Utility of a Moisture Removal Polymer for Extraction Applications

Transcription

1 Utility of a Moisture Removal Polymer for Extraction Applications SM Rahmat Ullah, 1 Kannan Srinivasan, 1 Chris Pohl, 1 and Todd Anderson 2 1 Thermo Fisher Scientific, Sunnyvale, CA, USA; 2 Texas Tech University, Lubbock, TX, USA

2 Overview Purpose: To demonstrate the utility of a new absorbing polymer as a drying agent for extraction applications. Methods: Moisture absorption capacity of a new polymer was studied. The in-cell removal was performed in an extraction setup in an accelerated solvent extraction instrument at high temperature and pressure. in the extract were measured by high-pressure liquid chromatography and gas chromatography. Results: The absorbing polymer and the diatomaceous earth can remove when mixed with wet sample for in-cell, in-line extraction method. An addition of a small amount of polymer in the collection bottle can also result in complete water removal from the collected extract. Introduction Analyses of organic pollutants are becoming increasingly important, and often with the need to isolate and analyze trace organic compounds from a variety of matrices such as soil, sediment, fruits, and vegetables. In this regard, sample pretreatment constitutes an important step prior to analysis. The purpose of the sample pretreatment step is to selectively isolate or concentrate the analytes of interest from matrix components and present a sample suited for routine analysis by established analytical techniques such as gas chromatography or high-pressure liquid chromatography. Typical sample pretreatment steps include techniques such as solid phase extraction, liquid-liquid extraction, solid-liquid extraction, dilution, evaporation, distillation, etc. Accelerated solvent extraction is a technique used for extracting the analytes of interest from a solid, semisolid or liquid sample by performing extraction using an organic solvent at elevated temperature and pressure. The elevated pressure also elevates the boiling temperature of the solvent, thereby allowing faster extraction to be conducted at relatively higher temperatures. The benefit of a relatively high temperature extraction is primarily speed; thus the extraction process is significantly faster than traditional methods such as soxhlet extraction. In some samples containing or water such as soil samples or food samples (fruits, vegetables etc.) an additional step may be needed either before the extraction to remove the from the samples or post extraction to remove the from the extracted solvent (containing the extracted analytes). Sample drying can be accomplished in several ways such as air drying and oven drying prior to extraction. However, these approaches are not suited when analyzing volatile or semi-volatile components as they would be removed from the sample prior to extraction or analysis. Another common method for removal is by using salts such as sodium sulfate, calcium chloride, magnesium sulfate, calcium sulfate and the like. These salts tend to associate to water molecules to form hydrated salts. Sodium sulfate for example tends to clump together when water is present. Sodium sulfate is not suitable for in-cell removal and extraction in accelerated solvent extraction technique. Sodium sulfate can dissolve in hot solvent to a certain extent and can precipitate downstream in some instances clogging the outlet frit, tubes and valves. Moreover, sodium sulfate becomes an aggregate hard lump upon water absorption and is not easy to process during sample preparation for in-cell removal and extraction (1). Polymers have been used for removal, and such polymers have been designated super absorbent polymers (2). The most common polymer is the sodium salt of polyacrylic acid. Although this polymer removes water by absorbing it into the polymer matrix, the water absorbing capacity decreases as the ionic strength increases. Another limitation of the polymer is poor water absorbing property under high temperature conditions. Yet another limitation of this polymer is that it becomes a hard plug inside the extraction cell (1). The present research solves these issues. Here, the authors synthesized a absorbent polymer comprising