RESUMEN
Crosslinked polymeric ionic liquid (PIL)-based sorbent coatings were employed in the extraction of 21 polychlorinated biphenyls (PCBs) from ocean water and bovine milk using solid-phase microextraction (SPME). The extraction temperature, time, and concentration of sodium chloride added to the matrix were optimized in order to determine the best extraction conditions for the extraction of PCBs. The analytical performance of the crosslinked PIL-based SPME fibers was compared with a commercial 7 µm polydimethylsiloxane (PDMS) fiber using gas chromatography (GC) employing an electron capture detector (ECD) and mass spectrometric detection (MS). Higher sensitivities for PCBs were achieved using PIL-based fibers when compared to PDMS fiber due to the incorporation of benzyl moieties into the PIL structures. The limits of detection (LOD) for all PCBs were determined to be in the low ng L(-1) range using the three studied coatings. Recovery studies were performed for PCBs in ocean water and bovine milk to validate the applicability of the current SPME method.
Asunto(s)
Reactivos de Enlaces Cruzados/química , Leche/química , Océanos y Mares , Bifenilos Policlorados/análisis , Hidrocarburos Policíclicos Aromáticos/química , Polímeros/química , Microextracción en Fase Sólida , Agua/química , Animales , Bovinos , Cromatografía de Gases y Espectrometría de Masas , Líquidos Iónicos , Límite de Detección , Bifenilos Policlorados/aislamiento & purificaciónRESUMEN
A reversed-phase high performance liquid chromatography (HPLC) method is described for the determination of boronic acids that are commonly present as impurities in pinacolboronate ester reagents. Boronic acids and their pinacolboronate esters are key reagents in the Suzuki-Miyaura coupling reaction. The retention of hydrophilic boronic acids in reversed-phase chromatography is often a challenge, especially in very high pH mobile phases, which are needed to mitigate the on-column degradation of pinacolboronate esters. In this study, a hydrophilic boronic acid, 2-aminopyrimidine-5-ylboronic acid, was complexed with specifically functionalized glucaminium-based ionic liquids that were added to the diluent. The two glucaminium-based ILs possess cis-diol moieties that are capable of forming complexes with boronic acids. In addition, aromatic functional groups within the glucaminium cation allow strong π-π interactions with the polymeric stationary phase. Using this approach, the limit of detection for 2-aminopyrimidine-5-ylboronic acid was found to be 3-4µM. The quantification of 2-aminopyrimidine-5-ylboronic acid within a 2-aminopyrimidine-5-pinacolboronate ester sample was successfully achieved using this method.
Asunto(s)
Ácidos Borónicos/química , Cromatografía Líquida de Alta Presión/métodos , Ésteres/química , Líquidos Iónicos/química , Pirimidinas/química , Ácidos Borónicos/aislamiento & purificación , Cromatografía de Fase Inversa , Ésteres/aislamiento & purificación , Interacciones Hidrofóbicas e Hidrofílicas , Límite de Detección , Pirimidinas/aislamiento & purificación , Reproducibilidad de los Resultados , TemperaturaRESUMEN
Six ionic liquids (ILs) were applied for the first time as solvents in the extraction and preconcentration of deoxyribonucleic acid (DNA) using an in situ dispersive liquid-liquid microextraction (DLLME) approach. The effect of different IL substituents and functional group on the extraction efficiency of DNA was investigated. The highest extraction efficiencies of DNA were obtained using 1-(1,2-dihydroxypropyl)-3-hexadecylimidazolium bromide (C(16)POHIM-Br) and N,N-didecyl-N-methyl-d-glucaminium bromide [(C(10))(2)NMDG-Br]. Extraction efficiencies higher than 97% were obtained using small amounts of IL (0.50mg) for each extraction. The extraction of DNA from a sample matrix containing metal ions and protein revealed that the metal ions did not interfere with the extraction of DNA and that the co-extraction of protein can be mitigated by performing the extraction under moderately acidic conditions. Data from (31)P NMR spectroscopy suggest that a combination of electrostatic and π-π interactions dominate IL-DNA complexation and that the extraction is concentration dependant.
Asunto(s)
ADN/aislamiento & purificación , Líquidos Iónicos/química , Microextracción en Fase Líquida/métodos , Solventes/química , Concentración de Iones de Hidrógeno , Espectroscopía de Resonancia Magnética , Electricidad Estática , Factores de Tiempo , Agua/químicaRESUMEN
Glucaminium-based ionic liquids are a new class of solvents capable of extracting boron-species from water with high efficiency. The complexation behavior of these ILs with borate was thoroughly studied using (11)B NMR. Two different complexes, namely, monochelate complex and bischelate complex, were observed. (11)B NMR was used extensively to determine the formation constants for monochelate and bischelate complexes. The IL concentration was observed to have a significant effect on the IL-borate complexes. Using an in situ dispersive liquid-liquid microextraction (in situ DLLME) method, the extraction efficiency for boron species was increased dramatically when lithium bis[(trifluoromethyl)sulfonyl]imide (LiNTf(2)) was used as the metathesis salt in an aqueous solution containing 0.1M sodium chloride. IL regeneration after extraction was achieved using 0.1M hydrochloric acid. The extraction efficiency of boron species was consistent when the IL was employed after three regeneration cycles. The selectivity of the IL for boron species in synthetic seawater samples was similar to performing the same extraction from Milli-Q water samples.
