Search PubMed⌕ Search

Biomedical subjects

W Fritz

Publications and source records attributed to W Fritz.

At least 55 records · Page 3Linked to original sources
PubMed1979

[Method for identifying and determining polycyclic aromatic hydrocarbons in foods, soil and drinking water].

A method is described for identifying and determining polycyclic aromatic hydrocarbons in foods, soil and drinking water that, owing to the combination of extractive, chromatographic and spectrophotometric techniques, permits to detect 0,01 microgram of bezo(a)pyrene/kg in the presence of other polycyclic aromatic hydrocarbons. The preparation, pretreatment and concentration of the samples depend upon their nature. The isolation and separation of the polycyclic aromatic hydrocarbons are achieved with the aid of two consecutive thin-layer chromatographic systems, silica gel and acetylated cellulose. The subsequent identification and determination are based on the ulta-violet spectra (limit of detection, almost 0,5 microgram/ml) and, in the nanogram range, on the in situ fluorescence spectral analysis (limit of detection, 0,005 microgram of benzo(a)pyrene/spot). Fluorescence excitation and emission spectra obtained directly from the acetylated cellulose plate permit not only the reliable identification but also the determination of the polycyclic aromatic hycrocarbons; fluorescence transfer loci obtained under various conditions, the simultaneous determination. Depending upon the kinds of sample material, the recovery values range from 75 to 99.6% with a variation coefficient between 10.3 and 22.1%. Furthermore, a limiting value method is presented that permits to take yes-no decisions, by means of thin-layer chromatographic screening without using complicated measuring techniques, indicating whether or not the respective sample complies with the benzo(a)pyrene standard.

Chromatography, Thin Layer↗
PubMed1979

[Determination and the hygienic-toxicologic significance of patulin in fruit and fruit products].

The combination of extracting, chromatographic and fluorescence densitometric steps permits to determine patulin in fruits and fruit products with great precision and sensitivity. The limit of detection is 10 microgram/kg; the recovery rates range from 86 to 92% with a variation coefficient lying between 5.6 and 13.6%. Interferences due to patulin-simulating substances are widely excluded. Patulin concentrations ranging from 0.3 to 42 mg/kg were found in the brown-rotten portions of apples. Juices domestically prepared from healthy fruits and fruits rid of rotten portions, respectively, contained no patulin. On the contrary, patulin concentrations ranging from 0.02 to 0.3 mg/l were observed in commercial apple juices. As to products with subsequent mould infection, patulin values up to 50 mg/l were found in apple juices, and up to 0.4 mg/kg in peach preserves. In a further 24 commercial fruit and vegetable juices, patulin was not detectable even not in cider, in cereals which had gone mouldy spontaneously, and in bread samples. The fruits and fruit products were analysed not only for patulin, but also for aflatoxin and ochratoxin; the latter two, however, were found in none of the samples examined. The possibilities of manufacturing patulin-free products are discussed.

Chromatography, Thin Layer↗
PubMed1979

A mental health system in transition: profiles of change.

These profiles of the changing Saskatchewan mental health system reveal that there have been increases in the number of admissions, readmissions, discharges, and outpatients in both the public and private sectors. Divergent patterns in the utilization of services in the public sector occur among the Indian and non-Indian populations. Over the past several decades there have been considerable changes in the types of psychiatric problems treated in the psychiatric care system. The social, demographic and admission characteristics of the people receiving treatment in the system have changed substantially. The data presented here imply that the status of mental illness is not solely a function of a physical or psychiatric condition but has elastic features capable of being expanded or restricted by the prevailing organizational structure which has evolved to handle the "problem" of mental illness. The advent of community psychiatry plus attendant changes in the health system has altered the nature of mental illness treated in the province. Consequently, concerns about ways of evaluating the effectiveness of current programs, of choosing between alternate service delivery systems, of establishing criteria for equitable resource allocation, and of understanding the forces for change need to be raised and explicitly dealt with.

