**2.1 Sample collection and preparation**

Periwinkle (*Tympanotonus fuscatus)* samples were obtained from landings of artisanal fishermen in Ogbia, Niger Delta, Nigeria (**Figure 1**). Samples were collected monthly for six months (February to July 2018). The samples were placed in labeled container, preserved in ice-packs and immediately taken to the laboratory for further analysis. The samples (tissue) were removed from the shell and oven

**Figure 1.** *Map of study area (Ogbia) with an inset map of Nigeria.*

*Consumption Safety in Relation to Bioaccumulation of Heavy Metals in Periwinkles… DOI: http://dx.doi.org/10.5772/intechopen.94057*

dried at 80°C for 24 hours after which, the sample was ground to powder using ceramic mortar and pestle.
