Major Peaks (major + peak)

Distribution by Scientific Domains


Selected Abstracts


Cyclicity analysis of precipitation regimes in the Yangtze River basin, China

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 5 2008
S. Becker
Abstract Daily precipitation data of 148 weather stations located in the Yangtze River basin (P.R. China) are analysed to detect cycles in the annual frequency of occurrence of precipitation events of 1-, 5- and 10 days duration. These events were defined in terms of exceedances of some selected thresholds. The events corresponding to 10, 25 and 30 mm thresholds for 1-, 5- and 10-day precipitation totals, respectively, are analysed in detail. For the identification of cycles, basin-wide averaged standardized time series of frequency of precipitation events are used. It is found that peaks in the smoothed time series occurred around 1974, 1982 and 1991. The Fourier, autoregressive and wavelet analyses reveal distinct cycles of 7,9 and 2,3 year periods, which dominate large parts of the time series. In addition, a shift towards a 4,5 year period in the annual frequency of precipitation events is noticed since the mid- to late-nineties. Major peaks in the annual frequency of occurrence of precipitation events are expected to occur around 2012, 2015 and 2018 according to the spectrum analyses. Copyright 2007 Royal Meteorological Society [source]


Differentiation in life cycle of sympatric populations of two forms of Hyphantria moth in central Missouri

ENTOMOLOGICAL SCIENCE, Issue 2 2005
Makio TAKEDA
Abstract Wing patterns of Hyphantria adult male moths collected in central Missouri were examined throughout the breeding season. Three major peaks of adult flight were observed: the first peak consisted mainly of adults with spotted wings, while the second and third peaks consisted of immaculate adults. Black-headed larvae appeared in the field following the first major peak of moth flight, and red-headed larvae appeared in the field following the second peak. Sympatric red-headed and black-headed forms were collected in the field and subsequently reared on an artificial diet under conditions of 16 h light : 8 h dark (LD 16:8) at 25C. The larval period of the black-headed form was shorter than the red-headed, whereas the pupal period of the black-headed form was longer than the red-headed. Pupal development is retarded in some individuals at high temperatures in the black-headed form. Photoperiodic response curves for pupal diapause were different between the two forms. The critical photoperiod for pupal diapause was 15 h 10 min in the red-headed form, which was longer than that for the black-headed form (14 h 40 min). The two forms responded to shifts in photoperiod differently. These developmental responses temporally separate the two forms in the field; the red-headed and black-headed forms represent a set of adaptations favoring univoltinism and bivoltinism, respectively. Red-headed larvae fed mainly at night, while the black-headed larvae fed without a clear day,night rhythm. Nocturnal feeding in the red-headed form is adaptive to protection against predation, but fails to fully utilize heat units and thus to produce a second generation. [source]


Isomerization of delta-9-THC to delta-8-THC when tested as trifluoroacetyl-, pentafluoropropionyl-, or heptafluorobutyryl- derivatives,,

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 5 2008
Justin M. Holler
Abstract For GC,MS analysis of delta-9-tetrahydrocannabinol (delta-9-THC), perfluoroacid anhydrides in combination with perfluoroalcohols are commonly used for derivatization. This reagent mixture is preferred because it allows simultaneous derivatization of delta-9-THC and its acid metabolite, 11-nor-delta-9-THC-9-carboxylic acid present in biological samples. When delta-9-THC was derivatized by trifluoroacetic anhydride/hexafluoroisopropanol (TFAA/HFIPOH) and analyzed by GC,MS using full scan mode (50,550 amu), two peaks (P1 and P2) with an identical molecular mass of 410 amu were observed. On the basis of the total ion chromatogram (TIC), P1 with a shorter retention time (RT) was the major peak (TIC 84%). To identify the peaks, delta-8-THC was also tested under the same conditions. The RT and spectra of the major peak (TIC 95%) were identical with that of P1 for delta-9-THC. A minor peak (5%) present also correlated well with the latter peak (P2) for the delta-9-THC derivative. The fragmentation pathway of P1 was primarily demethylation followed by retro Diels-Alder fragmentation (M , 15,68, base peak 100%) indicating P1 as a delta-8-THC-trifluoroacetyl compound. This indicated that delta-9-THC isomerized to delta-8-THC during derivatization with TFAA/HFIPOH. Similar results were also observed when delta-9-THC was derivatized with pentafluoropropionic anhydride/pentafluoropropanol or heptafluorobutyric anhydride/heptafluorobutanol. No isomerization was observed when chloroform was used in derivatization with TFAA. In this reaction, the peaks of delta-8-THC-TFA and delta-9-THC-TFA had retention times and mass spectra matching with P1 and P2, respectively. Because of isomerization, perfluoroacid anhydrides/perfluoroalcohols are not suitable derivatizing agents for analysis of delta-9-THC; whereas the TFAA in chloroform is suitable for the analysis. Published in 2008 by John Wiley & Sons, Ltd. [source]


