ENVIRONMENTAL ANALYSIS I. Solid Phase Extraction oil & grease – EPA method 1664

O & G : Summary Definitions Liquid / Liquid Extraction methods Solid Phase Extraction methods Optimizing SPE: Special O&G Tube

Definitions The Samples Surface and Saline Waters Industrial and Domestic Aqueous Wastes Waste Water Sludge

Definitions (cont.) The Analytes HEM: n-Hexane Extractable Material TPH (or SGT-HEM): Total Petroleum Hydrocarbons = Silica Gel Treated HEM (HEMs not adsorbed by silica gel) Examples: non-volatile hydrocarbons, waxes, soaps, vegetable oils, animal fats, greases.

L / L Extraction Solvent: CCl4 Hungarian Standard MSZ 260/22-74 Solvent: Freon-113 ASTM Method 413.1 Montreal Protocol on Substances that Deplete the Ozone Layer  phase out the use of CFCs Solvent: n-Hexane EPA Method 1664

L / L Extraction of O & G Na2SO4 Drying Evaporation Purge Silica Gel pH ~2 Silica Gel Treatment Weigh Re-dissolve Evaporation Purge Weigh

Features of Method 1664 The solvent (n-Hexane) is lighter than water repouring the water means more labour Four QA/QC samples per analytical batch - blank - blank spike - matrix spike - ms duplicate Solvent-related matrix interferences see Table (next slide)

EPA CFC Replacement Study

EPA 1664 Criteria EPA 1664: Performance-Based Method

Why SPE? Reduce solvent usage Eliminate emulsion problem Reduce handling Readily amenable to automation

O & G on ISOLUTE TPH Sample: #2 Fuel Oil HCl to pH=2, 1. Sample pre-treatment 2. Column solvation 3. Column pre-equilibrium 4. Sample application 5. Interference elution 6. Analyte elution HCl to pH=2, MeOH wetting agent 10 mL MeOH 10 mL water One liter in 1/2 hour 10 mL water, 15 min N2 2 x 3 mL THF/nC6 1:1

Petroleum Hydrocarbon Recoveries: ISOLUTE TPH Conc % rec Std mg/L vs std Avg Dev 90 94 20.0 104 93 89 5 88 92 120.0 2

EPA Represention of O & G Fractions Formerly: #2 Fuel Oil or Wesson Oil Currently: Hexadecane - non-polar... Stearic Acid - polar fraction C H ( C H ) C H 3 2 1 4 3 O C H ( C H ) C 3 2 1 6 O H

Selective Elution Polar vs. Non-Polar Fractions First: Non-polar solvent  Non-polar interactions Second: Mixed solvent  Polar and Non- polar interactions

Selective Elution (cont.) Stearic Acid Hexadecane Hexane Hexane / THF + Stearic Acid

Recoveries from Selective Elution 20 ppm spike (90% C16, 10% stearic acid) Hexadecane (TPH) 96% Stearic Acid 113%

Extraction of EPA 1664 Standards at High Concentrations Stearic acid spike precipitates from solution Plugging of sample lines and extraction cartridges Low recoveries

Building a TPH / Total O & G Column Frits Polyester Depth Filter Large Particle Special Phase Std. Particle Silica

Polyester Depth Filter Oil and Grease: Distributes grease to prevent frit and cartridge plugging Particulates: Distributes solids to prevent packing from plugging

Loading Rate with Depth Filter Avg Loading Time, min: 34 Loading Rate, mL/min : 30 (n = 7)

O & G on ISOLUTE O & G HCl to pH=2, MeOH wetting agent (sample temperature?) 1. Sample pre-treatment 2. Column solvation 3. Column pre-equilibrium 4. Sample application 5. Interference elution 6. Analyte elution 10 mL MeOH 10 mL water, pH 2 1/2 liter in 15-30 min 10 mL water, 30 min N2 1st: 3 mL Hexane 2nd: 3 mL THF/nC6 1:1

Impact of Various Factors Elution solvent: Hexane / THF Wetting Agent: 1% Methanol Sorbents: 1/2 g or 1 g ISOLUTE O&G Bottle wash: 20 mL Acetone + 80 mL water

Recoveries for TPH / Total O&G Spike, mg/L Recovery, % %Recovery Total O & G 120 Hexadecane: 92 Stearic Acid: 104 98 60 94 96 95 24 88 102 12 87 100