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Salting-out homogenous extraction followed by ionic liquid/ionic liquid dispersive liquid-liquid micro-extraction system was developed and applied to the extraction of sulfonamides in blood. High-performance liquid chromatography was applied to the determination of the analytes. The blood sample was centrifuged to obtain the serum. After the proteins in the serum were removed in the presence of acetonitrile, ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, dipotassium hydrogen phosphate, ionic liquid 1-Hexyl-3-methylimidazolium hexafluorophosphate were added into the resulting solution. After the resulting mixture was ultrasonically shaken and centrifuged, the precipitate was separated. The acetonitrile was added in the precipitate and the analytes were extracted into the acetonitrile phase. The parameters affecting the extraction efficiency, such as volume of ionic liquid, amount of dipotassium hydrogen phosphate, volume of dispersant, extraction time and temperature were investigated. The limits of detection of sulfamethizole (STZ), sulfachlorpyridazine (SCP), sulfamethoxazole (SMX) and Sulfisoxazole (SSZ) were 4.78, 3.99, 5.21 and 3.77 μg L −1 , respectively. When the present method was applied to the analysis of real blood samples, the recoveries of analytes ranged from 90.0% to 113.0% and relative standard deviations were lower than 7.2%. [ABSTRACT FROM AUTHOR]

Ionic liquid/anionic surfactant aqueous two-phase system was developed and applied for the extraction of Sudan I–IV. High-performance liquid chromatography was applied to the determination of the analytes. The aqueous two-phase system (ATPS) was formed in the present of C 4 [MIM]BF 4 , sodium dodecyl benzene sulphonate and (NH 4 ) 2 SO 4 . The parameters affecting the extraction efficiency, such as volume of ionic liquid, amount of sodium dodecyl benzene sulphonate, ionic strength, pH value of system, extraction time and temperature were investigated. The limits of detection for Sudan I, II, III and IV were 5.45, 4.66, 3.68, 4.20 μg kg −1 , respectively. When the present method was applied to the analysis of candy samples, the recoveries of the analytes ranged from 82.3% to 112.1% and relative standard deviations were lower than 7.41%. [ABSTRACT FROM AUTHOR]

Cysteine (Cys) distribute widely in organisms as the crucial components of proteins, and play important roles in pathophysiological processes of human body. Low level of Cys might induce hepatic injury, edema and growth retardation, while superfluous level of Cys is found to be closely relevant to Alzheimer's and Parkinson's diseases. In this work, a novel near-infrared (NIR) fluorescent probe PFQ-C was developed for highly selective detection of Cys in living cells and mice by utilizing the cyclization removal reaction between acrylate group and Cys. The superior sensitivity (limit of detection, 0.036 μM), NIR emission (655 nm), large Stokes shift (135 nm) and low cytotoxicity of the probe highlight its broad potential for future clinical applications. The response mechanism of the probe towards Cys was clarified by spectroscopy, chromatography and theoretical calculation. In addition, results of fluorescence imaging of cells and mice revealed the good performance of the probe for monitoring the distributions and variations of Cys activity in vivo, which is very useful for the researches on diseases associated with Cys. [Display omitted] • A new probe PFQ-C with NIR emission and large Stokes shifts was synthesized. • Good water solubility and good specific recognition ability for Cys. • Cys in living cells and mice was detected. [ABSTRACT FROM AUTHOR]

Ionic liquid/anionic surfactant aqueous two-phase system was developed and applied for the extraction of sulfonamides in blood. High-performance liquid chromatography was applied to the determination of the analytes. The blood sample was centrifuged and added to sodium dodecyl sulfate (SDS), ionic liquid 1-Hexyl-3-MethylImidazolium Chloride([C 6 MIM] Cl), K 2 HPO 4 . After the resulting mixture was ultrasonically shaken and centrifuged, the aqueous two phase system was formed and analytes were extracted into the upper phase. The parameters affecting the extraction efficiency, such as volume of ionic liquid, amount of sodium dodecyl sulfate, ionic strength, pH value of system, extraction time and temperature were investigated. The limits of detection of Sulfamethyldiazine (SMZ), Sulfamethizole (STZ), sulfachlorpyridazine (SCP), sulfamethoxazole (SMX) and Sulfisoxazole (SSZ) were 3.29, 4.13, 3.74, 2.45 and 3.60 μg L − 1 , respectively. When the present method was applied to the analysis of real blood samples, the recoveries of analytes ranged from 85.5 to 110.9% and relative standard deviations were lower than 6.9%. [ABSTRACT FROM AUTHOR]

