In this work, the analytical performance of a microsecond-pulse glow discharge time of flight mass spectrometer (μs-pulse GD-TOFMS) is evaluated. By adjusting the delay time of repeller pulse, it is able to ignore significantly the background argon ions prior to the repelling of analytical ion pulse due to the repelled ion beam orthogonalized to the extracted ion beam, such that mass spectra are characterized by high discrimination against discharge gas species. The short-term relative standard deviation of 2.2% is achieved with 5-minute interval, which is found mainly up to the stability of discharge pressure. A fairly good resolving power of 220 has been reached for the linear mode mass spectrometer with a 1.25m drift tube. The potential of applying μs-pulse GD-TOFMS in isotope abundance measurement is studied, and the detection power of this μs-pulse GD-TOFMS is evaluated and some restricted problems are discussed.

View full abstract

Isotope dilution-inductively coupled plasma mass spectrometry (ID-ICP-MS) was applied to the determination of lead in natural water, and its precision was compared to that of the conventional calibration method. Trace amount of lead in natural water was preconcentrated using a chelating resin of Chelex 100 before ID-ICP-MS, where the preconcentration factor of 50 was obtained. The concentrations of lead were 26.1pg/g and 266pg/g for the certified river reference materials (JAC 0031) and the pond water sample, respectively, with the RSD less than 1%.

View full abstract

Substoichiometric isotope dilution mass spectrometry (SIDMS) as a new analytical method has been proposed for the accurate determination of iron. Iron(III) was extracted with a substoichiometric amount of 4- isopropyltropolone (Hipt) in xylene or heptane in the presence of 3, 5-dichlorophenol (DCP) as a synergist and then subjected to the isotope measurement (⁵⁴Fe) with amicrowave-induced plasma mass spectrometer. For more precise determination, ⁵⁹Co was used as an internal standard. In this method, the correction of the mass discrimination of isotope measurement is not required and the use of expensive enriched stable isotopes can be avoided.

View full abstract

High power nitrogen microwave induced plasma was used as a new excitation source for atomic emission spectrometry to determine low concentrations of arsenic in combination with hydride generation technique. Under the optimized experimental conditions, the best attainable detection limits at As(I)188.979nm was 3.13ngAs/ml with a linear dynamic range of 10 to 5000ngAs/ml. The presence of several diverse elements has been found to cause more or less a depressing interference with the determination of arsenic by the present technique. The present method was applied to the determination of total arsenic in the samples of sea weed and scallop to be issued as standard reference materials by National Institute for Environmental Studies, Japan. The samples were dissolved in a mixture of nitric and sulfuric acids with the addition of hydrofluoric acid. The results obtained by this method were very reproducible and satisfactory.

View full abstract

A method has been developed for the determination of silicon in urine and blood by graphite-furnace atomic absorption spectrometry. Nickel chloride was employed for the matrix modifier. The tolerable ashing temperature was raised to 2200°C in the presence of a matrix modifier. The urine was diluted 1+349 with distilled water and the blood was diluted 1+19 with Triton X(1%), and introduced into a pyrocoated graphite tube together with a nickel solution. Recoveries of the silicon added to the urine and the blood samples ranged from 85.5 to 89.3% for urine and 69.3 to 72.0 % for blood; the relative standard deviation was within 10% at the 10mg/l level. The silicon contents in urine and blood, determined by the proposed method, ranged from 2.6-23.7mg/l and 1.0-4.6mg/l, respectively.

View full abstract

Five types of silica microspheres of uniform size and composition were studied as refractory reference samples for quantification of He-MIP-AES particle analyzer. The cube root of Si emission pulse intensity of individual particles was plotted against their geometrical diameters. A quantitative relationship with the spectrum intensity was found at the highest pulse population of the spectral pulse distribution. However, the distribution of pulse intensity from an uniform fraction was wider than expected and the linear size range was also small between 3.0-6.0μm. On the other hand, each Si emission pulse synchronized within 390μsec with Ti emission pulse in two types of coated silica microspheres and the individual relative emission intensities (Ti vs Si) was almost constant.

View full abstract

Sample cuvette-tungsten boat furnace (TBF)-inductively coupled plasma atomic emission spectrometry was investigated for the direct determination of trace amounts of cadmium and lead in biological materials. To each small sample cuvette made by tungsten, the mixture of a ground biological sample and powdered dlammonium hydrogenphosphate was accurately weighed. Tetramethylammonium hydroxide solution was injected into it. Then, the cuvette temperature was maintained at a wet-digestion temperature to decompose the solid sample. After the on-furnace digestion was completed, the temperature was succeedingly elevated up to generate the analyte vapor to introduce into the plasma.

