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PubMedDate not supplied

Effects of injection solvent and mobile phase on efficiency in reverse-phase liquid chromatographic determination of aflatoxin M1.

The effects of injection solvent and mobile phase composition on the reverse-phase liquid chromatographic determination of aflatoxin M1 (M1) were examined. M1 was converted to the more highly fluorescent derivative aflatoxin M2a (M2a). Using a C-18 column and a mobile phase of H2O-MeCN-MeOH (60 + 20 + 20) (MP-A), M2a was dissolved in various ratios of MeCN-H2O prior to injection. Chromatographic efficiency for the M2a peak varied from ca 2000 theoretical plates when injected in 30% aqueous MeCN to ca 9000 plates when injected in water alone. However, using the same C-18 column but with a mobile phase of H2O-IPA-MeCN (80 + 12 + 8) (MP-B), the M2a peak exhibited 25,000 plates when injected in 30% aqueous MeCN and 10,000 plates when injected in water alone.

Aflatoxin M1↗
PubMed1977

Comparison of two methods for analysis of aflatoxin M1 in milk.

The cellulose chromatography method of the Association of Official Analytical Chemists for determination of Aflatoxin M1 was compared with a two-dimensional thin layer chromatography procedure. The minimum detectable Aflatoxin M1 by the Official procedure was approximately .01 mug/kg while the thin layer chromatography procedure has a claimed sensitivity of .004 mug/kg. Analyses of milk samples by thin layer chromatography agreed with results of the Official procedure in the range of .01 to .25 mug/liter. Each method consistently yielded recoveries greater than 87% and there was no significant difference between means or variances of each method. The thin layer chromatography method took less time than the Official method and showed a reproducible lower threshold sensitivity of .005 mug/liter.

Aflatoxins↗
PubMed1977

[On the presence and the content of aflatoxin M1 in milk shipped to a dairy plant (author's transl)].

Between March 4 and April 15, 1976, the aflatoxin M1 content of milk shipped to a dairy plant was investigated. Out of 419 samples, 79 (19%) were positive. 33% of these samples showed values of 0.05--0.1 microng/1, 38% of more than 0.1 microng/1 and the highest value was at 0.54 microng/1. Other aflatoxins were not found. From samples of milk producers showing positive reactions, feed samples (n = 105) were taken, 45 of which (43%) were also positive. 40% of the positive samples contained up to 20 microng/kg, 36% were in the range between 20--50 microng/kg and the highest values were at 280 resp. 300 microng/kg, especially in mixed feed. Out of these samples, 47% (DLG Standard IV) resp. 36% (DLG Standard III) were higher than the tolerated maximum level of 20 microng/kg. There is a qualitative relationship between the aflatoxin M1 content in milk and the aflatoxin B1 content in feed. In 61 cases where milk samples were positive, in 41 feed samples (67%) aflatoxin B1 was detected.

Aflatoxins↗
PubMed1992

Reduction of aflatoxin M1 in milk using hydrogen peroxide and hydrogen peroxide plus heat treatment.

Use of hydrogen peroxide (H2O2) under various conditions of temperature and time to inactivate aflatoxin M1 in artificially contaminated raw milk was examined. The degree of inactivation was measured by Enzym Linked Immunosorbent Assay (ELISA). It appeared that there is no change in the content of aflatoxin M1 in milk contained H2O2 and examined after 24 hours without heat treatment and in contaminated milk without add of H2O2 and heat treated treatment at (63 degrees C for 30 min, 75 degrees C for 15 sec) but slight inactivation (4.3%) was obtained in milk boiled for 5 min without H2O2. Maximum inactivation (27.8%, 28.8% and 45.1%) were obtained using 1% H2O2 followed by heat treatment at 36 degrees C for 30 min, 75 degrees C for 15 sec and boiling for 5 min respectively.

Aflatoxin M1↗
PubMed1997

Occurrence of aflatoxin M1 in commercial pasteurized milk determined with ELISA and HPLC.

