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Biomedical subjects

E Anklam

Publications and source records attributed to E Anklam.

33 records · Page 2Linked to original sources
PubMed2000

Comparison of HPLC and GLC techniques for the determination of the triglyceride profile of cocoa butter.

Current methods for the authentication of cocoa butter (CB) are mainly based on a knowledge of its triglyceride (TG) composition. The performances of capillary GLC and nonaqueous HPLC with an evaporative light-scattering detector (ELSD) for the quantification of TG of CB of different geographical origins were compared. Use of capillary columns coated with a polarizable stationary phase or two reversed-phase HPLC columns coupled in series efficiently separated the major TG species contained in CB. The velocity of the GLC carrier gas influenced the FID response factors of TG standard compounds, which were linearly related to the retention times of the analytes studied. Within a certain mass range the ELSD response of standard TG solutions did not deviate from unity to a greater extent, independent of the molecular structure of the TG species. The quantities of individual TG as obtained by both methods were in close agreement, and the precisions of the methods were also of comparable magnitude, so that either method can be applied to assess the purity of CB. Capillary GLC has the advantage of higher sample throughput due to a shorter run time and because the consumption of chemicals is negligible.

Chromatography, Gas↗
PubMed2000

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil.

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPLC with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1 mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether) analysed in the same products in the context of a previous study.

Animals↗
PubMed1999

Estimation of intake of bisphenol-A-diglycidyl-ether (BADGE) from canned fish consumption in Europe and migration survey.

The exposure to bisphenol-A-diglycidyl-ether (BADGE) from canned fish in oil was assessed from consumption data collected for each Member State of the European Union and Switzerland, and migration data from a European survey on 382 samples. Trade figures were used when no consumption data were available. The average consumption of canned fish in Europe was 2.3 kg per person per year, with values ranging from 0.2 kg per person per year in the United Kingdom to 5.1 kg per person per year in Denmark. The exposure to BADGE was calculated as microgram per person per day. The data indicated that exposure to BADGE was in the range below 4 mg per person per year, i.e. 9 micrograms per person per day, hence a fairly low exposure in part due to the fact that canned fish is a relatively minor dietary item. An approximation assuming the general figure of a 60 kg adult, would thus be 0.15 microgram/kg body weight per day. This is a fairly limited exposure considering the provisional limit in food had been set a 1 mg/kg and assumed 1 kg of food ingested. In countries for which increased exposure was found, the reason was mainly caused by one individual sample exhibiting a high concentration rather than a larger number of samples with mildly elevated concentrations.

Animals↗
PubMed1999

Investigation of various extractants for the analysis of aflatoxin B1 in different food and feed matrices.

Various extractants were investigated concerning their suitability for aflatoxin B1 determinations in different matrices including spices, infant formula and animal feed employing an immunoaffinity clean-up procedure. It was shown that the use of aqueous acetonitrile extractants was limited due to the fact that dry sample material can absorb significant amounts of water from the extractant. This can result in recoveries that are too high and therefore in incorrect values for the aflatoxin concentration if aliquots are taken for further analysis. A correction of the results by recovery calculation using spiked blank material is unsuitable, since material from the same group of food (e.g. paprika powder) or feed can vary significantly in the recovery values. Therefore it is recommended that aqueous methanol extractants are used, since no significant interaction with matrix constituents was observed. In addition, aqueous acetone extractants are a useful alternative with some limitations.

Aflatoxin B1↗
PubMed1999

Monitoring of bisphenol-A-diglycidyl-ether (BADGE) in canned fish in oil.

A survey at the European levels was initiated on the quantification of bisphenol-A-diglycidyl-ether (BADGE) in canned fish in oil in order to assess the exposure of BADGE. A total of 382 canned fish sample were collected from all 15 Member States and Switzerland and analysed for BADGE in fish. The fish was extracted first with hexane and reextracted with acetonitrile, followed by a membrane filtration and reverse phase HPLC analysis with fluorescence detection. The analysis of the fish showed that about 3% of the samples contained BADGE at a level above 1 mg/kg. The samples exceeding the limit by a larger margin were mostly from anchovy cans and cans manufactured in 1991-1995.

Animals↗
PubMed1994

A simple method of sample preparation for analysis of biphenyl residues in citrus fruit peels by gas chromatography.

