A completely automatic apparatus has been developed for the preparative-scale purification of compounds by gas-liquid chromatography. A clock timer periodically activates a pump that injects a sample into the column. The recording potentiometer on which the chromatogram is traced has a switch mounted at the upper margin. Collection of the purified main component occurs when the recorder pen goes to the end of the scale and trips the switch. The sensitivity of the detector bridge circuit is adjusted so that only the trace caused by the major component will activate the collection process. Toluene, ethylbenzene, and mesitylene were purified with the apparatus. Best results were obtained with toluene. In one pass through the apparatus, 92 percent of the impurities were removed from the toluene and the purified product was collected at a rate of 25 ml of liquid per day.
{"title":"Purification by Automatic Gas Chromatography","authors":"M. Tenenbaum, F. Howard","doi":"10.6028/jres.066A.026","DOIUrl":"https://doi.org/10.6028/jres.066A.026","url":null,"abstract":"A completely automatic apparatus has been developed for the preparative-scale purification of compounds by gas-liquid chromatography. A clock timer periodically activates a pump that injects a sample into the column. The recording potentiometer on which the chromatogram is traced has a switch mounted at the upper margin. Collection of the purified main component occurs when the recorder pen goes to the end of the scale and trips the switch. The sensitivity of the detector bridge circuit is adjusted so that only the trace caused by the major component will activate the collection process. Toluene, ethylbenzene, and mesitylene were purified with the apparatus. Best results were obtained with toluene. In one pass through the apparatus, 92 percent of the impurities were removed from the toluene and the purified product was collected at a rate of 25 ml of liquid per day.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"201 1","pages":"255 - 258"},"PeriodicalIF":0.0,"publicationDate":"1962-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75986413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recent publications from this laboratory describe some unusual properties, such as crimping and helical coiling, induced by heterogeneous, chemical crosslinking of polycaprolactam fibers. The following crosslinks are involved: It has been found that the —CH2—groups in these crosslinks can be hydrolyzed to yield one equivalent of formaldehyde for each equivalent of hydrolyzable methylene group. This permits the application of the chromotropic acid method for determining formaldehyde to the estimation of the number of crosslinks in the fiber, when used in conjunction with a previously reported conductometric method for the determination of sulfhydryl groups. A general method has been worked out, with special attention to sulfur-containing degradation products (of the crosslinks) that may interfere with the analysis.
{"title":"Determination of Methylene Groups in Disulfide and Methylene Sulfide Crosslinks in Polycaprolactam Fibers","authors":"S. D. Bruck","doi":"10.6028/jres.066A.025","DOIUrl":"https://doi.org/10.6028/jres.066A.025","url":null,"abstract":"Recent publications from this laboratory describe some unusual properties, such as crimping and helical coiling, induced by heterogeneous, chemical crosslinking of polycaprolactam fibers. The following crosslinks are involved: It has been found that the —CH2—groups in these crosslinks can be hydrolyzed to yield one equivalent of formaldehyde for each equivalent of hydrolyzable methylene group. This permits the application of the chromotropic acid method for determining formaldehyde to the estimation of the number of crosslinks in the fiber, when used in conjunction with a previously reported conductometric method for the determination of sulfhydryl groups. A general method has been worked out, with special attention to sulfur-containing degradation products (of the crosslinks) that may interfere with the analysis.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"40 1","pages":"251 - 254"},"PeriodicalIF":0.0,"publicationDate":"1962-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86370342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A set of best values for the temperatures and enthalpies of fusion and transition for the n-paraffins is presented. From an analysis of these data a general qualitative theory of the phase behavior of the n-paraffins is developed. Four distinct crystal structures—hexagonal, triclinic, monoclinic, and orthorhombic—describe the solid phases of all n-paraffins with more than nine carbon atoms in the chain. The latter two structures become equivalent at longer chain lengths. Odd-even differences are resolved in terms of reasonable differences in end group packing, and the smooth increase in melting and transition temperature with increasing chain length is attributed to a decrease in the ratio of end groups to chain groups. Double transitions are predicted for several pure n-paraffins above n-C34H70. Impurity effects are isolated from the pure n-paraffin properties and discussed. The equation, TM(°K) = 414.3 (n−1.5)/(n + 5.0) is presented as a correct description of the melting temperatures (TM) of all n-paraffins above n-C44H90. Sufficient data to permit an accurate extrapolation of the enthalpies and entropies of fusion to the infinite-chain limit are not available.
