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Elucidating the sorption mechanism of "mixed-mode" SPME using the basic drug amphetamine as a model compound.
Anal Chim Acta. 2013 Jun 11; 782:21-7.AC

Abstract

We studied the sorption of amphetamine as a model drug to represent small, polar organic cations to a new SPME coating combining C18 and propylsulfonic acid. This combination of hydrophobic and strong cation exchange (SCX) groups was compared to conventional SPME fibers with polyacrylate (PA) or C18 coating. The affinity of amphetamine at physiological pH (PBS) was 20 to 180 times greater for the new C18/SCX coating than for C18 alone and PA of different coating thickness. As amphetamine is a base and >99% protonated at physiological pH, this enhanced affinity is attributed to the ion-exchange phase in the coating. Tests at pH above the pKa of amphetamine show that, when normalized to the coating volume, neutral amphetamine also has a higher affinity compared to PA. As ion-exchange groups are not unlimitedly present in the coating, amphetamine isotherms level off to a saturation concentration on the C18/SCX fiber at the highest tested aqueous concentrations. Also, other cations (Na(+), K(+), Ca(2+)) compete for the SCX sites and decrease the sorption coefficients, e.g. by 1.7 log units when comparing Milli-Q water with PBS. The C18/SCX fiber provides improved sensitivity over some of the classic SPME fibers. However, care should be taken near the cation exchange capacity of the fiber and the fiber should be calibrated in an appropriate matrix so as to eliminate competition effects.

Authors+Show Affiliations

Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80177, 3508 TD Utrecht, The Netherlands. H.Peltenburg@uu.nlNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

23708280

Citation

Peltenburg, Hester, et al. "Elucidating the Sorption Mechanism of "mixed-mode" SPME Using the Basic Drug Amphetamine as a Model Compound." Analytica Chimica Acta, vol. 782, 2013, pp. 21-7.
Peltenburg H, Groothuis FA, Droge ST, et al. Elucidating the sorption mechanism of "mixed-mode" SPME using the basic drug amphetamine as a model compound. Anal Chim Acta. 2013;782:21-7.
Peltenburg, H., Groothuis, F. A., Droge, S. T., Bosman, I. J., & Hermens, J. L. (2013). Elucidating the sorption mechanism of "mixed-mode" SPME using the basic drug amphetamine as a model compound. Analytica Chimica Acta, 782, 21-7. https://doi.org/10.1016/j.aca.2013.04.030
Peltenburg H, et al. Elucidating the Sorption Mechanism of "mixed-mode" SPME Using the Basic Drug Amphetamine as a Model Compound. Anal Chim Acta. 2013 Jun 11;782:21-7. PubMed PMID: 23708280.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Elucidating the sorption mechanism of "mixed-mode" SPME using the basic drug amphetamine as a model compound. AU - Peltenburg,Hester, AU - Groothuis,Floris A, AU - Droge,Steven T J, AU - Bosman,Ingrid J, AU - Hermens,Joop L M, Y1 - 2013/04/22/ PY - 2013/02/05/received PY - 2013/04/12/revised PY - 2013/04/14/accepted PY - 2013/5/28/entrez PY - 2013/5/28/pubmed PY - 2013/12/29/medline SP - 21 EP - 7 JF - Analytica chimica acta JO - Anal. Chim. Acta VL - 782 N2 - We studied the sorption of amphetamine as a model drug to represent small, polar organic cations to a new SPME coating combining C18 and propylsulfonic acid. This combination of hydrophobic and strong cation exchange (SCX) groups was compared to conventional SPME fibers with polyacrylate (PA) or C18 coating. The affinity of amphetamine at physiological pH (PBS) was 20 to 180 times greater for the new C18/SCX coating than for C18 alone and PA of different coating thickness. As amphetamine is a base and >99% protonated at physiological pH, this enhanced affinity is attributed to the ion-exchange phase in the coating. Tests at pH above the pKa of amphetamine show that, when normalized to the coating volume, neutral amphetamine also has a higher affinity compared to PA. As ion-exchange groups are not unlimitedly present in the coating, amphetamine isotherms level off to a saturation concentration on the C18/SCX fiber at the highest tested aqueous concentrations. Also, other cations (Na(+), K(+), Ca(2+)) compete for the SCX sites and decrease the sorption coefficients, e.g. by 1.7 log units when comparing Milli-Q water with PBS. The C18/SCX fiber provides improved sensitivity over some of the classic SPME fibers. However, care should be taken near the cation exchange capacity of the fiber and the fiber should be calibrated in an appropriate matrix so as to eliminate competition effects. SN - 1873-4324 UR - https://www.unboundmedicine.com/medline/citation/23708280/Elucidating_the_sorption_mechanism_of_"mixed_mode"_SPME_using_the_basic_drug_amphetamine_as_a_model_compound_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0003-2670(13)00541-2 DB - PRIME DP - Unbound Medicine ER -