A liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) method has been developed and validated to detect and confirm the marker residue of eprinomectin (B1a component) in bovine liver when present at levels ≥2400 ng/g. Sample extracts prepared for assay by the LC/fluorescence determinative method (prior to the derivatization step) and standard solutions were used to validate the confirmatory method. The chromatographic retention time of the eprinomectin B1a component and the relative ion intensities of the parent ion ([M + H]+ at m/z 914) and three product ions (m/z 896, 468, and 330) generated by fragmentation of the parent ion are compared to those determined from standards. Keywords: Eprinomectin; residue; confirmatory; bovine liver; LC/MS/MS

A rapid, specific, and sensitive method has been developed for the determination of abamectin and its delta 8,9-isomer in tomatoes. Sample homogenization and extraction are performed simultaneously with acetonitrile/water/hexane(1:1:5). Abamectin and its delta 8,9-isomer are selectively concentrated by passing the hexane layer through an aminopropyl solid-phase extraction cartridge. The abamectin and delta 8,9-isomer are then eluted from the cartridge and derivatized by an instantaneous reaction with trifluoroacetic anhydride (TFAA)/1-methylimidazole. Quantitation is achieved by HPLC with fluorescence detection. A set of 12 samples can be analyzed by this rapid method in 4 h; conventional fluorescence methods require a much longer time. The recovery of abamectin at levels between 5 and 70 ppb averaged 95%, and the recovery of delta 8,9-isomer at levels between 5 and 67 ppb averaged 84%. For each analyte a quantitation limit of 5 ppb and a limit of detection of 2 ppb were obtained. The method was used to quantitate the incurred residue in the tomato samples from a field trial. Very good agreement was observed between this method and the conventional fluorescence method.

We have developed an FT-IR method, using a Spectra-Tech Monit-IR 400 systems, to monitor off-line the completion of a reaction in real-time. The reaction is moisture-sensitive and analysis by more conventional methods (normal-phase HPLC) is difficult to reproduce. The FT-IR method is based on the shift of a diazo band when a conjugated beta-diketone is transformed into a silyl enol ether during the reaction. The reaction mixture is examined directly by IR and does not require sample workup. Data acquisition time is less than one minute. The method has been validated for specificity, precision and accuracy. The results obtained by the FT-IR method for known mixtures and in-process samples compare favorably with those from a normal-phase HPLC method.

An analytical method has been developed for the extraction, derivatization, and fluorescence HPLC determination of MK-0244 [4"-deoxy-4"-(epimethylamino)avermectin B1 benzoate salt] and its delta 8,9-isomer from lettuce and celery at trace (parts per billion) levels. MK-0244 and its delta 8,9-isomer are extracted with methanol, and the extract is cleaned up on a reverse-phase C-8 cartridge followed by a liquid-liquid extraction with ethyl acetate before passing through a propyl sulfonyl cation-exchange cartridge. MK-0244 and its delta 8,9-isomer are then derivatized with trifluoroacetic anhydride/1-methylimidazole/ acetonitrile reagent system to form a fluorescent derivative which is separated on a reverse-phase HPLC system and detected with a fluorescence detector. The average recoveries were 95 +/- 10% for celery and 96 +/- 8% for lettuce. For both lettuce and celery matrix, concentrations as low as 2 ppb (S/N = 10) can be detected in a 10-g sample. This method was used to determine the MK-0244 levels in samples from a lettuce field trial.

The structure of lysinomicin, a new aminocyclitol antibiotic, was established as 3-epi-2'-N-(L-beta-lysyl)-4',5'-didehydro-6'-de-C-methylfortimi cin B (1) on the basis of spectral evidence and chemical degradation of the antibiotic. In the course of the degradation of 1, three additional compounds with interesting biological properties were obtained: 3-epi-2'-N-(L-beta-lysyl)-6'-de-C-methylfortimicin B (4), 3-epi-4',5'-didehydro-6'-de-C-methylfortimicin B (6) and 3-epi-6'-de-C-methylfortimicin B (7).

The preparation of 4-de-N-methylfortimicin A analogs as well as the preparation of 4-de-N-methyl-4-N-(beta-aminoethyl)-4-N-ethylfortimicin B is reported. It was shown that the 4-N-methyl group in fortimicin analogs is essential for antibacterial activity since neither the 4-de-N-methylfortimicin A nor the 4-de-N-methyl-4-N-(beta-aminoethyl)-4-N-ethylfortimicin B exhibited useful biological activity.

