Analysis of Chloramphenicol Residues in Honey by Liquid Chromatography–Tandem Mass Spectrometry

Antibiotics are often used in bee-keeping to control European and American foulbrood. The broad spectrum antibiotic chloramphenicol (CAP) was used for curative purposes in veterinary medicine, but is now forbidden in numerous countries, although still used in south-east Asia. A liquid-chromatographic method with tandem mass spectrometric detection (LC–MS–MS) has been developed for analysis of sub-g kg^–1 residues of chloramphenicol in honey. Results from full validation of the procedure and analysis of 75 honey samples obtained commercially in Switzerland are presented. These show the method is satisfactory and useful for monitoring chloramphenicol residues in honey.     

Analysis of scopolamine and its eighteen metabolites in rat urine by liquid chromatography-tandem mass spectrometry

A rapid and sensitive method is described for the determination of scopolamine and its metabolites in rat urine by combining liquid chromatography and tandem mass spectrometry (LC–MS/MS). Various extraction techniques (free fraction, acid hydrolyses and enzyme hydrolyses) and their comparison were carried out for investigation of the metabolism of scopolamine. After extraction procedure, the pretreated samples were injected into a reversed-phase C18 column with mobile phase of methanol/ ammonium acetate (2 mM, adjusted to pH 3.5 with formic acid) (70:30, v/v) and detected by an on-line MS/MS system. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular masses (ΔM), retention-times and full scan MSⁿ spectra with those of the parent drug. The results revealed that at least 18 metabolites (norscopine, scopine, tropic acid, aponorscopolamine, aposcopolamine, norscopolamine, hydroxyscopolamine, hydroxyscopolamine N-oxide, p-hydroxy-m-methoxyscopolamine, trihydroxyscopolamine, dihydroxy-methoxyscopolamine, hydroxyl-dimethoxyscopolamine, glucuronide conjugates and sulfate conjugates of norscopolamine, hydroxyscopolamine and the parent drug) and the parent drug existed in urine after ingesting 55 mg/kg scopolamine to healthy rats. Hydroxyscopolamine, p-hydroxy-m-methoxyscopolamine and the parent drug were detected in rat urine for up 106 h after ingestion of scopolamine.     

MALDI-TOF-MS法对重组人内皮抑素蛋白分子质量测定

肿瘤的生长依赖于血管的生成,新生血管不仅为肿瘤生长提供必需的营养物质,而且为肿瘤细胞扩散提供了重要的途径。1997年哈佛大学的O'Reilly等发现了一种内源性新血管生成抑制因子内皮抑素(Endoscatin),显示出特异抑制激活的血管内皮细胞增殖和肿瘤新血管生成的生物学活性,其抗肿瘤作用具有高效、低毒、无耐药性的优点。目前,内皮抑素的研究引起了国内外广泛的兴趣,在美国已进行以安全性为目的的I期临床实验,国内也有多家公司对内皮抑素进行了抗肿瘤研究并申报一类新药。内皮抑素有望成为医治肿瘤而又没有化疗和放疗的毒副作用的一种新的治疗方法,但是否能作为药物应用于临床,尚需对内皮抑素的结构特点及抑制肿瘤和内皮细胞的作用机制等方面进行许多深入的研究。     

All-glass open-split interface for capillary GC/MS

This paper describes a design for an all-glass GC/MS interface. The design has advantages due to low dead volume, lack of column effluent adsorption and degradation, simple interface production and installation, and ease of column mounting/dismounting.     

Chemical Constituents of the Essential Oil of <Emphasis Type="Italic">Nepeta oxyodonta</Emphasis>

Water-distilled essential oil from the aerial parts of Nepeta oxyodonta Boiss. was analyzed by GC/MS for the first time. Fifty-eight components were identified. The major components were (E)-caryophyllene (12.6%), spathulenol (8.5%), β-bourbonene (8.1%), germacrene-D (7.4%), α-cadinol (7.3%), germacrene-D-4-ol (6.8%), T-cadinol (5.6%), and caryophyllene oxide (5.3%).__________Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 141–142, March–April, 2005.     

Dialysis-Chelex method for determination of exchangeable copper in human plasma

A method based on dialysis in the presence of histidine, and subsequent copper adsorption and preconcentration using Chelex-100 resin, has been developed for selective extraction of exchangeable copper from blood plasma. The method was verified by comparative analysis using two different instrumental techniques, ICP–MS and AAS. The results obtained were in excellent agreement. Accurate quantification of the exchangeable copper and the firmly bound copper was achieved. The method was further validated by analysis of a lyophilised human serum certified reference material.     

