Walter A. Aue

On the unexpected behavior of a common gas chromatographic phase

Abstract Carbowax 20M was coated on Chromosorb W, heat-treated at 280°, and exhaustively extracted. The remaining support performed chromatographically in a manner similar to highly efficient, well deactivated gas—liquid chromatographic packings, even though the non-extractable polymer film was too thin to permit reliable combustion analysis. This phase was well suited for the analysis of polar compounds, producing symmetric, sharp peaks with very short retention times. A strong surface effect was evident, which could be utilized for otherwise difficult separations.

Preparation and chromatographic uses of surface-bonded silicones☆

Abstract Silicones can be synthesized from a variety of pure or mixed monomers on and chemically bonded to silicic surfaces — typically to chromatographic supports. The resulting materials are non-extractable, thermally stable coatings, which perform well in GLC and can be used for some of the more demanding types of analysis.

A photometric tin detector for gas chromatography

Abstract The presence of organotins in the environment appears to become a future public concern and, consequently, pose problems for the trace analyst. Since gas chromatography is capable of separating volatile tin compounds, a gas chromatographic detector selective for tin was developed. It is based on a modified Shimadzu flame photometric detector operating without wavelength discrimination. Tin compounds can be detected in amounts below 10−12 g and temperature programming can still be used at this sub-picogram level. Organotins respond approximately 100 to 1000 times stronger than phosphorus- and/or sulfur-containing compounds, and approximately 10,000 to 100,000 times stronger than hydrocarbons.

The determination of part-per-billion levels of citric and nitrilotriacetic acids in tap water and sewage effluents.

Abstract Citric and nitrilotriacetic acids can be determined at the 1–10,000 p.p.b. 1 levels in aqueous systems ranging from tap water to sewage effluents by use of anion-exchange clean-up, derivatization with butanol—HCl and gas chromatography. A variety of metals present at legal tolerance limits do not interface. The two esterfied acids separate well on a special gas chromatographic phase; however, citric acid can also be separated from nitrilotriacetic acid by ion exchange prior to derivatization, if so desired.

Studies and speculations on an alternative mechanism for the response of direct-current electron-capture detectors☆

Abstract The classical theory of electron-capture detection does not allow for hypercoulometric response such as has been found recently under conditions of elevated pressure in some electron-capture detectors (ECDs), nor does it predict certain other experimental observations. In an effort to understand why and how hypercoulometric performance can occur, measurements have been made of the ionization region and characteristic current—voltage relationships in real and simulated ECDs. The centre-of-ionization was found much closer to the foil than is commonly assumed, namely at approximately 1 mm for 63Ni and approximately 0.2 mm for 3H in nitrogen at ambient conditions. A hypothetical response mechanism, alternative and, in certain ways, complementary to the classical theory was therefore developed. It sees detector response, distinct from the initial electron—capture reaction, as the effect of a space charge formed by migrating negative ions, which decrease the field gradient (and therefore increase electron—positive ion recombination) in the ionization region. Estimates of the counterfield established by the migration of anions show that it can indeed produce hypercoulometric response and that, in agreement with experimental observations, increased pressure leads to higher response. Some simple experimental tests of the proposed mechanism have been carried out and others, more crucial ones, are suggested for future investigation.

A tobacco related epidemic of congenital limb deformities in swine

Abstract An epidemic of congenital limb deformities in swine is described. The epidemic occurred among 79 Duroc sows and gilts on a farm in Howard County, Missouri, during the period September 11, 1967, to March 3, 1968. The 79 females farrowed 782 pigs: 742 (95%) were born alive, 40 (5%) were born dead, and 59 (7.5%) were born with congenital abnormalities. The abnormal pigs were farrowed by 14 sows. These sows farrowed 149 pigs and 59 (40%) were abnormal. Tobacco stalks were placed in a swine lot and pasture between October 25, 1967, and December 7, 1967, and some of the sows were observed eating the stalks. On December 7, 1967, four sows had an illness which lasted 24–48 hours. The first 38 days of pregnancies in those sows with the affected progeny occurred during the time when the tobacco was available to them. Other animals not exposed to the tobacco stalks as a food source had no birth defects. The animals involved in the epidemic during prior and later reproductive periods had no abnormalities in their litters. The tobacco stalks, therefore, appeared to have some association with the epidemic. The tobacco stalks were tested for nitrate-nitrogen, pesticides, fungi, nicotine, and maleic hydrazide. The nitrate-nitrogen varied from 20 to 1390 ppm, and no significant amounts of aldrin, dieldrin, or pp′ -DDT were found. The fungi consistently isolated included a species of Penicillium identified as a variant of Penicillium cyclopium . Other species of fungi were isolated only sporadically, and no Aspergilli were found. Nicotine, other alkaloids or components of the tobacco stalks, appeared to be the most likely cause of the epidemic. The tobacco stalks eaten by the swine contained 1058 ppm of nicotine and 115 ppm of maleic hydrazide. The possible relationship of this epidemic of birth defects in swine associated with the ingestion of tobacco stalks to the increased fetal loss described among smoking mothers is discussed.

Sampling of air pollutants with support-bonded chromatographic phases☆

Abstract Support-bonded silicones, such as (C18H37SiO3/2)n on various types of Chromosorb, can be used to trap organic vapors from the atmosphere. The trapped compounds can then be extracted and the concentrated extracts analyzed by various analytical techniques.

Surface-bonded silicones from volatile monomers for chromatography

Abstract In an earlier report12 we have described a multistage process which produces silicones polymerized on, and chemically bonded to, chromatographic supports. While only monomers of low volatility could be used at that time, we have now modified the process to accommodate highly volatile starting materials. Di- and trifunctional compounds of different polarity could be partially hydrolyzed in solution and subsequently polymerized in fluidized bed. The resulting phases were characterized by gas—liquid chromatography in terms of column bleed, solute retention and resolution; by liquid phase extractability, by thermogravimetric analysis, and C, H analysis. Most of the phases showed virtually complete surface bonding and bleed comparable to chromatography grade SE-30. Resolution and retention time of various solutes appeared related to liquid phase cross-linking and substituent carbon chain length. Plate numbers generally improved, and retention times increased, through secondary heat treatments. The developed phases have been utilized in typical gas-liquid chromatographic separations.

Characteristics of a novel gas chromatographic phase

Abstract A novel gas chromatographic phase, obtained by heat-treatment and exhaustive extraction of a 6% Carbowax packing, has been characterized by various chromatographic tests of its sorption chemistry. The polymer layer remaining after extraction represents a 0.1 to 0.2% load; and it allows fast, efficient, and selective separations, which bear characteristics, and represent the more desirable features, of both gas-solid and gas-liquid chromatography.

Alternative method for bonding polymer layers to chromatographic supports

Abstract An alternative method for producing “bonded” (= non-extractable) layers of polymers on diatomaceous supports has been developed. Whereas the original method used a treatment of the support with the neat polymer, the new one uses solution-coating in a refluxing hydrocarbon. Judged by the gas chromatographic performance of the packings obtained from the most useful of the polymers, Carbowax 20M, the two methods yield equivalent products. The new method, though restricted in scope, is the faster and more gentle one of the two.