Analysis of nifursol residues in turkey and chicken meat using liquid chromatography-tandem mass spectrometry.

Nifursol (3,5-dinitrosalicylic acid (5-nitrofurfurylidene) hydrazide) is mainly used as a feed additive for the prevention of blackhead disease in turkeys. The objective of the present work was to establish information on nifursol residues in turkey and chicken meat. The analytical method was based on conversion of nifursol and its metabolites with an intact 3,5-dinitrosalicylic acid hydrazide (DNSH) side chain to the 2-nitrophenyl analogue of nifursol (NPDNSH) by treatment with dilute hydrochloric acid and 2-nitrobenzaldehyde. Nifuroxazide (salicylic acid (5-nitrofurfurylidene) hydrazide) added as an internal standard was converted to the 2-nitrophenyl analogue NPSH. After the addition of ammonia, proteins were precipitated with acetonitrile. Chromatographic separation was achieved on a C18 column and negative-ion electrospray ionization mass spectrometry was employed using m/z 183 and 226 (daughter ions of the NPDNSH phenolate ion m/z 374) for quantification and m/z 93 (daughter ion of the NPSH phenolate ion m/z 284) as a retention time reference. The decision limit (CCa) and detection capability (CCbeta) of the analytical method were 0.05 and 0.08 microg kg(-1), respectively. In the range 0.5-1 microg kg(-1), the repeatability, within-laboratory reproducibility and trueness were 8, 11 and -1%, respectively. A total of 37 samples of turkey meat and 16 samples of chicken meat were purchased at retail outlets in early spring, summer and winter 2003, and analysed for nifursol residues. No residues were found in the chicken samples, but nine of 18 samples of turkey meat collected in the spring had between 0.05 and 0.6 microg kg(-1) (average 0.25 microg kg(-1)) nifursol residues.

Analysis of glyphosate residues in cereals using liquid chromatography-mass spectrometry (LC-MS/MS).

A fast and specific method for the determination of glyphosate in cereals is described. The method is based on extraction with water by ultrasonication. The samples are cleaned up and separated by high-performance liquid chromatography on a polystyrene-based reverse-phase column (clean-up) in series with an ion chromatography column (separation) using NaHCO(3) as eluent. A micro-membrane suppressor was inserted after the separator column to remove the Na(+) ions before detection by electrospray ionization mass spectrometry in the negative-ion mode. In MS/MS, mode the following transitions were monitored m/z 168--> 150 (glyphosate) and 170-->152 (internal standard 2-(13)C(15)N-glyphosate) for quantification. The mean recovery was 85% (n=32) at spiking levels from 0.03 to 0.33 mg kg(-1). From 1998 to 2001, from the analysis of about 50 samples per annum, a reduction in the glyphosate residues was observed owing to a Danish trade decision not to use grain with glyphosate residues for milling or bread production.

Investigation of the herbicide glyphosate and the plant growth regulators chlormequat and mepiquat in cereals produced in Denmark.

An LC-MS/MS method for analysing glyphosate and aminomethylphosphonic acid (AMPA) in cereals was developed. The method is based on extraction with water and detection of the ions from the fragmentation m/z 170-->88 (glyphosate) and m/z 112-->30 (AMPA), using electrospray interface in the positive mode. Investigation from the harvests of 1998 and 1999 showed residues of glyphosate and/or its degradation product AMPA in more than half of the cereal samples produced in Denmark. The average concentration of glyphosate in 46 samples from the 1999 harvest was 0.11 mg/kg compared with 0.08 mg/kg for the 1998 harvest (n = 49). Thus, the figures were well below the maximum residue limit (MRL) and no violations were observed. The plant growth regulators chlormequat and/or mepiquat were investigated in cereals from the Danish harvest of 1999 where 83% of the samples contained chlormequat (n = 46) compared with 87% of the samples from the 1997 harvest (n = 52). The average concentration of chlormequat in 1999 was 0.32 mg/kg compared with 0.23 mg/kg in 1997. At 2.9 mg/kg, one sample of wheat bran was exceeding the MRL of 2 mg/kg for wheat. The intakes of the pesticides through the diet of cereals were estimated to comprise 0.04% of the acceptable daily intake (ADI) for glyphosate and 1% of the ADI for chlormequat for an adult Dane.

Residues of chlormequat and mepiquat in grain--results from the Danish National Pesticide Survey.