UV-B INDUCTION OF UV-B PROTECTION IN ULVA PERTUSA (CHLOROPHYTA),

JOURNAL OF PHYCOLOGY, Issue 3 2005
Young-Seok Han
The green macroalga Ulva pertusa Kjellman produced UV-B absorbing compounds with a prominent absorption maximum at 294 nm in response only to UV-B, and the amounts induced were proportional to the UV-B doses. Under a 12:12-h light:dark regime, the production of UV-absorbing compounds occurred only during the exposure periods with little turnover in the dark. There was significant reduction in growth in parallel with the production of UV-B absorbing compounds. The polychromatic action spectrum for the induction of UV-B absorbing compounds in U. pertusa exhibits a major peak at 292 nm with a smaller peak at 311.5 nm. No significant induction was detected above 354.5 nm, and radiation below 285 nm caused significant reduction in the levels of UV-B absorbing compounds. After UV-B irradiation at 1.0 Wm,2 for 9 h, the optimal photosynthetic quantum yield of the samples with UV-B absorbing compounds slightly increased relative to the initial value, whereas that of thalli lacking the compounds declined to 30%,34% of the initial followed by subsequent recovery in dim light of up to 84%,85% of the initial value. There was a positive and significant relationship between the amount of UV-B absorbing compounds with antioxidant activity as determined by the ,,,-diphenyl-,-picrylhydrazyl scavenging assay. In addition to mat-forming characteristics and light-driven photorepair, the existence and antioxidant capacity of UV-B absorbing compounds may confer U. pertusa a greater selective advantage over other macroalgae, thereby enabling them to thrive in the presence of intense UV-B radiation. [source]


UV-A/BLUE LIGHT,INDUCED REACTIVATION OF SPORE GERMINATION IN UV-B IRRADIATED ULVA PERTUSA (CHLOROPHYTA),

JOURNAL OF PHYCOLOGY, Issue 2 2004
Taejun Han
Recent reduction in the ozone shield due to manufactured chlorofluorocarbons raised considerable interest in the ecological and physiological consequences of UV-B radiation (,=280,315 nm) in macroalgae. However, early life stages of macroalgae have received little attention in regard to their UV-B sensitivity and UV-B defensive mechanisms. Germination of UV-B irradiated spores of the intertidal green alga Ulva pertusa Kjellman was significantly lower than in unexposed controls, and the degree of reduction correlated with the UV doses. After exposure to moderate levels of UV-B irradiation, subsequent exposure to visible light caused differential germination in an irradiance- and wavelength-dependent manner. Significantly higher germination was found at higher photon irradiances and in blue light compared with white and red light. The action spectrum for photoreactivation of germination in UV-B irradiated U. pertusa spores shows a major peak at 435 nm with a smaller but significant peak at 385 nm. When exposed to December sunlight, the germination percentage of U. pertusa spores exposed to 1 h of solar radiation reached 100% regardless of the irradiation treatment conditions. After a 2-h exposure to sunlight, however, there was complete inhibition of germination in PAR+UV-A+UV-B in contrast to 100% germination in PAR or PAR+UV-A. In addition to mat-forming characteristics that would act as a selective UV-B filter for settled spores under the parental canopy, light-driven repair of germination after UV-B exposure could explain successful continuation of U. pertusa spore germination in intertidal settings possibly affected by intense solar UV-B radiation. [source]


Phosphate buffer,extractable organic nitrogen as an index of soil-N availability for sorghum and pearl millet