{"title":"An Analysis of the Solid Phase Behavior of the Normal Paraffins","authors":"M. Broadhurst","doi":"10.6028/jres.066A.024","DOIUrl":"https://doi.org/10.6028/jres.066A.024","url":null,"abstract":"A set of best values for the temperatures and enthalpies of fusion and transition for the n-paraffins is presented. From an analysis of these data a general qualitative theory of the phase behavior of the n-paraffins is developed. Four distinct crystal structures—hexagonal, triclinic, monoclinic, and orthorhombic—describe the solid phases of all n-paraffins with more than nine carbon atoms in the chain. The latter two structures become equivalent at longer chain lengths. Odd-even differences are resolved in terms of reasonable differences in end group packing, and the smooth increase in melting and transition temperature with increasing chain length is attributed to a decrease in the ratio of end groups to chain groups. Double transitions are predicted for several pure n-paraffins above n-C34H70. Impurity effects are isolated from the pure n-paraffin properties and discussed. The equation, TM(°K) = 414.3 (n−1.5)/(n + 5.0) is presented as a correct description of the melting temperatures (TM) of all n-paraffins above n-C44H90. Sufficient data to permit an accurate extrapolation of the enthalpies and entropies of fusion to the infinite-chain limit are not available.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"1 1","pages":"241 - 249"},"PeriodicalIF":0.0,"publicationDate":"1962-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90005370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to provide standards for the calibration of small grating spectrometers over the region from 166 to 600 cm−1, tracings of the spectrum of atmospheric water vapor are presented. The lines are identified and tabulated. Wavenumbers obtained from energy levels derived from the best available high-resolution spectra are given, together with an indication of their relative reliability. The best lines are believed accurate to ±0.03 cm−1.
{"title":"Calibration of Small Grating Spectrometers from 166 to 600 cm−1","authors":"L. R. Blaine, E. K. Plyler, W. Benedict","doi":"10.6028/JRES.066A.021","DOIUrl":"https://doi.org/10.6028/JRES.066A.021","url":null,"abstract":"In order to provide standards for the calibration of small grating spectrometers over the region from 166 to 600 cm−1, tracings of the spectrum of atmospheric water vapor are presented. The lines are identified and tabulated. Wavenumbers obtained from energy levels derived from the best available high-resolution spectra are given, together with an indication of their relative reliability. The best lines are believed accurate to ±0.03 cm−1.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"8 1","pages":"223 - 225"},"PeriodicalIF":0.0,"publicationDate":"1962-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88291194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Franck-Condon factor arrays have been computed numerically to high vibrational quantum numbers for the band systems of the following diatomic oxides of interest in astrophysics and atmospheric physics SiO: (A1Π–X1Σ+) MgO: (B1Σ–A1Π) MgO: (B1Σ–X1Σ) SrO: (A1Σ–X1Σ) AlO: (A2Σ+–X2Σ+) VO: (A2Δ–X2Δ) NOβ: (B2Π –X2Π) NOγ: (A2Σ+–X2Π)
{"title":"Franck-Condon Factors to High Vibrational Quantum Numbers II: SiO, MgO, SrO, AlO, VO, NO","authors":"R. W. Nicholls","doi":"10.6028/JRES.066A.022","DOIUrl":"https://doi.org/10.6028/JRES.066A.022","url":null,"abstract":"Franck-Condon factor arrays have been computed numerically to high vibrational quantum numbers for the band systems of the following diatomic oxides of interest in astrophysics and atmospheric physics SiO: (A1Π–X1Σ+) MgO: (B1Σ–A1Π) MgO: (B1Σ–X1Σ) SrO: (A1Σ–X1Σ) AlO: (A2Σ+–X2Σ+) VO: (A2Δ–X2Δ) NOβ: (B2Π –X2Π) NOγ: (A2Σ+–X2Π)","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"21 1","pages":"227 - 231"},"PeriodicalIF":0.0,"publicationDate":"1962-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83517463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A set of five specially selected colored-glass filters to identify variables of malfunction of photoelectric recording spectrophotometers equipped with tristimulus integrators have been standardized on a number of spectrophotometers corrected for all known errors (wavelength, zero, 100 percent, slit-width, inertia, back-reflectance, and stray-energy). To these standardized spectrophotometric data definite amounts of these errors were deliberately introduced and converted to tristimulus values and chromaticity coordinates of the International Commission of Illumination system of colorimetry for Sources A, B, and C. Similar reductions show the effects of slit widths of 1, 5, 10, and 15 millimicrons (mµ) on computed results both by the selected-ordinate method of 10, 30, and 100 ordinates, and by the weighted-ordinate methods of 1-, 5-, 10-, and 15-mµ intervals. Duplicate sets of these glasses have been evaluated by visual comparison with this set of master standards, and are available as part of the Standard Materials Program of the National Bureau of Standards. By comparing the certified values of luminous transmittance and chromaticity coordinates for a set of these glasses with the values obtained on a particular integrator-spectrophotometer combination, the type and extent of instrumental errors may be evaluated.