Carboxylesterases in human body play pivotal roles for catalyzing the hydrolysis of endogenous and exogenous substances such as lipids, thioesters and amides. Carboxylesterase-2 (CES2) as a major isoform of carboxylesterases is highly expressed in human digestive tract, and usually serves as an important mediator for pharmacokinetics and pharmacodynamics of ester medications or ester prodrugs. Therefore, developing effective strategies to detect and track CES2 in cells or tissues is of great significance for understanding its physiological and pharmacological effects on various diseases and therapeutic outcomes. In this study, we synthesized a fluorescent probe (CHQ-E) with near-infrared (NIR) excitation and emission maxima based on dihydroxanthene fluorophore for highly selective and sensitive detection of CES2. This probe exhibited rapid response (3 min), excellent sensitivity (detection limit = 0.35 ng/mL) and high binding affinity (K m = 9.4 μM) towards CES2, as well as low cytotoxicity towards living biosamples. Significantly, the maximum fluorescence excitation and emission wavelengths led to excellent optical properties of this probe including less photodamage, few autofluorescence and superior tissue penetration depth (180 µm). Moreover, CHQ-E has been applied to monitoring CES2 activity in drug-induced liver injury and its remediation models. Results of fluorescence imaging in vivo indicate the broad potential of CHQ-E for clinical diagnosis and evaluation of pharmaceuticals. [Display omitted] • Probe for detecting CES2 with both excitation and emission maxima at NIR region. • High sensitivity (LOD = 0.35 ng/mL) and short response time (3 min) to CES2. • Great tissue penetration depth (180 µm) for bioanalysis. [ABSTRACT FROM AUTHOR]

A green, efficient and easy sample pretreatment method of magnetic ionic liquid-based liquid-liquid microextraction (MIL-based LLME) combined with a sensitive, rapid and precise analytical method of ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC-QqQ/MS2) was developed to simultaneously - determining of neurotransmitters (NTs) in biosamples. Two magnetic ionic liquids (MILs), [P 6,6,6,14 ] 3 [GdCl 6 ] and [P 6,6,6,14 ] 2 [CoCl 4 ] tested, and the latter was selected as the extraction solvent due to its advantages of visual recognition, paramagnetic behavior and higher extraction efficiency. Facile magnetic separation of MIL containing analytes from matrix was realized by applying external magnetic field without rather than centrifugation. Experimental parameters that would influence the extraction efficiency, including type and amount of MIL, extraction time, speed of the vortex process, salt concentration, and environmental pH, were optimized obtained. The proposed method was successfully applied to the simultaneous extraction and determination of 20 NTs in human cerebrospinal fluid and plasma samples. Excellent analytical performance indicates the broad potential of this method for clinical diagnosis and therapy of neurological diseases. [Display omitted] • Facile extraction of neurotransmitters using magnetic ionic liquid. • Simultaneous determination of 20 neurotransmitters by tandem mass spectrometry. • Human cerebrospinal fluid and plasma sample were tested. [ABSTRACT FROM AUTHOR]

A simple extraction method based on acetonitrile-K 2 HPO 4 aqueous two-phase system was developed for separation and enrichment of five triazines in milk samples. Acetonitrile was used for extraction of analytes from milk sample and precipitation of milk protein. Deproteinization and extraction were achieved in one single step. Analytes were extracted into the upper phase of the aqueous two-phase system. The parameters affecting the extraction efficiency, such as the volume of acetonitrile, the type and amount of salts, pH value of sample and extraction time were investigated. The limits of detection of atraton, desmetryn, atrazine, terbumeton and terbuthylazine were 2.1, 2.6, 2.3, 2.8 and 2.5 μg/L, respectively. When the present method was applied to the analysis of real milk samples, the recoveries of analytes ranged from 86.3 to 120.6% and relative standard deviations were lower than 7.9%. [ABSTRACT FROM AUTHOR]