Chemical Residue Analysis Research Articles

Chemical analyses of organic residues in archaeological pottery from Arbon Bleiche 3, Switzerland – evidence for dairying in the late Neolithic

Fatty acids distribution and stable isotope ratios (bulk δ 13C, δ 15N and δ 13C of individual fatty acids) of organic residues from 30 potsherds have been used to get further insights into the diet at the Late Neolithic (3384–3370 BC) site of Arbon Bleiche 3, Switzerland. The results are compared with modern equivalents of animal and vegetable fats, which may have been consumed in a mixed ecology community having agrarian, breeding, shepherd, gathering, hunting, and fishing activities. The used combined chemical and isotopic approach provides valuable information to complement archaeological indirect evidence about the dietary trends obtained from the analysis of faunal and plant remains. The small variations of the δ 13C and δ 15N values within the range expected for degraded animal and plant tissues, is consistent with the archaeological evidence of animals, whose subsistence was mainly based on C 3 plants. The overall fatty acid composition and the stable carbon isotopic compositions of palmitic, stearic and oleic acids of the organic residues indicate that the studied Arbon Bleiche 3 sherds contain fat residues of plant and animal origin, most likely ruminant (bovine and ovine). In several vessels the presence of milk residues provides direct evidence for dairying during the late Neolithic in central Europe.

Assessment of Dermal Pesticide Exposure with Fluorescent Tracer: A Modification of a Visual Scoring System for Developing Countries

A semi-quantitative dermal exposure assessment method based on visual observations of fluorescence images was presented by Fenske in 1988. We adapted the method to Nicaraguan working conditions and evaluated its performance. Thirty-two farmers applied chlorpyrifos and methamidophos marked with Tinopal CBS-X(R). Skin fluorescent depositions were observed with a portable UV lamp in a foldaway darkened room. We modified the two components of the original system-extent by weighting the size of exposed body parts according to total body surface and intensity by establishing criteria for reading the fluorescence images. This resulted in body segment scores (BSSs) for specific body parts as well as two summary measures, contaminated body area (CBA) as the percentage of contaminated skin in relation to total body surface and total visual score (TVS) as an overall score combining extent and intensity of contamination. The scoring of intensity was evaluated with quantitative chemical residue analyses. Hands were the most frequently contaminated, and the back had the highest BSS. The CBA ranged between 1 and 66% and the TVS between 0.5 and 270. The farmer with the highest TVS scored 60% of the maximum possible. Residues increased with increasing fluorescence intensities with some misclassification. Fluorescent images reflected work practices and contamination mechanisms. In conclusion, the visual score, as modified by us, provides information on the body segments most contributing to dermal exposure and degree of skin contamination during pesticide applications. Fluorescence patterns reflect exposure routes. The system is low-cost and practical for developing countries. Further improvements are recommended.

Organochlorine pesticides in chorioallantoic membranes of Morelet's crocodile eggs from belize.

Recent studies examined the utility of the chorioallantoic membrane (CAM) as a nonlethal, noninvasive indicator of environmental contaminant exposure in oviparous wildlife. The CAM is a highly vascularized extraembryonic membrane that functions as a site for respiration, nutrient transport, and waste storage during embryonic development. After hatching, the CAM is usually discarded with the eggshell and can be used for chemical residue analysis. Chorioallantoic membranes have been used successfully to examine contaminant exposure and predict chemical concentrations in multiple species of birds and reptiles. In this study, we examined organochlorine (OC) pesticide concentrations in CAMs from eggs of Morelet's crocodiles (Crocodylus moreletii) from northern Belize. Multiple OCs were detected in crocodile CAMs, including aldrin, dieldrin, endrin, dichlorodiphenyltrichloroethane, dichlorodiphenyldichloroethane, dichlorodiphenyldichloroethylene (DDE), heptachlor, lindane, and methoxychlor. Number and concentrations of OC compounds in CAMs were variable. The most prevalent contaminant detected was DDE, which occurred in 69% of CAMs, with concentrations ranging from 0.3 parts per billion (ppb) to 17.0 ppb. The OC burdens in crocodile CAMs confirm contamination of eggs and suggest exposure in embryos and maternal females. These results further support the use of CAMs as qualitative indicators of OC exposure in oviparous wildlife. The efficacy of this sampling technique in the field will depend on the logistics and cost associated with CAM collection and the specific life history traits of the wildlife species.

