RON values ranged from 90-91 which was within the ASTM specification range of 90 - 93. The PMS samples used in this study met the ASTM standards, indicating good quality and suitability for use. The slight deviations observed, such as in the IBP values, point to the need for continuous monitoring.