A pyrolytic-graphite-coated (PGC) carbon tube atomizer was made by passing PR gas (90 % Ar +10 % CH₄) into a carbon tube (60 mm in length, 3.5 mm in inner diameter, and 6.45 mm in outer diameter) and heating the tube up to 1600°C (150 A) for 2 min. The PGC carbon tube was used for determination of traces of dysprosium by atomic absorption spectrometry. The useful lifetime of the carbon tube for dysprosium incresed about 3 fold by this coating (a pyrolytic graphite on the carbon tube), although the peak absorbance enhancement was not observed. Therefore, in the present study, PGC carbon tubes were used for the determination of dysprosium. The effect of matrices in the phospate minerals on the determination of dysprosium was examined by comparing dysprosium in a standard solution with that in a synthetic solution which had an approximate composition of xenotime or monazite. In the range of (25250) μg/ml of the synthetic solution, dysprosium (2 ppm) was scarcely interfered. Phosphate sample (250 mg) was dissolved by heating it with 25 ml of concentrated sulfuric acid for about 3 h. The sample was diluted to a suitable volume with water and unsoluble residue was filtered. Ten microliters of the filtrate was injected into the atomizer. Dysprosium contents in the phosphate minerals were measured by both the calibration curve and standard addition methods. By these experiments, (0.743.60) % of dysprosium was found in the phosphate minerals, and these values were in good agreement with those given by ICP-AES.

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A fluorometric method for the determination of polyamines (putrescine, cadaverine, spermidine, and spermine) using polyamide thin-layer is descsibed. Dansylated polyamines obtained after the reaction with dansyl-chloride at pH 9.5 at 40°C for 1 h were extracted into toluene. An aliquot of the extract was spotted on the polyamide thin-layer plate, and developed with a solvent system of water-formic acidtriethylamine (54 : 15 : 2). Spots were measured with a scanning fluorometer. The fluorescence intensity of dansylated polyamines was stable on the plate at least 24 h. The relative standard deviation of the fluorescence intensity obtained on the same thin-layer plate was (1.55.0) % at 200 pmol/spot, and the lowest limit of determination was 10 pmol/spot for bis-DNS-putrescine, bis-DNS-cadaverine, and tri-DNS-spermidine, and 5 pmole/spot for tetra-DNS-spermine. This method was successfully applied for the determination of polyamines in tissues of male rats and guinea pigs.

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In reaction gas chromatography, boric acid deposited on supports has been used as a reagent for selectively subtracting alcohols. However, this method had a demerit that the subtracted compounds eventually bled off as borate esters. In this paper, styrylboronic acid polymer beads (PSBA), which were derived from porous styrene-divinylbenzene copolymer (7.5 % cross linking), were employed as subtractor for alcohols. The column (1 m × 4 mm i. d., glass column) which composed of the subtractor precolumn (5 cm) and an analytical column (95 cm) was used. The percentage removal of compounds was determined by comparing their peak areas, both in the presence and absence of the precolumn. Alcohols except for tertiary alcohols were completely subtracted by this column without bleeding off the reaction products. Hydrocarbons, ethers, esters, ketones, alkyl halides, mercaptanes, epoxides, and alde-hydes except for d-citronellal were not subtracted. The retention time and peak shape of these compounds were not affected by inclusion of the precolumn. PSBA column showed a strong interaction, such as delay of the retention time, reducing of peak height, and peak broadening, for amines. The capacity of the subtractor column was determined by repeating injection of 0.1 μl of 1-propanol and it was found that the alcohol could be quantitatively subtracted until 20 injections. The subtractor deteriorated could also be regenerated by hydrolysis of the esters with hydrochloric acid.

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2, 2'-Dihydroxyazobenzene (DHAB) reacts with titanium (IV) to form water-insoluble chelate, and the reaction was catalytically promoted in the presence of acetic acid as a buffer solution. The Ti-chelate was quantitatively extracted into dichloroethane, chloroform, etc. at pH 2.73.5. The extractability of the chelate from 50 ml of an aqueous solution containing 2 % dioxane into 10 ml of dichloroethane was 99 %. The composition of the chelate was Ti : DHAB=1 : 2, and the stability constant (β₂) was log β₂= 41.6 (μ=0.1, 30°C). Beer's law was obeyed up to 60 μg of Ti(IV) in dichloroethane. The molar absorptivity was 8500 l mol^-1 cm^-1 (495 nm), 7700 l mol^-1 cm^-1 (550 nm). Although many elements interfere with the determination of Ti, the interfering ions were masked with thiogtycollic acid. The recommended procedure is as follows: Take (130) ml of a sample solution containing less than 60μg Ti. Add 4 ml of acetic acid (1+4), and dilute to about 50 ml with water. Adjust the pH to 3.0, add 1 ml of 0.1 % DHAB (dioxane solution), and then stand for 15 min. Extract the Ti-chelate with 10 ml of dichloroethane by shaking for 3 min. Measure the absorbance of the organic phase at 495 nm or at 550 nm. The method, by no use of the masking agents, has been applied to the determination of Ti in cements. Good agreement was observed between the results obtained by the present method and the conventional method.

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An atomic fluorescence photometer with nondispersive system which is capable of the determination of mercury at the pico grams level found in atmosphere or natural water has been designed. Mercury was released from solution by reduction-aeration method and collected on gold wire, forming an amalgam. When the system was completely replaced with argon, the gold absorber was heated to 700°C. The mercury liberated from gold was then transferred by the argon to the special designed flow type fluorescence cell, and atomic fluorescence intensity was detected with solar blind photomultiplier. The presence of quenching agent such as nitrogen reduced the resonance fluorescence intensity and the accuracy of its measurement. Therefore, the interference from this quenching necessitates the removal of nitrogen in the system before the gold absorber was heated. The detection limit was estimated to be 0.005 ng (S/N=2) and the coefficient of variation was found to be 3.0 % for 1 ng of mercury.

