Lignin detaching from the oxidative delignified softwood during enzymatic hydrolysis and its effect on carbohydrate saccharification.

Most studies about the influence of lignin on enzymatic digestibility of lignocellulose have focused on the content and properties, but less on the detaching behavior of lignin. The samples were prepared from Pinus massoniana wood chips by kraft cooking followed by delignification using oxygen/alkali (KP-O) and chlorine dioxide (KP-D), respectively. Two oxidative delignified samples with a similar lignin content were subject to enzymatic hydrolysis at both pH of 5.0 and 5.5 to investigate the effects of lignin detached rate (LDR) on substrate enzymatic digestibility (SED). The LDRs and the SEDs from both samples increased with the enzymatic hydrolysis time, and the situations of KP-D were much higher than those of KP-O under the same enzymatic hydrolysis time. The results of enzymatic hydrolysis at an elevated pH of 5.5 and the changes in concentration of free cellulase of the two samples indicated that the lignin detaching increased the free cellulase concentration, and thus promoted the enzymatic digestibility. Moreover, lignin distribution analysis by X-ray photoelectric spectroscopy and confocal laser scanning microscopy indicated surface lignin being preferentially detached. This work provided a reference for rationally designing pretreatment strategies, which can improve the efficiency of enzyme hydrolysis of lignocellulosic biomass.

A novel and robust analytical method for the quantification of perospirone in human plasma using an LC-MS/MS system with self-internal standard calibration.

OBJECTIVES: This study aims to establish a novel method for measuring perospirone in human plasma for therapeutic drug monitoring (TDM) by liquid chromatography-mass spectrometry (LC-MS) coupled with an automatic liquid chromatograph mass spectrometer coupler 9500 (LC-MS/MS-Mate 9500), which has been equipped with self-internal standard (SIS) calibration technology. DESIGN & METHODS: A novel and attractive analytical calibration method designed for perospirone, calibration with SIS, was reported. After protein precipitation with acetonitrile-cyclopentanol (9:1, v/v) containing 1% NH3·H2O, LC-MS quantification of perospirone was performed by multiple reaction monitoring in the positive mode with quantitative and qualitative analysis of the ion pairs m/z 427.30 â†’ 177.15 and 427.30 â†’ 166.15 for perospirone and SIS. Chromatographic separation was accomplished in < 2.0 min on an Hypersil GOLDTM C18 column (2.1 mm × 50 mm, 3.0 µm) using a mobile methanol phase and 0.1% formic acid in water. RESULTS: This method showed good selectivity because no interfering peaks were observed in the plasma samples during the 2.0-min run time. The calibration curve range was 0.05-20 ng/mL, with a correlation coefficient of ≥ 0.9995. Intraday and interday accuracies were 98.3%-107.9%, respectively, with precision relative standard deviation values of < 10%. The matrix effects ranged from 92.7% to 96.1%, and extraction recoveries were between 97.3% and 108.8%. Finally, this method was successfully applied to routine clinical TDM for 142 patients. The perospirone plasma concentrations of the patients ranged between 0.07 and 10.96 ng/mL. CONCLUSIONS: This bioanalytical method can be used for the quantification of perospirone in human plasma by LC-MS/MS-Mate 9500 using perospirone itself as the SIS.

Adsorption behavior of two glucanases on three lignins and the effect by adding sulfonated lignin.

The adsorption behaviors of two glucanases, TvEG and TrCel7A, on three lignins were investigated. Three lignins were isolated from raw aspen and its pretreated solid residue. The isolated lignins were labeled as Asp-MWL, DA-MWL (pretreated by dilute acid), and GL-MWL (pretreated by green liquor), respectively. The surface properties of lignins and spin-coated lignin films were characterized by zeta potential, atomic force microscope (AFM) and contact angle. The enzyme adsorption behavior was monitored by quartz crystal microbalance (QCM) and fluorescence spectrometer. TlCel7A had similar adsorption capacities on the three lignin films but were higher than those of TvEG. The TrCel7A adsorptions on the three lignin films were affected by synergistic effect of electrostatic and hydrophobic interaction while the TvEG adsorptions on the three lignin films were mainly dominated by hydrophobic action. The adsorption capacities of TlCel7A and TvEG on the three lignin films were decreased by adding SL. Plausible explanation was that the SL and glucanase formed a complex with more negative charges, which suppressed the adsorption of glucannase on lignin through electrostatic repulsion. It also explained the improved enzymatic hydrolysis efficiency of lignocellulose upon adding SL.