View full abstract

A mini-column filled with Dowex 50x8 resin is developed and investigated for the analysis of trace level of rare earth element by ICP-AES. The column is installed between peristaltic pump and ICP-AES, and ng/ml level of rare earth element is analyzed directly by on-line FIA-ICP-AES. 6N hydrochloric acid is found to be an optimum concentration for stripping, and the optimum flow rates for loading and stripping are measured at 0.8 and 1.1ml./min, respectively. Easily ionized elements from flux such as Na and K would be eliminated easily by 2N hydrochloric acid before stripping the rare earth element deposited on the resin. For an analysis of Sm, the absolute detection limit and linearity are found to be and 0.9999, respectively. Less than 4% of reproducibility is observed for the analysis of Sm and Nd. The analytical result with NIST SRM 1633B is also found to be 20.3ng/ml, which agrees well with the certified value.

View full abstract

The optimized measurement of boron using graphite furnace atomic absorption spectrometry with a Zeeman effect background correction is described. Matrix modification and pretreatment. of graphite furnace were studied in an effort to improve the sensitivity and the elimination of memory effects. Based on this study, the tolerable ashing temperature was raised to 2100°C in the presence of matrix modifier, and the interferences from diverse elements were eliminated. The proposed method was applied for the determination of urinary boron. Recoveries of boron added to urine sample ranged from 95 to 8%;relative standard deviation were within 10% at the 10mg/l level. Boron contents determined by the proposed method ranged from <1.0-7.7mg/l.

View full abstract

Urine samples have been analyzed for silicon using graphite furnace atomic absorption spectrometry. The samples were simply diluted(1+349) with distilled water and introduced into pyrocoated graphite tube together with nickel modifier. Atomic absorption signal was recorded at 251.6nm wavelength. Under these conditions, the detection limits of silicon are less than 0.7mg/ml for urine sample. The quantitative performance of the proposed technique applied to urine samples was compared with that obtained from inductively coupled plasma emission spectrometry.

View full abstract

X-ray absorption spectroscopy combined with an in-situ electrochemical cell has been developed for characterization of unstable, but electrochemically stable metalloprotein model compounds with various oxidation states in solution. The technique has been applied to some dimanganese Schiff-base complexes as a model of Photosystem II and [Ru₂(μ-O)(μ-CH₃COO)₂(bpy)₂L₂](L=pyridine and 1-methylimidazole) as a model off hemerythrin. It has been found that X-ray absorption near-edge structure (XANES) patterns correlate well with the formal oxidation states of the metal ions and aggregation. The analysis of extended X-ray absorption fine structure (EXAFS) data has revealed characteristic metal-ligand and metal-metal distances within the model compounds with different oxidation states.

View full abstract

The technique of on-line direct precipitation preconcentration by sulfide precipitation for As has been developed and applied to ICP-AES. For 1.0mL of sample, the enrichment factor is 4 with the sampling speed of 15/hr. However, the enrichment factor can be increased to more than 40times when the sampling volume is increased to 10mL with the samplig speed of 5/hr. Analysis of NIST reference material yielded a good result with the certified value.

View full abstract

Some results are introduced in studying characters of matrices influencing the desorption ionization processes in MALDI-MS, which have not been reported. By the use of low angle laser scattering photometer the association state of four matrices with lysozyme are measured. The results demonstrated that 3-amino-4-hydroxybenzoic acid (3A4HA) is the best one which can be calculated 224 molecules to associate with one molecule of lysozyme. The other three matrices, nicotinic acid (NA), 2, 5 dihydroxybenzoic acid (DHB) and caffeic acid (CA) are in the order of several tens of matrix molecules associated with one protein molecule. It is interesting to point out that 3-amino-4- hydroxybenzoic acid is the only one that cannot perform MALDI-MS spectrum and the reason is discussed. The results of the investigation in negative MALDI mass spectra of different matrices demonstrated that the desorption ionization processes are different with that of positive ions, and their mechanisms were proposed.

