Tomosuke Ishizuki

2-(2-thiazolylazo)-4-methyl-5-(sulfomethylamino)benzoic acid as a reagent for the spectrophotometric determination of cobalt

Summary Some 2-(2-thiazolylazo)-5-(sulfomethylamino)benzoic acid derivatives are synthesized. Among them, 2-(2-thiazolylazo)-4-methyl-5-(sulfomethylamino)benzoic acid (TAMSMB) is very sensitive (e = 1.13 × 105 l mol-1 cm-1 at λmax 655 nm) and selective for the spectrophotometric determination of cobalt. The interference of copper and nickel can be eliminated by addition of EDTA after the cobalt(III)—TAMSMB complex has been formed. Cobalt is determined in nickel salts and glass.

Synthesis of 2-[2-(4-methylquinolyl)azo]-5-diethylaminophenol and its use for the spectrophotometric determination of nickel

2-[2-(4-Methylquinolyl)azo]-5-diethylaminophenol (QADP) was synthesized and the acidity constants of the reagent in 50% (v/v) ethanol and reactions with various metal ions were studied. QADP and its chelates are extracted into chloroform and the molar absorptivities of most complexes are higher than 105 1 mol−1 cm−1. QADP was applied to the selective spectrophotometric determination of nickel. Nickel (0.4–7.2 μg) could be determined by masking cobalt as the Co(III)-ammine complex.

Effects of manifold components on peak profiles in flow-injection analysis

Abstract The effects of pumps, mixing coils and joints on the peak profiles in flow-injection analysis are described. Four reciprocating pumps, three peristaltic pumps, single coils and double coils with helix diameters of 0.4–3 cm and two types of mixing joint were examined. When pumps yielding small pulsations and double coils with small helix diameter were used, well defined and reproducible peaks were obtained and the effects of mixing joints were small.

Synthesis of some antipyrinylazo and thiazolylazo compounds with pentan-2,4-dione and their reactions with metal ions

Abstract The reagents were synthesized by using pentan-2,4-dione as the coupling component with diazotized 4-aminoantipyrine or 2-aminothiazole. Two kinds of azo compounds were obtained under different conditions: 1-(4-antipyrinylazo)-1-(4-antipyrinylhydrazino)propan-2-one (Azonol A-1) and 3-(4-antipyrinylazo)pentan-2,4-dione (Azonol A-2) from 4-aminoantipyrine, and 1-(2-thiazolylazo)-1-(2-thiazolylhydrazino)propan-2-one (TAA-1) and 3-(2-thiazolylazo)pentan-2,4-dione (TAA-2) from 2-aminothiazole. The structure of Azonol A-1 was determined by single-crystal x-ray crystallography. The reactions of these reagents with various metal ions were examined. Azonol A-1 and TAA-1 form metal chelates at low pH values. Azonol A-1 is useful as a metallochromic indicator in titrations of bismuth with EDTA at pH 0.5–2, and as a spectrophotometric reagent for copper (II) (0.2–1.5 mg l−1) at pH 0.3–1.2.

Separation and simultaneous determination of cobalt, nickel and copper with 2-(4-methyl-2-quinolylazo)-5-diethylaminophenol by reversed-phase high-performance liquid chromatography

Performance of six quinolylazo compounds was studied as a pre-column derivatizing reagent for the separation of metal ions in the reversed-phase high-performance liquid chromatography. 2-(4-Methyl-2-quinolylazo)-5-diethylaminophenol (QADP) was suited for the determination of Co, Ni and Cu in the presence of a large amount of Fe. The detection limits under the optimized conditions [stationary phase: L-column ODS; mobile phase: acetone-water (62:38, v/v) containing 0.01 M NH(4)SCN and 0.01 M 2-morpholinoethanesulfonic acid-NaOH (pH 6); injection volume: 10 mul] were 0.24 ng for Co, 0.22 for Ni and 0.53 for Cu. This method was successfully applied to the determination of these metal ions in a standard steel sample.

Reversed-phase ion-pair partition liquid chromatography of chelates with 2-(3,5-dibromo-2-pyridylazo)-5-[N-ethyl-N-(3-sulphopropyl) amino] phenol and analogues

Abstract The ion-pair reversed-phase chromatography of some transition metal chelates with 2-(3,5-dibromo-2-pyridylazo)-5-[N-ethyl-N-(3-sulphopropyl)amino]phenol (3,5-diBr-PAESPAP) was studied. 3,5-DiBr-PAESPAP and its V(V), Cr(III), Fe(II), Co(III) and Ni(II) chelates were retained on and the copper (II), zinc(II) and cadmium(II) chelates dissociated in an ODS column using acetonitrile/water (37+63, v/v) (pH 7.0) containing 0.01 M acetate, 0.01 M 3-(N-morpholino)propanesulphonate buffer (pH 7.0) and 0.05 M Na+ as mobile phase. The chromatograms of 3,5-diBr-PAESPAP chelates were compared with those of the chelates with 2-(3,5-dibromo- 2-pyridylazo)-5-[N-(3-sulphopropyl)amino]phenol (3,5-diBr-PASPAP),2-(5-bromo-2- pyridylazo)-5-[N-(3-sulphopropyl)amino]phenol and 2-(5-bromo-2-pyridylazo)-5-[N-propyl-N- (3-sulphopropyl)amino] phenol. With 3,5-diBr-PAESPAP the Fe(II) and Ni(II) chelates were not resolved, but resolution was achieved with 3,5-diBr-PASPAP. The calibration graphs were linear over the ranges 2.0–10.0 ng (10-μl injection) of Fe, Ni and Co and for 20–100 ng (10-μl injection) for V with 3,5-diBr-PAESPAP and 3,5-diBr-PASPAP.

