2.3 Extraction Procedure and Analysis
TSP mass was determined gravimetrically prior to analysis ( Method IO-2.1 1999) For the metal estimation,each filter was extracted by nitric acid (Merck Suprapure 65%) and perchloric acid (Merck Suprapure 70%) mixture (10;1,v/v) (NIOSH Method-7300 1984). the extracted solution was filtered with washing by doubly distilled water and refrigerated in pre-cleaned strong polyethylene bottle until analysed (Gonzalez et al.1997) Filter andreagent blanks were also processed following the above procedure for sample treatment .Metals were determined by Atomic Absorption Spectrophotometer (Shimadzu,model AA-670,Japan) following Method IO-3.2 (1999).The metals estimated in blanks were