Eighty-one samples of commercial pasteurized milk from Athens market were analysed for the presence of aflatoxin M1 (AFM1). A combination of a commercial ELISA kit and a modified HPLC method was applied for the rapid and reliable determination of AFM1. AFM1 concentrations in milk extracts were initially estimated by ELISA. Samples found to contain more than 5 ng/l were further quantitated by HPLC. Determination was performed after derivatization of AFM1 to its hydroxylated product AFM2a. The recovery of the HPLC method used was found to be close to 100%. Thirty-two samples contained aflatoxin M1 at levels of 2.5-5 ng/l, none contained more than 5 ng/l, while 31 contained only traces of aflatoxin (0.5-1 ng/l). In nine samples no AFM1 was detected. There was no seasonal influence on the aflatoxin content of the milk samples analysed.

Aflatoxin M1↗
PubMed2001

Determination of aflatoxin M1 levels in cheese and milk consumed in Bursa, Turkey.

Aflatoxin M1 (AFM1) was determined by ELISA in 57 cheese and 10 milk samples collected from supermarkets and street milkmen during August in Bursa Province, Turkey. The highest AFM1 concentration was 810.00 ng/kg in full fatty white cheese. The incidence of AFM1 in the cheese was higher (89.47%) than that of milk (10%). The AFM1 in 7/57 (12.28%) cheese samples exceeded the Turkish AFM1 tolerance limits of 250 ng/kg, but none of the milk samples exceeded the FAO/WHO, European Union and Turkish tolerance limit of 50 ng/L.

Aflatoxin M1↗
PubMedDate not supplied

Aflatoxin M1 occurrence in samples of Grana Padano cheese.

A total of 223 samples of Grana Padano cheese manufactured in 4 years (1991-94) by dairies in 11 provinces of the Po valley were checked for aflatoxin M1. Grated cheese was extracted with chloroform and the defatted extract was purified by an immunoaffinity column; aflatoxin M1 was determined by HPLC using a fluorescence detector. From the analysis of the data it has emerged that only one sample exceeded the maximum tolerated level in cheese in some European countries (250 ng/kg). Most samples (91%) were in the range 5-100 ng/kg and only 15 (6.7%) in the range 100-250 ng/kg. Notwithstanding a diffuse microcontamination, the situation regarding the AFM1 levels can be considered fairly satisfactory. Mean contamination levels of 1992 and 1994 were significantly higher (P < 0.05) than those of 1993 and 1991. No significant difference was observed among provinces or dairies of origin.

Aflatoxin M1↗
PubMed1983

[Aflatoxin M1 - isolation of a toxin-producing strain of the mold Aspergillus flavus].

A strain of Aspergillus flavus producing aflatoxins B1, G1 and M1 was obtained. Aflatoxin M1 constitutes about 5% of the total amount of aflatoxins produced. Aflatoxin M1 was isolated from a crude chloroform extract and was identified by thin silica-gel layer chromatography (TLC), by high-performance liquid chromatography (HPLC) and spectral analysis.

Aflatoxin M1↗
PubMed1992

Determination of aflatoxin M1 using a dialysis-based immunoaffinity sample pretreatment system coupled on-line to liquid chromatography. Reusable immunoaffinity columns.

A liquid chromatographic column-switching system containing a dialysis unit and an anti-aflatoxin immunoaffinity precolumn (immuno precolumn) is described for the automated determination of aflatoxin M1 in milk samples. Both a flat membrane dialysis unit working according to the flowing donor-flowing acceptor principle and a laboratory made hollow-fibre dialysis unit working according to the stagnant donor-flowing acceptor principle were evaluated. The hollow-fibre unit is superior with respect to repeatability (3% relative standard deviation) and detection limit (10 ng/l for aflatoxin M1 in milk), in spite of the fact that the overall recovery is only 6%. Interfering compounds, which would destroy the activity of the immuno precolumn, are efficiently removed from the system by the dialysis step; a single immuno precolumn can then be used for over 70 milk analyses. No decrease in the performance of either the immuno precolumn or the hollow-fibre dialysis unit is observed.

Aflatoxin M1↗
PubMed1984

[Relay toxicity of aflatoxin M1 in powdered milk. Medium term study on ducklings].

