Column Chromatography To Obtain Organic Cation Sorption Isotherms

Jolin, William C.; Sullivan, James K; Vasudevan, Dharni; MacKay, Allison A.

doi:10.1021/acs.est.6b01733

Cited by 16 publications

(26 citation statements)

References 44 publications

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“…Sorption affinities of phytotoxins to clay minerals were determined by continuous flow column sorption experiments using manually packed HPLC columns [12]. This approach was shown to be directly comparable to traditional batch sorption experiments on numerous occasions [17,18]. Empty HPLC columns (stainless steel, length 14 mm, inner diameter 3 mm) and additional equipment (pre-columns, connecting nuts, stainless steel sieves of 3 µm pore size, glass fiber filters of < 1.5 µm pore size and PTFE sealing rings) were purchased from Bischoff Chromatography (distributed by WICOM International AG, Maienfeld, Switzerland).…”

Section: Continuous Flow Column Sorption Experimentsmentioning

confidence: 99%

Phytotoxin sorption to clay minerals

2021

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Background Phytotoxins of various classes and origin are often found in their cationic form in the soil environment and thus, their overall soil behavior may be strongly affected by all geosorbents presenting cation exchange capacity (CEC). In addition to soil organic carbon (SOC), clays may exhibit great potential as sorbents for cationic organic chemicals. Therefore, 52 compounds of the major phytotoxin classes alkaloids, terpenoids and steroids were investigated with regard to their sorption behavior to the clay minerals kaolinite (low CEC) and montmorillonite (high CEC) by means of continuous flow column sorption experiments as a high-throughput alternative to traditional batch sorption experiments. Results In total, sorption coefficients log Dclay [L kg−1] were quantifiable for 26 phytotoxins on kaolinite (log Dclay > 0.1) and 33 on montmorillonite (log Dclay > 0.5). They ranged from 0.14 ± 0.09 for the pyrrolizidine alkaloid senkirkine on kaolinite to 3.05 ± 0.03 for the indole alkaloid brucine on montmorillonite. Although maximum sorbed concentrations lay well below the CEC for both clay minerals, sorption non-linearity was observed in some cases where as little as 0.1% of all cation exchange sites were occupied. Contrary to the expectations, sorption non-linearity could not be wholly explained by saturation of available sorption sites; for protonated tertiary amines with aromatic moieties, cooperative sorption seemingly took place and the results indicated a significant increase in sorption affinities within a very limited concentration range. Comparing montmorillonite and SOC, notable differences in preferences of cationic sorbates were observed between phytotoxins with and without aromatic moieties (e.g., isoquinoline versus pyrrolizidine alkaloids) as well as between N-heterocycles and N-heteroaromatics in particular (e.g., strychnine versus gramine; both indole alkaloids). Conclusions Overall, clay sorption seems a result of the interplay of charge location on the sorbent and various structural features of the sorbates. To confirm observed tendencies towards cooperative sorption for certain cationic phytotoxins, further studies with higher concentrations are needed. Nevertheless, obtained sorption coefficients indicate that a high proportion of phytotoxin sorption in soils may be attributed to clay minerals. Thus, clay minerals possess the ability to decrease total cationic phytotoxin environmental mobility.

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Section: Continuous Flow Column Sorption Experimentsmentioning

confidence: 99%

Phytotoxin sorption to clay minerals

2021

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“…1−3 Cell membranes are expected to be the dominant sorption site for organic cations in tissue. 4,5 Just like sorption coefficients to individual soil components are much more relevant for IOCs than K OW , 6−10 the membrane–water distribution coefficient ( D MW ) is a logical alternative for K OW as the main model parameter to predict, for example, the tissue distribution and critical membrane burden in organisms. 4,11 Many IOCs are highly relevant from an ecotoxicological perspective because of designed bioactive properties and/or continuous input via wastewater streams.…”

Section: Introductionmentioning

confidence: 99%

Sorption of Cationic Surfactants to Artificial Cell Membranes: Comparing Phospholipid Bilayers with Monolayer Coatings and Molecular Simulations

Timmer

Droge

2017

Environ. Sci. Technol.

