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ENVIRONMENTAL ANALYSIS I. Solid Phase Extraction sorbent configurations – layered phases.

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Presentation on theme: "ENVIRONMENTAL ANALYSIS I. Solid Phase Extraction sorbent configurations – layered phases."— Presentation transcript:

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

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

4 Role of Layered Phases v Extending the range v Enhancing the selectivity v Separate cartridges not required

5 Layered Phases (Loading) C 2 ENV+ENV+ ENV+ Small, polar Large, non- polar Broad Range

6 Layered Phases (Eluting) ENV+ C 2 ENV+ENV+ Small, polar Large, non- polar Broad Range

7 OC Pesticides from Water Extraction on Layered Phases Sample pre-treatment Column solvation Column equilibration Sample application Interference elution Analyte elution HCl to pH=2, Methanol, 0.5% 5 mL Methanol 10 mL reagent water One liter in 1/2 hour 10 mL water, 10 min N 2 Two x 2 mL THF ISOLUTE ® C2 / C18(EC)

8 OC Pesticides from Water Percent Recovery

9 Interference Removal NH2 Analyte + Interferences Analytes (e.g..., PAHs) ENV+ Interferences (e.g., Humic Acids) NH2 ENV+ Interferences Retained Analytes Eluted Analytes Eluted Organic Elution Solvent

10 Extraction of PAHs from Natural Waters Extraction of analytes such as PAHs from natural waters, can be problematic due to co-extracted humic and fulvic substances that can interfere with the final analysis technique.

11 PAHs and Humic Acids Naphthalene Benzo[a]pyrene [ R - CH - C OO - ] n “Humic Acid”

12 ISOLUTE PAH ISOLUTE PAH is designed to alleviate this problem. It consists of a layer of NH2 sorbent above a layer of C18. The NH2 layer (positively charged at neutral pHs) retains the acidic interferences, while PAHs are retained by and eluted from the C18 layer.

13 ISOLUTE PAH NH2 Analyte + Interferences Analytes ( PAHs) C18 Interferences (Humic Acids) NH2 C18 Interferences Retained Analytes Eluted Organic Elution Solvent

14 SPE Conditions 1. Sample pre-treatment 2. Column solvation 3. Column equilibration 4. Sample application 5. Interference elution 6. Analyte elution 10% IPA 5 mL IPA 5 mL 2% IPA in water One liter in 30 to 60 min. Bottle wash required. 5 mL water/IPA 9: min drying 2 x 3 mL THF:nC6 (1:1) ISOLUTE PAH Column (NH2/C18) (AN 1025)

15 HPLC Conditions ColumnHiChrom PAH2 (150x4.6mmx5  m) Mobile phaseA= ACN/Water (30/70, v/v) B= 100% ACN Gradient100% A to 100% B in 35 mins. 100% B for 3 mins Flow rate 1 ml / min DetectionUV, 254 nm 20  l sample injected

16 HPLC chromatogram of blank river water with a high humic acid content extracted using C18 only

17 HPLC chromatogram of blank river water with a high humic acid content extracted using ISOLUTE PAH

18 HPLC Chromatogram of 16 PAHs extracted from river water with a high humic acid content using ISOLUTE PAH

19 PAH Recoveries Naphthalene 62 (13.8) Acenaphthylene 73 (9.5) Acenaphthene 98 (2.1) Fluorene 82 (3.6) Phenanthrene 94 (1.6) Fluoranthene 84 (2.8) Anthracene 101 (2.0) Pyrene 92 (3.1) Benzo(a)anthracene 99 (3.5) Chrysene 100 (3.6) Benzo(b)fluoranthene 94 (4.1) Benzo(k)fluoranthene 95 (4.4) Benzo(a)pyrene 96 (3.5) Indeno(123-cd)pyrene 98 (1.2) Dibenz(ah)anthracene 92 (2.7) Benzo(ghi)perylene 92 (3.1) Average: 91 (4.0)

20 ISOLUTE PAH HC v clean-up of HEXANE extracts of oil contaminated soil v designed to separate the aromatic PAHs from hydrocarbon interference (up to C30) v clean baseline in GC analysis

21 PAH Method (IST AN 1070A) ActionMethod Column conditioning / equilibration Condition columns with hexane (8ml) at 2ml / min Sample loadingLoad 0.5ml of sample in apolar solvent (hexane, i-octane) Interference elutionRinse column with pentane (3ml) at 0.5ml / min PAH elutionElute PAHs with 2-propanol (isopropanol) / hexane (3.4 ml in 100ml, v/v), 6ml at 1ml / min SPE clean-up using ISOLUTE PAH HC, 1g / 3ml

22 ISOLUTE EPH Column v fractionate pentane or hexane extract of oil contaminated soil v designed to separate the C10-C22 aromatics from C8-C40 aliphatics v proprietary blend of silica / alumina v based on MADEP procedure

23 PAH Method (IST TN 142) ActionMethod Column conditioning / equilibration Condition columns with hexane (20ml) under gravity flow Sample loadingLoad (max) 1ml of sample in heptane or hexane Aliphatic elutionElute aliphatics with 12ml of hexane PAH elutionElute aromatics with 20ml of DCM SPE clean-up using ISOLUTE EPH-M, 5g / 20ml


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