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 2 2010
Asako Mori
Abstract The availability of soil nitrogen (N) is usually quantified by the amount of mineralized N as determined after several weeks of soil incubation. Various alternative methods using chemical solvents have been developed to extract the available organic N, which is easily mineralized. We compared one such solution, neutral phosphate buffer (NPB), with conventional incubation and 0.01 M,CaCl2 extraction, as measures of soil N available to two major cereal crops of the semiarid tropics, based on the total N uptake by plants in a pot experiment. Mineralized N had the highest correlation with N uptake by pearl millet (Pennisetum glaucum L., r = 0.979***) and sorghum (Sorghum bicolor [L.] Moench, r = 0.978***). NPB-extractable N was also highly correlated with N uptake (pearl millet, r = 0.876***; sorghum, r = 0.872***). Only one major peak was detected when NPB extracts were analyzed using size-exclusion high-performance liquid chromatography, regardless of soil properties. In addition, the organic N extracted with NPB was characterized by determining the content of peptidoglycan, the main component of bacterial cell walls. Although the characteristics of NPB-extractable organic N are still unclear, it offers a promising quick assay of available N. [source]


Coupling between limb tremor and postural sway in Parkinson's disease

MOVEMENT DISORDERS, Issue 3 2008
Graham Kerr BSc, MPhED
Abstract Increased tremor and postural instability are motor problems commonly associated with Parkinson's disease (PD). Despite the similarity between these oscillatory forms, little is known about the relation between them, especially for individuals with enhanced tremor. This study was designed to examine the nature of any relation between center of pressure (COP) excursions and postural/resting limb tremor of young, older individuals, and Parkinsonian participants in their different medication states. The resting and postural tremor for the PD participants was characterized by a single, prominent peak frequency between 4 and 7 Hz. The postural tremor for young/older participants contained smaller peaks between 1 to 4 and 7 to 12 Hz although no prominent peak was seen in their resting tremor. The AP and ML COP dynamics of all participants was characterized by a major peak between 0.1 and 0.5 Hz. An additional peak was observed in the COP output of the PD participants between 4 and 7 Hz. While no tremor-COP coupling was observed for the young/old groups, coherence analysis revealed a significant degree of coupling between COP motion and tremor between 4 and 7 Hz for PD participants. These results highlight that the amplified tremor in PD can manifest itself in COP dynamics. This finding may have implications for postural stability for this patient group. 2007 Movement Disorder Society [source]


Biclonal low grade B-cell lymphoma confirmed by both flow cytometry and karyotypic analysis, in spite of a normal kappa/lambda Ig light chain ratio

AMERICAN JOURNAL OF HEMATOLOGY, Issue 6 2007
J.P. Delville
Abstract Composite low grade lymphoma with two subpopulations in a same site is uncommon. We herewith report the case of an 80-year-old woman who presented with isolated bilateral dacryoadenomegaly. Pathological examination of an incisional biopsy of her right lacrimal gland was consistent with a marginal zone lymphoma. Flow cytometry immunophenotyping showed two distinct clonal B-cell populations expressing sIg D lambda or sIg M kappa restriction in the lacrimal gland, blood, and bone marrow. Both B-cells populations were sorted from peripheral blood for molecular biology investigations and comparison with molecular data performed on tumor and bone marrow cells. IgH PCR performed on purified blood populations disclosed two monoclonal peaks: 98 bp-sized peak in the sIg M kappa and a 107 bp in the sIg D lambda clones, respectively. The lacrimal gland tumor expressed mainly sIg M kappa population, and showed a major 98 bp-sized peak coexisting with a very minor 107 bp peak. Cytogenetic studies showed a 46, XX,del (7) (q22q32) karyotype. Bone marrow examination at diagnosis revealed the same B-cell clones distribution than the one observed in blood with a dominant sIg D lambda population, a Genescan profile showing a major peak of 107 bp and a minor peak of 98 bp. Chromosomal analysis disclosed a 46,XX,del (10) (?p14) karyotype without detectable 7q deletion. To our knowledge, this observation represents the first reported case of biclonal low grade lymphoma hidden behind a normal classical kappa/lambda Ig light chain ratio in blood, but clearly demonstrated by the combination of three ancillary techniques (flow cytometry both analytical and cell sorting, molecular biology, and cytogenetics) and analysis of different tissues (i.e., in this case, lacrimal gland biopsy, blood, and bone marrow. Am. J. Hematol., 2007. 2007 Wiley-Liss, Inc. [source]