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This study reports the distribution coefficient between phospholipid bilayer membranes and phosphate buffered saline (PBS) medium (DMW,PBS) for 19 cationic surfactants. The method used a sorbent dilution series with solid supported lipid membranes (SSLMs). The existing SSLM protocol, applying a 96 well plate setup, was adapted to use 1.5 mL glass autosampler vials instead, which facilitated sampling and circumvented several confounding loss processes for some of the cationic surfactants. About 1% of the phospholipids were found to be detached from the SSLM beads, resulting in nonlinear sorption isotherms for compounds with log DMW values above 4. Renewal of the medium resulted in linear sorption isotherms. DMW values determined at pH 5.4 demonstrated that cationic surfactant species account for the observed DMW,PBS. Log DMW,PBS values above 5.5 are only experimentally feasible with lower LC-MS/MS detection limits and/or concentrated extracts of the aqueous samples. Based on the number of carbon atoms, dialkylamines showed a considerably lower sorption affinity than linear alkylamine analogues. These SSLM results closely overlapped with measurements on a chromatographic tool based on immobilized artificial membranes (IAM-HPLC) and with quantum-chemistry based calculations with COSMOmic. The SSLM data suggest that IAM-HPLC underestimates the DMW of ionized primary and secondary alkylamines by 0.8 and 0.5 log units, respectively.

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“…Column chromatography was used to obtain sorption coefficients for compounds with a packing mixture of a single aluminosilicate and inert SiC. We followed our methods described previously 19 that confirmed sorption coefficients from the column approach to match those from batch set-ups. Solid-to-water ratios for individual columns (Table S1) were designed to balance compound retention against peak spreading.…”

Section: ■ Methodsmentioning

confidence: 99%

Aluminosilicate Mineralogy and the Sorption of Organic Cations: Interplay between Electrostatic Barriers and Compound Structural Features

Jolin

Richard

Vasudevan

et al. 2020

Environ. Sci. Technol.

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Current predictive models of organic cation sorption assume that sorbates interact with all sites on aluminosilicate minerals in the same manner. To examine whether differences in aluminosilicate structure and the resultant changes in electrostatic potential influence the sorption of organic cations, seven smectites were chosen with different proportions of isomorphic substitutions (origin of clay charge) located in octahedral versus tetrahedral layers and with the presence or absence of aluminosilicate interlayers. Sorption coefficients for 14 benzylamine derivatives with systematic differences in compound structures were collected to understand the possible influence of aluminosilicate mineralogy. Benzylamine compounds with methyl group substitution on the charged amine or with electron-donating or -withdrawing ring substituents displayed decreases in cation exchange-normalized sorption coefficients (K CEC ), by up to one order of magnitude, between hectorite (100% isomorphic substitution in the octahedral layer) and nontronite (100% isomorphic substitution in the tetrahedral layer). To understand this difference across aluminosilicates, stochastic molecular models of the various aluminosilicate minerals with interlayers were performed. These models showed that negative charge density associated with tetrahedral sites results in high positive electrostatic energy barriers within the interlayer, creating a penalty for compounds with positive charge spread over a larger compound surface area as occurs from primary to quaternary amines. Conversely, clays with charge originating from octahedral sites produce low electrostatic potential barriers within the interlayer, decreasing the penalty for quaternary amine sorption. Trends for nine cationic pharmaceutical compounds, which varied in size, group alkylation, and/or polar substituents, demonstrated similar decreases in K CEC values to aluminosilicate minerals with high electrostatic energy barriers. Overall, aluminosilicate mineralogy was found to exert a large influence (0.5−1 order of magnitude in sorption coefficients) on organic cation sorption. The application of atomistic electrostatic potential mapping of both sorbent and sorbate structures provided insights to explain trends in sorption coefficients that could not be described by the basic electrostatic potential theory or by assuming that sorbate structure moieties yielded additive sorption contributions.

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Column Chromatography To Obtain Organic Cation Sorption Isotherms

Cited by 16 publications

References 44 publications

Phytotoxin sorption to clay minerals

Phytotoxin sorption to clay minerals

Sorption of Cationic Surfactants to Artificial Cell Membranes: Comparing Phospholipid Bilayers with Monolayer Coatings and Molecular Simulations

Aluminosilicate Mineralogy and the Sorption of Organic Cations: Interplay between Electrostatic Barriers and Compound Structural Features

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