Asunto(s)
Boro/aislamiento & purificación , Quelantes/química , Líquidos Iónicos/química , Microextracción en Fase Líquida , Meglumina/química , Boro/química , Cromatografía Líquida de Alta Presión , Líquidos Iónicos/síntesis química , Espectroscopía de Resonancia Magnética , Meglumina/análogos & derivados , Meglumina/síntesis química , Solventes/síntesis química , Solventes/químicaRESUMEN
A series of polymeric ionic liquids (PILs) possessing varied chemical makeup and composition were applied as selective solid-phase microextraction (SPME) sorbent coatings for the analysis of genotoxic impurities (GTIs) and related structurally alerting compounds, namely, alkyl halides and aromatics. In addition to exploiting two previously synthesized PILs as selective coatings, two new PILs, namely, N,N-didecyl-N-methyl-D-glucaminium poly(2-methyl-acrylic acid 2-[1-(3-{2-[2-(3-trifluoromethanesulfonylamino-propoxy)-ethoxy]-ethoxy}-propylamino)-vinylamino]-ethyl ester) (poly([DDMGlu][MTFSI])), and poly(1-vinyl-3-propylphenylimidazolium) chloride (poly([VPPIM][Cl])), were designed, synthesized, and their selectivity examined in the extraction of the selected analytes. The glucaminium-based coating was developed to exploit the hydrogen bond-acidic hydroxyl groups within the carbohydrate moiety of the PIL in addition to dispersive capabilities resulting from the cation and anion. The poly([VPPIM][Cl]) coating was tailored to possess π-π interaction capabilities through the phenyl functionality while also containing the hydrogen bond-basic chloride anion. Calibration studies were performed via headspace extraction to determine the sensitivity and limit of detection (LOD) for all analytes with respect to each PIL-based sorbent coating and compared to the polyacrylate (PA) and polydimethylsiloxane (PDMS) sorbent coatings. PILs containing the chloride anion exhibited high selectivity for aniline-based compounds. The glucaminium-based PIL exhibited good sensitivity for larger aliphatic alkyl halides. The poly(1-4-vinylbenzyl-3-hexadecylimidazolium) bis[(trifluoromethyl)sulfonyl] imide (poly([VBHDIM][NTf2])) PIL coating demonstrated superior selectivity for larger aliphatic/aromatic analytes. The LODs of both commercial and PIL-based coatings for the two classes of GTIs ranged from low part-per-billion (ppb) to mid part-per-trillion (ppt) levels. Recovery studies were performed at two concentration levels within the linear range in order to validate the accuracy of the technique. Scanning electron micrographs were obtained for three PIL-based coatings following approximately 70 extraction/desorption steps, wherein the fiber coatings were observed to be largely smooth and intact.
Asunto(s)
Hidrocarburos Halogenados/aislamiento & purificación , Líquidos Iónicos/química , Mutágenos/aislamiento & purificación , Hidrocarburos Policíclicos Aromáticos/aislamiento & purificación , Microextracción en Fase Sólida/instrumentación , Contaminación de Medicamentos , Imidazoles/química , Límite de Detección , Ácidos Polimetacrílicos/química , Reproducibilidad de los Resultados , Cloruro de Sodio , Microextracción en Fase Sólida/métodosRESUMEN
A novel class of ionic liquids (ILs), exhibiting high selectivity towards boron species as well as the ability to phase separate from water, were synthesized from N-methyl-D-glucamine. The complexation of boric acid/borate with the ILs was confirmed using (11)B NMR.
Asunto(s)
Boratos/aislamiento & purificación , Ácidos Bóricos/aislamiento & purificación , Líquidos Iónicos/síntesis química , Meglumina/síntesis química , Agua/química , Boro/química , Líquidos Iónicos/química , Espectroscopía de Resonancia Magnética , Meglumina/análogos & derivados , Meglumina/químicaRESUMEN
In this work is described the investigation of bivalent versus monovalent enantioselective molecular recognition in the context of enantioselective separations. Electrospray ionization-mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) are used for evaluating enantioselective systems through the measurement of (1) relative solution-phase binding constants via titration and (2) relative gas-phase binding via collision threshold dissociation. In HPLC, a cinchonane-type chiral stationary phase (CSP) based on tert.-butylcarbamoylquinine provides vastly increased retention and enantioselectivity for separation of bivalent versus monovalent alkoxy-benzoyl-N-blocked leucine enantiomers. The bivalent enantiomers are able to span and simultaneously interact with multiple interaction sites on the CSP surface, leading to enhanced separation. ESI-MS titration measurements also show an increased avidity for binding between bivalent selector and bivalent selectand, compared with the monovalent system. However, enhanced enantioselectivities measured in HPLC for the bivalent system cannot be reproduced by MS due to inherent mechanistic differences. Assumed discrepancies in relative response factors also give rise to systematic errors which are discussed. The results of MS/MS gas-phase experiments show that enantioselectivity is essentially lost in the absence of solvation, but that dissociation thresholds can provide a measure of relative dissociation energy in the bivalent interaction system compared to the monovalent counterpart. Such measurements may prove useful and efficient in better understanding multivalent interactions, in line with current theoretical considerations of effective concentrations and ion trap effects. This is the first application of mass spectrometric methods for assessing increased avidity of binding in multivalent enantioselective molecular recognition.