A simple method of sample preparation for analysis of residues of the fungicide biphenyl in peels of citrus fruits by gas chromatography (GC) is described. The blended peels are macerated after addition of anhydrous sodium sulphate in dichloromethane for 2 h. After filtration the biphenyl is quantified directly without concentration of the solution by GC with a flame ionization detector (FID) or a mass selective detector (MSD) under single ion mass conditions. Due to the simple method of sample preparation and good average recoveries of 98-103% with standard deviations of 1-4% in the concentration range of 1-10 ppm, the method described is reliable for analysis of biphenyl in citrus fruit peels. In order to avoid loss of the relatively volatile biphenyl no evaporation of the extraction solution occurs.

Biphenyl Compounds↗
PubMed1992

Biphenyl and fluorinated derivatives: liver enzyme-mediated mutagenicity detected in Salmonella typhimurium and Chinese hamster V79 cells.

Hepatocarcinogenic polychlorinated and polybrominated biphenyls usually show negative results in in vitro mutagenicity assays. Problems in their testing result from their low water solubility and their slow rate of metabolism. We therefore investigated better soluble model compounds, namely biphenyl and its 3 possible monofluorinated derivatives. In the direct test, these compounds proved to be nonmutagenic in Salmonella typhimurium TA98 and TA100 (reversion to histidine prototrophy) and in Chinese hamster V79 cells (acquisition of resistance to 6-thioguanine). However, when the exposure was carried out in the presence of NADPH-fortified postmitochondrial fraction of liver homogenate from Aroclor 1254-treated rats, all 4 compounds showed mutagenic activity in V79 cells. 3-Fluorobiphenyl produced strong mutagenic effects in S. typhimurium TA100 as well, whereas the other biphenyls were inactive. In strain TA98, 3- and 4-fluorobiphenyl showed mutagenic activity. This mutagenicity was enhanced in the presence of 1,1,1-trichloropropene 2,3-oxide, an inhibitor of microsomal epoxide hydrolase, thus suggesting that epoxides may be active metabolites.

Animals↗
PubMedDate not supplied

IUPAC collaborative trial study of a method to detect genetically modified soy beans and maize in dried powder.

This paper presents results of a collaborative trial study (IUPAC project No. 650/93/97) involving 29 laboratories in 13 countries applying a method for detecting genetically modified organisms (GMOs) in food. The method is based on using the polymerase chain reaction to determine the 35S promotor and the NOS terminator for detection of GMOs. reference materials were produced that were derived from genetically modified soy beans and maize. Correct identification of samples containing 2% GMOs is achievable for both soy beans and maize. For samples containing 0.5% genetically modified soy beans, analysis of the 35S promotor resulted also in a 100% correct classification. However, 3 false-negative results (out of 105 samples analyzed) were reported for analysis of the NOS terminator, which is due to the lower sensitivity of this method. Because of the bigger genomic DNA of maize, the probability of encountering false-negative results for samples containing 0.5% GMOs is greater for maize than for soy beans. For blank samples (0% GMO), only 2 false-positive results for soy beans and one for maize were reported. These results appeared as very weak signals and were most probably due to contamination of laboratory equipment.

Agrobacterium tumefaciens↗
PubMedDate not supplied

Immunoaffinity column cleanup with liquid chromatography using post-column bromination for determination of aflatoxins in peanut butter, pistachio paste, fig paste, and paprika powder: collaborative study.

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for the determination of aflatoxin B1 and total aflatoxins at European regulatory limits. The test portion is extracted with methanol-water (8 + 2) for dried figs and paprika, and with methanol-water (8 + 2) plus hexane (or cyclohexane) for peanut butter and pistachios. The sample extract is filtered, diluted with phosphate buffer saline, and applied to an immunoaffinity column. The column is washed with water and the aflatoxins are eluted with methanol. Aflatoxins are quantitated by reversed-phase LC with post-column derivatization (PCD) involving bromination. PCD is achieved with either an electrochemical cell (Kobra cell) and addition of bromide to the mobile phase or pyridinium hydrobromide perbromide. Determination is by fluorescence. Peanut butter, pistachio paste, dried fig paste, and paprika powder samples, both naturally contaminated with aflatoxins and containing added aflatoxins, were sent to 16 collaborators in 16 European countries. Test portions of samples were spiked at levels of 2.4 and 9.6 ng/g for total aflatoxins which included 1.0 and 4.0 ng/g aflatoxin B1, respectively. Recoveries for total aflatoxins ranged from 71 to 92% with corresponding recoveries for aflatoxin B1 of 82 to 109%. Based on results for spiked samples (blind duplicates at 2 levels) as well as naturally contaminated samples (blind duplicates at 4 levels, including blank), the relative standard deviation for repeatability ranged from 4.6 to 23.3% for total aflatoxins and from 3.1 to 20.0% for aflatoxin B1. The relative standard deviation for reproducibility ranged from 14.1 to 34.2% for total aflatoxins, and from 9.1 to 32.2% for aflatoxin B1. The method showed acceptable within-laboratory and between-laboratory precision for all 4 matrixes, as evidenced by HORRAT values <1, at the low levels of determination for both total aflatoxins and aflatoxin B1.

