Odor Perception by Dogs: Evaluating Two Training Approaches for Odor Learning of Sniffer Dogs.

In this study, a standardized experimental set-up with various combinations of herbs as odor sources was designed. Two training approaches for sniffer dogs were compared; first, training with a pure reference odor, and second, training with a variety of odor mixtures with the target odor as a common denominator. The ability of the dogs to identify the target odor in a new context was tested. Six different herbs (basil, St. John's wort, dandelion, marjoram, parsley, ribwort) were chosen to produce reference materials in various mixtures with (positive) and without (negative) chamomile as the target odor source. The dogs were trained to show 1 of 2 different behaviors, 1 for the positive, and 1 for the negative sample as a yes/no task. Tests were double blind with one sample presented at a time. In both training approaches, dogs were able to detect chamomile as the target odor in any presented mixture with an average sensitivity of 72% and a specificity of 84%. Dogs trained with odor mixture containing the target odor had more correct indications in the transfer task.

Determination of ethyl glucuronide in hair: a rapid sample pretreatment involving simultaneous milling and extraction.

A combination of simultaneous milling and extraction known as micropulverized extraction was developed for the quantification of the alcohol marker ethyl glucuronide (EtG) in hair samples using a homogeneous reference material and a mixer mill. Best extraction results from 50 mg of hair were obtained with 2-mL plastic tubes containing two steel balls (∅ = 5 mm), 0.5 mL of water and with an oscillating frequency of 30 s(-1) over a period of 30 min. EtG was quantified employing a validated GC-MS procedure involving derivatization with pentafluoropropionic acid anhydride. This micropulverization procedure was compared with dry milling followed by separate aqueous extraction and with aqueous extraction after manual cutting to millimeter-size snippets. Micropulverization yielded 28.0 ± 1.70 pg/mg and was seen to be superior to manually cutting (23.0 ± 0.83 pg/mg) and equivalent to dry grinding (27.7 ± 1.71 pg/mg) with regard to completeness of EtG extraction. The option to process up to 20 samples simultaneously makes micropulverization especially valuable for the high throughput of urgent samples.

Quantification of ethyl glucuronide in hair: effect of milling on extraction efficiency.

AIM: The objective of the study was to provide conclusive evidence for the effect of particle size reduction as by milling on the extractable content of ethyl glucuronide (EtG) of hair samples. METHODS: A number of real case hair samples and two pooled hair materials with EtG contents in the range of 10-30 pg/mg were systematically compared with regard to the extraction yield of EtG after cutting to 2-3 mm length and pulverization with a ball mill. After the respective treatment the samples were submitted to aqueous extraction followed by quantification of EtG using HPLC-MS/MS. RESULTS: It was unequivocally demonstrated that milling of hair samples prior to aqueous extraction significantly increases the extractable EtG content compared with cut hair. The effect ranged between 137 and 230% and was seen to occur regardless of the extent of pulverization. Cooling of samples was not necessary to prevent partial degradation of EtG during the grinding procedure. CONCLUSION: The options currently employed at choice in analytical practice (cutting or milling) were seen to significantly affect the extractable amount of EtG in hair. This is suspected to influence the degree of equivalence of quantification results obtained in different laboratories as well as their respective classification of a test subject's drinking behaviour on the basis of currently recommended cut-off values.

N-(ß-Carb-oxy-eth-yl)-α-isoleucine.

The title compound, {2-[(2-carbamoyleth-yl)amino]-3-methyl-penta-noic acid}, C(9)H(18)N(2)O(3), is of inter-est with respect to its biological activity. It was formed during an addition reaction between acryl-amide and the amino acid isoleucine. The crystal structure is a three-dimensional network built up by inter-molecular N-H⋯O and O-H⋯N hydrogen bonds.

1-(4-Bromo-3,5,5,6,8,8-hexa-methyl-5,6,7,8-tetra-hydro-naphthalen-2-yl)ethan-1-one: a precursor for phase-I metabolite of AHTN.

The title compound, C18H25BrO, crystallized as a racemate with four independent mol-ecules in the asymmetric unit. In the crystal, three of these four mol-ecules are linked via C-Br⋯Br-C halogen bonds [Br⋯Br = 3.662 (2) and 3.652 (2) Å], forming dimers.

Isopropyl 2,3,4,6-tetra-O-acetyl-ß-d-glucopyran-oside.