a copolymer of a basic monomer and an acidic monomer. This combination is suitable for removal under high ionic strength conditions. Results shown here also demonstrate that when the polymer is mixed with diatomaceous earth (DE) the water removal efficiency increases significantly. Different formats of using the polymer such as in-cell, in-vial and a combination of the two are discussed. Methods Polymer Used Thermo Scientific Dionex here. Sample Preparation Sample containing polymer or the polymer was DE and loaded into the Ther Extractor System cell for the technique. Extraction Using the Dion Sample extraction at high te ASE system. Dionex ASE system extracti Pressure: 1500 psi Temperature: 100 ⁰C Static time: 5 min Cycles: 1-3 Flush: 10-75% Purge: 120 sec Solvent: 1/1 Acetone/Hexan Measurement of Moisture Known amounts of water we to measure the water remov solvent. Similarly, water rem temperature for comparison Water Removal Capacity o The water removal capacity water present in the cell with bottle. Liquid Chromatography A P680 pump, PDA-100 pho used for chromatographic s 6.8 Chromatography Data S separation column was a Th x 150 mm, flow rate was 1.0 comprising 25 mm acetic ac where composition of B cha wavelength was 280 nm. Gas Chromatography A Gas Chromatograph (GC) analysis of polyaromatic hyd used for data acquisition. Th 30 m x 0.25 mm x µm temperature profile was 65 The run time was 40 min. A Gas Chromatograph (GC) analysis of organochlorine p m x 0.25 mm x µm. T temperature profile was Utility of a Moisture Removal Polymer for Extraction Applications

3 sorbing polymer as a drying r was studied. The in-cell an accelerated solvent nalytes in the extract were s chromatography. aceous earth can remove xtraction method. An addition lso result in complete water important, and often with the a variety of matrices such mple pretreatment se of the sample he analytes of interest from e analysis by established h-pressure liquid de techniques such as solid ction, dilution, evaporation, ue used for extracting the e by performing extraction ssure. The elevated pressure by allowing faster extraction nefit of a relatively high tion process is significantly. il samples or food samples either before the extraction n to remove the tes). Sample drying can be n drying prior to extraction. g volatile or semi-volatile prior to extraction or analysis. salts such as sodium ate and the like. These salts ts. Sodium sulfate for and extraction in accelerated in hot solvent to a certain clogging the outlet frit, tubes ate hard lump upon water aration for in-cell polymers have been on polymer is the sodium ter by absorbing it into the s the ionic strength absorbing property under polymer is that it becomes a rch solves these issues. er comprising a copolymer ation is suitable for wn here also demonstrate (DE) the water removal g the polymer such as in-cell, Methods Polymer Used Thermo Scientific Dionex ASE Prep MAP, absorbing polymer was used here. Sample Preparation Sample containing was used or a spiked sample with water was added to the polymer or the polymer was combined with Thermo Scientific Dionex ASE Prep DE and loaded into the Thermo Scientific Dionex ASE Accelerated Solvent Extractor System cell for the extraction in the accelerated solvent extraction technique. Extraction Using the Dionex ASESystem Sample extraction at high temperature and pressure was performed using the Dionex ASE system. Dionex ASE system extraction condition: Pressure: 1500 psi Temperature: 100 ⁰C Static time: 5 min Cycles: 1-3 Flush: 10-75% Purge: 120 sec Solvent: 1/1 Acetone/Hexane or 1/1 Acetone/Dichloromethane Measurement of Moisture Removal Capacity at Room Temperature Known amounts of water were spiked as the sample and was mixed with the polymer to measure the water removal capacity at room temperature in the presence of organic solvent. Similarly, water removal capacity of sodium sulfate was measured at room temperature for comparison purposes. Water Removal Capacity of Polymer and Polymer-DE The water removal capacity of the polymer was measured as the maximum amount of water present in the cell without any breakthrough of the water into the collection bottle. Liquid Chromatography A P680 pump, PDA-100 photodiode