Folin Ciocalteu (F-C) assay is the most widely used and convenient method to determine the total phenolics content in foods, herbs, and other plant extracts. Different phenolics standards such as gallic acid, ferulic ...Folin Ciocalteu (F-C) assay is the most widely used and convenient method to determine the total phenolics content in foods, herbs, and other plant extracts. Different phenolics standards such as gallic acid, ferulic acid, chlorogenic acid, catechol, and vanillic acid have been used for calibration curves in this assay method. Comparison of these standards, in single or combination of two or more, for more accurate determination of phenolics has not been reported so far. This study tested five single phenolics and seven combinations of mixed phenolic standards to evaluate the optimal standards for F-C method. The different standards were tested to calculate the phenolic content in three known test solutions. We also evaluated interference effect of various compounds in phenolics estimation by F-C method that is usually present in the lignocellulosic biomass-derived sugar solution, and in food products along with phenolics. Finally, the optimal standards with five phenolics were used for the determination of phenolics in alkali pretreated biomass extract. The results indicated that gallic acid was the best standard among the single phenolic compounds and five phenolic compounds solution was the best standard among the mixed phenolic solutions. The presence of glucose, HMF, furfural, and vitamin-B12 did not interfere in phenolic determination;whereas ascorbic acid, tyrosine, formic acid, and acetic acid strongly interfered the results. The results also showed that biomass pelleting process did not affect the generation of phenolics in alkali pretreatment extract.展开更多
选取150份干扰物和浓度不同的葡萄糖样本数据,按照全干扰、缺失胆固醇、缺失乳酸、缺失白蛋白和缺失尿素将数据划分5个子集。每个子集进行卷积平滑滤波法(Savitzky-Golay smoothing,SG)处理后,建立偏最小二乘回归(Partial Least Squares...选取150份干扰物和浓度不同的葡萄糖样本数据,按照全干扰、缺失胆固醇、缺失乳酸、缺失白蛋白和缺失尿素将数据划分5个子集。每个子集进行卷积平滑滤波法(Savitzky-Golay smoothing,SG)处理后,建立偏最小二乘回归(Partial Least Squares Regression,PLSR)模型。利用克拉克误差网格(Clarke Error Grid,CEG)及t检验分析4种干扰物对葡萄糖预测影响。结果表明,子集1~5对应模型预测集相关系数(Correlation Coefficient of Prediction,R p)分别为0.9131、0.7115、0.7624、0.8578和0.8658,预测集均方根误差(Root Mean Square Error of Prediction,RMSEP)分别为54.8993、239.5512、162.3715、133.9682和106.0521 mg/dL。5个子集位于CEG的A+B区分别为100%、71.43%、66.66%、85.71%和88.89%。t检验中每1 mg/dL的胆固醇、乳酸和白蛋白分别使葡萄糖预测值降低5.288 mg/dL、增高2.214 mg/dL和增高0.031 mg/dL。故胆固醇和乳酸的影响相当显著,其次是白蛋白,而尿素的影响则相对较弱。因此,在中红外血糖定量分析中必须考虑胆固醇、乳酸和白蛋白对血糖检测的影响。展开更多
Inductively coupled plasma mass spectrometry （ICP-MS） is the most commonly used technique to deter- mine the abundances of trace elements in a wide range of geological materials. However, incomplete sample digestion...Inductively coupled plasma mass spectrometry （ICP-MS） is the most commonly used technique to deter- mine the abundances of trace elements in a wide range of geological materials. However, incomplete sample digestion, isobaric interferences and instrumental drift remain obvious problems that must be overcome in order to obtain precise and accurate results, For this reason, we have done many experi- ments and developed a set of simple, cost-effective and practical methods widely applicable for precise and rapid determination of trace element abundances in geological materials using ICP-MS. Commonly used high-pressure digestion technique is indeed effective in decomposing refractory phases, but this inevitably produces fluoride complexes that create new problems. We demonstrate that the fluoride complexes formed during high-pressure digestion can be readily re-dissolved using high-pressure vessel at 190 ℃ for only 2 h for 50 mg sample. In the case of isobaric interferences, although oxide （e.g., MO^＋/M^＋） and hydroxide （e.g., MO^＋/M^＋） productivity is variable between runs, the （MO^＋/M^＋）/（CeO^＋/Ce^＋） and （MOH^＋/M^＋）/（CeO^＋/Ce^＋） ratios remain constant, making isobaric interference correction for all other elements of interest straightforward, for which we provide an easy-to-use off-line procedure. We also show that mass-time-intensity drift curve is smooth as recognized previously, for which the correction can be readily done by analyzing a quality-control （QC） solution and using off-line Excel VBA procedure without internal standards. With these methods, we can produce data in reasonable agreement with rec- ommended values of international rock reference standards with a relative error of 〈8% and precision generally better than 5%. Importantly, compared to the widely used analytical practice, we can effectively save 〉60% of time （e.g., 〈24 h vs. 〉60 h）.展开更多
