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21.
Summary A rapid and simple method for the determination of both lysinoalanine (LAL) and protein hydrolysate amino acids after derivatization
with dansyl chloride (5-dimethylaminoaphtalene-1sulfonyl chloride) and separation with RP-HPLC (UV detection) is presented.
LAL is analysed in less than 15 minutes and complete separation of 22 amino acids is achieved in less than 30 minutes using
single linear gradients of solvents (phosphate buffer and acetonitrile). Quantitative results obtained by HPLC compare well
with results of the ion-exchange chromatography (amino acid analyser). The importance of the duration of the derivatization
reaction and of the excess of reagent is discussed. As examples, the results of the determination of LAL in two samples of
base treated α-casein and 22 samples of soy protein and the results of the analysis of amino acids in two balanced diet mixtures
are presented.
Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984 相似文献
22.
The investigation of the electrochemical reduction and the adsorption of meso-tetra(4-trimethylammoniumphenyl)porphine (T(4-TMAP)P) at a mercury electrode in alkaline solution shows that the overall reduction involves three two-electron steps, of which the first step is reversible and the latter two are irreversible. In addition, T(4-TMAP)P and its metal complexes of Cu(II) and Mg(II) can be strongly adsorbed on the surface of a mercury electrode. The adsorption phenomena have been utilized as a preconcentration step for the determination of trace amounts of the two ions by single sweep polarography. For copper, the detection limit is 1 × 10–8 mol dm–3, for magnesium, 1 × 10–7 mol dm–3, the latter being limited by the reagent blank. The proposed method was applied to the determination of Cu and Mg in various types of samples (chemicals, hair and liver tissues) with satisfactory results. 相似文献
23.
氯化血红素催化新型荧光反应测定葡萄糖的研究 总被引:3,自引:0,他引:3
本文用流动注射分析了研究了过氧化物模拟酶催化过氧新型荧光底物(N,N-二氰甲基邻苯二胺,DCMOPA)的最优条件。结果表明,该系统可用于定量测定氧化氢及催化氯化血红素的浓度。 相似文献
24.
Aluminum and copper ions are selectively estimated spectrophotometrically. These ions form colored complexes with spadns which have a maximum absorbance at 580 nm. The complexes formed with both cations are stable and pH dependant; aluminum is favorably complexed at pH 5, while copper is complexed at pH 7.The percentage recoveries were found to be 99.69 ± 0.75 and 99.32 ± 0.6 with a minimum detection limit of 0.08 and 0.23 g ml–1 for aluminum and copper ions respectively. There is insignificant interference from the 10-fold concentrations of other metal ions under the proposed reaction conditions. 相似文献
25.
Branko Stanovnik Uroš Urleb Miha Tišler 《Monatshefte für Chemie / Chemical Monthly》1987,118(5):601-606
An unequivocal synthesis of 5-chloro-7-methyl- (8) and 7-methyl-1,2,4-triazolo[1,5-a]pyrimidine (10) from 2-amino-4-chloro-6-methylpyrimidine (5) through the corresponding amidine6 and formamide oxime7 was developed. It was unambigously shown by comparison of the chemical shifts and the magnitude of coupling constants that the compounds obtained by condensation of 3-amino-1,2,4-triazole (12) and ethyl acetoacetate (13) and some further transformations are isomeric 5-methyl substituted 1,2,4-triazolo[1,5-a]pyrimidines1,9, and11.
Eine eindeutige Synthese einiger substituierter 1,2,4-Triazolo[1,5-a]pyrimidine
Zusammenfassung Es wurde ein eindeutiger Syntheseweg für 5-Chlor-7-methyl- (8) und 7-Methyl-1,2,4-triazolo[1,5-a]pyrimidin (10) ausgehend von 2-Amino-4-chlor-6-methylpyrimidin (5) über das entsprechende Amidin6 und das Formamidoxim7 entwickelt. Durch Vergleich von chemischen Verschiebungen und Kopplungskonstanten konnte eindeutig gezeigt werden, daß die Verbindungen, die bei der Kondensation von 3-Amino-1,2,4-triazol (12) and Ethylacetoacetat (13), sowie einige weitere Transformationsprodukte, isomere 5-Methylsubstituierte 1,2,4-Triazolo[1,5-a]pyrimidine sind (1,9,11).相似文献
26.
27.