In milk from dairy Cows eating Peanut meal containing 1.71 mg/kg of aflatoxin B1, 6 to 11.7 p. cent is transformed into aflatoxin M1. 7.5 micrograms/kg of this, brought by 30 p. cent of dried milk in diet, given 69 days to Duckling is without any toxic effect. There are important lesions with a diet containing 10 to 30 p. cent of Peanut meal bringing in aflatoxin B1.

Aflatoxin M1↗
PubMed1988

Comparative metabolism and DNA binding of aflatoxin B1, aflatoxin M1, aflatoxicol and aflatoxicol-M1 in hepatocytes from rainbow trout (Salmo gairdneri).

DNA binding and metabolism patterns of 3H-labeled aflatoxin B1 (AFB1) and its phase I metabolites, aflatoxicol (AFL), aflatoxin M1 (AFM1), and aflatoxicol-M1 (AFL-M1), were compared in freshly prepared rainbow trout (Salmo gairdneri) hepatocytes. Aflatoxins were incubated with hepatocytes for periods up to 1 h, cellular DNA was isolated and specific activities determined by scintillation counting and Burton analysis. Data for (pmol bound aflatoxin/micrograms DNA)/(mumol dose) versus time fit a linear function (P less than 0.002) passing nearly through the origin for each aflatoxin. DNA binding at 1 h relative to AFB1 was: AFL, 0.53 +/- 0.07; AFM1, 0.81 +/- 0.20 AFL-M1, 0.83 +/- 0.24. Statistical analysis indicated that binding of AFL, AFM1 and AFL-M1 were significantly less than that of AFB1. HPLC analysis of the cellular supernatants indicated that the major metabolites were AFL, AFB1, AFL-M1, and AFM1 from AFB1, AFL, AFM1 and AFL-M1 substrates, respectively. Small quantities of hydroxylated metabolites and glucuronides also were detected in some of the incubations. The time-course data suggested that initial formation of major metabolites was rapid and that, by 20-30 min, net changes in metabolite levels decreased or approached zero. Because the four compounds possess a 8,9-double bond, DNA binding could be due to activation of the parent substrates as well as of their phase I metabolites. Based on current mutagenicity data and limited carcinogenicity studies, AFM1 and AFL-M1 have binding levels which are higher than expected compared to AFB1 and AFL.

Aflatoxin B1↗
PubMed2005

An electrochemical immunosensor for aflatoxin M1 determination in milk using screen-printed electrodes.

The production and assembling of disposable electrochemical AFM1 immunosensors, which can combine the high selectivity of immunoanalysis with the ease of the electrochemical probes, has been carried out. Firstly immunoassay parameters such as amounts of antibody and labelled antigen, buffer and pH, length of time and temperature of each steps (precoating, coating, binding and competition steps) were evaluated and optimised in order to set up a spectrophotometric enzyme-linked immunosorbent assay (ELISA) procedure. This assay exhibited a working range between 30 and 160 ppt in a direct competitive format. Then electrochemical immunosensors were fabricated by immobilising the antibodies directly on the surface of screen-printed electrodes (SPEs), and allowing the competition to occur between free AFM1 and that conjugated with peroxidase (HRP) enzyme. The electrochemical technique chosen was the chronoamperometry, performed at -100 mV. Furthermore, studies of interference and matrix effects have been performed to evaluate the suitability of the developed immunosensors for the analysis of aflatoxin M1 directly in milk. Results have shown that using screen-printed electrodes aflatoxin M1 can be measured with a detection limit of 25 ppt and with a working range between 30 and 160 ppt. A comparison between the spectrophotometric and electrochemical procedure showed that a better detection limit and shorter analysis time could be achieved using electrochemical detection.

Aflatoxin M1↗
PubMed1995

Aflatoxin M1 in human breast milk samples from Victoria, Australia and Thailand.

This study examined the exposure of infants to aflatoxin M1 (AFM1) and of lactating mothers to aflatoxin B1 (AFB1), using AFM1 in breast milk as a biomarker for exposure to AFB1. An enzyme-linked immunosorbent assay was modified for the analysis of AFM1 in breast milk samples from 73 women from Victoria for comparison with breast milk samples from Thailand (n = 11). The results were compared with those obtained by HPLC. AFM1 was detected in 11 samples from Victoria and five samples from Thailand at median concentrations of 0.071 ng/ml (range 0.028 to 1.031 ng/ml) and 0.664 ng/ml (range 0.039 to 1.736 ng/ml), respectively. Levels of AFM1 in Thai milk samples were significantly higher than those in milk samples from Victoria.