The use of biomarkers in aquatic biomonitoring: the example of esterases

Abstract1. The term biomarker refers to the physiological, biochemical, and histological changes used as indicators of exposure to chemical contaminants and/or of its effects at the suborganismal or organismal level. Recently the development of sensitive biochemical markers for monitoring environmental quality in aquatic ecosystems has raised a great deal of interest.2. Selected biochemical markers measured in feral organisms can provide sensitive indexes, or early warning signals, of potential ecosystem degradation caused by contaminants. Compared with chemical residue analysis, biomarkers have the advantage of measuring the stress on the organism, thus being more biologically relevant.3. Some of the most frequently used biomarkers in aquatic biomonitoring in different countries are briefly described.4. The use of cholinesterase activity as a biomarker of pesticide exposure for biomonitoring in estuarine areas is also given as an example. Copyright © 2001 John Wiley & Sons, Ltd.

Immunochemical approaches for purification and detection of TNT traces by antibodies entrapped in a sol-gel matrix.

A highly sensitive immunochemical method for immunoaffinity purification (IAP) and detection of trace amounts of TNT was developed on the basis of antibodies (Abs) in a ceramic matrix (sol-gel). The study resulted in: (i) a highly sensitive and reproducible TNT ELISA (I50 and I20 values of 0.4 +/- 0.09 ppb and 0.12 +/- 0.03 ppb, respectively; n = 12), which is highly specific to TNT; and (ii) successful entrapment of the Abs that bound free analyte from solution. Binding was found to be highly reproducible, dose dependent, and only slightly (1.2-1.8-fold) lower than that in solution. The entrapped Abs did not leach from the matrix and were tolerant of absolute ethanol, acetone, and acetonitrile. Bound analytes could be easily eluted from the sol-gel matrix at high recoveries. The sol-gel-based IAP method described above introduces a simple one-step procedure that has a high potential to serve as a suitable and convenient immunochromatographic device for cleanup and concentration of TNT from "real field" samples in a manner that complies with both chemical and immunochemical residue analysis methods.

Effects of the sulfonylurea herbicide metsulfuron methyl on growth and reproduction of five wetland and terrestrial plant species

AbstractTwo wetland plant species (Mimulus ringens L. [monkey‐flower] and Bidens cernua L. [bur‐marigold]), two terrestrial species (Sinapis arvensis L. [wild mustard] and Phaseolus vulgaris L. [beans‐variety, Kentucky blue]), and one species found in both wet and dry habitats (Echinochloa crusgalli [L.] Beauv. [barnyardgrass]) were exposed to 1% (0.045 g a.i./ha) and 10% (0.45 g a.i./ha) of recommended label rate of metsulfuron methyl, a sulfonylurea herbicide used in western Canada. The objective of the study was to investigate the effect of metsulfuron methyl on these plant species and to determine the most sensitive phenological stage. Chemical analyses of herbicide residues showed that there was good correspondence between the quantity measured in the tank mix compared with that detected on glass fiber papers, the latter representing the dose reaching the test plants during the spray event. All species exhibited marked effects on the vegetative growth and reproductive performance when sprayed at 10% label rate. Less pronounced but significant effects were shown at 1% label rate. Seed weight was reduced for B. cernua and S. arvensis. The seedling stage was the most sensitive period for all species tested, although surviving plants sprayed at later stages showed considerable effects on the reproductive parts. All species tested would be at risk from small doses of metsulfuron methyl drifting away from the sprayed areas. This study highlights the shortcomings of the current testing schemes required prior to pesticide registration.