View full abstract

Laser two-photon ionization technique has been applied to monitor dissolving processes of probe molecules from solution surfaces. The time courses of the photoionization charge decay were measured by changing the properties of the bulk phase after the addition of the amphipathic molecules. The dissolving rate of pyrenebutyric acid, aminopyrene and pyrenesulfonic acid was strongly depended on pH in the bulk solution. The dissociation equilibrium of the conjugated acid-base system governed the solubility of the amphipathic molecules. Effects of surfactants were also observed in the dissolving process of pyrenedecanoic acid.

View full abstract

Quantitative analysis of p-chlorotoluene in the presence of o-chlorotoluene as an interferent was attempted by using HPLC with diode array detection and second-order calibration methods. An emphasis was placed on a further comparison between two methods, i.e., the traditional parallel factor analysis (PARAFAC) and the alternating trilinear decomposition (ATLD) methods. The following conclusions have been confirmed for the calibration examples tested. PARAFAC does not always converge to chemical meaningful solutions and its convergence rate is slow for the . This seems to be owing to the deficiency of a real trilinear sense in PARAFAC. The convergence rate of the ATLD algorithm is extremely fast. The ATLD-based calibration not only retains the advantage of second-order calibration but can give satisfactory concentration predictions.

View full abstract

Upon mixing of oxovanadium(IV) acetylacetonate, this complex caused an increase in the chemiluminescence (CL) of luminol in a reverse micellar medium of cetyltrimethylammonium chloride in chloroform-cyclohexane (6:5 vlv)-water (buffered with NaOH-Na₂CO₃, pH 12.5) even in the absence of an oxidizing reagent such as hydrogen peroxide. In this CL process, the reaction of Luminol with the oxovanadium(IV) ion produced from the decomposition of the oxovanadium(IV) complex in the reverse micelles is probably significant. A flow-injection method for the oxovanadium(IV) determination based on the present reversed micellar mediated CL reaction was examined. All the analytical conditions were optimized using the sample solution of oxovanadium(IV) acetylacetonate in chloroform. A detection limit (DL) of 0.1ng cm^-3 and a linear calibration graph was obtained with a dynamic range from the DL to 50ng cm^-3.

View full abstract

A simple and rapid method for the determination of trace amount of iron(III) by stopped-flow photochemical method has been developed based on the catalysis of iron(III) on the photochemical decoloration of methylene blue. The linear range of this method was in the range of 0.003-0.28μg/mL of iron(III). It is satisfactory to apply this method in the analysis of iron(III) in tap water and honey samples with RSD 1.80% and 1.03%, respectively.

View full abstract

A novel spectrofluorimetric method for determination of L-ascorbic acid is described. It is based on the inhibition of L-ascorbic acid on the formation of 2, 3-diaminophenazine, which is an oxidation product of o-phenylenediamine catalyzed by laccase, in the presence of Brij-35, which shows strong enhancement on the fluorescence(at λem/λex=530nm/430nm) of the product, while no effect on the laccase-catalyzed reaction. The mechanism of o-phenylenediamine oxidation reaction catalyzed by laccase in the presence of L-ascorbic acid is discussed. L-ascorbic acid is determined in the range of O.02-2.Oμg/ml with a detection limit of 0.014μg/ml. The method is applied to the determination of L-ascorbic acid in pharmaceuticals, the results agree well with the nominal values and those obtained by the reference method.

View full abstract

The electrochemiluminescence (ECL) phenomena of some hydroxyl compounds in the presence of tris(2, 2′- bipyridyl) ruthenium(III)[Ru(bpy)₃²⁺] have been found.. The experiments were performed in a flow injection system equipped with a thin-layer electrolysis cell. A three-electrode system with a working electrode of a glassy carbon disk (22.1mm²), was used for potentiosatic control of the electrolytic system. The ECL behaviors of sucrose, fructose, glucose, mannose, glycerol, ascorbic acid, citric acid, tartaric acid, some monohydric alcohols and polyhydric alcohols, have been discussed. The ECL reaction mechanisms of these compounds and Ru(bpy)₃²⁺ were also discussed.

View full abstract

A Laser-induced confocal microscope system with the CCD-camera detection suitable both for spectroscopic investigation and for direct imaging is described. In combination with a spatial pinhole, depth discrimination was obtained. A method based on the reflected light from a quartz plate was proposed to detect the capability and a vertical resolution of 2.7μm in terms of the full width at half maximum was achieved. The spatially- registered and temporal fluorescence spectra can be acquired by this system. Without using monochromator, direct real time fluorescence imaging with temporal time as short as 0.5ms can be obtained. The potential applications of the confocal microscopy to air-liquid interface studies are discussed.

