Determination of ortho-cresyl phosphate isomers of tricresyl phosphate used in aircraft turbine engine oils by gas chromatography and mass spectrometry.

Tricresyl phosphate (TCP) is used as an anti-wear additive in aircraft turbine engine oil. Concerns about its toxicity are largely based on the tri-o-cresyl phosphate isomer content. However, the presence of other and more toxic isomers has been previously suggested. In this work, the structural isomers of TCP have been determined by two methods (experimental and semi-theoretical). First, the TCP isomers were separated by gas chromatography (GC) and identified by mass spectrometry (MS). Second, after base cleavage of TCP, GC was used to quantify the cresol precursors. These results were used to calculate the TCP isomer distribution based on the assumption of a statistical distribution of the TCP isomers. The results from the two determinations showed reasonable agreement for three of the four oils studied. The o-cresyl isomers were found to be present almost exclusively as the more toxic mono-o-cresyl isomers in the concentration range 13-150 mg/L. The ability to analyse for the mono-o-cresyl isomers allows the toxicity of TCP to be based on the latter isomers rather than on the less toxic tri-o-cresyl phosphate isomer.

Evaluation and use of a dry chemistry analyser in Antarctica.

The Australian National Antarctic Research Expeditions (ANARE) currently operate scientific stations at four remote locations in Antarctica. Each of these stations requires an accurate, easy to use, and flexible biochemical analyser for clinical diagnosis and management. The Ektachem DT60, DTE and DTSC modules were selected and initially assessed during a wintering expedition at the ANARE station on sub-Antarctic Macquarie Island and during an extended scientific voyage to Antarctica. In the initial field assessment, accuracy was assessed by measuring a range of analytes in samples from pathology interlaboratory quality assurance programs. In 90% of the samples tested, analyte recordings were within 2 standard deviations of the mean provided. Kodatrol controls were tested regularly to assess the calibration stability of the machine and to measure within-day and between-day imprecision. Blood was also taken monthly from all expeditioners, analysed, and immediate results of cholesterol and triglyceride compared with results from identical samples frozen and analysed later in Australia. Cholesterol and triglyceride were the analytes chosen as the results obtained could be used as part of a larger study concerning dietary fats and cardiovascular risk factors. Analysis of the results indicated that the Ektachem DT modules satisfied criteria of accuracy and precision. They were relatively economical to use. Maintenance and training were simple and appropriate to the conditions of use. As a result of this favourable assessment, Ektachem machines were obtained for all four of the Australian Antarctic stations and have been in use at those sites for the last six years. Comment is made on experience with these analysers during that time, including discussion of clinical cases in which the availability of such biochemistry has proved useful. Some of the problems encountered are also discussed. It is considered that use of these biochemical analysers has assisted the solo medical practitioner in the isolated Antarctic region.

Energy intake, anthropometry and blood pressure of expeditioners in the Antarctic.

The energy intakes, anthropometry and blood pressure of 62 expeditioners at one Australian sub-Antarctic (Macquarie Island) and two Antarctic stations (Davis and Casey) were examined over a 12 month period. High mean energy intakes were found at all stations (approximately 16,000 kJ/subject/day). Mean subject body weight tended to rise during the winter months (midway during the study) and fall during the spring, although there were no significant changes (p < 0.05) seen at any of the stations over the year. Subjects were generally leaner at the end of 12 months as evidenced by significant falls (p < 0.01) in mean sum of skinfold thickness at two stations over the year. At all stations, blood pressure trended downwards during the year, with significant rises (p < 0.01) seen at one station during the spring. Two 12-week dietary intervention periods were introduced during the year at one of the Antarctic stations to investigate the effects of low-cholesterol (< 300 mg/day), low-fat (< 30% of energy) and high-fibre (> 30 g/day) diets. The average energy intake/day during these two periods (14,973 kJ and 14,515 kJ) was slightly less than during the baseline diet (average of 16,228 kJ). This was reflected in the anthropometric measurements with the mean body weight, sum of skinfold thickness and waist/hip ratios trending down during the diet periods. The study confirms earlier reports of high mean energy intake in Antarctica and suggests that the techniques of measuring intake may have been more accurate than those used in large population studies where intake may have been under-estimated. The results indicate seasonal fluctuations in blood pressure and anthropometric parameters and demonstrate that these anthropometric parameters were affected by the balance of energy intake and activity.

Applications of automated amino acid analysis using 9-fluorenylmethyl chloroformate.

A rapid and sensitive fully automated method for the determination of primary and secondary amino acids in different matrices is described. Amino acids are derivatized with 9-fluorenylmethyl chloroformate using an automated precolumn derivatization technique. Data are presented to show that the technique is both reproducible and highly sensitive. Applications of the technique are presented, including the analysis of peptide and protein hydrolysates and the profiling of free amino acids in physiological fluids.

Amino acid analysis using derivatisation with 9-fluorenylmethyl chloroformate and reversed-phase high-performance liquid chromatography.

A simple procedure for the precolumn derivatisation of amino acids with 9-fluorenylmethyl chloroformate and a liquid chromatographic method for the separation of the derivatives with fluorimetric detection in the picomole range are reported. The procedure does not involve a solvent extraction and gives single, stable derivatives of the common protein amino acids. The method has been demonstrated on hydrolysates of proteins and peptides.

3-Amino-5-hydroxybenzoic acid in antibiotic biosynthesis. VI. Directed biosynthesis studies with ansamycin antibiotics.

Biosynthesis of the ansamycin antibiotic actamycin (2) was markedly increased by the addition of the precursor 3-amino-5-hydroxybenzoic acid (1) to the producing Streptomyces fermentation. Similar addition of the 4-chloro, 6-chloro, N-methyl and O-methyl analogues 4, 6, 5 and 7 of the amino acid 1 reduced actamycin production and did not yield structurally modified ansamycins. These results with the analogues 4, 5 and 7 indicate that the corresponding chlorine, N-methyl and O-methyl substituents present in the nuclei of various ansamycins are introduced at biosynthetic stages beyond the level of the amino acid 1.