{"title":"Glass Filters for Checking Performance of Spectrophotometer-Integrator Systems of Color Measurement","authors":"H. J. Keegan, J. C. Schleter, D. B. Judd","doi":"10.6028/jres.066A.020","DOIUrl":"https://doi.org/10.6028/jres.066A.020","url":null,"abstract":"A set of five specially selected colored-glass filters to identify variables of malfunction of photoelectric recording spectrophotometers equipped with tristimulus integrators have been standardized on a number of spectrophotometers corrected for all known errors (wavelength, zero, 100 percent, slit-width, inertia, back-reflectance, and stray-energy). To these standardized spectrophotometric data definite amounts of these errors were deliberately introduced and converted to tristimulus values and chromaticity coordinates of the International Commission of Illumination system of colorimetry for Sources A, B, and C. Similar reductions show the effects of slit widths of 1, 5, 10, and 15 millimicrons (mµ) on computed results both by the selected-ordinate method of 10, 30, and 100 ordinates, and by the weighted-ordinate methods of 1-, 5-, 10-, and 15-mµ intervals. Duplicate sets of these glasses have been evaluated by visual comparison with this set of master standards, and are available as part of the Standard Materials Program of the National Bureau of Standards. By comparing the certified values of luminous transmittance and chromaticity coordinates for a set of these glasses with the values obtained on a particular integrator-spectrophotometer combination, the type and extent of instrumental errors may be evaluated.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"38 1","pages":"203 - 221"},"PeriodicalIF":0.0,"publicationDate":"1962-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91191952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The vapor pressure and heat of sublimation of palladium were measured using a vacuum microbalance technique. The mean heat of sublimation obtained was 89.2 ± 0.8 kcal/mole. Over the temperature range of 1,294 to 1,488 °K the measured vapor pressures may be represented by: Log Pmm = 8.749 – 18655/T. The normal boiling point is estimated to be 3,200 °K.
{"title":"The Vapor Pressure of Palladium","authors":"R. F. Hampson, R. F. Walker","doi":"10.6028/jres.066A.015","DOIUrl":"https://doi.org/10.6028/jres.066A.015","url":null,"abstract":"The vapor pressure and heat of sublimation of palladium were measured using a vacuum microbalance technique. The mean heat of sublimation obtained was 89.2 ± 0.8 kcal/mole. Over the temperature range of 1,294 to 1,488 °K the measured vapor pressures may be represented by: Log Pmm = 8.749 – 18655/T. The normal boiling point is estimated to be 3,200 °K.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"1 1","pages":"177 - 178"},"PeriodicalIF":0.0,"publicationDate":"1962-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87559779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A simple conductometric titration method is discussed for the determination of sulfhydryl groups in nonionic polymer networks, such as disulfide and alkylene sulfide crosslinked polycaprolactam fibers. The diffusion of the titrant into the crosslinked polymer is accomplished by swelling the network structure, thereby eliminating the necessity of destroying the crosslinks and/or breaking the polymer chains.
