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Sorption of structurally different ionized pharmaceutical and illicit drugs to a mixed-mode coated microsampler.

Journal of chromatography. A (2016-04-17)
Hester Peltenburg, Niels Timmer, Ingrid J Bosman, Joop L M Hermens, Steven T J Droge
ABSTRACT

The mixed-mode (C18/strong cation exchange-SCX) solid-phase microextraction (SPME) fiber has recently been shown to have increased sensitivity for ionic compounds compared to more conventional sampler coatings such as polyacrylate and polydimethylsiloxane (PDMS). However, data for structurally diverse compounds to this (prototype) sampler coating are too limited to define its structural limitations. We determined C18/SCX fiber partitioning coefficients of nineteen cationic structures without hydrogen bonding capacity besides the charged group, stretching over a wide hydrophobicity range (including amphetamine, amitriptyline, promazine, chlorpromazine, triflupromazine, difenzoquat), and eight basic pharmaceutical and illicit drugs (pKa>8.86) with additional hydrogen bonding moieties (MDMA, atenolol, alprenolol, metoprolol, morphine, nicotine, tramadol, verapamil). In addition, sorption data for three neutral benzodiazepines (diazepam, temazepam, and oxazepam) and the anionic NSAID diclofenac were collected to determine the efficiency to sample non-basic drugs. All tested compounds showed nonlinear isotherms above 1mmol/L coating, and linear isotherms below 1mmol/L. The affinity for C18/SCX-SPME for tested organic cations without Hbond capacities increased with longer alkyl chains, ranging from logarithmic fiber-water distribution coefficients (log Dfw) of 1.8 (benzylamine) to 5.8 (triflupromazine). Amines smaller than benzylamine may thus have limited detection levels, while cationic surfactants with alkyl chain lengths >12 carbon atoms may sorb too strong to the C18/SCX sampler which hampers calibration of the fiber-water relationship in the linear range. The log Dfw for these simple cation structures closely correlates with the octanol-water partition coefficient of the neutral form (Kow,N), and decreases with increased branching and presence of multiple aromatic rings. Oxygen moieties in organic cations decreased the affinity for C18/SCX-SPME. Log Dfw values of neutral benzodiazepines were an order of magnitude higher than their log Kow,N. Results for anionic diclofenac species (logKow,N 4.5, pKa 4.0, log Dfw 2.9) indicate that the C18-SCX fiber might also be useful for sampling of organic anions. This data supports our theory that C18-based coatings are able to sorb ionized compounds through adsorption and demonstrates the applicability of C18-based SPME in the measurement of freely dissolved concentrations of a wide range of ionizable compounds.

MATERIALS
Product Number
Brand
Product Description

Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 85 μm (CAR/PDMS), for use with autosampler, needle size 23 ga, metal alloy fiber
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), for use with autosampler, needle size 23 ga, metal alloy fiber, fiber L 1 cm
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), for use with autosampler, needle size 23 ga, metal alloy fiber, fiber L 2 cm
Supelco
SPME Portable Field Sampler, coating CAR/PDMS
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), needle size 23 ga, StableFlex, for use with manual holder or autosampler, fiber L 2 cm
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), needle size 23 ga, StableFlex, for use with autosampler
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 85 μm (CAR/PDMS), needle size 23 ga, StableFlex, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 7 μm (PDMS), needle size 23 ga, for use with autosampler
Supelco
SPME fiber assembly polyacrylate (PA), df 85 μm (PA), for use with autosampler, needle size 23 ga
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), metal alloy fiber, df 100 μm (PDMS), needle size 23 ga, for use with autosampler
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), needle size 24 ga, for use with manual holder
Supelco
SPME Sampling Stand, for use with 15 mL vials
Supelco
SPME fiber assembly polyacrylate (PA), df 85 μm (PA), for use with autosampler, needle size 24 ga
Supelco
SPME Sampling Stand, for use with 4 mL vials
Supelco
SPME Portable Field Sampler, coating PDMS/DVB
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 100 μm (PDMS), needle size 24 ga, for use with manual holder
Supelco
SPME Portable Field Sampler, coating PDMS
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 75 μm (CAR/PDMS), needle size 23 ga, for use with manual holder
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 75 μm (CAR/PDMS), for use with manual holder, needle size 24 ga
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 30 μm (PDMS), needle size 24 ga, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 100 μm (PDMS), for use with autosampler, needle size 23 ga
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 85 μm (CAR/PDMS), needle size 24 ga, for use with manual holder, StableFlex fiber
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 75 μm (CAR/PDMS), needle size 24 ga, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 7 μm (PDMS), needle size 24 ga, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 100 μm (PDMS), for use with autosampler, needle size 24 ga
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 30 μm (PDMS), needle size 24 ga, for use with manual holder
Supelco
SPME fiber assembly Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS), needle size 24 ga, StableFlex
Supelco
SPME fiber assembly polyacrylate (PA), df 85 μm (PA), for use with manual holder, needle size 24 ga
Supelco
SPME fiber assembly Carboxen/Polydimethylsiloxane (CAR/PDMS), df 75 μm (CAR/PDMS), needle size 23 ga, for use with autosampler
Supelco
SPME fiber assembly Polydimethylsiloxane (PDMS), df 7 μm (PDMS), needle size 24 ga, for use with manual holder