The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Shuting Zhang - One of the best experts on this subject based on the ideXlab platform.
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preparative high speed counter current chromatography separation of grape seed proanthocyanidins according to Degree of Polymerization
Food Chemistry, 2017Co-Authors: Shuting Zhang, Lingxi Li, Yuanyuan Li, Peiyu ZhouAbstract:Abstract Separation of plant proanthocyanidins remains a major challenge for scientists due to the structural diversity and complexity. In this work, a new and effective method was developed for preparative separation of grape seed proanthocyanidins (GSPs) according to Degree of Polymerization (DP) by high-speed counter-current chromatography (HSCCC). Under the optimized HSCCC conditions, GSPs could be separated into seven distinct fractions (F1–F7) with mean Degree of Polymerization in increasing order, from 1.44 to 6.95. High yields for these fractions (53.7, 12.2, 29.5, 30.2, 11.2, 50.8 and 169.8 mg, respectively) were achieved by only one-step HSCCC of 400 mg of GSPs. Further, seventeen individual proanthocyanidins, most of which are commercially not available, were efficiently isolated by re-chromatography on HSCCC or prep-HPLC; each of the isolated compounds presented high yields (7.1–78.9 mg) and high purity (70.0–95.7%). The positive correlation was observed between DP and antioxidant activity of proanthocyanidins.
Peiyu Zhou - One of the best experts on this subject based on the ideXlab platform.
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preparative high speed counter current chromatography separation of grape seed proanthocyanidins according to Degree of Polymerization
Food Chemistry, 2017Co-Authors: Shuting Zhang, Lingxi Li, Yuanyuan Li, Peiyu ZhouAbstract:Abstract Separation of plant proanthocyanidins remains a major challenge for scientists due to the structural diversity and complexity. In this work, a new and effective method was developed for preparative separation of grape seed proanthocyanidins (GSPs) according to Degree of Polymerization (DP) by high-speed counter-current chromatography (HSCCC). Under the optimized HSCCC conditions, GSPs could be separated into seven distinct fractions (F1–F7) with mean Degree of Polymerization in increasing order, from 1.44 to 6.95. High yields for these fractions (53.7, 12.2, 29.5, 30.2, 11.2, 50.8 and 169.8 mg, respectively) were achieved by only one-step HSCCC of 400 mg of GSPs. Further, seventeen individual proanthocyanidins, most of which are commercially not available, were efficiently isolated by re-chromatography on HSCCC or prep-HPLC; each of the isolated compounds presented high yields (7.1–78.9 mg) and high purity (70.0–95.7%). The positive correlation was observed between DP and antioxidant activity of proanthocyanidins.
Harold H Schmitz - One of the best experts on this subject based on the ideXlab platform.
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high performance liquid chromatography separation and purification of cacao theobroma cacao l procyanidins according to Degree of Polymerization using a diol stationary phase
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Mark A Kelm, Chris J Johnson, Rebecca J Robbins, John F Hammerstone, Harold H SchmitzAbstract:A new chromatographic approach for separating cacao procyanidins according to their Degree of Polymerization has been developed. It utilizes diol stationary phase columns operating in normal phase mode with a binary gradient of acidified acetonitrile and methanol-water. Performance of the diol stationary phase was evaluated on an analytical scale utilizing classical chromatographic conditions for the normal phase separation of procyanidins according to their Degree of Polymerization. The new separation approach was developed on an analytical scale but further extended to the preparative scale. These newly developed analytical and preparative high-performance liquid chromatography procedures were successfully applied to the separation, as well as isolation, of cacao procyanidins from unfermented cacao seeds. The Degree of Polymerization associated with each molecular weight fraction was determined by mass spectrometry.
Maria Fernanda Pimentel - One of the best experts on this subject based on the ideXlab platform.
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determination of Degree of Polymerization of insulating paper using near infrared spectroscopy and multivariate calibration
Vibrational Spectroscopy, 2010Co-Authors: Edmilson Oliveira Dos Santos, Andrea Monteiro Santana Silva, Wallace D Fragoso, Celio Pasquini, Maria Fernanda PimentelAbstract:Abstract A simple alternative method to determine the Degree of Polymerization (DP) in transformer insulating papers, using near infrared spectroscopy (NIR), was developed to reduce the costs and the analysis time of the conventional method. Seventy-five samples of Kraft, crepe and cardboard types of paper, in different stages of degradation (DP varying between 200 and 900 units) were collected from transformers over a period of 3 years. The sample set was analyzed according to the conventional method to compare with the proposed alternative spectroscopic method. The spectra were obtained by diffuse reflectance using the spectral range between 1260 and 2500 nm. Some pre-processing strategies of the spectral data were evaluated and the best results were obtained when the derivatives spectra were used (Savitzky–Golay algorithm employing a 21 point window). NIR spectroscopy combined with partial least squares regression method revealed a simple and fast technique to determine the DP of the papers. The prediction error of 83, obtained after external validation, is acceptable for evaluation of the remaining useful life of insulating paper.
Haining Na - One of the best experts on this subject based on the ideXlab platform.
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hydrolysis behavior of regenerated celluloses with different Degree of Polymerization under microwave radiation
Bioresource Technology, 2015Co-Authors: Jinping Ni, Na Teng, Haizhen Chen, Jinggang Wang, Haining NaAbstract:Abstract This work studied the hydrolysis behavior of regenerated celluloses (RCs) with different Degree of Polymerization (DP) by using the catalyst of dilute acid under microwave radiation. Results showed that the DP had a considerable influence on hydrolysis of cellulose. The reactivity of RCs was significantly improved when DP was lower than 51. The highest sugar yield of 59.2% was achieved from RC with lowest DP of 23 at 160 °C for 15 min. But the lowest yield of 32.6% was obtained when RC with highest DP of 132 was used. Recrystallization of cellulose was found to hinder the further hydrolysis particularly with the high DP. The effect of recrystallization can be reduced by the decrease of DP of RCs. This research demonstrates that the DP of RCs plays a crucial role on hydrolysis and it provides a preliminary guide based on DP to find a suitable pretreatment method for cellulose hydrolysis.