Thermogravimetric analysis of silica gel has shown that the loss in weight between 30° and 910°C can be quantitatively explained on the basis of water being lost from three distinct and different populations of sites on the silica gel surface. The results indicate that the site energies of the three different populations are randomly distributed and, consequently, the resulting weight loss steps from each population can be described by the integral of a simple normal distribution with temperature. The calculated weight loss obtained by assuming three different site-groups having randomly distributed adsorption energies is, within experimental error, coincident with the experimental data. It is also shown that the water evolved from the second population of sites originates from strongly bound water and may also contain water generated by the condensation of (geminal) silanol groups contained in the overlapping and neighbouring population.

The purity of alkylnitrile compounds has been investigated using gas chromatography (GC), gas chromatography-mass spectrometry (CC-MS) and high performance liquid chromatography (HPLC). The investigation was carried out to supplement earlier reported work using the alkylnitrile compounds, hexanenitrile and valeronitrile, as mobile phase additives in HPLC. GC impurity profiling and CC-MS experiments showed the presence of low level nitrogenous impurities in the alkylnitrile compounds. Analytical interrogation and chemical isolation were employed to identify the impurities as alkylamines. Tri-n-butylamine (TEA) and di-n-pentylamine (DPA) impurities were found in batches of hexanenitrile and valeronitrile respectively and it was found that it was the amine impurities, at very low levels, which caused the observed chromatographic improvements for basic solutes when using the alkylnitrile compounds as mobile phase additives in reversed-phase HPLC. The amines themselves were subsequently used at extremely low levels (ppm) in the mobile phase and were found to be very effective in their action.

A previous study using intrapleural administration of surface-modified amosite asbestos showed a difference in the number of pleural mesotheliomas induced with C18-hydrocarbon derivatised fibres compared to native amosite asbestos. The study has been repeated with larger groups of animals (30) under specific pathogen free conditions, resulting in an increase in the mean animal survival time for both fibre-treated groups. Under these conditions there was no significant difference between the numbers of pleural mesotheliomas induced by C18 hydrocarbon-modified amosite asbestos and native amosite asbestos. The major difference between the two studies was the mean time to death from tumour of rats exposed to fibres. The C18 amosite treated rats in the first study may not have had a mean survival time long enough to allow mesotheliomas to develop.

A sample of amosite asbestos was modified by effectively adding C8 and C18 hydrocarbon chains to the fibre surfaces. The altered fibres interacted less readily with cells in vitro and were less cytotoxic. In whole animals the number of mesotheliomas produced by the C8 material was the same as that with the parent material but the tumours occurred earlier. The C18 derivatized fibre was markedly less active in the production of tumours. This is the first report demonstrating that similar size fibres with differing surfaces have different pathogenic properties.

Twelve Florida native wethers were given ammonium metavandate, calcium orthovanadate and calcium pyrovanadate by capsule in a study to examine the toxicity of the compounds. The initial daily dosage of 100 mg elemental vanadium was increased by 50 mg at 2-d intervals for an assessment not only of the toxic effects, but also to determined the amount that caused a decline in feed intake to 25% of that of control animals. The initial decline in feed intake was observed at 400 to 500 mg vanadium/d (9.6 to 12 mg/kg body weight, 310 to 350 ppm); a rapid decline in feed intake was accompanied by diarrhea. One sheep fed 550 mg vanadium as calcium orthovanadate died 3 d after dosing. One animal on each of the other three treatments was killed and necropsied for immediate comparison. Extensive mucosal hemorrhage of the small intestine and diffuse or petechial subcapsular hemorrhages of the kidneys were observed for sheep fed all compounds. The three vanadium compounds appeared to be similar in toxicity, as determined by abrupt declines in feed intake and pathological changes of the intestine and kidney. For a determination of acute toxicosis, three sheep were given 40 mg/kg body weight of vanadium as NH4VO3 in gelatin capsules and two sheep were included as controls. Two of the treated animals died within 80 h after administration and the other three were killed at 96 h. Vanadium content of kidney, liver, bone, spleen, lung and muscle was elevated by treatment.

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The effect of varying carrier gas (nitrogen) flow-rate on the absolute molar and weight responses of a flame-ionization detector operated under conditions of a hydrogen-rich flam using oxygen as the supporter of combustion has been investigated and shows that a considerable degree of flexibility is available for achieving these detector responses. Selective detection of chlorine has been shown to depend upon high hydrogen and low nitrogen flow-rates with intermediate to high oxygen flow-rates. Additional compounds have been shown to respond equally to carbon content in the molar mode of operation.

It has been generally accepted that the use of the flame-ionization detector (FID) in the quantitative determination of differing types of solute in gas chromatographic eluents necessitates prior detector calibration for each species in question.

Porous polymer gas chromatographic columns are used in the quantitative estimation of water in organic samples. The reliability of using porous polymer beads for wate—alcohol analyses has been studied and the quantitative results are presented. Variations in the results were attributed to preferntial losses by adsorption of water within the columns. This was demonstrated qualitatively by introducing pure deuterated water into the gas chromatograph, allowing the water to elute, and then detecting amy residual water by raising the temperature of the column and passing the effluent into a mass spectrometer. A measure of the amounts of water lost was made by injecting known amounts of pure water onto the column, allowing the water to elute, and then driving off any residual water for subsequent detection with a calibrated gas density detector.

Summary Combination GC-MS interfacial systems have now been developed to a stage where it is possible to transfer the components of complex mixtures unchanged and without loss in GC resolution. It would, however, appear that no one separator is completely satisfactory for all applications, particularly if the solutes under examination are of low molecular weight and present in submicrogram quantities. In the author's opinion the following three interfaces would satisfy all possible requirements: 1. Palladium separator – specifically for low-molecular-weight volatile inorganic compounds and compounds that would not be reduced by the presence of active hydrogen. 2. Micro silicone rubber membrane separator for organic compounds up to a molecular weight of 250. 3. Jet separator – single-stage (variable) or double-stage, dependent on carrier-gas flow rate, for molecular weights from 100 upwards.

Abslract: Viral agents producing both a syncytial-type cytopathic effect and type A intranuclear inclusion bodies i,z vitro were isolated from the kidneys of five of 10 wild turkeys. A plaque assay system for viral infectivity was developed and used to characterize one of the wild turkey viruses (WTV). WTV replication was inhibited by 5-bromodeoxyunidine, indicating the virus contained DNA as its genetic material. Virus infectivity could be transferred only as viable whole cell preparations; one cycle of rapid freezing and thawing completely inactivated the virus. Typical herpes- like virions were found within the nuclei when cells infected with WTV were ex- amined by electron microscopy. WTV had characteristics typical of the herpes group of viruses.