View full abstract

A measurement system for resonant second harmonic(RSH) spectroscopy using an optical arrangement of total internal reflection was developed as an analytical method for investigating molecules adsorbed on substrate surfaces. RSH spectra were measured for the rhodamine B molecules adsorbed on a fused quartz substrate with different coverages. It was demonstrated for the first time by the polarization measurements that aggregation of rhodamine B occurred on a fused quartz, and that both of the dimeric and monomeric species coexisted on the surface.

View full abstract

New vanadium (V) complex, diammomum (nitrilotriacetato)dioxovanadate (V) has been synthesized. The structure of the complex has been studied by NMR spectzoscopies as well as X-ray crystallography. The unit cell of the monoclinic crystals contains four molecules with a=6.923 (1) Å, b=8.824 (2) Å and β =91.60 (3)° in the space group of P2₁/n. The anion, [VO₂NTA]^2- has irregular and distorted octahedral geometry around vanadium with two double-bonded oxo atoms cis to each other. It is confirmed from NMR studies that the chemical exchange between glycinate rings cis to and trans to V=O bond has occurred fast in aqueous solution at elevated temperature.

View full abstract

Attenuated total reflectance Fourier transform infrared (ATR/FT-IR) spectrometry was applied to the determination of calcium carbonate in limestone. Both of the simple and multiple linear regression methods have been investigated. The correlation coefficient was found to be increased to 0.985 when the multiple linear regression analyses using the absorbance values at all of the wavelengths were applied. The standard deviation of calibration for 37 samples by this method was 0.601. In order to test the applicability of the multiple linear regression method to routine analyses of limestones, 31 samples collected from the various mines distributed in Korea were analyzed by chemical and ATR/FT-IR methods. The range of CaCO₃ concentrations of the tested samples were 86-97%. The standard error of prediction (SEP) was found to be 0.294 when the absorbance values at all of the three wavelengths were used, whereas the SEP values were 1.340, 1.072 and 0.961 for the wavenumbers of 711, 1406 and 875cm^-1, respectively. The results indicate that the ATRIFT-IR method can be applied to the routine determination of CaCO₃ in limestone by mid-infrared spectroscopy. The present method required virtually no pretreatment procedure and thus took less time comparing with the conventional wet chemical methods.

View full abstract

The present paper reviews the applications and recent developments of microwave digestion or extraction as a sample preparation technique. This technique has been applied successfully in both organic and inorganic determinations for various sample matrices. It offers the benefits of rapid sample preparation, ease of automation and reduction in background contamination. Good recoveries are generally obtained.

View full abstract

Highly selective ligands for group 13 metal ions (Al³⁺, Ga³⁺ and In³⁺) have been successfully designed taking into consideration the bite size (O-O distance in the chelate ring) and the interligand contact in the complex. The complexation of Al³⁺ was found to be under the effect of the interligand contact and that of In³⁺ the bite size. The appropriate substituents were introduced to ß-diketone type ligands to control the bite size and the volume of the ligand.

View full abstract

Both Sr²⁺ and Cs⁺ have been acknowledged as serious components of high level radioactive waste. The separation of Cs⁺ from solutions containing other alkali metal ions has already been accomplished by ion-exchange method using dihydrogen tetratitanate hydrate fibers. The separation of Sr²⁺ from other alkaline earth metal ions, however, is complicated because Sr²⁺ is in the middle of the selectivity series of any known separation method involving either solvent-extraction and ion-exchange methods. Separation of alkaline earth metal ions was studied by a triple-phase separation method which combined ion-exchange and solvent-extraction methods. In this study, the complete separation of individual alkaline earth metal ion has been sought for an aqueous solution containing Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺. The selectivity series of the ion-exchange system using dihydrogen tetratitanate hydrate fibers was Ba²⁺ _??_Sr²⁺>Ca²⁺_??_Mg²⁺. Ba²⁺ and Mg²⁺ can be separated from other alkaline earth metal ions because of the large separation factors to neighboring ions, but Sr²⁺ and Ca²⁺ cannot be separated each other in this manner. The extractability of alkaline earth metal ions with the solvent extraction system using thenoyltrifluoroacetylacetone (TTA, extractant) is Mg²⁺>Ca²⁺>Sr²⁺>Ba²⁺. Although the separation between Sr²⁺ and Ca²⁺ is better than that by the ion-exchange method, it is not sufficient for complete separation. To accomplish complete separation of Sr²⁺ and Ca²⁺, the organic phase containing TTA was added to the ion-exchange system. Because of their reverse relationship of the selectivity series, the smaller metal ions in an aqueous phase were extracted into the organic phase, while the larger metal ions were sorbed onto the ion exchanger. The separation factors of metal ions are much larger than those obtained by solvent extraction and ion exchange methods used separately.

View full abstract

A new aqueous two-phase system of cationic-anionic surfactant mixture (ATP-CAS) is proposed for the extractions of porphyrin compounds. ATP-CAS is formed when 0.05mol/l aqueous solutions of dodecyl triethylammonium bromide (C₁₂NE) and sodium dodecyl sulfate (SDS) are mixed with a molar ratio of 1.62:1. The two phases are of mixed surfactant solutions but the concentration in the upper phase is much higher than that of the lower phase. Effects of strong acid, base solutions on the two-phase system are investigated. The results show that negatively charged porphyrins such as meso-tetraphenyl porphine tetrasulfonic acid (TPPS₄) and protoporphyrin (proto) are extracted into the upper phase efficiently while other porphyrins like meso-tetraphenyl porphine (TPP) and tetrakis(4-trimethylammoniophenyl)porphine (T-4(TAP)P) and vitamin B₁₂ distributed in the two phases almost uniformly.

View full abstract

The completion of cobalt(II), nickel(II), copper(II), and zinc(II) with thiocyanate ions has been studied in micellar solutions of nonionic surfactant Triton X-100 by titration spectrophotometry and calorimetry. The complexation has been also studied by varying length of POE (polyoxyethylene) chain. With regard to Co(II), the [Co(NCS)₄]^2-, which hardy forms in aqueous phase, is extensively formed in micelles. With Zn(II), the [Zn(NCS)₃]^- and [Zn(NCS)₄]^2- are formed in micelles. With Ni(II), no completion occurs in micelles. In the case of Cu(II), the formation of [Cu(NCS)₂] is concluded in both micelles and aqueous phase. The complercation behavior of [Co(NCS)₄]^2- and [Cu(NCS)₂] depends significantly on the length of POE chain, suggesting that these complexes exist both in the relatively hydrophilic POE site and hydrophobic core site.

View full abstract

The equilibrium of ion-pair extraction of lithium porphyrin [octabromoporphyrin: 2, 3, 7, 8, 12, 13, 17, 18-octabromo-5, 10, 15, 20-tetrakis(4-sulfonatophenyl)porphyrin, Hobtpps^4-; HP^4-] with tetrabutylammonium ion (X) was studied at 25°C and I=0.1 (NaCl, NaOH). Extraction and dissociation constants of the ion-pair complexes of free base porphyrin, deprotonated porphyrin and lithium porphyrin, defined as K_ex(Hp)=[XHP]/[HP^4-][X], K′_ex(HP)=[XHP]/[HP⁵⁺][X], K"_ex(Lip)=[XLiP]/[LiP^5-][X], K_disl(HP)=[XHP][X][XHP] and K"_disl(Lip)=[XLiP][X]/[XLiP], were determined. These values were found to be K_ex(HP)=(9.5±1.5)×10¹³ (mol^-4dm¹²), K_disl(H2P)=(3.5± 0.7)×10^-7 (mol dm^-3), K′_ex(HP)=(4.7±0.4)×10¹⁶ (mol^-5dm¹⁵) and K"_ex(LiP)K"_disl(Lip)=(8.4±0.7)×10¹² (mol^-4dm¹²), respectively.

View full abstract

A new type of water-soluble sulfonated crown ether has been prepared and utilized as an ion size selective masking reagent with a view to establishing a highly selective extraction-separation system. In the synergistic extraction of alkaline earths with 4-benzoyl-3-methyl-1-phenyl-5-pyrazolone and trioctylphosphine oxide in cyclohexane, the extraction of these with larger ionic radii shifted to a higher pH region on adding the sulfonated crown ether to the aqueous phase, giving improved separations. A similar result was achieved in the extraction of lanthanides into cyclohexane with bis(2-ethylhexyl)phosphoric acid. The complex formation of alkaline earth and lanthanide ions with the sulfonated crown ethers in the aqueous solution were evaluated via the solvent extraction method.

View full abstract

Diazapolyoxabicyclic ligands (cryptands) have been applied as ion-size selective masking reagents with the aim of establishing a quantitative extraction-separation system among alkaline earths. Calcium can be quantitatively separated from strontium in the synergistic solvent extraction with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) and tri-n-octylphosphine oxide (TOPO), and with benzoyltrifluoroacetone (BFA) and tri-n-butylphosphate (TBP) into cyclohexane in the presence of cryptand[2.2.2] as a masking reagent. Magnesium can also be quantitatively separated from calcium in the synergistic extraction with BFA and TBP into cyclohexane in the presence of cryptand[2.2.1] as a masking reagent.

View full abstract

A sensitive and selective spectrophotometric determination of cobalt (II) using 2-(5-bromo-2-pyridylazo) -5-(N-propyl-N-sulfopropylamino)aniline (5-Br-PSAA) is described. 5-Br-PSAA reacts with cobalt to form red-violet and red colored complexes in various pH ranges and only cobalt(II) complexes, which are formed at pH 8, is concentrated on the membrane filter. After dissolving the analyte and filter in N, N-dimethylformamide(DMF), the absorbance of the DMF solution is measured at 550nm against the reagent blank as a reference. Cu(II), Fe(II) and Ni(II) give strong interference, but other metal ions do not interfere. The calibration curve shows a good proportionarity in the concentration range of 2 ppb to 50ppb cobalt(II).

View full abstract

Recovery of organophosphorus insecticides, quinalphos, chlorpyrifos and methidathion from soil were examined by extracting with carbon dioxide under supercritical state. Extraction conditions were designed at 100, 150, 200, 250 and 300 atm and under 40, 50 or 60°C. The better recovery was obtained by amending 2ml of methanol into soil sample before extraction. The best extraction condition was found to be at 300 atm and under 50°C, at 200 atm and under 60°C, and at 100 atm and under 60°C for quinalphos, chlorpyrifos and methidathion, respectively.

View full abstract

It was found that poly(N-isopropylacrylamide) could be used as a transferring medium to effect the concentration of tris(1, 10-phenanthroline)iron(II) in homogeneous aqueous solution without using organic solvents at all. The optimum conditions, such as pH, poly(N-isopropylacrylamide) concentration, kind and concentration of counter anion, and the time for centrifugal phase separation were examined.

View full abstract

The synergic extractions of rare earth metals (scandium, lanthanum and lutetium, M³⁺) with ortho- substituted 4-aroyl derivatives of 1-phenyl-3-methyl-5-pyrazolone (HA) and a neutral ligand, trioctylphosphine oxide (TOPO, L) in benzene were studied. Eight ortho-substituted 4-aroyl derivatives of pyrazolone have been prepared. Linear relationships between the extraction constants and the acid dissociation constants of aroylpyrazolones were obtained when TOPO was not added. The metal chelates of aroylpyrazolones react with TOPO to form MA₃L and MA₃L₂ types of adducts in the synergic extractions. Obvious steric hindrances of the terminal substituents at ortho- position of 4-aroyl group of the ligands on the adduct formation reaction were observed by the comparison of adduct formation constants.

View full abstract

The solvent extraction of molybdenum(VI) and uranium(VI) with α-hydroxy oxime, 5, 8- diethyl-7-hydroxydodecan-6-one oxime (LIX 63) and their stripping behavior have been investigated. A cationic species of Mo(VI) was preferentially extracted in an acidic region, and the extraction was greatly depressed above pH 4. Uranium(VI) species were extracted in a nearly neutral region and selectively stripped with a dilute acid. The transport of these metal complexes across a supported liquid membrane (SLM) has been investigated employing LIX 63 as a mobile carrier. Uranium(VI) was selectively transported on the product side, while Mo(VI) species was retained in the SLM in the low pH region and remained in the feed solution in the nearly neutral region. This improves their mutual separation, and only U(VI) was recovered in the product solution, depressing the transport of Mo(VI).

View full abstract

The extraction behavior of rare earth elements was systematically investigated by using bis(1, 1, 3, 3- tetramethylbutyl)phosphinic acid (HMBP) in HNO₃ medium. The extraction mechanism was evaluated through a log-log plot analysis, and the overall extraction equilibrium constant K was calculated for each rare earth element(III). The degree of mutual separation of adjacent pair of rare earth elements was discussed from the value of separation factor S.F. _z+I/z and explained by thermodynamic function- the relative free energy change of adjacent rare earth elements(III) Δ(ΔG°)_z+1/z. The separation of scandium from lanthanoids and yttrium was achieved by a single HMBP extraction and the mutual separation of lanthanum. cerium and praseodymium was achieved by HMBP-extraction chromatography.

View full abstract

A water-soluble octabromoporphyrin has been synthesized and developed for the determination of lithium ion in aqueous solution. The porphyrin reacts with lithium ion in alkaline solution to form the lithium complex along with a shift of absorption maximum to shorter wave length. But sodium and potassium ions do not react with the porphyrin. The equilibrium constant of the Li(I) porphyrin complex was determined and applied to the determination of lithium(I) in natural water. Interference of metal ions was removed by ligand buffer of Mg-EDTA complex.

View full abstract

Selective colorimetry of alkali metal ions in aqueous dioxane solution by calix[4]crown chromoionophore possessing three dimensionally designed ion recognition site has been examined. Based upon a tautomerism from phenylazophenol to quinone hydrazone structure by forming MHL complex, chromoionophore was found to show a selective color change for Na⁺ in acidic aqueous media. In the same condition, no response was observed for Li⁺, K⁺, and TMA⁺.

View full abstract

The effects of cyclodextrins (α-, β-, and γ-CDs) on the monomer-dimer equilibria of phenothiazine dyes (methylene blue (MB), thionine (TH), and 1, 9-dimethyl-methylene blue (DMMB)) have been studied using absorption spectroscopy. The positions of the monomer-dimer equilibria do not change by the presence of α-CD, while the addition of β-CD suppresses the dimerization. This is attributed to that the cavity of β-CD is large enough to stabilize dye monomers by the formation of inclusion complexes, while that of α-CD is too narrow to include the dye molecules. The apparent dimerization is enhanced upon addition of γ-CD for MB and TH due to inclusion complexation of the dimers of dyes with γ-CD. However, the suppression of the apparent dimerization by addition of γ-CD is observed for DMMB. It can be explained in terms of size-selective formation of inclusion complexes of phenothiazine dye monomers and dimers with γ-CD: the cavity size of γ-CD is not large enough to accommodate dimers of DMMB though it accommodate the dimers of MB or TH. The dimerization constants (K_D) were determined as 9.6x10³M^-1 for MB, 3.2x10³M^-1 for TH, 1.6x10⁵M^-1 for DMMB. The association constants of dye monomers (K_C1) and dimers (K_C2) with CDs are determined from the dependence of the apparent dimerization constants (K_D′) on concentrations of CDs. The K_C2 values obtained for MB and TH with γ-CD are larger than the corresponding K_C1 values by two orders of magnitude. An opposite trend is found for binding with β-CD.

View full abstract

Ion-transfer voltammetry of calcium antagonists, propranolol, and acetylcholine were carried out by current-scan polarography with an ascending water electrode. The pH effect of the aqueous phase on the half-wave potential of the ion-transfer voltammogram was examined for each drug. For nicardipine, bamidipme and benidipine, the half-wave potential became more positive by 0.059V per unit pH over the pH range (pH 4-8). For propranolol, the half-wave potential became more positive by 0.059V per unit pH at pH values above 6.8, whereas at pH values below 6.8, this potential remained constant. The half wave potential of acetylcholine was independent of pH at pH 5-8.5. These results could be explained by the E_1/2 equations of for ion transfer of drugs based on the ionization of drugs in the aqueous phase and distribution of neutral drugs between the nitrobenzene and aqueous phases.

View full abstract

Bis-intercalator 2 with two acridine moieties separated by a bis(hexamethylene)viologen linker was synthesized and its binding of calf thymus DNA was studied. Bis-intercalator 2 was designed to cover about a 24 Å stretch of double stranded DNA. The binding constant of bis-intercalator 2 for calf thymus DNA was 1.7x10⁵M^-1 in 10mM MES, 1mM EDTA and 0.1M NaCl (pH 6.25). The two acridine units of 2 stacked with each other in solution and upon its binding the structure of DNA was perturbed considerably. The binding affinities of the bis-intercalator for DNA duplex fragments of different length, d(AT)_n where n=3-8, were estimated by its effect on the DNA melting temperature. It was found that d(AT)₅ with a length of 34 Å was stabilized most by 2. By contrast, quinacrine 1 did not show any stabilizing effect on these DNAs. These results suggest that the bis-intercalator was capable of discriminating the length of double-stranded DNA fragments precisely. This ability of 2 may be applied for the precise separation of double-stranded DNA fragments according to their length.

View full abstract

Solvent properties of temperature-responsive polymer, poly(N-isopropylacrylamide) [PNIPAAm], in the aqueous solution was evaluated from the fluorescence spectra of probe molecules, 1-phenyl-N-naphthylamine and 8-anilinonaphthalene sulfonate, With increasing in the concentration of PNIPAAm, the fluorescence intensities of the probes increased and the wavelength for the maximum emission shift to be shorter. From the correlation between the fluorescence intensity and PNIPAAm concentration, the extent of the probe distributed into the polymer media and its fluorescence intensity were successfully determined. The results indicated that the hydrated PNIPAAm has solvent properties similar to alcoholic solvents such as 1-propanol.

View full abstract

Construction and preliminary characterization of open tubular capillary column ion chromatography is described. Increasing the column temperature resulted in a dramatic increase of the column efficiency. Two different kinds of columns were developed and investigated for capillary ion chromatography. One was a 50μm i.d. fused silica capillary tubing, and another was a 50μm i.d. silica capillary coated with Latex particles (diameter: about 360nm). Both columns showed good separations of inorganic anions, although the capillary coated with Latex particles showed much larger retention than a bare silica capillary.

View full abstract

Photoacoustic spectroscopy (PAS) was used to study the vertical concentration distribution of compounds on TLC plates. The results suggest that under the given experimental conditions compounds exhibit irregular concentration profiles in vertical direction and tend to concentrate in the uppermost 61μm thick layer. This irregularity was accounted for by photoacoustic probing of thicker sorbent layers what lead to an improved linearity of calibration curves compared to those obtained by reflectance densitometry.

View full abstract

A stationary phase was prepared by modification of octadecyl silanized silica gels (ODS) with phthalocyanine cobalt (III) for separation of anions. The elution sequence of anions on the column packed with the modified ODS is in the order of Cl^-<NO₃^- <ClO₄^-<I^-<SCN^-<NO₂^-, which was quite different from the elution sequence observed on a conventional anion exchange column. The strong retention of NO₂^- on the column was explained by a result of adsorption experiment of NO₂^- and NO₃^- on the modified ODS.

View full abstract

A refined cryogenic sampling method and a modification of a commercialized thermal desorber for automatic analysis of atmospheric sulfur compounds with a gas chromatography coupled to the sulfur chemiluminescence detector is reported. Twenty eight reduced sulfur compounds were analyzed on a 30mx0.32mm i.d., 4μm film thickness, Quadrex 007 series (dimethyl silicon phase) capillary column. The problems of retention time shift and peak splitting caused by the water were significantly improved by connecting a 70-cm deactivated column before the analytical column. For one-liter air sample with 80% relative humidity at 30°C, the retention time shift can be diminished to 1% for the compounds with boiling point higher than ethanethiol.

View full abstract

We developed a procedure that can effectively separate and determine precious metal ions, such as Ag(I) and Pd(II), in some samples with reverse phase ion-pair high performance liquid chromatography, employing indirect spectrophotometric detection method of their tetrathiacrown ether complexes. Eluting the solutions of the metal-thiacrown ether complexes with a MeCN-waterr mobile phase(pH 2.20 adjusted with CH₂ClCOOH buffer) containing 0.000-0.025M sodium dodecyl sulfate(SDS) and 1.0x10^-4M sodium 1-naphthalene sulfate(SNS) through μ-Bondapak CN column, the elution behaviors were elucidated as ion-pairing in case of [SDS]<0.010M and micelle forming in case of [SDS]>0.010M. As three applications, Ag(I) ion in black-white photographic fixing solution, Pd(II) ion in an artificial sea water and palladium metal in a catalyst for the clean up of car exhaust gases were analyzed in the optimum condition.

View full abstract

Oligonucleotides carrying a ferrocene moiety at their 5′-end were used as a primer of polymerase chain reaction (PCR) and part of the v-myc and muscular dystrophin genes were amplified with them. The PCR products thus obtained were rapidly separated and detected with high sensitivity at femtomole (fmol) level by the HPLC-ECD system. The ECD response for the PCR products was linear over a range of 1 to 1000fmol. We tried to quantitate the muscular dystrophin gene in a chromosomal sample prepared from leukocytes of healthy men and women, which is located in their X-chromosomes. The quantitative PCR procedure with a ferrocenyl primer gave a 1.4 to 2.0 ratio of the amount of the gene for men to women, which is in reasonable agreement with the expected ratio of 1.0 to 2.0. These results demonstrate that ferrocenyl oligonucleotides serve as a useful tool for DNA analysis.

View full abstract