Formation of semicarbazide (SEM) in food by hypochlorite treatment: is SEM a specific marker for nitrofurazone abuse?

Semicarbazide (SEM) is considered to be a characteristic protein-bound side-chain metabolite of the banned veterinary drug nitrofurazone. It is therefore used as a marker for nitrofurazone abuse. Recently, there has been concern about other sources of SEM in tissue samples, which are not linked to the illegal use of nitrofurazone. The present studies have shown that SEM can occur naturally, e.g. in algae, shrimps and eggs, and is formed from natural substances, e.g. arginine and creatine. A significant formation of SEM was observed in samples treated with hypochlorite commonly used in food processing for disinfection or bleaching. SEM was formed in different kinds of nitrogen compound-containing samples (0.3-20 microg kg(-1)) after treatment with 1% active chlorine. It was detected in the mg kg(-1) range after hypochlorite treatment (0.015% active chlorine) of creatine. Lower levels were also formed from creatinine, arginine and urea. SEM present in hypochlorite-treated carrageenan proved mostly to occur in the tissue-bound form. Therefore, differentiation between SEM from nitrofurazone abuse and SEM originating from natural constituents (due to hypochlorite treatment) seems not to be unambiguously possible.

Evaluation of the results from an inter-laboratory comparison study of the determination of acrylamide in crispbread and butter cookies.

Analytical methods currently employed for determination of acrylamide (AA) in two carbohydrate-rich food samples, crispbread and butter cookies, obtained commercially, and native and spiked bread extract samples have been evaluated in a collaborative study. The objective of the study was to obtain information about the performance of the participating laboratories when analysing samples with an AA content close to the limit of quantification ( LOQ) and at a higher AA level, and to investigate the influence of sample-preparation procedures on the results of the analysis. For this purpose an aqueous native extract of white bread crumb, a fortified extract, and AA standard solutions, the analyte content of which were not disclosed to the participants, were included in the study. A total of 62 laboratories, applying seven different measurement techniques and a broad spectrum of analyte extraction and sample-preparation procedures reported their analytical results. Because the measurement data were not normally distributed, they were evaluated by application of robust statistics. The relative performance of the laboratories was highlighted by calculation of z-scores. For the crispbread sample, especially, a large percentage of the calculated z-scores were outside the satisfactory range. From their distribution it became obvious that one of the analytical techniques might be biased, if not applied correctly. Consequently, the impact of the applied methods was examined in more detail. Information about the analytical technique, extraction solvent, quantity weighed, calibration method, clean-up, and the experience of the participating laboratories were extracted from the analytical protocols and transcribed into a data matrix which was evaluated by multifactor analysis of variance. The applied measurement technique seems to have a statistically significant influence on the analytical results.

Synthetic musks in the environment. Part 1: Species-dependent bioaccumulation of polycyclic and nitro musk fragrances in freshwater fish and mussels.

Bioaccumulation of polycyclic musks (HHCB, AHTN) and nitro musks (musk xylene, musk ketone, and their amino metabolites) in aquatic biota was investigated by analyzing 18 fish samples (rudd, tench, crucian carp, eel) and 1 pooled zebra mussel sample from the pond of a municipal sewage treatment plant. Furthermore, water samples taken at the effluent of the sewage plant as well as water samples and two series of semipermeable membrane devices (SPMDs) from the pond were included. This comprehensive data set allowed the determination of species-dependent bioaccumulation factors on a lipid basis (BAF(L)), e.g., for HHCB the BAF(L) in tench were more than 20 times higher than in eel. The BAF(L) for HHCB and AHTN in biota were lower than the partition coefficients K(SPMD/W) obtained from SPMD samples, which are assumed to represent model bioconcentration values. This stresses that metabolism of these compounds in fish must not be neglected.

Synthetic musks in the environment. Part 2: Enantioselective transformation of the polycyclic musk fragrances HHCB, AHTN, AHDI, and ATII in freshwater fish.

A method for the enantioselective separation of the chiral polycyclic musks HHCB, AHTN, AHDI, and ATII is presented. Eighteen fish samples (rudd, tench, crucian carp, eel) and one pooled zebra mussel sample from the pond of a municipal sewage treatment plant were investigated with regard to their concentrations and the enantiomeric ratios (ERs) of polycyclic musks. In addition, three water samples taken at the effluent of the sewage plant, as well as two water samples and two series of semipermeable membrane devices (SPMDs) consisting of six samples each from the pond were included in the present study. This comprehensive data set allowed a reliable evaluation of species-dependent metabolization processes. The pattern of the polycyclic musks in the chromatograms obtained by enantioselective gas chromatography seems to be typical of each species, like a fingerprint. The highest deviations from the racemic ER were found for trans-HHCB and trans-ATII in crucian carp with values of or below 0.1. Calculations showed that enantioselective transformation seems to be the most important process, resulting in the observed lower concentrations in crucian carp compared to tench. Consequences for a risk assessment are discussed.

