Determination of phosphate in natural waters by capillary electrophoresis. Influence of solution composition on migration time and response.

This paper deals with the determination of the more complex phosphate anion by capillary electrophoresis using indirect UV detection. First, the pH of the running electrolyte influences both the migration time and the response of the phosphate anion. Both effects could be explained well by taking into account phosphorus speciation in solution. In addition, the experimental method has been applied to three different sets of natural water systems; (i) groundwater, (ii) surface water and (iii) stemflow samples. The migration time behaviour of phosphate was different for the three sample sets and, hence, difficulties arise with respect to a clear and unique identification of the compound. Deviations herein could be minimized by applying a correction method for migration time drift. Concentrations of phosphate could be quantified in most samples and were confirmed by a colorimetric method. Average recoveries of additions of phosphate to groundwater, surface water and stemflow samples were 105, 83 and 103%, respectively. For one stemflow sample, quantitative recovery of phosphate was possible only by changing the pH of the running electrolyte solution. The latter observation might be very useful in setting up speciation-related measurement methods.

[Tissue reactions and residues in slaughter cattle after administration of long-acting oxytetracycline formulations]. / Binnespierse weefselreaksie en residue in slagbeeste na toediening van langwerkende oksitetrasiklien formulasies.

Samples from 40 slaughter cattle were investigated over 10 weeks for determining macroscopic tissue reaction following intramuscular administration of Liquamycin/LA (Pfizers) into the thigh and Terramycin/LA (Pfizers) G 333 into the neck respectively. Antibiotic residues in the lesions were assessed under ultra violet light and by microbiological means. Antibiotic residues were still detected after 7 weeks in the thigh and 5 weeks in the neck. One week old lesions in the thigh consisted mainly of a local necrotic centre, up to 120 mm in diameter, with a haemorrhagic zone and surrounded by oedema and petechia in adjacent muscle. This was gradually replaced by mainly fibrotic tissue as the weeks went by and eventually by local abscess formation still apparent 10 weeks later. Much the same pattern was seen in the neck but of milder degree and shorter duration - 6 weeks. Alarming is the fact that only in one case out of 40, a lesion could be detected in the carcass on the slaughter line, the others could have passed fit for human consumption in an abattoir. Because the manufacturer suggests a 28 day withholding period before slaughter and after administration of the product, results of this investigation raise several questions on format, completeness and contents of such directions for use and their implications for meat inspection, meat hygiene and public health.

Electron microscopic observations on the luminal surface of teat cup liners of milking machines used under South African conditions.

An investigation undertaken with the aid of scanning electron microscopy (SEM) on new and used teat cup liners revealed the generally poor quality of luminal surfaces. Even those of the brand-new distributor controls showed significant faults in the evenness and continuity of the liner surface. A hundred and 500 milkings apparently tend to aggravate faults like cracks, pores, grooves and pits, because of the general brittleness of some of the teat cup liners. The poor quality of the liners investigated raises various questions about the method of distribution of teat cup liners and serious concern about the role they play in predisposing bovine udders to mastitogenic infections, spreading mastitis, affecting the production and quality of milk, increasing the cost of milk production and reducing profits of dairy farming.

Determination of the physicochemical and microbiological quality of carcass, bone and blood meal.

The pH value and the moisture, fat and protein content of abattoir by-products which are commercially available in the Republic of South Africa were examined, and the total bacterial count and the extent of Salmonella, Escherichia coli, Bacillus, yeast and fungus contamination were determined. The extremes and reasonably attainable quality standards were deduced from the highest frequency and mean values of these figures. The total bacterial count was not statistically predictable from variables such as pH, moisture, protein and fat, but was found to be related to the combined effect of all 4 independent variables.

The control of bacterial contamination in carcass meal with propionic acid.

The effect of the addition of 2, 3, 5, 7 and 10% respectively of propionic acid on known numbers of bacteria added to or contained in carcass meal was examined. Escherichia coli was totally inhibited by 2% propionic acid, while 5% of the acid both inhibited Salmonella typhimurium and brought about a 74,7% reduction in the total aerobic bacterial count.

Observations on the effect of different methods of processing on the bacterial contaminants of bovine and ovine tripe.

A comparison was made of the multiplication of bacteria in specimens of tripe processed in different ways. There was little difference in this respect between commercial tripe as offered for purchase to the consumer and rough and scraped tripe incubated at 30 degrees C for 24 h. Tripe stored at 4 degrees C or in acetic acid (pH 4) at 30 degrees C for 24 h, however, had appreciably fewer bacteria.

The preparation, mincing and canning of bovine offal (ruminal and intestinal wall) for human consumption.

The results of a sudy of methods of cleaning and preserving bovine ruminal and intestinal wall by canning are described. Such offal could be converted into a hygienically satisfactory and safe food by laboratory washing and canning, and töe end product had a extended shelf life. Methods are described and suggested as a basis for ensuring safe utilisation of a valuable food product.