Ontogeny of energy homeostatic pathways via neuroendocrine signaling in Atlantic salmon

DEVELOPMENTAL NEUROBIOLOGY, Issue 9 2010
Anne-Grethe Gamst Moen
Abstract Leptin and ghrelin are known to regulate energy homeostasis via hypothalamic neuropeptide signaling in mammals. Recent studies have discovered that these hormones exist in teleosts, however, very little is known concerning their role during teleost ontogeny. Here, we have examined the steady state levels of leptins, ghrelins, their target neuropetides and several growth factors during Atlantic salmon development. Initial experiments revealed differential expression of leptin genes and ghrelin isoforms during embryogenesis. In larvae, equal upregulation of ghrl1 and ghrl2 was observed just prior to exogenous feeding while a surge of lepa1 occurred one week after first-feeding. Subsequent dissection of the embryos and larvae showed that lepa1, cart, pomca1, and agrp are supplied as maternal transcripts. The earliest zygotic expression was observed for lepa1 and cart at 320 day degrees. By 400 day degrees, this expression was localized to the head and coincided with upregulation of ghrl2 and npy. Over the hatching period growth factor signaling predominated. The ghrelin surge prior to first-feeding was exclusively localized in the internal organs and coincided with upregulation of npy and agrp in the head and agrp in the trunk. One week after exogenous feeding was established major peaks were detected in the head for lepa1 and pomca1 with increasing levels of cart, while lepa1 was also significantly expressed in the trunk. By integrating theses data into an ontogenetic model, we suggest that the mediation of Atlantic salmon energy homeostatic pathways via endocrine and neuropeptide signaling retains putative features of the mammalian system. 2010 Wiley Periodicals, Inc. Develop Neurobiol 70: 649,658, 2010 [source]


Direct determination of gentamicin components by capillary electrophoresis with potential gradient detection

ELECTROPHORESIS, Issue 1 2005
LingLing Yuan
Abstract A simple and fast method was developed to determine non-UV active compounds directly without derivatization. The usefulness of the method was demonstrated by detecting the major components in aminoglycoside antibiotic mixtures using capillary zone electrophoresis with potential gradient detection. Under optimized separation conditions (0.2 mM cetyltrimethylammonium bromide (CTAB), 1 mM ammonium citrate, pH 3.5), gentamicin was separated into three major peaks (C1, C1a, and C2+C2a) within 15 min. This method showed better sensitivity than other capillary electrophoresis (CE) methods for determining underivatized gentamicin. The linear range was from 10 to 500 ppm. Because of its good repeatability and simplicity, this new method could be a good alternative for the current assays given by US Pharmacopoeia and European Pharmacopoeia. [source]


Differentiation in life cycle of sympatric populations of two forms of Hyphantria moth in central Missouri

ENTOMOLOGICAL SCIENCE, Issue 2 2005
Makio TAKEDA
Abstract Wing patterns of Hyphantria adult male moths collected in central Missouri were examined throughout the breeding season. Three major peaks of adult flight were observed: the first peak consisted mainly of adults with spotted wings, while the second and third peaks consisted of immaculate adults. Black-headed larvae appeared in the field following the first major peak of moth flight, and red-headed larvae appeared in the field following the second peak. Sympatric red-headed and black-headed forms were collected in the field and subsequently reared on an artificial diet under conditions of 16 h light : 8 h dark (LD 16:8) at 25C. The larval period of the black-headed form was shorter than the red-headed, whereas the pupal period of the black-headed form was longer than the red-headed. Pupal development is retarded in some individuals at high temperatures in the black-headed form. Photoperiodic response curves for pupal diapause were different between the two forms. The critical photoperiod for pupal diapause was 15 h 10 min in the red-headed form, which was longer than that for the black-headed form (14 h 40 min). The two forms responded to shifts in photoperiod differently. These developmental responses temporally separate the two forms in the field; the red-headed and black-headed forms represent a set of adaptations favoring univoltinism and bivoltinism, respectively. Red-headed larvae fed mainly at night, while the black-headed larvae fed without a clear day,night rhythm. Nocturnal feeding in the red-headed form is adaptive to protection against predation, but fails to fully utilize heat units and thus to produce a second generation. [source]