Chemischer InformationsdienstVolume 12, Issue 30 Natural Products ChemInform Abstract: CHEMISTRY OF CHELOCARDIN. V. CONDENSATION WITH AMINO REAGENTS D. T. W. CHU, D. T. W. CHUSearch for more papers by this authorS. N. HUCKIN, S. N. HUCKINSearch for more papers by this authorE. BERNSTEIN, E. BERNSTEINSearch for more papers by this authorD. L. GARMAISE, D. L. GARMAISESearch for more papers by this authorR. S. EGAN, R. S. EGANSearch for more papers by this authorR. S. STANASZEK, R. S. STANASZEKSearch for more papers by this author D. T. W. CHU, D. T. W. CHUSearch for more papers by this authorS. N. HUCKIN, S. N. HUCKINSearch for more papers by this authorE. BERNSTEIN, E. BERNSTEINSearch for more papers by this authorD. L. GARMAISE, D. L. GARMAISESearch for more papers by this authorR. S. EGAN, R. S. EGANSearch for more papers by this authorR. S. STANASZEK, R. S. STANASZEKSearch for more papers by this author First published: July 28, 1981 https://doi.org/10.1002/chin.198130346Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume12, Issue30July 28, 1981 RelatedInformation

The nature of the products obtained from the reaction of chelocardin (1) and the model compound 2-acetyldimedone (5) with a variety of amines was investigated. It was observed that amines react with β-triketones having an exocyclic carbonyl side-chain to give exclusively β,β′-diketoenamines with substitution at the side-chain carbonyl.

We have shown previously that the esters of adenosine-5'-carboxylic acid (10) represent a new class of potent nontoxic coronary vasodilators. For example, the ethyl ester (12), which is active by an intraduodenal or intravenous route in dogs, causes a large increase in coronary sinus PO2 and coronary blood flow. Because of the pronounced vasoactive properties of the esters of adenosine-5'-carboxylic acid, a systematic study of the corresponding amides (14--50) was undertaken. In addition, several other analogues containing the N1-oxide function (51--52) or 2',3' substituents (3--9, 53--54) were studied.

Chemischer InformationsdienstVolume 10, Issue 2 Heterocyclic Compounds ChemInform Abstract: THE DEOXYDATIVE SUBSTITUTION OF PYRIDINE N-OXIDES. PART XVI. CARBON-13 SPECTRA OF SOME TETRAHYDROPYRIDINES. THE STRUCTURE OF THE TETRAHYDROPYRIDINES FROM 3,5-LUTIDINE 1-OXIDE AND MERCAPTANS IN ACETIC ANHYDRIDE J. M. KOKOSA, Search for more papers by this authorI. CHU, Search for more papers by this authorL. BAUER, Search for more papers by this authorR. S. EGAN, Search for more papers by this author J. M. KOKOSA, Search for more papers by this authorI. CHU, Search for more papers by this authorL. BAUER, Search for more papers by this authorR. S. EGAN, Search for more papers by this author First published: January 9, 1979 https://doi.org/10.1002/chin.197902195Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume10, Issue2January 9, 1979 RelatedInformation

Following the discovery by Hamao Umezawa (1) and co-workers that certain aminoglycoside resistant organisms of clinical origin owed their resistance to an R-factor mediated ability to phosphorylate kanamycin and neomycin at the 3'-hydroxyl group chemical modification of these antibiotics was directed at possible ways of overcoming this inactivation. The 3'-O-methyl and 3'-deoxy derivatives of kanamycin A were prepared by glycosidation of a suitably protected pseudodisaccharide with appropriately substituted glucopyranosyl chlorides (2). The 3'-O-methylkanamycin 1 obtained was a 1:1 mixture of anomers at the 1' position and was found to be essentially devoid of antibacterial activity whereas the 3'-deoxy derivative, obtained as the α-glycoside was found to have strong antibacterial activity against strains of Escherichia coli and Pseudomonas aeruginosa resistant to the parent antibiotic. Similar preparations of 3'-O-methylneamine 2 and 4'-O-methylneamine 3 (3) by the same group led to the same disappointing lack of antibacterial activity. Subsequently the wide variety of

AbstractDie Struktur von Isochelocardin wird zu (I) sichergestellt.

The conversion of fortimicin E, a minor metabolite from the Micromonospora olivoasterospora fermentation which also produces fortimicin A and fortimicin B, to four 4-N-aminoacylfortimicins E was accomplished. The new 4-N-aminoacylfortimicins E showed only weak antimicrobial activity against several Gram-negative and Gram-positive microorganisms.