Sabry K. Mohamed 《Analytica chimica acta》2006,562(2):204-209
A poly(vinyl chloride)-based membrane of 2,9-dimethyl-4,11-diphenyl-1,5,8,12-tetraazacyclotetradeca-1,4,8,11-tetraene (DDTCT) with sodium tetraphenyl borate (STB) as an anion excluder and dibutyl phthalate (DBP), dibutyl butylphosphonate (DBBP), tris(2-ethylhexyl) phosphate (TEP) and tributyl phosphate (TBP) as plasticizing solvent mediators was prepared and investigated as a Ga(III)-selective electrode. The best performance was observed with the membrane having the ligand-PVC-DBP-STB composition 1:4:1:1, which worked well over a wide concentration range (1.45 × 10−6 to 0.1 mol L−1) with a Nernstian slope of 28.7 mV per decade of activity between pH 4.0 and 10.0. This electrode showed a fast response time of 12 s and was used over a period of 100 days with good reproducibility (s = 0.3 mV). The selectivity coefficients for monovalent, divalent and trivalent cations indicate excellent selectivity for Ga(III) ions over a large number of cations. Anions such as Cl− and SO42− do not interfere and the electrode also works satisfactorily in partially water-alcohol medium. The practical utility of the membrane sensor has also been observed in solutions contaminated with detergents, i.e., cetyltrimethylammonium bromide and sodium dodecyl sulfate and used for the determination of gallium in nickel alloy, fly-ash and biological samples. 相似文献
28.
Juan M. Kok Kevin C. Lim Brian W. Skelton Allan H. White 《Journal of Cluster Science》2004,15(3):377-386
The structural characterizations of some copper(I) halide (CuX) adducts with norbornadiene (nbd) are recorded. CuCl : nbd (1:1)4 (a redetermination), (2:1)2(|), are systems both based around Cu4Cl4 cubane-type cluster arrays. CuBr : nbd (7:3)(|)( 0.5 MeOH), a complex polymer with 3-symmetry, is believed to be the complex previously described as an adduct of 2:1 stoichiometry. Attempts to obtain an iodide counterpart have resulted in the definition of an ephemeral adduct CuI : MeCN (3:2)(|). 0.5 C7H8 in which, remarkably, the nbd is uncoordinated; the complex is a polymer, related to the [AgX(quinoline)](|) (X = Cl, Br) saddle polymer. 相似文献
29.
Synthesis and Structure of Silver(II) Tetrafluoroaurate(III) Ag[AuF4]2 Intensive green single crystals of Ag[AuF4]2 can be obtained by heating up micro crystalline Ag[AuF4]2 in autoclaves (p(F2) ~ 200 bar, T ~ 400°C, t ~ 14 d). It crystallizes monoclinic, space group P21/n ? C; (No. 14) with a = 522.3(1), b = 1101.3(3), c = 550.5(2) pm, β = 94.98(3), Z = 2 and is isotypic with Pd[AuF4]2. 相似文献
30.
Alkylidynephosphanes and -arsanes. I [P ≡ C? S]?[Li(dme)3]+ – Synthesis and Structure O,O′-Diethyl thiocarbonate and bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide dissolved in 1,2-dimethoxyethane, react below 0°C to give ethoxy trimethylsilane and tris(1,2-dimethoxyethane-O,O′)lithium 2λ3-phosphaethynylsulfanide – [P≡C? S]? [Li(dme)3]+ – ( 1a ). Apart from bis(trimethylsilyl)sulfane or carbon oxide sulfide, dark red concentrated solutions of λ3-phosphaalkyne 1 are also obtained from reactions of carbon disulfide with bis(tetrahydrofuran)-lithium bis(trimethylsilyl)phosphanide or with the homologous lithoxy-methylidynephosphane ( 2 ) [1]. The ir spectrum shows two absorptions at 1762 and 747 cm?1 characteristic for the P≡C and C? S stretching vibrations. The nmr parameters {δ(31P) ? 121.3; δ(13C) 190.8 ppm; 1JCP 18.2 Hz} resemble much more values of diorganylamino-2λ3-phosphaalkynes than those of bis(1,2-dimethoxyethane-O,O′)lithoxy-methylidyne-phosphane ( 2a ). As found by an X-ray structure analysis (P21/c; a = 1192.6(16); b = 1239.1(19); c = 1414.8(26) pm; β = 105.91(13)° at ?100 ± 3°C; Z = 4 formula units; wR = 0.064) of pale yellow crystals (mp. + 16°C) isolated from the reaction with O,O′-diethyl thiocarbonate, the solid is built up of separate [P≡C? S]? and [Li(dme)3]+ ions. Typical bond lengths and angles are: P≡C 155.5(11); C? S 162.0(11); Li? O 206.4(17) to 220.3(20) pm; P≡C? S 178.9(7)°. 相似文献