Three pheromone-binding proteins in olfactory sensilla of the two silkmoth species Antheraea polyphemus and Antheraea pernyi

FEBS JOURNAL, Issue 10 2000
Rosario Maida
Females of the sibling silkmoth species Antheraea polyphemus and A. pernyi use the same three sex pheromone components in different ratios to attract conspecific males. Accordingly, the sensory hairs on the antennae of males contain three receptor cells sensitive to each of the pheromone components. In agreement with the number of pheromones used, three different pheromone-binding proteins (PBPs) could be identified in pheromone-sensitive hairs of both species by combining biochemical and molecular cloning techniques. MALDI-TOF MS of sensillum lymph droplets from pheromone-sensitive sensilla trichodea of male A. polyphemus revealed the presence of three major peaks with m/z of 15702, 15752 and 15780 and two minor peaks of m/z 15963 and 15983. In Western blots with four antisera raised against different silkmoth odorant-binding proteins, immunoreactivity was found only with an anti-(Apol PBP) serum. Free-flow IEF, ion-exchange chromatography and Western blot analyses revealed at least three anti-(Apol PBP) immunoreactive proteins with pI values between 4.4 and 4.7. N-Terminal sequencing of these three proteins revealed two proteins (Apol PBP1a and Apol PBP1b) identical in the first 49 amino acids to the already known PBP (Apol PBP1) [Raming, K., Krieger, J. & Breer, H. (1989) FEBS Lett.256, 2215,2218] and a new PBP having only 57% identity with this amino-acid region. Screening of antennal cDNA libraries with an oligonucleotide probe corresponding to the N-terminal end of the new A. polyphemus PBP, led to the discovery of full length clones encoding this protein in A. polyphemus (Apol PBP3) and in A. pernyi (Aper PBP3). By screening the antennal cDNA library of A. polyphemus with a digoxigenin-labelled A. pernyi PBP2 cDNA [Krieger, J., Raming, K. & Breer, H. (1991) Biochim. Biophys. Acta1088, 277,284] a homologous PBP (Apol PBP2) was cloned. Binding studies with the two main pheromone components of A. polyphemus and A. pernyi, the (E,Z)-6,11-hexadecadienyl acetate (AC1) and the (E,Z)-6,11-hexadecadienal (ALD), revealed that in A. polyphemus both Apol PBP1a and the new Apol PBP3 bound the 3H-labelled acetate, whereas no binding of the 3H-labelled aldehyde was found. In A. pernyi two PBPs from sensory hair homogenates showed binding affinity for the AC1 (Aper PBP1) and the ALD (Aper PBP2), respectively. [source]


An algorithm for thorough background subtraction from high-resolution LC/MS data: application for detection of glutathione-trapped reactive metabolites

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2008
Haiying Zhang
Abstract A control sample background-subtraction algorithm was developed for thorough subtraction of background and matrix-related signals in high-resolution, accurate mass liquid chromatography/mass spectrometry (LC/MS) data to reveal ions of interest in an analyte sample. This algorithm checked all ions in the control scans within a specified time window around the analyte scan for potential subtraction of ions found in that analyte scan. Applying this method, chromatographic fluctuations between runs were dealt with and background and matrix-related signals in the sample could be thoroughly subtracted. The effectiveness of this algorithm was demonstrated using four test compounds, clozapine, diclofenac, imipramine, and tacrine, to reveal glutathione (GSH)-trapped reactive metabolites after incubation with human liver microsomes supplemented with GSH (30 M compound, 45-min incubation). Using this algorithm with a 1.0 min control scan time window, a 5 ppm mass error tolerance, and appropriate control samples, the GSH-trapped metabolites were revealed as the major peaks in the processed LC/MS profiles. Such profiles allowed for comprehensive and reliable identification of these metabolites without the need for any presumptions regarding their behavior or properties with respect to mass spectrometric detection. The algorithm was shown to provide superior results when compared to several commercially available background-subtraction algorithms. Many of the metabolites detected were doubly charged species which would be difficult to detect with traditional GSH adduct screening techniques, and thus, some of the adducts have not previously been reported in the literature. Copyright 2008 John Wiley & Sons, Ltd. [source]


Changes in the pectic fraction of bush butter (Dacryodes edulis (G Don) HJ Lam) fruit pulp during ripening