The objective of the present work was to establish information on chlormequat and mepiquat residues in grain for human consumption. Chlormequat (2-chloro-N,N,N-trimethylethylammonium, CAS RN 7003-89-6) and mepiquat (1,1-dimethylpiperidinium, CAS RN 15302-91-7) are plant growth regulators used to stabilize stalks in cereals. The study was part of the Danish National Pesticide Survey, managed by the Danish Veterinary and Food Administration. Samples were collected in autumn 1997. Residue contents were determined with a newly developed liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method for chlormequat analysis. The method was extended to include mepiquat in the present study. Quantitation was done by the internal standards method, using mass chromatograms of the most intense daughter ions of mepiquat (m/z 98), chlormequat (m/z 58), and [13C]-chlormequat (m/z 61, internal standard). For chlormequat, the overall limit of detection (LD) was 6 micrograms/kg and the limit of determination (LOD) was 10 micrograms/kg. For mepiquat, LD was 2 micrograms/kg and LOD was 3 micrograms/kg. Of 77 samples analyzed, 51 contained chlormequat and 11 contained mepiquat. The highest levels of chlormequat were found in samples of oatmeal (3.76 mg/kg) and rye (1.08 mg/kg). In 9 rye grain samples containing chlormequat, 5 also contained mepiquat. However, in all samples analyzed, the residues of chlormequat and mepiquat were below maximum residue limits.

Analysis of ochratoxin A in pig kidney and rye flour using liquid chromatography tandem mass spectrometry (LC/MS/MS).

A liquid chromatography electrospray tandem mass spectrometric (LC/MS/MS) method is described for analysis and confirmation of ochratoxin A in pig kidney and rye flour using derivatization of ochratoxin A to the methyl ester. Ochratoxin A methyl(d3)ester is used as internal standard. The method works well, the detection limit is 0.02 microgram/kg and the repeatability (coefficient of variation) is between 6% and 16% in the contamination range 0.5 to 8 micrograms/kg.

A survey of ethyl carbamate in beverages, bread and acidified milks sold in Denmark.

A sensitive gas-chromatographic method of analysis using mass specific detection has been applied to a study of ethyl carbamate in the Danish diet. Beverages and foods which were assumed to give a major contribution to the exposure of the Danish population to this potentially carcinogenic compound were investigated. Average values, ranges obtained for concentrations of ethyl carbamate and the number of analyses were 534 micrograms/l (< 5-5000 micrograms/l, n = 22) in spirits, 30 micrograms/l (7-61 micrograms/l, n = 14) in fortified wines, 7 micrograms/l (< 3-29 micrograms/l, n = 57) in wine, 3 micrograms/l (0.2-6.6 micrograms/l, n = 50) in beer, 3.5 micrograms/kg (0.8-12 micrograms/kg, n = 33) in bread and 0.2 microgram/kg (< 0.1-0.3 microgram/kg, n = 19) in yogurts and other acidified milk products. It is estimated that the average daily intake of ethyl carbamate is approximately 2 micrograms per person. The 5% of Danish males who have the highest alcohol intake probably consume more than 7 micrograms of ethyl carbamate per day.

HPLC profiles of mutagens in lean ground pork fried at different temperatures.

Ground lean pork was formed into patties and fried under ordinary conditions making sure that the crust was not charred. No fat was added when frying. The meat was fried at pan temperatures of 200 degrees C, 250 degrees C, and 300 degrees C until the temperature at the centre of the patties was either 65 degrees C or 70 degrees C. The crust was extracted with aqueous acid followed by concentration of the mutagens on an XAD-2 column and elution with acetone. The total mutagenic activity and high-pressure liquid chromatography (HPLC) analysis of the mutagenic components ("mutagrams") in the eluates were determined for the different frying procedures using the Salmonella/mammalian microsome test strain TA 98. Each 50 degrees C increase in the pan temperature (from 200 degrees C to 250 degrees C and from 250 degrees C to 300 degrees C) resulted in a doubling of the total mutagenic activity. The HPLC profiles of the mutagens were quite similar for the different frying temperatures, although a strong increase in the relative amount of more apolar mutagens was seen at 300 degrees C (the highest temperature). The major mutagenic activity of the HPLC fractions was confined to seven regions (mutagenic peaks) and a comparison of the HPLC profiles of the mutagens in fried beef and pork patties showed identical profiles. It is therefore concluded that the mutagenic compounds formed in fried beef and pork are similar in structure.