Synthesis of 2-[2-(8-hydroxyquinolyl)azo]-1-naphthol and its use in the spectrophotometric determination of calcium in potable water

Abstract The synthesis of a novel reagent, 2-[2-(8-hydroxyquinolyl)azo]-1-naphthol (HQAN), is described. The acidity constants of the reagent and its reactions with various metal ions are reported. The HQAN reagent forms a soluble calcium chelate in 50% (v/v) dioxane/ water at pH > 8.5 (ϵ = 24 000 l mol −1 cm t-1 at 570 nm). It also forms chelates with magnesium, other alkaline earth metals, and ivalent Mn, Fe, Ni, Cu, Zn, Cd and Pb. These interferences (except for Mn) can be avaoided by pH adjustment or by adding masking agents, and a very simple procedure for the determination of calcium in potable waters is obtained.

Flow-injection spectrophotometric determination of cadmium with quinolylazo compound after on-line separation using a silica gel column.

2-[2-(4-Methylquinolyl)azo]-5-diethylaminophenol(QADP) reacts with cadmium in aqueous ethanol and the molar absorptivity of the QADP-cadmium complex is the highest (1.51 x 1O(5)M(-1) cm(-1), gamma(max) 569 nm) of the reagents reported previously. A flow-injection spectrophotometric determination of cadmium with QADP after on-line separation using silica gel column was proposed. A 450 mug/l cadmium concentration could be determined in the presence of 13 mg/l zinc, 83 mg/l lead and 11 mg/l iron.

Direct determination of copper in serum by flow-injection analysis

Abstract Copper in serum was determined with a flow-injection system based on spectrophotometry using 2-(2- thiazolylazo)-4-methyl-5-(sulphomethylamino)benzoic acid TAMSMB) as chromogenic reagent. A serum sample (30 μl) is directly injected into the carrier containing 0.5 M acetic acid-sodium acetate buffer (pH 4.2), 1% Triton X-100 and 3% ethanol. the carrier merges into the stream of 3.5 M guanidine hydrochloride containing 4.5 × 10 −3 M KIO 3 and 4.0 × 10 −4 M KI, and the Cu(II) reacts with TAMSMB in the flow system. The absorbances are monitored at 600 nm. The sampling frequency is 60 h −1 .

Synthesis of 2-(2-thiazolylazo)-4-methyl-5-(sulfopropyl-amino) benzoic acid and the application to the flow-injection analysis of copper(II)

Summary2-(2-Thiazolylazo)-4-methyl-5-(sulfoethylamino)benzoic acid (TAMSEB) and 2-(2-thioazolylazo)-4-methyl-5-(sulfopropylamino)-benzoic acid (TAMSPB) were synthesized. The acidity constants of these reagents and the formation constants of the copper(II) and nickel complexes were determined, and the effects of the length of sulfoalkyl groups on the properties as analytical reagent are discussed by comparing with those of 2-(2-thiazolylazo)-4-methyl-5-(sulfomethylamino) benzoic acid (TAMSMB). The sensitivity is high in the order of TAMSPB, TAMSEB and TAMSMB. The molar absorptivity of copper(II)-TAMSPB chelate is 58000 l mol−1cm−1. The spectrophotometric determination of copper (II) (25 ppb-25ppm) with a flow-injection system is described. Copper in Normal Control Serum was determined.Zusammenfassung2-(2-Thiazolylazo)-4-methyl-5-(sulfoethylamino)benzoesäure (TAMSEB) und 2-(2-Thiazolylazo)-4-methyl-5-(sulfopropylamino)benzoesäure (TAMSPB) wurden synthetisiert. Die Aciditätskonstanten dieser beiden Reagenzien sowie die Bildungskonstanten der entsprechenden Komplexe mit Kupfer(II) und Nickel wurden bestimmt. Der Einfluß der Kettenlänge der Sulfoalkylgruppen auf die Eignung als analytisches Reagens wurde durch Vergleich mit 2-(2-Thiazolylazo)-4-methyl-5-(sulfomethylamino)benzoesäure (TAMSMB) untersucht. Die Höhe der Empfindlichkeit entspricht der Reihenfolge TAMSPB-TAMSEB-TAMSMB. Die molare Absorptivität des Kupfer(II)-TAMSPB-chelates beträgt 58000 l·mol−1·cm−1. Die spektrophotometrische Bestimmung von 25 ppb-25 ppm Kupfer(II) mit Hilfe eines Fließinjektionssystems wurde beschrieben und zur Kupferbestimmung in normalem Kontrollserum verwendet.