Enantiomeric composition of the polycyclic musks HHCB and AHTN in different aquatic species

Synthetic polycyclic musk fragrances are mainly represented by the compounds HHCB (Galaxolide(TM)) and AHTN (Tonalide(TM)). Because of their volume of use and their bioaccumulation potential, there is concern with respect to their environmental safety. HHCB and AHTN are chiral compounds, and gas chromatography using modified cyclodextrins as chiral stationary phases coupled to high-resolution mass spectrometry enabled enantioselective analysis even under unfavorable matrix conditions. The gas chromatographic elution order of (4S,7RS)- and (4R,7RS)-HHCB was assigned using synthetic (4S, 7RS)-HHCB. Fish and mussels reared in a pond associated with a municipal waste water treatment plant and semipermeable membrane devices exposed in the pond were analyzed for HHCB and AHTN. The highest lipid concentrations of HHCB and AHTN were observed in mussels (Dreissena polymorpha), tench (Tinca tinca), and crucian carp (Carassius carassius). Pronounced deviations in enantiomeric composition from racemic HHCB were observed in crucian carp and from racemic AHTN in tench. Correlations between lipid levels, enrichment, and enantioselective biotransformation of HHCB or AHTN were not seen. Selective biotransformation depended on both the compound and the species involved. The present study gives the first account of the enantiomeric composition of HHCB and AHTN in aquatic species. The lactone, 1,3,4,6,7,8-hexahydro-4,6,6,7,8, 8-hexamethylcyclopenta[g]-2-benzopyran-1-one, an oxidation product of HHCB, has been identified for the first time in environmental samples. Copyright 1999 Wiley-Liss, Inc.

Musk xylene and musk ketone amino metabolites in the aquatic environment.

The monoamino metabolites of the nitro musk fragrances musk xylene (MX) and musk ketone (MK) were analysed simultaneously with their parent compounds by GC/ECD, GC/PND and GC/EI/MS in the various compartments of the aquatic environment. In this review the data of the metabolites 4-NH2-MX, 2-NH2-MX, and 2-NH2-MK in five river water and seven sewage samples, six sediment samples and in a total of 33 biota samples are summarized and discussed. In the effluents of two municipal sewage plants low nitro musk concentrations and comparatively high levels of the amino metabolites (maximum concentrations: 34 ng 4-NH2-MX/L, 250 ng 2-NH2-MK/L) were analysed indicating that besides adsorption to the sludge the metabolization pathway plays an important role in the sewage plant. In water samples from the river Elbe the transformation products were the dominant compounds as well. In general, in water samples the concentrations of 2-NH2-MK exceeded those of the main MX metabolite 4-NH2-MX significantly. In biota samples 4-NH2-MX seems to be the main metabolite, very often its contents were higher than those of the parent compound. Maximum concentrations of 4-NH2-MX were found in tenches from a sewage pond (3600 microg/kg lipid), a species dependent bioaccumulation was discussed. The bioconcentration of 2-NH2-MK in biota samples is relatively low. There are only few toxicological studies on the mixed amino nitroaromatics, whose data indicate the relevance of the monoamino metabolites in environmental analysis and toxicology and the urgent need of further investigations.

Synthetic musks in environmental samples: indicator compounds with relevant properties for environmental monitoring.

Synthetic musks (nitro and polycyclic musks) are a group of chemicals offering a wide range of important properties for environmental monitoring programs. They are produced as odorous chemicals and added to a wide variety of perfumes, toiletry products and other household products. As such, they are directly applied in cosmetic products or in washed textiles to the human body in considerable concentrations and accumulate owing to dermal resorption. In addition, synthetic musks also enter the environment via waste water treatment. Several polycyclic musks are chiral. By using chiral gas chromatographic methods, it is possible to determine the enantiomeric ratio and assess their bioavailability. Although an comprehensive quality assurance program must be followed during the analysis of synthetic musks in environmental samples, the determination of these compounds is not very demanding and can be carried out by a standard analytical laboratory specialising in trace analysis of organic pollutants. Owing to the pheromone-like behavior of some synthetic musks, the induction of receptors in olfactory systems should be investigated. For HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyran, e.g., Galaxolide), three-dimensional structural similarities with androstenone (5 alpha-androst-16-en-3-one), a mammalian steroid pheromone, were found, which support the hypothesis of HHCB as an artificial pheromone. Owing to their environmental abundance, their relation to human activities and their potential for pheromone-like environmental behavior, synthetic musks are especially valuable as future indicator chemicals for environmental monitoring.