An automated HPLC determination of meticlorpindol in eggs with UV absorbance detection, using on-line dialysis and pre-concentration as sample clean-up; occurrence in and carry over to eggs.

A fully automated HPLC determination of the coccidiostat meticlorpindol in whole egg, egg white and yolk is described. The sample homogenate is dialysed on-line against water. The dialysate is concentrated on-line on a short reversed-phase (RP) column. The contents of this column are transferred to the reversed-phase analytical column by means of the mobile phase. Meticlorpindol is detected using an absorbance detector at 270 nm. Linear calibration graphs are obtained in the range 40-900 ng/g in whole egg and egg white (detection limit 10 ng/g) and 80-1800 ng/g in yolk (detection limit 20 ng/g). Out of 111 commercially obtained egg samples 12 contained meticlorpindol with levels varying from 10 to 433 ng/g. A group of laying hens, kept in cages, received 10 mg/kg of Lerbek (meticlorpindol and methylbenzoquate; Dow Chemical) in the feed for 10 days. Meticlorpindol residues in the eggs rose to a level of 622 ng/g. Meticlorpindol was found in the eggs until 6 days after withdrawal of the medicated feed. Another group received 110 mg/kg in the feed. Meticlorpindol residues rose to levels of 4480 ng/g in the eggs, 5880 ng/g in the egg white and 2660 ng/g in the yolk. Meticlorpindol was found in the eggs and the egg white until 14 days and in the yolk until 8 days after withdrawal of the medicated feed.

[Amprolium residues in eggs following administration of amprolium/ethopabate in laying hens and breeding hens]. / Residuen van amprolium in eieren na toediening van amprolium/ethopabaat aan leghennen en opfokleghennen.

Amprolium may be used as a coccidiostat in rearing hens and is a therapeutical agent used in laying hens. As a result of cross contamination, low amprolium levels may occur in feed. Feed containing a concentration of amprolium ranging from 5 to 250 mg/kg was therefore supplied to groups of laying hens. The amprolium residues in the yolks during and after treatment were subsequently determined. These levels varied from 1.75 mg/kg in the group fed 250 mg/kg to 0.2 mg/kg in the group fed 5 mg/kg. Amprolium levels in the whites of eggs were much lower than those in the yolks. The residues in yolks decreased below detectable levels (less than 0.005 mg/kg) within approximately ten days after treatment. Rearing hens in a tiered wire floor system were given amprolium in their feed until the first egg was laid. Amprolium residues in yolks were detected for well over a fortnight after the onset of laying. The amprolium residues determined in yolk did not exceed US tolerance levels of 8 mg/kg.

[The occurrence of sulfa residues in unpasteurized farm milk]. / Het voorkomen van 'sulfa'-residuen in rauwe boerderij(tank)melk.

The results of studies in 1984 and 1985 on the incidence of residues of sulphonamides in raw tank milk showed that, from 2 to 11 per cent milk was contaminated with Dapsone in the Netherlands. In 1984 sulphadimidine was found to be present in approximately six per cent of the samples of tank milk. In 1985, residues of Dapsone were detected, in approximately six per cent of the milk destined for consumption.

[The occurrence of dapsone residues following a one-time oral, intramuscular and intramammary application in healthy dairy cows]. / Het voorkomen van Dapson-residuen na éénmalige orale, intramusculaire en intramammaire toepassing bij gezonde melkrunderen.

Dapsone is frequently used as a bacteriostatic drug in the treatment of mastitis, endometritis and footrot (necrotic pododermatitis). The farmer usually obtains this drug by 'non-ethical' channels. A regular scheme of checking the milk for residues of sulphonamides will be introduced in 1986. The sensitivity of the test is approximately 25 ppb for Dapsone. This will result in lower milk price in the case of positive tests. In healthy animals, it is shown that intramuscular treatment with 35 grammes (+/- 70 mg/kg-1 body weight) of Dapsone results in residues of Dapsone and its metabolite monoacetyldapsone above this detection level for more than 6 1/2 days. Within 5 days after oral treatment with 48.75 grammes (+/- 100 mg/kg-1 body weight) and 2 1/2 days after single intramammary treatment with 0.8 grammes, the concentrations of residues detected dropped below 25 ppb. The other well-known metabolite diacetyldapsone was only present in detectable quantities in the first milkings after oral treatment.

[Automated determination of 4,4'-diaminodiphenylsulfone (DDS) and acetyl metabolites (MADDS and DADDS) in milk with the FAST-LC system]. / Automatisierte Bestimmung von 4,4'-Diaminodiphenylsulfon (DDS) und Acetylmetaboliten (MADDS und DADDS) in Milch mit dem FAST-LC-System.

With the described method it is possible to determinate residues of Dapsone (DDS) and its acetylated metabolites (mono- and diacetyldapsone) in milk. The determination is being carried out with a FAST-LC system (Fully Automated Sample Treatment Liquid Chromatography). The purification is a combination of dialysing the milk against water and absorption of the nonpolar components from the dialysate on the preconcentration column of the LC-system used (RP, 40 microns). With back-flush, the concentrate is being injected into the analytical column (RP-8, 5 microns). The detection is being carried out with the help of a UV-absorbance detector, at a wavelength of 296 mm. The detection limit is approximately 2 micrograms/l (DADDS: 5 micrograms/l). The required amount of the sample is 5 ml. The recovery, reproducibility and linearity for the three components in milk are good.

[Chloramphenicol excretion in milk studied with a FAST (fully automated sample treatment) liquid chromatography method. Preliminary communication]. / Onderzoek naar de uitscheiding van chlooramfenicol (CAP) in melk met een FAST L.C. methode. Voorlopige mededeling.

The concentration of chloramphenicol (CAP) in milk following parenteral administration to cows was determined by FAST Liquid Chromatography. This method is 200 times more sensitive than microbiological procedures and may be used in examination on an extensive scale. The lowest detection limit is 0.05 ppm. Residues of CAP could be detected in the milk up to and including 32 hours after i.m. administration to three cows of a preparation containing 200 mg of CAP per ml.

Automated determination of the density of liquids adoption of the kratky density meter in the continuous-flow system.

For the determination of the density of liquids, the density meter according to Kratky [1] has been adopted in the continuous flow system of the Technicon AutoAnalyzer. The result is that 50-60 density measurements can be carried out in one hour. The precision is superior as compared with those of the conventional methods.

Automated analysis of benzoic acid in food: colorimetric determination after continuous volatilization.

A method is developed to determine benzoic acid colorimetrically with the Technicon AutoAnalyzer. After a selective hydroxylation of benzoic acid by means of hydrogen peroxide and a catalyzing reagent consisting of a buffered solution of cupric ion, catechol and sorbic acid, a reaction follows with 4-aminoantipyrine. The reddish brown reaction product formed is measured at 505 nm. In a distillation unit benzoic acid is continuously separated from the acidified sample stream by volatilization into a stream of nitrogen. With simple manual treatments solid samples can be analysed. Possible interferences caused by naturally present or added compounds in food were investigated. The precision of the method is very good. The coefficient of variation is 0.6% at 50 mug/ml. For several products the recovery was determined with a mean of 98.4%. The working range covered is 0--100 mug benzoic acid/ml.