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2001
Crpin Ella Missang
Abstract CDTA-soluble polysaccharides were extracted from cell wall material (prepared as alcohol-insoluble solids) of bush butter fruit endocarp tissue at three stages of ripeness. The amount of soluble pectins remained constant but they underwent a gradual depolymerisation during ripening. The CDTA extracts were fractionated by anion exchange and the subfractions were analysed for their sugar composition and molecular weight distribution. For all degrees of ripeness the extracts were composed of three minor peaks and two major peaks. The minor peaks appeared to be composed of xyloglucan and mannan-type polymers for the first peak and arabinogalactan-type polymers for the other two peaks. The two main peaks were retained on the column. The first was exclusively composed of homogalacturonan polymers and the second contained principally highly branched rhamnogalacturonan polymers. During ripening, both homogalacturonan and rhamnogalacturonan populations were modified. Modifications in the rhamnogalacturonan fraction were principally marked by the accumulation of low-molecular-weight rhamnoglacturonan polymers in the course of ripening. 2001 Society of Chemical Industry [source]


Stress-related RNase PR-10c is post-translationally modified by glutathione in birch

PLANT CELL & ENVIRONMENT, Issue 6 2002
K. M. Koistinen
Abstract The PR-10c (previously termed as Bet v 1-Sc3) protein of birch belongs to the family of intracellular pathogenesis-related proteins. The high-performance liquid chromatography electrospray ionization ion trap mass spectrometry (HPLC-ESI-MS) analysis of PR-10c-His fusion protein, produced in Escherichia coli, revealed three major peaks and masses. Enzymatic digestions and HPLC-ESI-MS and matrix assisted laser desorption/ionization , time of flight mass spectrometry (MALDI-TOF-MS) analyses of each fraction indicated that PR-10c-His protein is post-translationally modified by carbamylation and S-glutathiolation. Carbamylation was localized into the N-terminal end of PR-10c-His and does not represent a biologically significant modification. The possible nuclease activity of PR-10c was analysed with S-glutathiolated and reduced fractions of PR-10c-His fusion protein. Both forms of PR-10c-His as well as the dimeric form of the protein possess RNase activity which is capable of digesting different RNA substrates. None of the fractions showed activity against single- or double-stranded DNA. The MALDI-TOF-MS analysis of PR-10c polypeptide extracted from zinc-exposed birch roots showed that the protein is post-translationally modified by glutathione (, -Glu-Cys-Gly) also in vivo. The S-glutathiolated cysteine residue of PR-10c is not conserved among Bet v 1 homologous proteins and is also unique in the PR-10 family. As far as we know this is the first observation of S-glutathiolation in plants, or any post-translational modification in the PR-10 family of proteins. [source]


Evaluation of tramadol and its main metabolites in horse plasma by high-performance liquid chromatography/fluorescence and liquid chromatography/electrospray ionization tandem mass spectrometry techniques

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 2 2009
Marinella De Leo
Tramadol is a centrally acting analgesic drug that has been used clinically for the last two decades to treat pain in humans. The clinical response of tramadol is strictly correlated to its metabolism, because of the different analgesic activity of its metabolites. O -Desmethyltramadol (M1), its major active metabolite, is 200 times more potent at the -receptor than the parent drug. In recent years tramadol has been widely introduced in veterinary medicine but its use has been questioned in some species. The aim of the present study was to develop a new sensible method to detect the whole metabolic profile of the drug in horses, through plasma analyses by high-performance liquid chromatography (HPLC) coupled with fluorimetric (FL) and photodiode array electrospray ionization mass spectrometric (PDA-ESI-MS) detection, after its sustained release by oral administration (5,mg/kg). In HPLC/FL experiments the comparison of the horse plasma chromatogram profile with that of a standard mixture suggested the identification of the major peaks as tramadol and its metabolites M1 and N,O -desmethyltramadol (M5). LC/PDA-ESI-MS/MS analysis confirmed the results obtained by HPLC/FL and also provided the identification of two more metabolites, N -desmethyltramadol (M2), and N,N -didesmethyltramadol (M3). Another metabolite, M6, was also detected and identified. The present findings demonstrate the usefulness and the advantage of LC/ESI-MS/MS techniques in a search for tramadol metabolites in horse plasma samples. Copyright 2008 John Wiley & Sons, Ltd. [source]