The UV-/Vis spectrophotometer employed was a Jenway 6505 with a 10 mm light path. The solid-phase extraction (SPE) cartridges employed were Strata-X 33 micromate polymeric reversed phase ones (pore size 88 Aฺ, surface area 818 m2/g and particle size 28 micromate; sorbent mass 200 mg/6ml & 1 g/20 ml) bought from Phenomenex (UK), which are suitable for the extraction and enrichment of polar and nonpolar neutral compounds.