Complexation-mediated electromembrane extraction of highly polar basic drugs – a fundamental study with catecholamines in urine as model system

TY - JOUR

T1 - Complexation-mediated electromembrane extraction of highly polar basic drugs – a fundamental study with catecholamines in urine as model system

AU - Fernández, Elena

AU - Vårdal, Linda

AU - Vidal, Lorena

AU - Canals, Antonio

AU - Gjelstad, Astrid

AU - Pedersen-Bjergaard, Stig

PY - 2017/7/1

Y1 - 2017/7/1

N2 - Complexation-mediated electromembrane extraction (EME) of highly polar basic drugs (log P < −1) was investigated for the first time with the catecholamines epinephrine, norepinephrine, and dopamine as model analytes. The model analytes were extracted as cationic species from urine samples (pH 4), through a supported liquid membrane (SLM) comprising 25 mM 4-(trifluoromethyl)phenylboronic acid (TFPBA) in bis(2-ethylhexyl) phosphite (DEHPi), and into 20 mM formic acid as acceptor solution. EME was performed for 15 min, and 50 V was used as extraction voltage across the SLM. TFPBA served as complexation reagent, and selectively formed boronate esters by reversible covalent binding with the model analytes at the sample/SLM interface. This enhanced the mass transfer of the highly polar model analytes across the SLM, and EME of basic drugs with log P in the range −1 to −2 was shown for the first time. Meanwhile, most matrix components in urine were unable to pass the SLM. Thus, the proposed concept provided highly efficient sample clean-up and the system current across the SLM was kept below 50 μA. Finally, the complexation-mediated EME concept was combined with ultra-high performance liquid chromatography coupled to tandem mass spectrometry and evaluated for quantification of epinephrine and dopamine. Standard addition calibration was applied to a pooled human urine sample. Calibration curves using standards between 25 and 125 μg L−1 gave a high level of linearity with a correlation coefficient of 0.990 for epinephrine and 0.996 for dopamine (N = 5). The limit of detection, calculated as three times signal-to-noise ratio, was 5.0 μg L−1 for epinephrine and 1.8 μg L−1 for dopamine. The repeatability of the method, expressed as coefficient of variation, was 13% (n = 5). The proposed method was finally applied for the analysis of spiked pooled human urine sample, obtaining relative recoveries of 91 and 117% for epinephrine and dopamine, respectively.

AB - Complexation-mediated electromembrane extraction (EME) of highly polar basic drugs (log P < −1) was investigated for the first time with the catecholamines epinephrine, norepinephrine, and dopamine as model analytes. The model analytes were extracted as cationic species from urine samples (pH 4), through a supported liquid membrane (SLM) comprising 25 mM 4-(trifluoromethyl)phenylboronic acid (TFPBA) in bis(2-ethylhexyl) phosphite (DEHPi), and into 20 mM formic acid as acceptor solution. EME was performed for 15 min, and 50 V was used as extraction voltage across the SLM. TFPBA served as complexation reagent, and selectively formed boronate esters by reversible covalent binding with the model analytes at the sample/SLM interface. This enhanced the mass transfer of the highly polar model analytes across the SLM, and EME of basic drugs with log P in the range −1 to −2 was shown for the first time. Meanwhile, most matrix components in urine were unable to pass the SLM. Thus, the proposed concept provided highly efficient sample clean-up and the system current across the SLM was kept below 50 μA. Finally, the complexation-mediated EME concept was combined with ultra-high performance liquid chromatography coupled to tandem mass spectrometry and evaluated for quantification of epinephrine and dopamine. Standard addition calibration was applied to a pooled human urine sample. Calibration curves using standards between 25 and 125 μg L−1 gave a high level of linearity with a correlation coefficient of 0.990 for epinephrine and 0.996 for dopamine (N = 5). The limit of detection, calculated as three times signal-to-noise ratio, was 5.0 μg L−1 for epinephrine and 1.8 μg L−1 for dopamine. The repeatability of the method, expressed as coefficient of variation, was 13% (n = 5). The proposed method was finally applied for the analysis of spiked pooled human urine sample, obtaining relative recoveries of 91 and 117% for epinephrine and dopamine, respectively.

U2 - 10.1007/s00216-017-0370-2

DO - 10.1007/s00216-017-0370-2

M3 - Journal article

C2 - 28451718

SN - 1618-2642

VL - 409

SP - 4215

EP - 4223

JO - Analytical and Bioanalytical Chemistry

JF - Analytical and Bioanalytical Chemistry

IS - 17

ER -