2. ENVIRONMENTAL ANALYSIS I. Solid Phase Extraction sorbent configurations – stacked phases

3. Sorbent Configurations to Enhance Selectivity v Stacked phases v Layered phases v Mixed phases

4. Role of Stacking Phases v Extending the range v Enhancing the selectivity v Method development v Multiple detection protocol

5. Stacked Columns CBA Bases, Acids and Neutrals Acids and Neutrals Retained ENV+ Analyte CBA ENV + Bases Retained (Paraquat, Diquat) HPLC Compatible Solvent GC Compatible Solvent Bases for HPLC Analysis Acids and Neutrals for GC Analysis

6. OC Pesticides on C18(EC) alpha - BHC beta - BHC gamma - BHC delta - BHC heptachlor aldrin heptachlor epoxide endosulfan I 4,4" DDE dieldrin endrin 4,4" DDD endosulfan II endrin aldehyde 4,4" DDT endosulfan sulfate methoxychlor AVG: 94 90 92 99 91 73 89 90 62 89 86 91 78 95 100 88 99 88

7. OC Pesticides, Stacked Phases alpha - BHC 0101101 beta - BHC 0101101 gamma - BHC 0100100 delta - BHC 0 97 97 heptachlor85 7 92 aldrin85 0 85 heptachlor epoxide57 47104 endosulfan I65 42107 4,4" DDE86 5 91 dieldrin80 21101 endrin67 34 101 4,4" DDD90 6 96 endosulfan II65 37102 endrin aldehyde11 84 95 4,4" DDT85 0 85 endosulfan sulfate29 57 86 methoxychlor 112 0112 AVG:54 43 97 C18 (EC) C2 C18 (EC) SUM VsVs 94 90 92 99 91 73 89 90 62 89 86 91 78 95 100 88 99 88