The title compound, C(17)H(26)O(10), was formed by a Koenigs-Knorr reaction of 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide and propan-2-ol. The central ring adopts a chair conformation. The crystal does not contain any significant inter-molecular inter-actions.

n-Propyl 2,3,4,6-tetra-O-acetyl-ß-d-glucopyran-oside.

THE TITLE COMPOUND [SYSTEMATIC NAME: (2R,3R,4S,5R,6R)-2-(acet-oxy-meth-yl)-6-propoxytetra-hydro-2H-pyran-3,4,5-triyl triacetate], C(17)H(26)O(10), was formed by a Koenigs-Knorr reaction of 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide and n-propanol. The central ring adopts a chair conformation. The crystal does not contain any significant inter-actions such as hydrogen bonds.

Degradation and epimerization of ergot alkaloids after baking and in vitro digestion.

The degradation and epimerization of ergot alkaloids (EAs) in rye flour were investigated after baking cookies and subsequently subjecting them to an in vitro digestion model. Different steps of digestion were analyzed using salivary, gastric, and duodenal juices. The degradation and bidirectional conversion of the toxicologically relevant (R)-epimers and the biologically inactive (S)-epimers for seven pairs of EAs were determined by a HPLC method coupled with fluorescence detection. Baking cookies resulted in degradation of EAs (2-30 %) and a shift in the epimeric ratio toward the (S)-epimer for all EAs. The applied digestion model led to a selective toxification of ergotamine and ergosine, two ergotamine-type EAs. The initial percentage of the toxic (R)-epimer in relation to the total toxin content was considerably increased after digestion of cookies. Ergotamine and ergosine increased from 32 to 51 % and 35 to 55 %, respectively. In contrast, EAs of the ergotoxine type (ergocornine, α- and ß-ergocryptine, and ergocristine) showed an epimeric shift toward their biologically inactive (S)-epimers. Further experiments indicated that the selective epimerization of ergotamine EAs occurs in the duodenal juice only. These results demonstrate that toxification of EAs in the intestinal tract should be taken into consideration.

How to improve reliability in groundwater analysis: over a decade of experience with external quality control in field campaigns on volatile halogenated compounds.

The reliability in measurement results obtained during environmental monitoring is crucial for the assessment and further planning of remediation efforts on the respective contaminated sites by the responsible authorities. A case study concerned with groundwater contaminated with perchloroethylene, trichloroethylene and 1,1,2-trichlorotrifluoroethane including their degradation products which involves private contract laboratories and an independent provider of quality assurance (QA) is presented. The experience gained with biannual monitoring campaigns over 14 years indicates that the selection of contractors on basis of accreditation status and successful performance in interlaboratory comparisons are not sufficient. Rather the auditing of the contractors by the QA provider prior to each campaign and the crosschecking of selected monitoring samples by the QA provider led to a lasting improvement of reliability in the contractors' measurement results. A mean deviation of 20% from the reference value determined by the QA provider for the crosschecked samples was reached.

Lysergol monohydrate.

IN THE TITLE COMPOUND [SYSTEMATIC NAME: (7-methyl-4,6,6a,7,8,9-hexa-hydro-indolo[4,3,2-fg]quinoline-9-yl)methanol monohydrate], C(16)H(18)N(2)O·H(2)O, the non-aromatic ring (ring C of the ergoline skeleton) directly fused to the aromatic rings is nearly planar, with a maximum deviation of 0.659 (3) Å, and shows an envelope conformation. In the crystal, hydrogen bonds between the lysergol and water mol-ecules contribute to the formation of layers parallel to (10[Formula: see text]).

Ergotaminine.

The title compound {systematic name: (6aR,9S)-N-[(2R,5S,10aS,10bS)-5-benzyl-10b-hy-droxy-2-methyl-3,6-dioxoocta-hydro-8H-oxazolo[3,2-a]pyrrolo-[2,1-c]pyrazin-2-yl]-7-methyl-4,6,6a,7,8,9-hexa-hydro-indolo[4,3-fg]quinoline-9-carboxamide}, C(33)H(35)N(5)O(5), was formed by an epimerization reaction of ergotamine. The non-aromatic ring (ring C of the ergoline skeleton) directly fused to the aromatic rings is nearly planar [maximum deviation = 0.317 (4) Å] and shows an envelope conformation, whereas ring D, involved in an intra-molecular N-H⋯N hydrogen bond exhibits a slightly distorted chair conformation. The structure displays chains running approximately parallel to the diagonal of bc plane that are formed through N-H⋯O hydrogen bonds.