Aquatic dissipation of the herbicide triclopyr in Lake Minnetonka, Minnesota

A study of the aquatic fate of the triethylamine salt of triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) was conducted in three bays of Lake Minnetonka, Minnesota. Triclopyr is under review by the US Environmental Protection Agency as a selective aquatic herbicide. The primary purpose of this study was to determine dissipation rates of the parent active ingredient, triclopyr, and its major metabolites, 3,5,6-trichloropyridinol (TCP) and 3,5,6-trichloro-2-methoxypyridine (TMP) in selected matrices including water, sediment, plants, finfish and shellfish. Two 6.5-ha plots dominated by the weedy species Eurasian watermilfoil (Myriophyllum spicatum L) were treated with triclopyr-triethylammonum at a rate of 2.5 mg AE liter−1 (2.5 ppm) on 21–23 June 1994. A third 6.5-ha plot was established as an untreated reference. Water and sediment samples were collected from within the plots and at selected locations up to 1600 m outside of the plots through six weeks post-treatment for chemical residue analysis. In addition, residue samples were collected from the target and non-target plants and other non-target matrices, including game and rough fish, clams and crayfish. All test animals were sequestered in cages located in the center of each plot and samples were collected through four weeks post-treatment. Half-lives for dissipation of triclopyr and TCP in water ranged from 3.7 to 4.7 days and from 4.2 to 7.9 days, respectively, with trace amounts of TMP found. Peak triclopyr sediment values ranged from 257 to 335 ng gram−1, with a mean half-life of 5.4 days, while peak TCP sediment levels ranged from 27 to 65 ng gram−1 (mean half−life = 11.0 days). Trace levels of TMP were detected at one treatment site at one sampling event. Triclopyr and TCP accumulated and cleared from animal tissues proportionately to concentrations in the water (triclopyr dissipation half-lives <11 days, TCP < 14 days). TMP levels were two to three times higher than those of the other compounds, particularly in visceral tissue. In all cases, residues of these compounds were higher in the inedible portions of the animals, and were usually higher in bottom-feeding fish species. © 2000 Society of Chemical Industry

The use of fish metabolic, pathological and parasitological indices in pollution monitoring

An integrated biological effect monitoring concept has been tested in flounder (Platichthys flesus L.) from four locations with different anthropogenic impact in the German Bight. During 3 years of sampling, biomarkers at all levels of biological organisation from the molecular to the ecosystem level were applied and tested on 742 individual fish of body lengths between 18 and 25 cm. At the ecosystem level, the fish were taken as a habitat for the parasite assemblage. The hypothesis was that changes in the environment might lead to changes in the species diversity of parasites and in the infection intensity of single species, as well as between heteroxenic and monoxenic parasite species (H/M ratio). At the molecular level, activity of the CYP1A-dependent monooxygenase ethoxyresorufin O-deethylase (EROD) was used as a biomarker of exposure. At the subcellular level, the integrity of lysosomal membranes in hepatocytes was taken as an indicator of non-specific acute and chronic toxic effects. Both biomarkers are recommended by the ICES Advisory Committee on the Marine Environment for the application in biological effects monitoring programmes. In addition, neutral lipid content in the liver was used as a marker for pathologically induced fat accumulation. In the same individual fish, a new method for the measurement of macrophage aggregate activity in the liver was tested for its application and reliability in reflecting immunosuppression. Tests were accompanied by chemical analysis of standard organochlorine and heavy metal residues in flounder tissue. A total of 33 parasite species were found. As an indicator species, the mean abundance of Trichodina sp. reflected best the pollution gradient observed with highest infection intensity at the most polluted location. Species diversity was significantly higher in fish caught near the reference site and significantly lower in fish from the polluted Elbe estuary. The use of the heteroxenous/monoxenous species ratio as a marker was not useful at the locations investigated because of the dominance of heteroxenous species at all habitats. Since EROD activity and macrophage aggregate activity were dependent on sex and maturity of female flounder, only male fish were taken into consideration for the integrated evaluation of data. All biochemical and histochemical tests were able to reflect accurately the site-specific differences, as well as an observed pollution event at the end of 1995 as determined by chemical analyses. The correlation analysis revealed a connection not only between the single parasitological and biochemical parameters but also within these groups. The non-specific immune response and Trichodina infection intensity were correlated with all other parameters, leading to the assumption that these may serve as links between the lowest and the highest levels of biological organisation. The simultaneous use of metabolic and parasitological results facilitated the interpretation of the observed variations of the data and the distinction between natural variation and pollution-mediated effects.

Fungicide Application for Late Blight Management: A Boom Attached to a Center Pivot Irrigation System.