Aflatoxin B1↗
PubMed2000

Occurrence of aflatoxin M1 in Korean dairy products determined by ELISA and HPLC.

The occurrence of aflatoxin M1 (AFM1) in pasteurized milk and dairy products was investigated by using direct competitive enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The recoveries of AFM1 from the samples spiked at levels between 5 and 500 pg/ml were 88.0-106.5% for pasteurized milk and 84.0-94.0% for yoghurt by ELISA. By HPLC, the recoveries were 103-120% for pasteurized milk and 87.0-93.0% for yoghurt. The limits of detection were found to be 2 pg/ml by ELISA and 10 pg/ml by HPLC. Among a total of 180 samples collected in Seoul, Korea, the incidence of AFM1 in pasteurized milk, infant formula, powdered milk and yoghurt was 76, 85, 75, and 83%, respectively, with a mean concentration of 18, 46, 200, and 29 pg/g, respectively, when determined by ELISA. These results obtained by ELISA were closely related to those by HPLC for AFM1 (r2 = 0.9783).

Aflatoxin M1↗
PubMed1982

Some effects of phenobarbital dosing of dairy cattle on aflatoxin M1 and fat in milk.

Eight Holstein cows were selected randomly to determine effects of phenobarbital on the fate of orally administered aflatoxin B1, milk fatty acid profiles, total milk fat, and milk production. Animals were grouped in pairs for one of four treatments: 1) control, 2) oral dosing with sodium phenobarbital for 5 days, 3) dosing with sodium phenobarbital followed by oral dosing with aflatoxin B1, and 4) oral dosing with aflatoxin B1 for 5 days. Daily composite raw milk samples were taken and assayed for aflatoxin M1 by thin-layer chromatography, and milk fatty acid profiles were measured by gas-liquid chromatography. Milk production for all treatments was less than that of controls. Total milk fat was not affected. Both aflatoxin B1 and phenobarbital affected fatty acid distribution, suppressing the amount of fatty acids carbons 8 through 14 while increasing the amount of 16-carbon fatty acids. No treatment effect was significant for the short chain fatty acids of 4 and 6 carbons and the 18-carbon acids oleic, stearic, and linoleic. Pretreatment with phenobarbital resulted in a significant difference between treated and untreated difference between treated and untreated animals. A greater than 50% reduction in the amount of aflatoxin B1 excreted as M1 in the milk was realized.

Aflatoxin M1↗
PubMed1990

A new method for the quantitation of aflatoxin M1 in urine by high performance liquid chromatography and its application to the etiologic study of hepatoma.

A high performance liquid chromatographic (HPLC) method for the analysis of aflatoxin M1 (AFM1) in urine is described. Urine samples were treated with saturated lead acetate and AFM1 was extracted with chloroform. After washing with water to remove impurities the compound was derivatized with trifluoroacetic acid and the AFM1 derivative was analyzed quantitatively by HPLC. The sample pretreatment is simple and more selective. A good line correlation between AFM1 peak height and its concentration was obtained when AFM1 content was in the range of 50-400 pg. The ratio of recovery was 87.42%. Sensitivity is 0.01 ppb. The method is applicable to trace analysis. Results in urine of residents who live in the high/low liver cancer incidence area in Fushui county were the same as that of previous epidemiological investigation.

Aflatoxin B1↗
PubMed2002

Aflatoxin M1 in white cheese and butter consumed in Istanbul, Turkey.

We studied the occurrence of Aflatoxin M1 (AFM1) in 183 sample of white cheese and butter in Istanbul, Turkey in 2001. The incidence of AFM1 in white cheese and butter samples was as high as 65 and 81, respectively. The particularly high AFM,concentrations imply that more importance should be given to routine analysis of these dairy products.

Aflatoxin M1↗