array detector and a chromatographic oven were used for chromatographic separation. Thermo Scientific Dionex Chromeleon 6.8 Chromatography Data System (CDS) software was used for data acquisition.the separation column was a Thermo Scientific Acclaim Polar Advantage C16 5µm 4.6 x 150 mm, flow rate was 1.0 ml/min. Separation was based on gradient elution of A comprising 25 mm acetic acid/ammonium acetate and B comprising of acetonitrile where composition of B changed from 25% to 70% over 17.5 min. Detection wavelength was 280 nm. Gas Chromatography A Gas Chromatograph (GC) with Flame Ionization Detector (FID) was used for the analysis of polyaromatic hydrocarbon (PAH). The Chromeleon 6.8 CDS software was used for data acquisition. The separation column was a Thermo Scientific TR-5MS 30 m x 0.25 mm x µm. The helium carrier gas flow rate was 1.5 ml/min. The temperature profile was 65 C (1 min), 25 C/min to 140 C, then 10 C/min to 290 C. The run time was 40 min. A Gas Chromatograph (GC) with Electron Capture Detector (ECD) was used for the analysis of organochlorine pesticides (OCPs). The separation column was a DB-5 30 m x 0.25 mm x µm. The helium carrier gas flow rate was 1.0 ml/min. The temperature profile was 150 C (1 min), 8 C/min ramp to 280 C with 1 min hold. Results Moisture Absorbing Capabilit The amount of absorb absorbing one gram of water at The Moisture Removal Forma a) In-cell (in-line) remo The absorbing polyme for in-cell removal and improved removal the earth (DE) dispersant for accele Prep DE is normally used with t extraction technique, therefore a customer s current practices. b) (off-line) rem The amount of absorb of water at room temperature. A (proportional to the amount of w complete water removal from th needed is 4 g to absorb one gra polymer in an aliquot basis. c) Combination Mode: In this mode, the in-cell removal (off line). If some break addition of a small amount of po removal. In fact a sma there would be no pres samples with unknown Analyte Recovery from Oyste Sample preparation is challengi sample. A mixtures of six OCPs the wet oyster sample. The spik DE (1:1) or by using sodium sul ASE. The extraction was perform extraction solvent. The extracts show recoveries ranging from 9 sample was dried using Thermo ASE Prep DE. The recoveries a to 81% for Lindane when oyster shows that MAP and DE were e excellent recoveries for the six O sulfate is not recommended in a pursued in this study for compa Table 1. In-cell remo MAP and the Dionex ASE Prep Compound Lindane Heptachlor Aldrin Dieldrin Endrin DDT Total Thermo Scientific Poster Note PN70546_PITTCON_2014_E_03/14S 3

4 sture absorbing polymer was used mple with water was added to the cientific Dionex ASE Prep ASE Accelerated Solvent rated solvent extraction was performed using the Dionex omethane oom Temperature and was mixed with the polymer erature in the presence of organic sulfate was measured at room -DE sured as the maximum amount of the water into the collection nd a chromatographic oven were ntific Dionex Chromeleon as used for data acquisition.the Polar Advantage C16 5µm 4.6 based on gradient elution of A d B comprising of acetonitrile ver 17.5 min. Detection etector (FID) was used for the romeleon 6.8 CDS software was s a Thermo Scientific TR-5MS flow rate was 1.5 ml/min. The 140 C, then 10 C/min to 290 C. etector (ECD) was used for the eparation column was a DB-5 30 w rate was 1.0 ml/min. The p to 280 C with 1 min hold. Results Moisture Absorbing Capability The amount of absorbing polymer needed is approximately 0.20 g for absorbing one gram of water at room temperature. The Moisture Removal Formats a) In-cell (in-line) removal: The absorbing polymer can remove when mixed with wet sample for in-cell removal and extraction. For improved flow characteristics and improved removal the polymer is used in conjunction with diatomaceous earth (DE) dispersant for accelerated solvent extraction technique. The Dionex ASE Prep DE is normally used with the sample when pursuing accelerated solvent extraction technique, therefore adding the polymer to this setup maintains the customer s current practices. b) (off-line) removal: The amount of absorbing polymer needed is 0.20 g for absorbing one gram of water