Chlorothalonil was applied to commercial potato fields of cvs. Russet Norkotah and Russert Burbank in replicated trials through either a center-pivot irrigation system or a spray-boom-attached-to-the-pivot system. Water rates were 26,192 and 675 liters/ha for the center pivot and attached boom, respectively. Three crop canopy levels were sampled within 2 h and again after 6 days following fungicide applications made at 7-day intervals. Efficacy of the two application methods was tested by inoculation of individual excised leaves with an isolate of strain US-1 or US-8 of Phytophthora infestans and by chemical residue analysis. Severity of late blight did not differ between the two fungicide application methods 2 h after application but, after 6 days, disease severity was significantly less on leaves where chlorothalonil was applied by the attached boom. Fungicide residues were three times higher on leaves where chlorothalonil was applied by the attached boom than with the center-pivot system. Significantly more disease occurred on fungicide-treated and non-treated leaves inoculated with the US-8 than the US-1 strain. Severity of late blight on inoculated leaves was inversely related to the amount of chlorothalonil residue on leaves.

９Ｃｒフェライト系耐熱鋼用溶接金属の高温強度特性に及ぼすＷの影響

GTA weld metals containing 0.58 mass%W, 1.01 mass%W, 1.47 mass%W and 1.68 mass%W have been prepared, and effects of W on the microstructure, precipitation behaviors, tensile strength and creep rupture strength of the weld metals were studied.X-ray diffraction analyses on extracted residues of the weld metals after PWHT at 1013 K for 2 h revealed the formation of M23C6 and MX type carbo-nitrides. Laves phase precipitated in the weld metals during creep rupture test or aging at 873 K. The addition of W enhanced the precipitation of Laves phase. The chemical analyses of extracted residues showed that the amount of dissolved W in matrix of weld metals after PWHT increased with W content in weld metals. The addition of W improved the tensile strength of weld metals at 293 K and 873 K. The results of chemical analysis suggested that this improvement in the tensile strength was attributable to the solid-solution hardening by W. The creep rupture strength of weld metals at 873 K and 973 K also improved by adding W to weld metals. However, there was little difference between the rupture life of 1.47 mass%W weld metal and that of 1.68 mass%W weld metal longer than roughly 5000 h - 10000 h at 873 K. These results suggest that there is an optimum W content that is most effective in to improving the creep rupture strength. Results of the chemical analyses of residues of aged weld metals suggested that the precipitation of Laves phase was enhanced by the stress or strain during the creep rupture test.

Effect of moisture on quinclorac dissipation in Lethbridge soil

This study examined the dissipation and carry-over of quinclorac residues in a Lethbridge sandy clay loam with 2% organic matter. Experiments were conducted in covered outdoor lysimeters using different simulated rainfall regimes. Quinclorac residues were monitored in the top 10 cm of soil using chemical residue analysis and the activity of carried-over residues assessed by bioassay. Quinclorac dissipation was very slow although, in general, the amount of residue remaining decreased with increased moisture (117–447 mm) applied. Forty-eight weeks after quinclorac application, 85, 66, 52, 49, and 48% of initial residues remained in the very dry, dry, normal, wet and very wet moisture regimes, respectively. Residue persistence could be accurately predicted (r2 = 0.96) using a simple moisture model (% quinclorac remaining = 101% −0.18 × mm cumulative moisture) for up to 300 mm moisture. Quinclorac dissipation was attributed mostly to the residues leaching beyond the 0- to 10-cm soil layer. A separate laboratory experiment showed that 80% of applied quinclorac leached through 9.7-cm deep soil columns when 304 mm of water was applied. The quinclorac residues remaining after 48 wk were biologically available and caused injury to fababeans (Vicia faba L.) under all moisture regimes. Key words: Quinclorac, persistence, moisture effects, leaching, residue carry-over, recropping

Analysis of biomass cellulose in simultaneous saccharification and fermentation processes.

A direct method for determining the cellulose content of biomass residues resulting from simultaneous saccharifiaction and fermentation (SSF) experiment has been developed and evaluated. The method improves on classical cellulose assays by incorporating the enzymatic removal of yeast glucans from the biomass residue prior to acid hydrolysis and subsequent quantification of cellulose-derived glucose. An appropriate cellulase-free, commercially available, yeast-lysing enzyme preparation from Cytophaga was identified. A freeze-drying step was identified as necessary to render the SSF yeast cells susceptible to enzymatic lysis. The method was applied to the analysis of cellulose and yeast-associated glucans in SSF residues from three pretreated feedstocks; hybrid poplar, switchgrass, and cornstover. Cellulose assays employing the lysing-enzyme preparation demonstrated relative errors up to 7.2% when yeast-associated glucans were not removed prior to analysis of SSF residues. Enzymatic lysis of SSF yeast cells may be viewed as a general preparatory procedure to be used prior to subsequent chemical and physical analysis of SSF residues.