Hexabromocyclododecane enantiomers: microsomal degradation and patterns of hydroxylated metabolites.

The degradation of the enantiomers of α-, ß-, and γ-hexabromocyclododecane (HBCD) by phase I metabolism was investigated using induced rat liver microsomes. HBCD isomers were quantified using HPLC-MS/MS (ESI(-)) after separation on a combination of a reversed phase and a chiral analytical column. The degradation of all six isomers followed first-order kinetics and the estimated half-lives ranged from 6.3 min for both ß-HBCD enantiomers to 32.3 min in case of (+)-γ-HBCD. (+)-α- and (-)-γ-HBCD displayed significantly shorter half-lives than their corresponding antipodes. It could be shown that this degradation led to a significant enrichment of the first eluting enantiomers (-)-α- and (+)-γ-HBCD. Individual patterns of mono- and dihydroxylated derivatives obtained from each α- and γ-HBCD enantiomer were seen to be distinctly characteristic. The patterns of monohydroxylated HBCD derivatives detected in liver and muscle tissues of pollack, mackerel and in herring gull eggs were largely similar to those observed in the in vitro experiments with rat liver microsomes. This enabled individual hydroxy-HBCDs to be assigned to their respective parent HBCD enantiomers.

Transformations of polycyclic musks AHTN and HHCB upon disinfection with hypochlorite: two new chlorinated disinfection by-products (CDBP) of AHTN and a possible source for HHCB-lactone.

In this work, the behavior of the polycyclic musks 6-acetyl-1,1,2,4,4,7-hexamethyltetraline (AHTN) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-γ-2-benzopyran (HHCB) was investigated upon disinfection by using sodium hypochlorite as disinfectant in a model disinfection basin in order to find new disinfection by-products (DBP). In the case of AHTN, the carboxylic acid 3,5,5,6,8,8-hexamethyl-5,6,7,8-tetrahydronaphthalene-2-carboxylic acid (AHTN-COOH) was generated by a haloform reaction, being the origin for two new chlorinated DBPs. In the case of HHCB, disinfection via hypochlorite led to the HHCB-lactone. All reaction products and intermediates were synthesized and isolated. The relevant degradation mechanisms are discussed in detail.

Methyl 3,5,5,6,8,8-hexa-methyl-5,6,7,8-tetra-hydro-naphthalene-2-carboxyl-ate (AHTN-COOMe).

Crystals of the title compound, C(18)H(26)O(2), were grown from ethyl acetate. Due to the racemic precursor, the title compound is also obtained as a racemate. Disorder was observed during structure refinement, originating from two possible half-chair conformations of the non-aromatic ring. The disorder was refined by introducing split positions in the cyclo-hexane ring regarding the two possible R and S-enantiomers at the chiral CH group [ratio 0.744 (3):0.256 (3)]. The crystal structure features pairs of inversion-related molecules connected by pairs of non-classical C-H⋯O hydrogen bonds.

(3,5,5,6,8,8-Hexamethyl-5,6,7,8-tetra-hydro-naphthalen-2-yl)methanol: a possible metabolite of the synthetic musk fragrance AHTN.

The title compound (AHTN-OH), C(17)H(26)O, was prepared in order to provide standard materials for the qualitative and quanti-tative analysis of environmental pollutants. The mol-ecule possesses a chiral C atom, although the structure determination was performed on racemic material, expressed in the structure as disordered chiral sites. The asymmetric unit consists of four AHTN-OH mol-ecules containing an hy-droxy group and forming a tetra-meric cyclic motif built up by four strong hydrogen bonds between these hy-droxy groups and additionally by two weak C-H⋯π inter-actions. Furthermore, these tetra-mers are linked via very weak C-H⋯π inter-actions, forming chains along the c axis.

Degradation kinetics of the Alternaria mycotoxin tenuazonic acid in aqueous solutions.