Community Mental Health Services↗
PubMed1977

[Comparative studies on the contamination of foods by cancerogenic hydrocarbons in the Soviet Union and in the GDR (author's transl)].

Investigations on the relationship of the environmental contamination with cancer are shown to be necessary. Epidemiologic investigations point to a connection of the increased occurence of cancer in the gastro-intestinal tract with dietetic factors. The high cancer rate in the gastro-intestinal tract (amongst other factors) is discussed as a result of the uptake of exogenic foreign matterns with the food. The possibilities of the contamination by cancerogenic compounds are summarized. The necessity of international co-operation in the field of finding out, as far as possible, sources and degree of food contamination by cancerogenic compounds is motivated beginning with polycyclic aromatic compounds, whereby at present benzo-(a)-pyrene comes into question as a reference substance. The laying down of controllable hygienic norms as preliminarily tolerable limits in the proper sense of an unavoidable dose are discussed. They could be a basis of oncological preventive measures (minimization or elimination of cancerogenic compounds in foods).

Benzopyrenes↗
PubMed1977

[Content of carcinogenic hydrocarbons in smoked foods in the German Democratic Republic and the Hungarian People's Republic].

In the GDR, industrially smoked foods contain on an average 0.43 microgram Benzo(a)pyrene (BaP)/kg; products smoked according to trade rules, 0.76 microgram/kg; home-smoked products, 0.74 microgram/kg. The mean BaP content of smoked meat and sausage products in the GDR is 0.55 microgram/kg. Smoked fishes (without skin) contained on an average 1.39 microgram BaP/kg. The following average values were found in the Hungarian People's Republic: 0.6 microgram/kg (industrially smoked), 0.74 microgram/kg (home-smoked), 0.7 microgram/kg (total mean). Smoked cheese contained on an average 0.85 microgram/kg. The average BaP value of home-smoked (softwood) products of a Slovene ethnic group in the Hungarian People's Republic is 4.16 microgram/kg; the population of this region shows a considerably increased rate of stomach cancer. Apart from this particular case, the techniques used in both countries permit to obtain smoked meat and sausage products and smoked cheese with BaP contents less than 1 microgram/kg.

Carcinogens↗
PubMed1977

[Determination and occurence of aflatoxin M1 and B1 in milk and dairy products].

The described method enables a simultaneous identification and determination of aflatoxin M1 and B1 in milk and dairy products by means of a self-registering fluorescence spectrophotometer with a thin-layer chromatographic accessory, directly from the plate. The semiquantitative estimation on the thin-layer chromatographic plate enables also routine analyses in the hygienic practice. The recovery rates for aflatoxin M1 and B1 in milk are about 83 and 82%, respectively -- the detection limit is about 0.1 microng per kg. The recovery rates for aflatoxin M1 and B1 in milk powder are about 89 and 94%, respectively -- the detection limit is bout 0.5 microng per kg. The reproducibility is given with a standard deviation between +/- 1.1 and 6,3% and a variation coeffecient of 1.3 and 6.7, respectively. 4 of 24 analized samples of commercial winter milk were aflatoxin M1-positive, whereas aflatoxin B1 could not be found. One of the milk powder products, a sample of the infant food, "Ki-Na", made in the GDR, contained, however aflatoxin B1. Aflatoxin M1 could not be found. Food-hygienic-toxicological conclusions are discussed.

Aflatoxins↗
PubMed1976

[Significance of byssochlamic acid in fruit juice mold].

The authors describe a method for the determination of byssochlamic acid in fruit juice. After extraction and purification, byssochlamic acid is separated by thin-layer chromatography on HF 254 silica gel. The quenching of fluorescence of byssochlamic acid is estimated quantitatively on the plate by means of the thin-layer attachment of a fluorescence spectrophotometer using reference substances. For fruit juices the recovery rate is 80%; the limit of detection lies at 0.5 p.p.m. Byssochlamic acid could not be detected in commercially-available fruit juice and neither in juices produced of fruits which had spontaneously got mouldy.

Food Analysis↗