摘要:

The stability of sunset yellow FCF (El 10) was investigated in a model soft drinks system, with and without the addition of sodium metabisulphite. The rate of dye degradation was monitored by spectrophotometry and HPLC. In samples containing both sunset yellow and sodium metabisulphite, the formation of a lemon‐yellow‐coloured compound was clearly demonstrated. Isolation and subsequent analysis by NMR and FAB‐MS showed the structure of the compound to be that resulting from sulphonation at carbon 4 of the sunset yellow molecule. Examination of a stored commercial soft drinks sample indicated the presence of the same lemon‐yellow compound.

ISSN:0265-203X    

DOI:10.1080/02652038909373783

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Among numerous methods that have been published for determination of aflatoxin M1in milk and milk products, the following have been selected for review of performance characteristics: methods for which interlaboratory testing has been carried out, methods proposed in support of national (Swiss) regulations following inclusion in check sample series, and methods that report detection limits for milk of ≤ 5 ng/1 (≤ 0·005 μg/1) or ≤ 10 ng/kg (≤ 0.01 μg/kg) for cheese. It is practical to determine aflatoxin M1in milk with good accuracy and precision down to low ng/1 concentrations using thin‐layer chromatography, high‐performance liquid chromatography or enzyme‐linked immunosorbent assay for quantitation. However, measurement at such low levels has not been tested by a true collaborative study. Confirmation of identity of aflatoxin M1at low ng/1 levels has also been reported. Recent evidence suggests that consideration should be given to inclusion of aflatoxin M4in methods for aflatoxin M1.

ISSN:0265-203X    

DOI:10.1080/02652038909373784

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The Community Bureau of Reference (BCR) is preparing a series of animal feed reference materials to provide a basis for analytical quality assurance for aflatoxin B1analysis, a problem of particular importance in view of Community legislation. Before reference values can be assigned to the reference materials the major errors in the underlying measurements must be identified and reduced. This paper presents the results of two intercomparison exercises involving some 20 European laboratories who applied a wide variety of analytical methods. It is shown that the major source of error and discrepancy is connected with incomplete extraction and/or losses during clean‐up and that, provided correction for recovery/background interference is made, many methods can achieve acceptable accuracy. Sources of error and their control are discussed, and essential details of the methods used are presented. It is concluded that analytical QA is more important than the use of standardized methods when a high degree of accuracy and comparability are required.

ISSN:0265-203X    

DOI:10.1080/02652038909373785

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

One hundred samples of commercially available cows milk, collected in the state of São Paulo, from July 1979 to September 1981, were analysed to determine the levels of aflatoxins M1and M2by the method of the AOAC. This investigation was also undertaken in 50 samples of cows milk from two farms located in the Médio Vale do Paraiba, from animals which had ingested stored feed. Aflatoxin M1was detected in only one sample of commercially available cows milk, while those from the farms were found to contain a minimum of 0.1 μg/1 and a maximum of 1.68 μg/l.

ISSN:0265-203X    

DOI:10.1080/02652038909373786

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The levels of aflatoxins and zearalenone were determined in 328 samples of corn from the States of Santa Catarina, Minas Gerais, São Paulo, Paraná, Rio Grande do Sul and Espirito Santo by thin‐layer chromatography; the samples were obtained from April 1985 through to March 1986. In 12·3% of these samples aflatoxin B1was detected in concentrations that varied from 10 to 900 ug/kg (ppb); 18 samples showed levels above those tolerated by Brazilian legislation. Zearalenone was found in 4.5% of the samples analysed in concentrations that varied from 653 to 9830 μg/kg (ppb). The limit of detection of the method for the determination of zearalenone was 260 μg/kg (ppb) and the recovery was 100%.

ISSN:0265-203X    

DOI:10.1080/02652038909373787

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A study was performed to evaluate the contamination by ochratoxin A in coffee beans. Twenty‐nine samples of green coffee were collected from large lots of material by representative sampling. The analyses of green coffee samples showed a significantly high contamination percentage (58%) ranging from 0.2 to 15 μg/kg. Naturally and artificially contaminated samples were roasted at different operation times (5–6 min) to verify the percentage of destruction of the mycotoxin. The percentage ranged from 48% to 87% and from 90% to 100% in artificially and naturally contaminated samples respectively. The beverages prepared from artificially contaminated coffee using the most common types of coffee makers showed no residues of ochratoxin A.

ISSN:0265-203X    

DOI:10.1080/02652038909373788

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An accurate and highly sensitive dry ashing/graphite furnace atomic absorption spectrometry (GFAAS) procedure has been developed for the measurement of lead in green vegetables. The accuracy of the method was established by analysis of standard reference materials and confirmed by isotope dilution using an inductively coupled plasma‐mass spectrometer (ICP‐MS). The limit of detection (wet weight) of the technique is 1–3 pg/kg with relative standard deviations ranging from 6% for a sample of kale containing 500 μg/kg to 20% for cabbage containing 3.0 μg/kg.

ISSN:0265-203X    

DOI:10.1080/02652038909373789

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

An investigation was undertaken to determine whether the wine treatments for elimination of iron and copper used in Western Europe—with tetrapotassium hexacyanoferrate(II): K4[Fe(CN)6]—and in the United States—with iron(II) and potassium hexacyanoferrate(II) ('Fessier compound')—are suitable for lowering the concentration of lead to within legal limits. In both series of experiments the decrease in lead concentrations remained very poor. It was concluded that the treatments using hexacyanoferrates lowered lead levels but not sufficiently to reduce completely lead contamination in wines.

ISSN:0265-203X    

DOI:10.1080/02652038909373790

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Selenium concentrations were measured in the serum of 244 patients attending the Norfolk and Norwich Hospital, and 246 attending the James Paget Hospital in Gorleston, Norfolk. Both the mean and the median serum selenium concentration was lower in Gorleston than in Norwich, the difference being much greater in women than in men. Whereas the selenium concentrations were normally distributed about the mean for the Norwich area, there was a skewed distribution for the Gorleston area. The results are discussed in relation to the previously observed high risk of intestinal type gastric cancer in the Gorleston area.

ISSN:0265-203X    

DOI:10.1080/02652038909373791

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A total of 93 fatty food composites from the cities of Ottawa and Halifax (Canada) were analyzed for 34 selected isomers of polychlorinated biphenyls (PCBs). All fatty foods contained some PCB isomers with the 2,3,4,2’,4’,5'‐ and 2,4,5,2’,4’,5'‐hexachlorobiphenyls present in all samples, except in skim milk and some dehydrated soups. The overall lowest PCB residues of all food commodities were found in skim milk, lamb, margarine and soups. Among the dairy products the highest PCB isomer levels were found in cheese and butter. The sum of all PCB isomers in these two commodities gave residue levels on a wet basis of 2.0 and 3.4 ng/g respectively. In the meat, fish and poultry class the highest specific PCB isomer levels were found in fish, especially freshwater fish, which contained a total of 21.0 ng PCB/g fish. In addition 28 out of the 34 selected PCB isomers were present in freshwater fish. Residue levels in canned fish were the second highest of all food commodities. The observed total PCB residue levels were below the Canadian guidelines for fish, dairy products, poultry, eggs and beef. A comparison of the percentage distribution of PCB isomers in fatty foods and human milk was difficult to evaluate due to the large variation of the fatty food data. However out of 31 PCB isomers reported in fatty foods, 25 were also found in human milk, although not to the same extent.

ISSN:0265-203X    

DOI:10.1080/02652038909373792

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor