Salting-out assisted liquid-liquid extraction (SALLE) applies the salting-out effect to separate water-miscible organic solvent such as acetonitrile from plasma or other aqueous biofluids, and can extract a wide range of drug and metabolites, including many hydrophilic compounds. In most cases, the separated organic phase can be directly injected for bioanalysis, or with a simple dilution. SALLE provides similar simplicity to protein precipitation, but cleaner extracts due to a true phase separation. SALLE is also faster, more environmentally friendly and more cost-efficient than conventional liquid-liquid extraction and SPE. Through 96-well automation, SALLE can be easily integrated into the overall high-throughput LC-MS/MS bioanalysis strategy to increase productivity. This article provides a critical overview of the literatures on SALLE and perspectives of the future bioanalytical application of this often overlooked extraction technique. Important parameters impacting SALLE-LC-MS/MS assays are also discussed.

The chitosan-based coating with antimicrobial agent has been developed recently to control the decay of fruits. However, its fresh keeping and antimicrobial mechanism is still not very clear. The preservation mechanism of chitosan coating with cinnamon oil for fruits storage is investigated in this paper. Results in the atomic force microscopy sensor images show that many micropores exist in the chitosan coating film. The roughness of coating film is affected by the concentration of chitosan. The antifungal activity of cinnamon oil should be mainly due to its main consistent trans-cinnamaldehyde, which is proportional to the trans-cinnamaldehyde concentration and improves with increasing the attachment time of oil. The exosmosis ratios of Penicillium citrinum and Aspergillus flavus could be enhanced by increasing the concentration of cinnamon oil. Morphological observation indicates that, compared to the normal cell, the wizened mycelium of A. flavus is observed around the inhibition zone, and the growth of spores is also inhibited. Moreover, the analysis of gas sensors indicate that the chitosan-oil coating could decrease the level of O2 and increase the level of CO2 in the package of cherry fruits, which also control the fruit decay. These results indicate that its preservation mechanism might be partly due to the micropores structure of coating film as a barrier for gas and a carrier for oil, and partly due to the activity of cinnamon oil on the cell disruption.

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Ultrafast liquid chromatography/tandem mass spectrometry (LC/MS/MS) bioanalysis was demonstrated with the use of packed silica columns operated under elevated flow rates. A special effort has been made to achieve ultrafast analysis without sacrificing chromatographic resolution. Two multiple analyte/metabolites assays, (1) morphine/morphine-6-glucuronide(M6G)/morphine-3-glucuronide(M3G) and (2) midazolam/1'-hydroxymidazolam/4-hydroxymidazolam, were used to demonstrate the speed, sensitivity, peak shape and separation of the ultrafast methods utilizing silica columns. In both methods adequate chromatographic separation was a necessity because quantitation results would be otherwise compromised due to cross interference between different selected reaction monitoring (SRM) transitions. Baseline resolutions between morphine, M6G and M3G in human plasma extracts were achieved within 30 s on a 50 x 3 mm Betasil silica column operated at 4 mL/min of isocratic acetonitrile/water mobile phase. The total injection-to-injection cycle time was 48 s with a simple, single-autosampler/single-column setup, when a Shimadzu SIL-HT autosampler was used. Baseline resolution between 1'-hydroxymidazolam and 4-hydroxymidalolam in monkey plasma extracts was achieved within 33 s using similar conditions. Due to the absence of carry-over in this case, no rinsing of the injection needle was necessary, resulting in a cycle time of only 39 s/sample. These ultrafast methods were successfully used to analyze extracted biological samples and proved to be reproducible, reliable and generated equivalent pharmaco-kinetic (PK) results to those obtained by regular flow LC/MS/MS analysis to support discovery PK studies.

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