{"title":"Conductometric Determination of Sulfhydryl Groups in Swollen Polycaprolactam Fibers Having Disulfide and Alkylene Sulfide Crosslinks","authors":"S. D. Bruck, S. Bailey","doi":"10.6028/jres.066A.017","DOIUrl":"https://doi.org/10.6028/jres.066A.017","url":null,"abstract":"A simple conductometric titration method is discussed for the determination of sulfhydryl groups in nonionic polymer networks, such as disulfide and alkylene sulfide crosslinked polycaprolactam fibers. The diffusion of the titrant into the crosslinked polymer is accomplished by swelling the network structure, thereby eliminating the necessity of destroying the crosslinks and/or breaking the polymer chains.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"131 1","pages":"185 - 187"},"PeriodicalIF":0.0,"publicationDate":"1962-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77867107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The classification of oils with respect to differences in composition is important in their use in the manufacture of oil-extended butadiene-styrene rubber. A rapid chromatographic method of analysis has been developed in which 2.5- to 3.0-gram samples of oil are desorbed from silica gel into five different fractions by successive elution with pentane, benzene, carbon tetrachloride, and ethanol as eluents. Six extender-oils were analyzed by this method. Physical properties of the separated fractions showed marked differences between fractions of the same oil and similarities between corresponding fractions of the different oils. The chromatographic separation of extender-oils into compositionally different fractions provides a method for evaluation of the effect of different components on specific properties of the finished rubber product.
{"title":"Chromatographic Analysis of Petroleum Fractions Used in Oil-Extended Rubber","authors":"D. J. Termini, A. Glasgow","doi":"10.6028/jres.066A.018","DOIUrl":"https://doi.org/10.6028/jres.066A.018","url":null,"abstract":"The classification of oils with respect to differences in composition is important in their use in the manufacture of oil-extended butadiene-styrene rubber. A rapid chromatographic method of analysis has been developed in which 2.5- to 3.0-gram samples of oil are desorbed from silica gel into five different fractions by successive elution with pentane, benzene, carbon tetrachloride, and ethanol as eluents. Six extender-oils were analyzed by this method. Physical properties of the separated fractions showed marked differences between fractions of the same oil and similarities between corresponding fractions of the different oils. The chromatographic separation of extender-oils into compositionally different fractions provides a method for evaluation of the effect of different components on specific properties of the finished rubber product.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"27 1","pages":"189 - 192"},"PeriodicalIF":0.0,"publicationDate":"1962-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82291002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
From the relative intensities of arc and spark lines observed in a d-c arc in air between copper electrodes, the degree of ionization of eleven elements added to the copper has been determined. With the aid of Saha’s ionization equation, the electron density in the arc was calculated to be 2.4×1014 cm−3. Partition functions for atoms and ions of 29 elements are newly calculated or estimated and a table of first ionization potentials and partition functions of atoms and ions for seventy elements is presented. The degree of ionization of seventy elements separately added to the arc is calculated. The electron density in the arc is confirmed by three independent spectroscopic and electrical determinations. The data developed in this paper will enable the calculation of relative transition probabilities from the intensities in the NBS Tables of Spectral-Line Intensities.
{"title":"Ionization in the Plasma of a Copper Arc","authors":"C. Corliss","doi":"10.6028/jres.066A.014","DOIUrl":"https://doi.org/10.6028/jres.066A.014","url":null,"abstract":"From the relative intensities of arc and spark lines observed in a d-c arc in air between copper electrodes, the degree of ionization of eleven elements added to the copper has been determined. With the aid of Saha’s ionization equation, the electron density in the arc was calculated to be 2.4×1014 cm−3. Partition functions for atoms and ions of 29 elements are newly calculated or estimated and a table of first ionization potentials and partition functions of atoms and ions for seventy elements is presented. The degree of ionization of seventy elements separately added to the arc is calculated. The electron density in the arc is confirmed by three independent spectroscopic and electrical determinations. The data developed in this paper will enable the calculation of relative transition probabilities from the intensities in the NBS Tables of Spectral-Line Intensities.","PeriodicalId":94340,"journal":{"name":"Journal of research of the National Bureau of Standards. Section A, Physics and chemistry","volume":"53 1","pages":"169 - 175"},"PeriodicalIF":0.0,"publicationDate":"1962-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90991709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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