Multivariate analysis of NMR and FTIR data as a potential tool for the quality control of beer

In this work, principal component analysis (PCA) is applied to the FTIR-ATR and the (1)H NMR spectra of 50 beers differing in label and type (ale, lager, alcohol-free), to identify the spectral parameters that may provide rapid information about factors affecting beer production. PCA of FTIR data resulted in the separation of beers mainly according to their alcoholic content, providing little information on components other than ethanol contributing to the variability within the samples. PCA of (1)H NMR spectra, performed on the region where major beer components resonate (3.0-6.0 ppm), resulted in the separation of samples into four groups: two groups characterized by the predominance of dextrins, one group of alcohol-free beers characterized by the predominance of maltose, and one group where glucose was found to predominate. By performing PCA on aliphatic and aromatic regions, the contribution of minor components was highlighted. In particular, most ales, lagers, and alcohol-free samples could be distinguished based on their aromatic composition, thus reflecting the high sensitivity of the low-field NMR region toward different types of beer fermentation.     

分编业务外包过程中数据质量的控制

本文通过探讨分编业务外包过程中的种种冲突和矛盾,就分编过程中数据的质量控制问题给出了自己的一些看法和建议。     

Preliminary studies for the differentiation of apple juice samples by chemometric analysis of solid-phase microextraction-gas chromatographic data

A combination of gas chromatography (GC) and chemometrics was evaluated for its ability to differentiate between apple juice samples on the basis of apple variety and applied heat treatment. The heat treatment involved exposure of 15 mL juice samples for 30 s in a 900 W domestic microwave oven. The chromatographic results were subjected to two chemometric procedures: (1) partial least squares (PLS) regression and (2) linear discriminant analysis (LDA) applied to principal component (PC) scores. The percent correct classification of samples were obtained from PLS and LDA in terms of separation on the basis of apple variety and applied heat treatment. PLS gave the highest level of correct classification of the apple juice samples according to both variety and heat treatment, 92.5% correct classification in each case. When LDA was performed on the PC scores obtained from GC analysis, 87.5% and 80% of samples were correctly classified according to apple variety used and applied heat treatment, respectively.     

自动化网络化环境下的图书馆书目数据质量控制

严格把好图书分编质量关，提高用户检索效率，是图书馆编目部门应尽的责任，该文结合本人的工作实际，提出了加强图书馆书目数据质量控制的几点见解。     

Analysis of water quality data using spectral analysis

Considerable effort has been expended by many State, Federal and private agencies in collecting data by installing automatic water quality monitoring stations on many streams and estuaries. This work discusses techniques for analyzing the data and presents some results based on the analysis of monitoring stations along the Ohio, Detroit, Missouri, and Coosa Rivers. Autocorrelation, spectral estimates, cross correlation, amplitude of transfer function and coherence square have been evaluated to correlate a water quality variable measured at different positions or different variables measured at the same location. Results from the different rivers have been compared and some conclusions have been drawn.     

Multivariate curve resolution of spectrophotometric data for the determination of artificial food colors

In the analysis of food additives, past emphasis was put on the development of chromatographic techniques to separate target components from a complex matrix. Especially in the case of artificial food colors, direct spectrophotometric measurement was seen to lack in specificity due to a high spectral overlap between different components. Multivariate curve resolution (MCR) may be used to overcome this limitation. MCR is able to (i) extract from a complex spectral feature the number of involved components, (ii) attribute the resulting spectra to chemical compounds, and (iii) quantify the individual spectral contributions with or without a priori knowledge. We have evaluated MCR for the routine analysis of yellow and blue food colors in absinthe spirits. Using calibration standards, we were able to show that MCR equally performs as compared to partial least-squares regression but with much improved chemical information contained in the predicted spectra. MCR was then applied to an authentic collective of different absinthes. As confirmed by reference analytics, the food colors were correctly assigned with a sensitivity of 0.93 and a specificity of 0.85. Besides the artificial colors, the algorithm detected a further component in some samples that could be assigned to natural coloring from chlorophyll.     

矢栅一体化的作物品质监测与调优栽培系统集成研究

分析了当前矢量栅格数据一体化分析应用系统的集成方式，并根据基于遥感和地理信息系统的作物品质监测与调优栽培系统的需求，分析了矢栅一体化集成应用系统对GIS软件平台的要求；以上述分析为基础，以解决遥感、专业应用模型与地理信息系统之间的一体化集成分析为目标，研究了基于组件技术、空间数据技术和模型库管理系统技术的作物品质监测与调优栽培系统的开发与实现。     

Comparison of the ion exclusion chromatographic method with the Monier-Williams method for determination of total sulfite in foods

Experimental data comparing the alkali extraction/ion exclusion chromatographic method with the Monier-Williams method for determination of total sulfite are presented in (a) enzymatic and nonenzymatic browning systems, (b) vegetables containing naturally occurring sulfite, and (c) a carbohydrate-type food additive, erythorbic acid. Excellent agreement, with a linear correlation coefficient of 0.99, was observed in fresh potato samples homogenized with sulfite and allowed to react for different time intervals (enzymatic browning system). A good overall correlation was observed in dehydrated, sulfited apple samples heated for different times (nonenzymatic browning system); however, as heating time increased, higher results were obtained by the Monier-Williams method than by the alkali extraction/ion exclusion chromatographic method. The results of determining sulfite in the alkali trapping solution following acid distillation or acid treatment without heat suggested that this deviation was due to a fraction of sulfite bound to the browning reaction products in such a way that it was released by acid distillation but not by alkali extraction or acid treatment without heat. Similar behavior was demonstrated in cabbage with naturally occurring sulfite, which was released by acid distillation but not by alkali extraction or acid treatment without heat. The ion exclusion chromatographic method could overcome interference by the volatile caramelization reaction products in the Monier-Williams determination of erythorbic acid.     

Gas chromatographic organic acid profiling analysis of brandies and whiskeys for pattern recognition analysis

An efficient gas chromatographic profiling and pattern recognition method is described for brandy and whiskey samples according to their organic acid contents. It involves solid-phase extraction of organic acids using Chromosorb P with subsequent conversion to stable tert-butyldimethylsilyl derivatives for the direct analysis by capillary column gas chromatography and gas chromatography-mass spectrometry. A total of 12 organic acids were reproducibly identified in liquor samples (1 mL). When the GC profiles were simplified to their retention index spectra, characteristic patterns were obtained for each liquor sample as well as for each group average. Stepwise discriminant analysis provided star symbols characteristic for each liquor sample and group average. As expected, canonical discriminant analysis correctly classified 23 liquor samples studied into two groups of either brandy or whiskey.     

Comparison of Carr-Price analysis and liquid chromatographic analysis for vitamin A in fortified milk

The determination of the vitamin A concentration in fortified milk was compared using Carr-Price analysis and liquid chromatography (LC). Carr-Price analysis required saponification of the sample with alcoholic potassium hydroxide, extraction with ether, and colorimetry with antimony trichloride in chloroform. LC analysis required hexane extraction of a 71% alcohol-sample solution and centrifugation at 2000 rpm. A 100 microL aliquot of the extract was analyzed on a LiChrosorb Si-60, 5 micron column, using an ethyl ether-hexane (2 + 98) mobile phase and detection at 313 nm. Each method was statistically evaluated for precision and sample-to-sample reproducibility. The LC extraction procedure was examined for efficiency. Each LC value was divided by the Carr-Price value obtained for the same sample; an average value of 0.975 with a coefficient of variation of 6.90% was obtained. It was concluded that the procedures were statistically equivalent.