Ultrasonic Assisted Extraction of Paclitaxel from Taxus x media Using Ionic Liquids as Adjuvants: Optimization of the Process by Response Surface Methodology.

(1) Background: Ionic liquids (ILs) are considered "green" solvents and have been widely used in the extraction and separation field in recent years; (2) Methods: In this study, some common ILs and functionalized magnetic ionic liquids (MILs) were used as adjuvants for the solvent extraction of paclitaxel from Taxus x media (T. x media) using methanol solution. The extraction conditions of methanol concentration, IL type and amount, solid-liquid ratio, extraction temperature, and ultrasonic irradiation time were investigated in single factor experiments. Then, three factors of IL amount, solid-liquid ratio, and ultrasonic irradiation time were optimized by response surface methodology (RSM); (3) Results: The MIL [C4MIM]FeCl3Br was screened as the optimal adjuvant. Under the optimization conditions of 1.2% IL amount, 1:10.5 solid-liquid ratio, and 30 min ultrasonic irradiation time, the extraction yield reached 0.224 mg/g; and (4) Conclusions: Compared with the conventional solvent extraction, this ultrasonic assisted extraction (UAE) using methanol and MIL as adjuvants can significantly improve the extraction yield, reduce the use of methanol, and shorten the extraction time, which has the potentiality of being used in the extraction of some other important bioactive compounds from natural plant resources.

Gas chromatography/negative chemical ionization mass spectrometry of transfluthrin in rat plasma and brain.

RATIONALE: Transfluthrin is a relatively non-toxic rapid-acting synthetic pyrethroid insecticide. It is widely used in household and hygiene products. A sensitive and accurate bioanalytical method is required for quantification of its concentration in plasma and its potential target organ, the brain for studies to assess its health effects and toxicokinetics in mammals. METHODS: The samples were prepared by liquid-liquid extraction. Gas chromatography mass spectrometry (GC/MS) analysis was performed for the determination of transfluthrin in biological samples with an overall method run time of 15 min. Transfluthrin was quantified using selected-ion monitoring (SIM) in the negative chemical ionization (NCI) mode. Chromatographic separation was achieved using a Zebron® ZB5-MS GC column operating with 1 mL/min constant flow helium. Cis-Permethrin was used as the internal standard. RESULTS: The method was validated to be precise and accurate within the linear range of 1.0-400.0 ng/mL in plasma and 4.0-400.0 ng/mL in brain homogenate, based on a 100 µL sample volume for both matrices. This method was applied to samples following administration of a 10 mg/kg oral dose to male adult rats. The plasma concentrations were observed to be 11.70 ± 5.69 ng/mL and brain concentrations 12.09 ± 3.15 ng/g when measured 2 h post-dose. CONCLUSIONS: A rapid GC/NCI-MS method was demonstrated to be sensitive, specific, precise and accurate for the quantification of transfluthrin in rat plasma and brain. The optimized method was successfully used to quantify the rat plasma and brain concentrations of transfluthrin 2 h after the oral dosing of Sprague-Dawley rats.

FAST: Size-Selective, Clog-Free Isolation of Rare Cancer Cells from Whole Blood at a Liquid-Liquid Interface.

Circulating tumor cells (CTCs) have great potential to provide minimally invasive ways for the early detection of cancer metastasis and for the response monitoring of various cancer treatments. Despite the clinical importance and progress of CTC-based cancer diagnostics, most of the current methods of enriching CTCs are difficult to implement in general hospital settings due to complex and time-consuming protocols. Among existing technologies, size-based isolation methods provide antibody-independent, relatively simple, and high throughput protocols. However, the clogging issues and lower than desired recovery rates and purity are the key challenges. In this work, inspired by antifouling membranes with liquid-filled pores in nature, clog-free, highly sensitive (95.9 ± 3.1% recovery rate), selective (>2.5 log depletion of white blood cells), rapid (>3 mL/min), and label-free isolation of viable CTCs from whole blood without prior sample treatment is achieved using a stand-alone lab-on-a-disc system equipped with fluid-assisted separation technology (FAST). Numerical simulation and experiments show that this method provides uniform, clog-free, ultrafast cell enrichment with pressure drops much less than in conventional size-based filtration, at 1 kPa. We demonstrate the clinical utility of the point-of-care detection of CTCs with samples taken from 142 patients suffering from breast, stomach, or lung cancer.

Characterization of matrix effects in developing rugged high-throughput LC-MS/MS methods for bioanalysis.

AIM: There is an ever-increasing demand for high-throughput LC-MS/MS bioanalytical assays to support drug discovery and development. RESULTS: Matrix effects of sofosbuvir (protonated) and paclitaxel (sodiated) were thoroughly evaluated using high-throughput chromatography (defined as having a run time ≤1 min) under 14 elution conditions with extracts from protein precipitation, liquid-liquid extraction and solid-phase extraction. A slight separation, in terms of retention time, between underlying matrix components and sofosbuvir/paclitaxel can greatly alleviate matrix effects. CONCLUSION: High-throughput chromatography, with proper optimization, can provide rapid and effective chromatographic separation under 1 min to alleviate matrix effects and enhance assay ruggedness for regulated bioanalysis.

Development and validation of a UPLC-MS/MS method for the determination of cucurbitacin B in rat plasma and application to a pharmacokinetic study.

Cucurbitacin B (CuB), one of the most abundant forms of cucurbitacins, is a promising natural anticancer drug candidate. Although the anticancer activity of CuB has been well demonstrated, information regarding the pharmacokinetics is limited. A rapid, selective and sensitive UPLC-MS/MS for CuB was developed and validated using hemslecin A (HeA) as internal standard (IS). Plasma samples were pre-treated by liquid-liquid extraction with dichloromethane. Separation was achieved on a reversed-phase C18 column (50 × 4.6 mm, 5 µm) at 35°C using isocratic elution with water-methanol (25:75, v/v) at a flow rate of 0.3 mL/min. The analytes were monitored by a triple quadrupole tandem mass spectrometer with positive electrospray ionization mode. The calibration curve was linear (r > 0.995) in a concentration range of 0.3-100 ng/mL with a limit of quantification of 0.3 ng/mL. Intra- and inter-day accuracy and precision were validated by percentage relative error and relative standard deviation, respectively, which were both lower than the limit of 15%. This assay was successfully applied to a pharmacokinetic study of CuB in Wistar rats.

Comprehensive Urine Drug Screen by Gas Chromatography/Mass Spectrometry (GC/MS).

Drug screening is an essential component of clinical toxicology laboratory service. Some laboratories use only automated chemistry analyzers for limited screening of drugs of abuse and few other drugs. Other laboratories use a combination of various techniques such as immunoassays, colorimetric tests, and mass spectrometry to provide more detailed comprehensive drug screening. Mass spectrometry, gas or liquid, can screen for hundreds of drugs and is often considered the gold standard for comprehensive drug screening. We describe an efficient and rapid gas chromatography/mass spectrometry (GC/MS) method for comprehensive drug screening in urine which utilizes a liquid-liquid extraction, sample concentration, and analysis by GC/MS.