at room temperature. A simple addition of a small amount of polymer (proportional to the amount of water present) in the collection bottle can result in complete water removal from the extract. In comparison the amount of sodium sulfate needed is 4 g to absorb one gram of water. Further there is no need to add the polymer in an aliquot basis. c) Combination Mode: In this mode, the in-cell removal (in-line) is followed by in-vial removal (off line). If some breakthrough of water is observed in the extract then addition of a small amount of polymer in the collection bottle can result in complete removal. In fact a small amount in the collection vessel always ensures that there would be no present in the samples. This mode is particularly useful for samples with unknown content. Analyte Recovery from Oyster Sample for In-Cell Moisture Removal Sample preparation is challenging for a wet animal tissue sample such as an oyster sample. A mixtures of six OCPs at a concentrations of 500 ng/g each was spiked on to the wet oyster sample. The spiked oyster samples were either treated with MAP and DE (1:1) or by using sodium sulfate as the drying agent prior to in-cell extraction in the ASE. The extraction was performed at 100 C using hexane: acetone (1:1) as the extraction solvent. The extracts were analyzed by GC-ECD. The results in Table 1 show recoveries ranging from 91% for Lindane to 114% for DDT when the oyster sample was dried using Thermo Scientific Dionex ASE Prep MAP and Dionex ASE Prep DE. The recoveries are considerably lower ranging from 64% for Heptachlor to 81% for Lindane when oyster sample was dried with sodium sulfate. The data shows that MAP and DE were effective drying agents for wet oyster samples with excellent recoveries for the six OCPs. It should be noted that in-cell drying with sodium sulfate is not recommended in accelerated solvent extraction technique but was pursued in this study for comparison purposes. Table 1. In-cell removal from oyster sample using the Dionex ASE Prep MAP and the Dionex ASE Prep DE, in comparison to sodium sulfate. Compound In-cell removal by the polymer-de, % recovery In-cell removal by the sodium sulfate, % recovery Lindane Heptachlor Aldrin Dieldrin Endrin DDT Total Analyte recovery for in- Analyte recovery from the phenols, two anilines and presence of 8 g of the pol ml standard solution in a was then extracted using dichloromethane: acetone was evaporated to 10 ml µg/ml for a 10 ml extract The 10 ml extract was an instrument The results fro recovery data showed ac based on an acceptance indicates that there is no for these test analytes. Analyte recovery for in-via using the same concentra water (5 ml) was spiked polymer or by sodium sul recoveries were obtained sulfate. Table 2. Recovery of ana 2, 4-Dinitrophenol Phenol P-Toluidine 4-Nitrophenol 2-Chlorophenol 4-Ethylaniline 4-Chloroaniline 2-Nitrophenol 2, 4- Dichlorophenol 2, 4, 6- Trichlorophenol Polyaromatic hydrocarbo cell (in-line) rem soil sample was spiked w ) by adding wate polymer and DE and load using the Dionex ASE 35 acetone) at an extraction under nitrogen stream at final extract volume of 1 The extract was analyzed experiment are shown in it was still deemed accep method The extrac these two PAHs, naphtha 4 Utility of a Moisture Removal Polymer for Extraction Applications

5 is approximately 0.20 g for ture when mixed with wet sample roved flow characteristics and conjunction with diatomaceous ction technique. The Dionex ASE rsuing accelerated solvent to this setup maintains the is 0.20 g for absorbing one gram a small amount of polymer collection bottle can result in rison the amount of sodium sulfate there is no need to add the s followed by in-vial observed in the extract then ion bottle can result in complete lection vessel always ensures that. This mode is particularly useful for ll Moisture Removal tissue sample such as an oyster of 500 ng/g each was spiked on to were either treated with MAP and gent prior to in-cell extraction in the g hexane: acetone (1:1) as the C-ECD. The results in Table 1 14% for DDT when the oyster x ASE Prep MAP and Dionex er ranging from 64% for Heptachlor with sodium sulfate. The data nts for wet oyster samples with noted that in-cell drying