Chemical Characterisation of Artisanal Soap Products from Sokoto State for Safety and Quality Regulation in North West Nigeria

Artisanally produced soaps and toiletry products from potassium hydroxide saponification of locally sourced fats dominate daily hygiene product markets in many North West Nigerian communities, yet they lack standardised quality and safety characterisation data, creating regulatory and public health gaps that current National Agency for Food and Drug Administration and Control monitoring programmes have not addressed systematically in this zone. This study conducts comprehensive chemical characterisation of thirty artisanal soap samples collected from twelve producers and seven market outlets in Sokoto State, North West Nigeria. Analytical parameters include total fatty matter content, free caustic alkali, moisture and volatile matter, chloride content, total alkali, pH, foam stability, and glycerol content, determined according to Nigerian Industrial Standard and ISO methods for soap quality. Heavy metal contamination (lead, cadmium, arsenic, chromium, nickel, and mercury) is assessed by inductively coupled plasma mass spectrometry following microwave-assisted acid digestion, and compared against cosmetics safety regulations. Preservative compound identification employs high-performance liquid chromatography-diode array detection. Skin sensitisation potential of aromatic additives is assessed through in silico structure-activity relationship prediction tools. Microbial contamination is evaluated by aerobic plate count and selective pathogen screening. Fatty acid composition of the underlying fat feedstocks, predominantly shea butter and groundnut oil, is determined by gas chromatography. A risk stratification of identified non-conformances is produced to guide prioritised regulatory enforcement. Keywords: artisanal soap, chemical characterisation, Sokoto State, heavy metals, safety regulation