The degradation kinetics of the Alternaria mycotoxin tenuazonic acid (l-TA) in aqueous buffer were studied over a period of 4 months at different pH levels (3.5 and 7.0) and temperatures (4, 25 and 40 degrees C). l-TA and its degradation products were quantified by newly developed high-performance liquid chromatography methods with UV or electrospray multistage mass spectrometry detection. At pH 3.5, significant degradation occurred at 25 and 40 degrees C, the respective l-TA half-lives being 73.8 +/- 0.4 and 14.0 +/- 0.1 days. Two degradation processes, epimerization and hydrolysis, were evaluated kinetically. The hydrolytically formed iso-deacetyl TA (iso-DTA, epimeric mixture) was found to be the stable end product of l-TA degradation under the conditions of this study. This indicates that iso-DTA as well as the l-TA epimer u-TA are formed in aqueous beverage matrices.

Determination of mycotoxins in foods: current state of analytical methods and limitations.

Mycotoxins are natural contaminants produced by a range of fungal species. Their common occurrence in food and feed poses a threat to the health of humans and animals. This threat is caused either by the direct contamination of agricultural commodities or by a "carry-over" of mycotoxins and their metabolites into animal tissues, milk, and eggs after feeding of contaminated hay or corn. As a consequence of their diverse chemical structures and varying physical properties, mycotoxins exhibit a wide range of biological effects. Individual mycotoxins can be genotoxic, mutagenic, carcinogenic, teratogenic, and oestrogenic. To protect consumer health and to reduce economic losses, surveillance and control of mycotoxins in food and feed has become a major objective for producers, regulatory authorities and researchers worldwide. However, the variety of chemical structures makes it impossible to use one single technique for mycotoxin analysis. Hence, a vast number of analytical methods has been developed and validated. The heterogeneity of food matrices combined with the demand for a fast, simultaneous and accurate determination of multiple mycotoxins creates enormous challenges for routine analysis. The most crucial issues will be discussed in this review. These are (1) the collection of representative samples, (2) the performance of classical and emerging analytical methods based on chromatographic or immunochemical techniques, (3) the validation of official methods for enforcement, and (4) the limitations and future prospects of the current methods.

The quantification of hydrogen and methane in contaminated groundwater: validation of robust procedures for sampling and quantification.

A number of currently recommended sampling techniques for the determination of hydrogen in contaminated groundwater were compared regarding the practical proficiency in field campaigns. Key characteristics of appropriate sampling procedures are reproducibility of results, robustness against varying field conditions such as hydrostatic pressure, aquifer flow, and biological activity. Laboratory set-ups were used to investigate the most promising techniques. Bubble stripping with gas sampling bulbs yielded reproducible recovery of hydrogen and methane which could be verified for groundwater sampled in two field campaigns. The methane content of the groundwater was confirmed by analysis of directly pumped samples thus supporting the trueness of the stripping results. Laboratory set-ups and field campaigns revealed that bubble stripping of hydrogen may be restricted to the type of used pump. Concentrations of dissolved hydrogen after bubble stripping with an electrically driven submersible pump were about one order of magnitude higher than those obtained from diffusion sampling. The gas chromatographic determination for hydrogen and methane requires manual injection of gas samples and detection by a pulsed discharge detector (PDD) and allows limits of quantification of 3 nM dissolved hydrogen and 1 µg L⁻¹ dissolved methane in groundwater. The combined standard uncertainty of the bubble stripping and GC/PDD quantification of hydrogen in field samples was 7% at 7.8 nM and 18% for 78 nM.

rac-(1R,2R,4S)-1,2-Dibromo-4-[(1R)-1,2-dibromo-eth-yl]cyclo-hexa-ne.

In the title compound, C(8)H(12)Br(4), the cyclo-hexane ring exhibits a chair conformation. The C-Br distances range from 1.964 (6) to 1.985 (5) Šand the C-C distances range from 1.496 (6) to 1.543 (7) Å. Short inter-molecular Br⋯Br contacts [3.467 (4) Å] occur in the crystal.

Alternariol.

IN THE TITLE COMPOUND (SYSTEMATIC NAME: 3,7,9-trihydr-oxy-1-methyl-6H-benzo[c]chromen-6-one), C(14)H(10)O(5), the methyl group is shifted out of the molecular plane due to a steric collision, thus causing a slight twist of the benzene rings. The mol-ecular structure is stabilized by an intra-molecular O-H⋯O hydrogen bond, generating an S(6) ring. In the crystal, mol-ecules are connected by inter-molecular O-H⋯O hydrogen bonds into a three-dimensional network.