摘要:

A spectrophotometric determination of hydrogen peroxide (H2O2) was proposed with 2-(5-bromo-2-pyridylazo)-5-(N-pro-pyl-N-sulfopropylamino)phenol(5-Br.PAPS)-molybdenum(VI) complex at pH 1.9, 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol (5-NO2. PAPS)-vanadium(V) complex at pH 0.9 or 6.2 in the presence of anionic or cationic surfactant, sodium dodecylbenzenesulfonate (SDBS) or hexadecyltrimethylammonium chloride (HTAC). The calibration curves were linear in the range of 0–2.5 × 10−5M(0–8.5 μg/10 ml) H2O2or 0–2.0 × 10−5M(0–6.8 μg/10 ml) H2O2with apparent molar absorptivities (ε) 4.6 × 10−41 mol−1cm−1at 640 nm(5-Br.PAPS-molybdenum(VI) complex), 7.7 × 10−41 mol−1cm−1at 600 nm(5-NO2. PAPS-vanadium(V)-SDBS complex) and 9.2 × 10−41 mol−1cm−1at 605 nm(5-NO2PAPS-vanadium(V)-HTAC complex), respectively.

ISSN:0003-2719    

DOI:10.1080/00032719508000343

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

This paper describes fragmentation modes of conventional and tandem mass spectrometry of the derivatives of monosialoganlioside GM1, including isopropyl monosialoganglioside GM1and acetyl lysomonosialoganglioside GM1. In the analysis of the former, it has been found that: (i) the abundant sodiated molecule of the lipid derivative is readily desorbed by positive-ion liquid secondary-ion mass spectrometry utilizing 3-nitrobenzyl alcohol as liquid matrix; (ii) the isopropyl derivatized-N-acetylneuraminic acid moiety can be detected by the positive-ion mode and collisionally induced dissociation tandem mass spectrometry; and (iii) the saccharide composition and sequence can be identified by negative-ion liquid secondary ion mass spectrometry. For the latter, the molecular mass, oligosaccharide sequence and modified ceramide moiety in the lipids can be characterized by coventional negative-ion liquid secondary-ion mass spectrometry and tandem mass spectrometry.

ISSN:0003-2719    

DOI:10.1080/00032719508000344

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The paper reports the synthesis of a new fluorescent reagent 3-pheny1-5-(2′-carboxy1phenylazo)-2-thioxo-4-thiazolinone (3PRACP). The product has been purified by column absorption chromatography. Its conposition has been confirmed by elemental analysis, IR, HNMR and MS. We also studied its fluorescent properties At pH=5.6, 3PRACP can form a chelate with trace Cu2+and when λ ex/λ em=305nm/405nm, the fluorescence is very intense. The fluorescent intensity has a linear relationship with the concentration of Cu2+in the range of (0.1 – 48) × 10−9M. The sensitivity is 8X10−9. Using the method, we detected trace copper in pork and vegetable, with good results.

ISSN:0003-2719    

DOI:10.1080/00032719508000345

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An improved procedure for precise measurement of chlorine isotope ratios in geological samples based on Cs2Cl+ion by thermal ionization mass spectrometry is reported. Using this procedure the37Cl/35Cl ratio of NIST SRM 975 is determined to be 0.318929±0.000028(1[sgrave]) with a precision of 0.009%(1 [sgrave]). The procedure has been successfully applied to study the variation of chlorine isotopic compositions in seawater and to determine atomic weight of chlorine.

ISSN:0003-2719    

DOI:10.1080/00032719508000346

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An HPTLC method for identification and determination of 12 synthetic dyes (Amaranth, Allura red, Brilliant black BN, Brilliant blue E, Carmoisine, Erythrosine, Indigotine, Patent blue V, Ponceau 4R, Quinoline yellow, Sunset yellow, Tartazine) has been developed. Amberlite XAD-2 was used as a stationary phase for column chromatography. Elution was performed with various acidified alcohols (i-propanol,n-propanol,n-butanol) and recoveries between 81.5 - 100.2% were obtained. The low limit of detection is in the range of 4 – 10 ng. The method was tested on commercial products as: carbonated soda, candies, chewing gum, identical natural flavours, etc.

ISSN:0003-2719    

DOI:10.1080/00032719508000347

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0003-2719    

DOI:10.1080/00032719508000348

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0003-2719    

DOI:10.1080/00032719508000351

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor