Yoshio Narusawa

Flow-injection spectrophotometric determination of silicate, phosphate and arsenate with on-line column separation

Abstract The simultaneous determination of silicate, phosphate and arsenate by using flow-injection analysis with on-line column separation is described. Determinations are based on measurement of the absorbance at 810 nm of the heteropoly blue formed with ascorbic acid as reducing reagent. Effects of flow rates, temperature of reaction coils and sample injection volumes are reported; optimum conditions are 0.25 ml min −1 for the ascorbic acid stream, 95°C for the reaction coils and 300 μl for the injection volume. With the anion-exchange column (TSK-gel SAX), the optimal flow rate of the eluent is 0.75 ml min −1 . Relative retention times depend on the concentration of the KCl/NH 3 /EDTA eluting solution; separation and simultaneous determination of the three ions are satisfactory at around 10 −4 mol l −1 concentrations of the three ions.

Radial dispersion by computer-aided simulation with data from zone circulating flow-injection analysis

By analysing damped response curves obtained by zone circulating flow-injection analysis (ZCFIA), correlations between FIA parameters and radial dispersion were obtained with the aid of computer simulation. This paper proposes definitions of axial and radial dispersion, and axial and radial diffusion. Quantitative correlations among residence time, flow rate, length and inner diameter of tube, sample volume and radial dispersion coefficient of dichromate ion were obtained by evaluating constants, K, and exponents, μ, for each qualitative formulation. Six qualitative expressions were obtained, and the three most important expressions are: D = K1Lrμ1Qcμ2 + 1 (0 < μ1 < 1, μ2 < 0) K1 = 0.349 ± 0.000, μ1 = 0.558 ± 0.003, μ2 = −0.222 ± 0.008 D = K2Qcμ2tμ3 + 1 (0 < μ2, μ3 < 1) K2 = 0.449 ± 0.002, μ2 = 0.339 ± 0.013, μ3 = 0.564 ± 0.006 D = K3Lrμ1tμ3 + 1 (0 < μ1, μ3 < 1) K3 = 0.388 ± 0.002, μ1 = 0.351 ± 0.019, μ3 = 0.206 ± 0.028 Data obtained by computer simulation are fairly consistent with the prospective ranges and signs. This paper mainly describes the radial dispersion.

Zone circulating flow-injection analysis: theory

Abstract Zone circulating flow-injection analysis (ZCFIA) is a method for multi-detection of a sample zone injected into a closed-flow system formed by connecting the two ports of a single FIA manifold. Using an FIA instrument assembled with a multi-step pump, detection was carried out at various flow-rates. Subsequent analysis of the damped curves yielded a great deal of information concerning the theory of FIA. The data thus obtained were arranged to clarify correlations among general residence time, flow-rate, length and inner diameter of the reactor, sample volume injected and dispersion coefficient. As a result, several shortcomings and errors in FIA theory were discovered. Several qualitative formulations, containing variables suitable for the various conditions involved, were established and six qualitative conclusions were drawn.

Kinetics and mechanism of acid hydrolysis of trichlorotrithioureachromium (III) complex and chloride anation of trans-dichlorotetraquochromium (III) complex ion☆

Abstract The kinetics of an acid hydrolysis (aquation) of the trichlorotrithioureachromium (III) complex and the chloride anation of trans -dichlorotetraquochromium (III) complex ion have been investigated in a strong acid medium. In 9·0 M hydrochloric or 9·0 M perchloric acid, the reaction proceeds in four steps, whereas in the case of 12·0 M hydrochloric acid it proceeds in three steps, where the final product of the reaction is found to be the trichlorotriaquochromium (III) complex. The results for the pseudo first-order rate constants for the equation in 12·0 M hydrochloric acid at 25°C were k 1 = (6·87 ± 0·89) · 10 −3 sec −1 , k 2 = (2·64 ± 0·21) · 10 −3 sec −1 , and k 3 = (2·43 ± 0·12) · 10 −4 sec −1 . For the chloride anation, 8·89 · 10 −4 (l/mole) 2 ·sec −1 was obtained. The results for the energies and entropies of activation for the aquation obtained in 12·0 M hydrochloric acid were 15·7 kcal/mole and −17·6 e.u. for the first step, 15·6 kcal/mole and −20·1 e.u. for the second step, and 15·1 kcal/mole and −26·4 e.u. for the third step, respectively.

Evidence of axial diffusion accompanied by axial dispersion with zone circulating flow-injection analysis data

Axial dispersion free from any contribution of diffusional effects has been obtained by computer aided simulation with zone circulating flow-injection analysis (FIA) data. The present paper deals with the relationships between axial dispersion and FIA parameters (flow rate, length and inner diameter of the tube, residence time, sample volume, etc.) as well as the relationship between axial dispersion and radial dispersion. Furthermore, the relationship between axial dispersion and residence time, which was ambiguous with the manual analysis, has been cleared up with the computer aided simulation. Analytical expressions already obtained and reported have been analyzed with the computer aided simulation, and constants, K, and exponents, μ, have been determined. DA = K4L1μ′rQ2μ′c + θt (μ′1 ≥ 1, μ′ 2 < 0); K4 = 0.045 ± 0.001, μ′1 = 1.01 ± 0.01, μ′2 = −1.46 ± 0.01. DA = K5Q2μ′ct3μ′ + θt (μ′2 < 0, μ′3 ≥ 1); K5 = 0.076 ± 0.001, μ′2 = −0.42 ± 0.01, μ′3 = 1.02 ± 0.01. (D − 1)(DA − θt) = K7Lr1μ″Q2μ″c (μ″1 < 0, μ″2 ≥ 1); K7 = 7.50 ± 0.01, μ″1 = −0.45 ± 0.01, μ″2 = 1.24 ± 0.01. In the relationship between axial dispersion and radial dispersion, another relationship was also obtained: (D − 1)(DA − θt) = K8Q2μ″ct3μ″ (0 < μ″2 < 1, μ″3 < 0); K8 = 6.70 ± 0.01, μ″2 = 0.75 ± 0.01, μ″3 = −0.48 ± 0.01.

Simultaneous determination of silicon and phosphorus in biological standard materials with on-line column flow-injection spectrophotometry

SummaryA simultaneous determination of silicon and phosphorus in biological standard materials with on-line column flow-injection spectrophotometry (FIA) is described. Biological materials are ashed, fused with a lithium carbonate-boric acid mixture, and dissolved in a hydrochloric acid solution. Interfering cations are removed by a simple cation-exchange column filtration. The acid effluent is evaporated to dryness, fused with a small amount of sodium carbonate for depolymerization, taken up in dilute EDTA solution, and analyzed for silica and phosphorus by FIA. For the simultaneous determination of these elements, TSK-gel SAX was used, and the eluent was 0.085 mol/l NaCl/0.01 mol/l NH3/0.001 mol/l EDTA. Several standard reference materials [bovine liver (NBS), chlorella and pepperbush (NIES)] were analyzed for both elements. The results of phosphorus determination for bovine liver are in satisfactory agreement with the NBS certificated value. ICP measurements were applied to analyses of chlorella and pepperbush for silica and phosphorus. The agreement of the analytical results between FIA and ICP is satisfactory. Silica in bovine liver was determined in the present study for the first time.

Analysis and interpretation of the oxidation reaction of tris(2,2′-bipyridine)chromium(II) complex with hexaamminecobalt(III) ion[1]

Abstract Oxidation of [Cr(bpy)3]2+ with [Co(NH3)6]3+ in an acetic acid-sodium acetate buffer solution under different conditions in excess 2,2′-bipyridine was examined by means of a stopped-flow method. It was found that a simulation procedure with an analogue computer was effective for analyzing the reaction curves for this system. The rate equation for the reaction was found to be: d[Cr(bpy)3 2+ ] d t = k 1 [ Co(NH 3 ) 6 3+ +][Cr(bpy) 3 2+ ] + k 2 [Cr(bpy) 3 2+ ] where k1 is a second-order rate constant for the direct oxidation-reduction between these reactants, and k2 a first-order rate constant for the ligand dissociation of [Cr(bpy)3]2+. The reaction mechanism proposed was as follows: [ Cr(bpy) 3 ] 2+ + [ Co(NH 3 ) 6 ] 3+ → k 1 [ Cr(bpy) 3 ] 3+ + Co 2+ + 6NH 3 [ Cr(bpy) 3 ] 2+ + 2H 2 O → k 2 [ Cr(H 2 O) 2 (bpy) 2 ] 2+ + bpy [ Cr(H 2 O) 2 (bpy) 2 ] 2+ + [Co(NH 3 ) 6 ] 3+ → k 4 [Cr(H 2 O) 2 (bpy) 2 ] 3+ + Co 2+ + 6NH 3 The values of k1 and k2 were 187±4M−1 s−1 and 0.104±0.002 s−1(μ = 0.20, 25°C), respectively.

Decisive problems of zone-circulating flow injection analysis and its solution

Although experiment and computer analysis of zone-circulating flow injection analysis (ZCFIA) data have been investigated, there are still some essential problems inherent to ZCFIA. Computer program of high dimensional modified simplex method was used for resolving peaks of ZCFIA damped response curves. Peaks are resolved on the basis of the criterion that each area of the peak surrounded by the curve and the abscissa is equal, because each sample zone circulates repeatedly in the manifold in equal volume. As a result, the peaks of the damped response curve have been resolved into each component and the curve obtained by summing these components has been proved to be equal to the original response curve. By following up the data analysis of ZCFIA, it was found that there were many conflicts in the manual analysis of data by Li. At least, the dispersion in a flow system should not be investigated by ZCFIA, and it might be studied by the single-line manifold of FIA.