Aflatoxin B1↗
PubMedDate not supplied

Validation of an immunoassay for detection and quantitation of a genetically modified soybean in food and food fractions using reference materials: interlaboratory study.

An immunoassay for detection of a specific genetically modified soybean (Roundup-Ready) was validated on dried soybean powder in an interlaboratory study. Different percentages of genetically modified soybeans in nonmodified soybean matrix were evaluated in a blind study. Thirty-eight laboratories from 13 countries participated. The immunoassay was evaluated for 2 endpoints: (1) To give a semiquantitative result, i.e., determination of a given sample above or below a given threshold, or (2) to compute a quantitative result, i.e., percentage of genetically modified soybeans in the sample. Semiquantitative results showed that a given sample which contained <2% genetically modified soybeans was identified as below 2% with a 99% confidence level. Quantitative use of the assay resulted in a repeatability (r) and reproducibility (R) that were computed to be RSDr = 7% and RSDR = 10%, respectively, for a sample containing 2% genetically modified soybeans. Application of this method depends on availability of appropriate reference materials for a specific food matrix. Only matrix-matched reference materials can be used for analysis of food or food fractions.

Antibodies, Monoclonal↗
PubMedDate not supplied

Determination of aflatoxin B1 in baby food (infant formula) by immunoaffinity column cleanup liquid chromatography with postcolumn bromination: collaborative study.

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for determination of aflatoxin B, in a milk powder based infant formula at a possible future European regulatory limit (0.1 ng/g). The test portion was extracted with methanol-water (8 + 2 [v + v]), filtered, diluted with water, and applied to an immunoaffinity column. The column was washed with water to remove interfering compounds, and the purified aflatoxin B1 was eluted with methanol. The separation and determination of the aflatoxin B1 was performed by reversed-phase LC and detected by fluorescence after postcolumn derivatization (PCD) involving bromination. PCD was achieved with either pyridinum hydrobromide perbromide (PBPB) or an electrochemical (Kobra) cell by addition of bromide to the mobile phase. The baby food (infant formula) test samples, both spiked and naturally contaminated with aflatoxin B1, were sent to 14 laboratories in 13 different European countries. Test portions were spiked at levels of 0.1 and 0.2 ng/g for aflatoxin B1. Recoveries ranged from 101 to 92%. Based on results for spiked test samples (blind pairs at 2 levels) and naturally contaminated test samples (blind pairs at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 3.5 to 14%. The relative standard deviation for reproducibility (RSDR) ranged from 9 to 23%. Nine participants used PBPB derivatization, and

Aflatoxin B1↗
PubMedDate not supplied

Development of a rapid method for the detection of cocoa butter equivalents in mixtures with cocoa butter.

A simple and rapid gas chromatographic (GC) method was developed for the detection of cocoa butter equivalents (CBEs) in cocoa buffer (CB). It is based on the use of a 5 m nonpolar capillary column for the separation of the main triglycerides of CB according to their acyl/carbon numbers. The GC procedure was optimized to avoid thermal degradation of the triglycerides. By computing the ratio C54/C50 and (C54/C50) x C52 and by 2-dimensional plotting of these values, authentic CB samples were clearly distinguished from samples containing various CBEs. The detection of little as 1% CBE in CB (corresponding to about 0.3% CBE in chocolate) in a model system was shown to be possible. Under real conditions, for a wide range of CBs, about 2.5% CBEs in CB were detected. With this method, quantitation was possible at a concentration of 5% CBEs in CB mixtures, which corresponds to around 1% in chocolate; this value is far below the maximum level of 5% CBEs allowed to be added to chocolate.

Chromatography, Gas↗
PubMedDate not supplied

Post process product control of rendering plant sterilization conditions by ELISA.

Experiments were conducted in a laboratory autoclave and in a commercial rendering plant to set a limit for the R-value of an enzyme-linked immunosorbent assay (ELISA) to prove that animal meal had been sufficiently heat-treated. The immunoassay method is currently the only technique used to check for appropriate sterilization of animal meal. The results of these experiments were statistically assessed using operation characteristic curves and confirmed that insufficiently heat-treated animal meal has an R-value > 2. Results of the trials also demonstrated that the main parameters of sterilization, temperature, and duration strongy influence the R-value, thus indicating that deviation from the target sterilization conditions is verifiable by the ELISA method.

Animal Feed↗