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Biomedical subjects

E Anklam

Publications and source records attributed to E Anklam.

At least 19 recordsLinked to original sources
PubMed2001

Analysis of procyanidins in chocolate by reversed-phase high-performance liquid chromatography with electrospray ionisation mass spectrometric and tandem mass spectrometric detection.

The analysis of procyanidins in crude chocolate extracts by reversed-phase high-performance liquid chromatography (HPLC) with electrospray ionisation mass spectrometry (MS) is described in this report. Catechin monomers and procyanidin oligomers (dimers to hexamers) were identified according to the mass of the single charged pseudomolecular ion ([M-H]-). Identification was further confirmed by collision-induced dissociation MS-MS analysis, which in addition, permitted the identification of double charged pentameric, hexameric, and heptameric ions. This study demonstrates the capability of the combination of HPLC and modern ion trap mass analysers to significantly reduce sample preparation and analysis time in combination with high specificity and structural information for compound identification.

Biflavonoids↗
PubMed2001

Supercritical fluid extraction for liquid chromatographic determination of carotenoids in Spirulina Pacifica algae: a chemometric approach.

An experimental design procedure was used to investigate the effects of some operating parameters on the supercritical fluid extraction of carotenoids beta-carotene, beta-cryptoxanthin and zeaxanthin from Spirulina Pacifica algae, a carotenoid-rich dietary product. Variables tested were temperature and pressure of the supercritical fluid, dynamic extraction time and percentage of ethanol added as the modifier. Each variable was tested at three levels; 31 experiments were performed in random order. Analyses of the extracts were performed by high-performance liquid chromatography with UV-Vis photodiode array detection. Analytical responses (chromatographic peak areas) were processed by using a stepwise multiple regression analysis, in order to find polynomial functions describing the relationships between variables and responses. For all the analytes the experimental conditions providing the highest extraction yield inside the experimental domain considered were found. Supercritical fluid extraction results obtained in these conditions were compared with those obtained by performing solvent extraction in order to evaluate the effectiveness of the supercritical fluid extraction procedure.

Carotenoids↗
PubMed2001

Use of an immunoassay as a means to detect polychlorinated biphenyls in animal fat.

In this paper we describe the validation and utilization of the Hybrinzme DELFIA immunoassay for detecting polychlorinated biphenyls (PCBs) in animal fat. The immunoassay incorporates a rapid sample processing protocol that has been optimized to detect concentrations of PCBs in animal fat at or above 200 ng/g. The limit of detection of the assay was less than 50 ng/g. When the action level for the DELFIA assay was set at 100 ng/g to detect samples having 200 ng/g or more PCBs, the false negative rate was estimated at 0.2%. The false positive rate depends on the concentration of PCBs in the sample population and was estimated at 4% and 7% for samples having 10 ng/g and 20 ng/g PCBs, respectively. By utilizing the DELFIA assay system to select for positive samples and GC/MS analysis for confirmation analysis, an accurate and cost-effective programme has been established for the high throughput detection of PCBs in animal products.

Adipose Tissue↗
PubMed2000

Immunoaffinity column clean-up prior to thin-layer chromatography for the determination of aflatoxins in various food matrices.

A one-dimensional TLC method to determine aflatoxins (B1, B2, G1, G2) in various food matrices was elaborated which abstains fully on the use of chlorinated solvents. It implements an immunoaffinity clean-up step after extraction with methanol. The aflatoxins were quantified by densitometry. The method has shown to be rapid and efficient. In-house performance characteristics were established. The limit of quantification was found to be significantly lower than current regulatory limits for aflatoxin control outside and within the European Community. The obtained recovery and precision data gave a strong indication, that the method is likely to give satisfactory performance if tested in a future collaborative trial.

Aflatoxins↗
PubMed2000

Development of a simplified densitometer for the determination of aflatoxins by thin-layer chromatography.

A simple, miniaturised and low power consuming (battery, fully semiconductor based) detector cell (SeBaDeC) was developed for the densitometric measurement of aflatoxins on TLC plates. A UV-light emitting diode (UV-LED) with a peak emission wavelength of 370 nm was used for fluorescence excitation, while a photo diode with a peak sensitivity of 440 nm in combination with a 418 nm cut-off filter was applied for detecting the fluorescence intensity. The resulting signal was further amplified by means of a commonly used operational amplifier integrated circuit (OA) and directly converted into a digital signal with a simple analogue-digital-converter (ADC). This signal was recorded at the serial (RS232) port of a portable PC and processed with a spreadsheet program. The software used for data recording is freeware and available in its source code, and the long lifetime of the UV-LED (up to 10 000 h) permits a maintenance free application of this device. This simplified device has shown to be able to detect concentrations of aflatoxins of 1 ng, thus offering a cheap and sensitive alternative to currently available TCL scanners.

Aflatoxins↗
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↗