Here we refer the native language to Chinese and the second language to English especially college English. According to linguistic study, there are certain native language interferences in secondlanguage acquisition...Here we refer the native language to Chinese and the second language to English especially college English. According to linguistic study, there are certain native language interferences in secondlanguage acquisition when one is learning the second language,i. e. when a Chinese is learningEnglish, due to the influence of mother tongue which is habitually applied in learning the second language, his pronounciation, his grammar and his vocabulary are quite likely influencedor interfered by his native language or his dialect. Unfortunately, we did find certain first language interferences in our English teaching and learning processes on various items or subjects.展开更多
文摘Folin Ciocalteu (F-C) assay is the most widely used and convenient method to determine the total phenolics content in foods, herbs, and other plant extracts. Different phenolics standards such as gallic acid, ferulic acid, chlorogenic acid, catechol, and vanillic acid have been used for calibration curves in this assay method. Comparison of these standards, in single or combination of two or more, for more accurate determination of phenolics has not been reported so far. This study tested five single phenolics and seven combinations of mixed phenolic standards to evaluate the optimal standards for F-C method. The different standards were tested to calculate the phenolic content in three known test solutions. We also evaluated interference effect of various compounds in phenolics estimation by F-C method that is usually present in the lignocellulosic biomass-derived sugar solution, and in food products along with phenolics. Finally, the optimal standards with five phenolics were used for the determination of phenolics in alkali pretreated biomass extract. The results indicated that gallic acid was the best standard among the single phenolic compounds and five phenolic compounds solution was the best standard among the mixed phenolic solutions. The presence of glucose, HMF, furfural, and vitamin-B12 did not interfere in phenolic determination;whereas ascorbic acid, tyrosine, formic acid, and acetic acid strongly interfered the results. The results also showed that biomass pelleting process did not affect the generation of phenolics in alkali pretreatment extract.
基金supported by National Natural Science Foundation of China(41130314 and 41630968)Chinese Academy of Sciences Innovation Grant(Y42217101L)+1 种基金Qingdao National Laboratory for Marine Science and Technology(2015ASKJ03)Marine Geological Process and Environment(U1606401)
文摘Inductively coupled plasma mass spectrometry （ICP-MS） is the most commonly used technique to deter- mine the abundances of trace elements in a wide range of geological materials. However, incomplete sample digestion, isobaric interferences and instrumental drift remain obvious problems that must be overcome in order to obtain precise and accurate results, For this reason, we have done many experi- ments and developed a set of simple, cost-effective and practical methods widely applicable for precise and rapid determination of trace element abundances in geological materials using ICP-MS. Commonly used high-pressure digestion technique is indeed effective in decomposing refractory phases, but this inevitably produces fluoride complexes that create new problems. We demonstrate that the fluoride complexes formed during high-pressure digestion can be readily re-dissolved using high-pressure vessel at 190 ℃ for only 2 h for 50 mg sample. In the case of isobaric interferences, although oxide （e.g., MO^＋/M^＋） and hydroxide （e.g., MO^＋/M^＋） productivity is variable between runs, the （MO^＋/M^＋）/（CeO^＋/Ce^＋） and （MOH^＋/M^＋）/（CeO^＋/Ce^＋） ratios remain constant, making isobaric interference correction for all other elements of interest straightforward, for which we provide an easy-to-use off-line procedure. We also show that mass-time-intensity drift curve is smooth as recognized previously, for which the correction can be readily done by analyzing a quality-control （QC） solution and using off-line Excel VBA procedure without internal standards. With these methods, we can produce data in reasonable agreement with rec- ommended values of international rock reference standards with a relative error of 〈8% and precision generally better than 5%. Importantly, compared to the widely used analytical practice, we can effectively save 〉60% of time （e.g., 〈24 h vs. 〉60 h）.
文摘Here we refer the native language to Chinese and the second language to English especially college English. According to linguistic study, there are certain native language interferences in secondlanguage acquisition when one is learning the second language,i. e. when a Chinese is learningEnglish, due to the influence of mother tongue which is habitually applied in learning the second language, his pronounciation, his grammar and his vocabulary are quite likely influencedor interfered by his native language or his dialect. Unfortunately, we did find certain first language interferences in our English teaching and learning processes on various items or subjects.