Determining Stone Tool Use: Chemical and Morphological Analyses of Residues on Experimentally Manufactured Stone Tools

We report on experimental and chemical investigation of bamboo and bone residues on used and unused modern stone tools. Flakes used were manufactured from a chert nodule and employed in three ways: splitting of bamboo, scraping and splintering of bone; others were left unused. Specimens were examined using light microscopy, SEM, and EDS elemental analysis. Tools used to process bamboo and bone exhibited chemically and morphologically distinct bamboo and bone residues. Similarity in morphology between isolated bamboo mineral and residue on stone tools used to process bamboo indicates the bamboo mineral material adheres to tool surfaces. All residue morphologies persisted through a treatment designed to simulate diagenesis, suggesting that processing residues may persist on ancient tools. The elemental signatures of the residues were slightly altered by the diagenesis treatment, but remained distinctly different from one another. EDS elemental analysis and SEM examination, when used in conjunction with the chemical signature and morphology of suspected residue sources, has potential to yield definitive answers to questions of ancient tool use.

Evaluation of impact craters on solar cell samples and thermal MLI blankets

During space exposure solar cell arrangements and cover shields of satellites are subject to intense bombardement by natural and man-made debris which causes impact craters and other damage on the surfaces. In order to calibrate particle impact properties of retrieved material a number of defined projectiles were shot under controlled conditions at samples of solar cells and thermal Multi-Layer-Insulation (MLI) blankets identical to those used on ESA's “EURECA” satellite. In each sample, crater morphology and impact residues were determined in detail by optical microscopy and electron microprobe. Correlations between impact parameters such as projectile's size or impact angle and degradation characteristics like eccentricity or diameter of the impact crater were investigated. Additionally, chemical analyses of impact residues were made. It turned out to be difficult to deduce the composition or other impact parameters of micro-meteoroids or small debris particles by post-flight investigations of complex satellite surfaces. Some of the problems with evaluations of simulated particle impacts are discussed.

Secondary poisoning of birds of prey by the organophosphorus insecticide, phorate

As a part of a monitoring study, five dead or debilitated bald eagles (Haliaeetus leucocephalus) and a red-tailed hawk (Buteo jamaicensis) from the Fraser River Delta of British Columbia (BC), Canada tested positive for residues of the organophosphorus insecticide, phorate. The first group of three birds was found during January and February 1992, from which two eagles were confirmed to have been poisoned by phorate. The second poisonings took place from December 1993 to March 1994, when three eagles and a hawk were confirmed as phorate poisoned. The brain and plasma cholinesterase results are presented along with data on chemical residue analyses of ingesta. Granular phorate, used in the area to control pests on potatoes and other root crops, appears to have a prolonged half-life similar to carbofuran and fensulfothion, two other granular insecticides associated with secondary mortality of raptors in the Fraser Delta. The soil persistence of phorate combined with a high acute toxicity poses a risk to waterfowl which are attracted to flooded fields in the autumn and winter and, thus, to raptors scavenging on dead waterfowl. The manufacturer has voluntarily withdrawn phorate, marketed as Thimet 15G, from the BC market as a result of the evidence presented here

Efficacy of Surface Dust Treatments of Pirimiphos-Methyl and Etrimfos when Applied to Commercially Stored Wheat and Barley

Commercially stored wheat and barley were surface treated with dust formulations of pirimiphos-methyl and etrimfos at the manufacturer's recommended application rate. Samples were taken at four-weekly intervals for 32 and 16 weeks for wheat and barley respectively. Pesticide efficacy was determined using insect bioassays and chemical analysis of residues. There was no evidence to suggest a decline in residue levels of either pesticide over the experimental period. However, considerable variation was observed in the residue levels recorded at different sample points and also between residue levels recorded for the same point over the trial period. Control of susceptible strains of Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L.) and Sitophilus granarius (L.) was achieved where recovered pesticide residues remained above 1 mg kg -1 pirimiphos-methyl and 1.6 mg kg -1 etrimfos.