Simultaneous determination of theophylline,tolbutamide, mephenytoin,debrisoquin, and dapsone in human plasma using high‐speed gradient liquid chromatography/tandem mass spectrometry on a silica‐based monolithic column

Theophylline, tolbutamide, mephenytoin, debrisoquin, and dapsone are marker substrates for CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, respectively. A silica‐based monolithic column (Chromolith SpeedROD RP‐18e, 50×4.6 mm) was used to separate these five marker substrates of cytochrome P450 within only 84 s. Linear gradient elution was from acetonitrile‐water‐formic acid (10 : 90 : 1, v/v/v) to acetonitrile‐water‐formic acid (90 : 10 : 1, v/v/v) in 1.4 min. The flow rate was 2.5 mL/min. The retention time was 0.52 min for theophylline, 0.67 min for debrisoquin, 0.78 min for dapsone, 0.96 min for mephenytoin, and 1.13 min for tolbutamide. Detection was by tandem mass spectrometry using a PE Sciex API 3000 mass spectrometer with a Turbo‐Ionspray source in positive mode. A simple protein precipitation method was used. This method was validated over the concentration range of 5–2000 ng/mL based on the sample volume of 0.1 mL.     

Fatty Acid Compositions of Seed Oils of Three Turkish <Emphasis Type="Italic">Salvia</Emphasis> Species and Biological Activities

The fatty acid composition of seed extracts of Salvia bracteata, S. aethiopis, and S. candidissima ssp. candidissima were analyzed by GC/MS. The main compound of S. bracteata, S. aethiopis, and S. candidissima ssp. candissima was found to be 9,12-octadecenoic acid at 64.3%, 73.4%, and 20.8%, respectively. The seed extracts of S. bracteata showed activity against S. aureus E. coli, M. smegmatis, and C. albicans with MIC values of 1.1, 0.5, 1.1, and 1.1 mg/mL, respectively, while the seeds extract of S. aethiopis showed activity against the same microorganisms with MIC values of 2.2, 2.2, 1.1, and 1.1 mg/mL, respectively. However, the seed extract of S. candidissima ssp. candidissima showed activity only against M. smegmatis with a MIC value of 0.25 mg/mL.__________Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 223–225, No. 3, May–June 2005.     

Development and validation of a hydrophilic interaction liquid chromatography-tandem mass spectrometric method for the analysis of paroxetine in human plasma

A sensitive, simple, fast and rugged hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method for the determination of paroxetine was developed and validated over curve range 0.050-50 ng/mL using only 0.4 mL plasma. This is the first published LC-MS/MS method and the low limit of quantitation of this method is 10-fold lower than previously published methods. A simple liquid-liquid extraction method using methyl-tert butyl ether (MTBE) as the extraction solvent was used to extract paroxetine and the internal standard (IS) fentanyl-d(5) from plasma. The extract was evaporated to dryness, reconstituted and injected onto a silica column using a low aqueous-high organic mobile phase. The chromatographic run time was 2.0 min per injection, with retention times of 1.1 and 1.2 min for paroxetine and IS, respectively. The detection was by monitoring paroxetine at m/z 330 --> 192 and IS at m/z 342 --> 188, respectively. The inter-day precision and accuracy of the quality control (QC) samples were <5.0% relative standard deviation (RSD) and <2.9% relative error (RE). This method can be used for supporting therapeutical drug monitoring and pharmacokinetic or drug-drug interaction studies.     

Determination of Tetracyclines in Honey Using Liquid Chromatography with Ultraviolet Absorbance Detection and Residue Confirmation by Mass Spectrometry

A determination method has been optimized and validated for the simultaneous analysis of tetracycline （TC）, oxytetracycline （OTC）, chlortetracycline （CTC） and doxycycline （DC） in honey. Tetracyclines （TCs） were removed from honey samples by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns and eluted with Na2EDTA-Mcllvaine pH 4.0 buffers. Extracts were further cleaned up by Oasis HLB solid-phase extraction （SPE）, while other solid-phase extraction cartridges were compared. Chromatographic separation was achieved using a polar end-capped C 18 column with an isocratic mobile phase consisting of oxalic acid, acetonitrile and methanol. LC with ultraviolet absorbance at 355 nm resulted in the quantitation of all four tetracycline residues from honey samples fortified at 15, 50, and 100 ng/g, with liner ranges for tetracyclines of 0.05 to 2 μg/mL. Mean recoveries for tetracyclines were greater than 50% with R.S.D. values less than 10% （n= 18）. Detection limits of 5, 5, 10, 10 ng/g for oxytetracycline, tetracycline, chlortetracycline and doxycycline, respectively and quantitation limits of 15 ng/g for all the four tetracyclines were determined. Direct confirmation of the four residues in honey （2-50 ng/g） was realized by liquid chromatography-tandem mass spectrometry （LC/MS/MS）. The linear ranges of tetracyclines determined by LC/MS/MS were between 5 to 300 ng/mL, with the linear correlation coefficient r〉 0.995. The limits of detection of 1 to 2 ng/g were obtained for the analysis of the TCs in honey.