with sodium extraction technique but was mple using the Dionex ASE Prep on to sodium sulfate. oval, % In-cell removal by the sodium sulfate, % recovery Analyte recovery for in-cell removal and in-vial removal Analyte recovery from the extraction using the polymer was studied using a mixture of phenols, two anilines and a neutral analyte. An in-cell extraction was pursued in the presence of 8 g of the polymer and a spike with a standard solution that contained 1.5 ml standard solution in acetonitrile and 8.5 ml of water. The spiked polymer sample was then extracted using the Dionex ASE 350 instrument and a 1:1 ratio of dichloromethane: acetone solvent at an extraction temperature of 100⁰ C. The extract was evaporated to 10 ml under nitrogen stream at 40⁰C. The spike level was 30 µg/ml for a 10 ml extract. The 10 ml extract was analyzed using high-pressure liquid chromatography (HPLC) instrument The results from the above experiment are shown in Table 2. The per cent recovery data showed acceptable performance of the polymer for these test analytes based on an acceptance criteria of ± 30% as per EPA method Moreover, it also indicates that there is no detrimental effect of using this polymer for in-cell extraction for these test analytes. Analyte recovery for in-vial removal at room temperature was also studied using the same concentration level of analytes in a 10 ml solvent. A known amount of water (5 ml) was spiked into the 10 ml solvent. The water was removed either by the polymer or by sodium sulfate. The results are shown in Table 2. Comparable recoveries were obtained for the polymer compared to sodium sulfate. Table 2. Recovery of analytes. Total spike level in 10 ml In-cell the polymer the polymer the sodium sulfate µg % recovery % recovery % recovery 2, 4-Dinitrophenol Phenol P-Toluidine Nitrophenol Chlorophenol Ethylaniline Chloroaniline Nitrophenol , 4- Dichlorophenol , 4, 6- Trichlorophenol Polyaromatic hydrocarbon (PAH) recovery from spiked soil sample was pursued for incell (in-line) removal and extraction in the Dionex ASE system. A 5 g clean soil sample was spiked with PAHs and then the soil was made moist (to about 30% ) by adding water. The spiked wet soil sample was mixed with 4 g of 1:1 polymer and DE and loaded into a 34 ml ASE cell. The soil sample was then extracted using the Dionex ASE 350 instrument by solvent (1:1 ratio of dichloromethane: acetone) at an extraction temperature of 100⁰ C. The extract was evaporated to 1 ml under nitrogen stream at 40⁰C. The spike level was calculated as 20 µg/ml for the final extract volume of 1 ml. The extract was analyzed using a GC instrument with FID. The results from the above experiment are shown in Table 3. Although two compounds showed a lower recovery, it was still deemed acceptable based on the acceptance criteria of ± 30% as per EPA method The extraction condition yet to optimize to increase the recovery of these two PAHs, naphthalene and acenaphthylene. Table 3. PAH recovery b Naphthalene Acenapththyene Acenaphthylene Phenanthrene Anthracene Fluoranthene Pyrene Benzo(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(a)pyrene Indeno((1,2,3,c,d)pyre Dibenzo(a,h)anthracen Benzo(g,h,i)perylene Analyte recovery for in-vi studied using the same s spiked with PAHs. A know as an extract. The water The extract was evapora was 20 µg/ml for the fina Comparable recoveries w compared to sodium sulfa was evident from the abo Conclusion Excellent analyte r from web The new polymer i technique and is in removal a The unique formula accelerated solven sample ionic streng can be easily mixe removal application Dionex ASE system The polymer overc removal and extrac Investigations are u /water con References 1. Burford, M. D., Haw line supercritical flu 2. Obana, H.; Okihas Methamidophos in 1997, 34, Thermo Fisher Scientific Inc. Al its subsidiaries. This information is not intended t intellectual property rights of othe PO70546_E 03/14S Thermo Scientific Poster Note PN70546_PITTCON_2014_E_03/14S 5