Toxicokinetics‐based survival analysis in bioassays using nonpersistent chemicals

AbstractPresent statistical analysis of survivorship data obtained from bioassays using nonpersistent toxicants does not explicitly take into account that exposure decreases with time due to degradation of the toxicant. Such a situation typically occurs in static aquatic toxicity tests and in soil tests. We develop a model for the analysis of survival data obtained in such experiments and show how estimates for the initial LC50, the degradation rate constant, and the elimination rate constant may be obtained from observations on time‐dependent survival rates. The model assumes linear one‐compartment toxicokinetics with exponentially decreasing input. The probability of dying is assumed to be directly proportional to the internal concentration. An explicit expression for time‐ and concentration‐dependent survival is obtained. The model predicts that, with increasing exposure time, survival will approach a nonzero baseline value for certain initial concentrations. Application of the model is illustrated by curve‐fitting to experimental observations, made over 6 weeks, for the effect of diazinon on the terrestrial isopod Porcellio scaber. The fit to data is fairly good, but the parameter estimates tend to have a high coefficient of variation. A considerable increase of precision may be obtained if the degradation rate constant is given a fixed value (for example, following from chemical residue analysis of the medium). The approach is applicable to all situations where, due to loss of the toxicant during the test, mortality shows no further increase after a certain exposure period.

Health of red morwong, Cheilodactylus fuscus, and rock cale, Crinodus lophodon, from Sydney cliff-face sewage outfalls

Health of red morwong, Cheilodactylus fuscus and rock cale, Crinodus lophodon was assessed using histology to determine effects of the Sydney cliff outfalls on these two species. Ten individuals of each species were sampled from three outfall sites and three control sites. Benign epitheliocystis, presence of metazoan parasites, epithelial lifting, telangiectasis, haemorrhage and inflammation were found in the gills of some individuals. Hemosiderin was present in melanomacrophage aggregates in liver and spleen of some fish and also in kidneys of a few fish collected in Malabar outfall site. Hyaline droplets were present in tubular epithelium in kidney of some fish, particularly in the individuals collected from Malabar. Although for some changes there was a trend of greater prevalence at the outfall sites, there was no statistically significant difference between the fish from outfall sites and control sites. Most changes were species specific and the differences were statistically significant. This suggests problems with extrapolating results from one species to others. Greater replication, smaller range of size, chemical analysis of tissue residues as well as better knowledge of the fate of sewage and oceanographic processes would improve interpretation of any future surveys. A multidisciplinary approach would be most beneficial for pollution studies.

Toxicological foundations of ecological risk assessment: biomarker development and interpretation based on laboratory and wildlife species.

Ecological risk assessments based on chemical residue analysis and species demographics tend to ignore the bioavailability and bioaccumulation of the chemicals of concern. This study describes the incorporation of mechanistically based biomarkers into an ecological risk assessment of a poly-cyclic aromatic hydrocarbon (PAH)-contaminated site. A combination of soil residue analysis, tissue residue analysis, biomarkers in one-site trapped animals and biomarkers in animals confined to enclosures was used. In particular, the use of captured deer mice (Peromyscus maniculatus) for these studies is compared to the use of laboratory-raised deer mice placed in enclosures. This study indicates that the higher degree of variability in the responses of wild deer mice make the use of enclosure studies advantageous. Positive control studies performed by dosing laboratory-raised deer mice with the same PAHs as found on the site were used to validate this approach. These studies indicate that immune suppression occurred at PAH concentrations an order of magnitude below those required for the induction of ethoxyresorufin-O-dealkylase activity.

Beer from the early dynasties (3500–3400 cal B.C.) of Upper Egypt, detected by archaeochemical methods

Physical and chemical analyses of beer residues recovered from a vat site at Hierakonpolis (Upper Egypt) were carried out. Radiocarbon dates of the residues suggest a dating of 3500–3400 cal B.C. and are believed to represent the oldest known beer in the world. Macroscopic and microscopic examinations of the residues revealed the presence of intact remains of grains and spikelets of wheat and barley, as well as fragments of dates and grape pips. Chemical analyses included percentages of sample ingredients, pH and total soluble ions, quantitative determinations of sugars, carboxylic acids and free amino acids. A total of 25 compounds were identified, which are components of fermentation processes that are believed to have formed in connection with the preparation of what is called Nekhen-Hoffman beer.