6 d in-vial removal er was studied using a mixture of ll extraction was pursued in the ndard solution that contained 1.5 ter. The spiked polymer sample ment and a 1:1 ratio of mperature of 100⁰ C. The extract 0⁰C. The spike level was 30 liquid chromatography (HPLC) re shown in Table 2. The per cent e polymer for these test analytes A method Moreover, it also his polymer for in-cell extraction temperature was also studied 0 ml solvent. A known amount of water was removed either by the in Table 2. Comparable e polymer compared to sodium y r the polymer the sodium sulfate ry % recovery % recovery ed soil sample was pursued for in- Dionex ASE system. A 5 g clean was made moist (to about 30% ple was mixed with 4 g of 1:1 The soil sample was then extracted 1 ratio of dichloromethane: e extract was evaporated to 1 ml calculated as 20 µg/ml for the ith FID. The results from the above pounds showed a lower recovery, nce criteria of ± 30% as per EPA ze to increase the recovery of Table 3. PAH recovery by using GC-FID. Analyte recovery for in-vial (off-line) removal at room temperature was studied using the same solvent, 1:1 dichloromethane: acetone. A 40 ml solvent was spiked with PAHs. A known amount of water was added to the spiked solvent acting as an extract. The water was removed either by the polymer or by the sodium sulfate. The extract was evaporated to 1 ml under nitrogen stream at 40 ⁰C. The spike level was 20 µg/ml for the final extract volume of 1 ml. The results are shown in Table 3. Comparable recoveries were obtained for in-vial the polymer compared to sodium sulfate. Therefore, the usefulness of the polymer as drying agent was evident from the above table. Conclusion Excellent analyte recoveries were achieved using the new polymer for removing from web samples as well as from a collected extract. The new polymer is designed to work with accelerated solvent extraction technique and is intended for in-cell (in-line) removal, in-vial (off line) removal and a combination of both in-cell and in-vial. The unique formulation of the polymer allows removal under accelerated solvent extraction technique conditions and is not affected by the sample ionic strength. The polymer is a free-flowing white granular material that can be easily mixed with Dionex ASE Prep DE and used for the removal applications. Additionally the polymer can be easily removed from the Dionex ASE system cell after the high-temperature extractions are complete. The polymer overcomes the limitation of sodium sulfate for in-cell removal and extraction. Investigations are underway to expand the applicability of this polymer to other /water containing samples. References In-cell the polymer-de the polymer the sodium sulfate % recovery % recovery % recovery Naphthalene Acenapththyene Acenaphthylene Phenanthrene Anthracene Fluoranthene Pyrene Benzo(a)anthracene Chrysene Benzo(b)fluoranthene Benzo(k)fluoranthene Benzo(a)pyrene Indeno((1,2,3,c,d)pyrene Dibenzo(a,h)anthracene Benzo(g,h,i)perylene Burford, M. D., Hawthorne, S. B., Miller, D. J. Evaluation of drying agents for offline supercritical fluid extraction. J. Chromatogr., A 1993, 657, Obana, H.; Okihashi, M.; Kakimoto, S.; Hori, S. Determination of Acephate and Methamidophos in Foods Using Super-absorbent Polymer, Anal. Commun., 1997, 34, Utility of a Moisture Removal Polymer for Extraction Applications Thermo Fisher Scientific Inc. All rights reserved. All trademarks are property of Thermo Fisher Scientific Inc. and its subsidiaries. This information is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. PO70546_E 03/14S

7 Thermo Fisher Scientific Inc. All rights reserved. ISO is a trademark of the International Standards Organization. All other trademarks are the property of Thermo Fisher Scientific Inc. and its subsidiaries. This information is presented as an example of the capabilities of Thermo Fisher Scientific Inc. products. It is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. Specifications, terms and pricing are subject to change. Not all products are available in all countries. Please consult your local sales representative for details. Africa Australia Austria Belgium Brazil Canada China (free call domestic) Denmark Europe-Other Finland France Germany India Italy Japan Korea Latin America Middle East Netherlands New Zealand Norway Thermo Fisher Scientific, Sunnyvale, CA USA is ISO 9001:2008 Certified. Russia/CIS Singapore Sweden Switzerland Taiwan UK/Ireland USA PN70546_E 03/14S