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A rapid and accurate analytical method of orthophosphate was establishid by flow injection analysis based on solvent extraction system as follows: Twenty μl of sample solution was injected to molybdenum reagent stream (1 % ammonium molybdate in 0.8 N HCl, 0.8 ml/min). The aqueous phase carrier stream containing a sample and isobutylacetate stream (an organic phase carrier, 1.0 ml/min) are mixed by the segmentor. Phosphomolybdic acid, H₃PO₄(MoO₃)₁₂, is formod and extracted away from other substances into organic segments in the extraction tube (0.5 mm i.d. × 2 m). The stream of alternative aqueous and organic phase segments entered to the membrane phase separator {L. Nord, B. Karlberg: Anal. Chim. Acta, 118, 285(1980)}. The organic phase was sucked through the membrane and the complex in the phase was measured at 310 nm. In this method, sampling rate was 80 samples/h and the detection limit was 0.01 ppm (200 pg as P). The relative standard deviations (RSD) were 2.1 % and 1.8 % for 1.0 ppm and 10 ppm phosphate, respectively. It was found that this method was effective in determining orthophosphate in human seminal plasma and urine without deproteinization.

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Formaldehyde and formic acid were simultaneously determined by isotachophoresis after derivatizing the former to hydroxymethane sulfonate with sodium hydrogen sulphite. The recommended procedure is as follows. The sample solution containing less than 30 mg of formaldehyde and 100 mg of formic acid was neutralized to pH 7 with dilute sulfuric acid. Sodium hydrogen sulphite was added in five-fold molar excess of formaldehyde, and the mixture was diluted to 100 ml with degassed water. The leading and terminating electrolyte solutions were {10^-2 M hydrogen chloride+ L-histidine} (pH 6.0) and 10^-2 M hexanoic acid (pH 3.4), respectively. The calibration curves were linear for 00.3 μg formaldehyde and for 01.0 μg formic acid. The detection limit was 0.05μg for formaldehyde and 0.1 μg for formic acid. The method was applied to the determination of formaldehyde and formic acid in non-electrolytic copper plating solutions. The results were in good agreement with those by spectrophotometric and ion chromatographic method.

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Preconcentration of divalent heavy metal ions, such as Cu, Co, Zn, Cd, Mn, and Ni, were investigated using a column of polystyrene gel beads impregnated with PAN (pyridylazonaphthol) or TAN (thiazolylazonaphthol) in chlorobenzene solution. Metal ions except Ni were trapped on the PAN or TAN gel column as their metal complexes when the metal ion solutions of suitable pH range were passed through the column. Cu and Zn were quantitatively recovered easily by eluting with 1 M hydrochloric acid. Cd and Mn were not recovered quantitatively under the same condition but recoved with 0.1 M aqueous EDTA (pH 8.6). While the recovery of Co from PAN gel column by eluting with 1 M hydrochloric acid was unsuccessful, the trapping and recovery of Co from TAN gel column were quantitative. Concentration factors of the metal ions except Ni, ranged from 12.5 to 17. The extraction rate of Ni onto these gel beads was so slow that the application of this method to Ni seemed to be of no practical value. By choosing the proper pH value (pH 2.44.5), the selective trapping of Cu was also possible in the presence of other divalent metal ions.

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Selective leaching experiments were carried out in order to study chemical forms of zinc, copper, and lead in estuarine sediments. Sulfides, oxides, and phosphates of these metals as well as copper hydroxide and lead carbonate were selected as model compounds. Five types of leaching solutions were used : type 1, 0.1 M acetate buffer with pH 5.0 for ion exchange leaching; type 2, 5 × 10^-2 M ethylenediaminetetraacetic acid for chelate formation; type 3, 2.5 % and 25 % acetic acid solutions for acid solubilization; type 4, 3 % hydrogen peroxide in 25 % acetic acid for oxidizing solubilization; type 5, 0.1 M L-ascorbic acid in 2.5 % acetic acid for reducing solubilization. The sulfides were leached by 3 % hydrogen peroxide in 25 % acetic acid. The oxides of zinc and lead were leached by 0.1 M L-ascorbic acid in 2.5 % acetic acid. Most of zinc was leached by 2.5 % acetic acid except for the sulfide. Leaching of copper was retarded by the reducing agent, but was in most cases enhanced by the oxidizing agent. Lead was leached both by the reducing agent and the oxidizing agent except for the phosphate. The use of 1 M hydroxylamine in 25 % acetic acid was unsuitable for the fractionation of the reducible metals. The 1 M hydroxylamine hydrochloride solution suppressed the leaching of lead due to the formation of lead chloride, and the low pH of the solution increased the leaching of zinc and copper. Estuarine sediments samples as well as manganese nodule samples were subjected to leaching, and the proposed leaching solutions were proved to be useful for the differenciation of the chemical forms of zinc, copper, and lead in the estuarine sediments.

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A derivative spectrofluorometry was studied for the determination of polynuclear aromatic hydrocarbons (PAH) in river sediment. The method includes a sample preparation, a ultra sonic extraction, a separation by a one-dimensional dual band thin-layer chromatography, and a measurement on a recording derivative spectrofluorometer. The existence of benzo (a) pyrene (BaP), chrysene (Chry), benzo (k) fluoranthene (BkF), benz (a) anthracene (BaA), perylene (Pery), pyrene (Py), and benzo(ghi)perylene (BghiP) were confirmed in river sediments. The following instrumental conditions were satisfactory for the determination: scanning speed, 60 nm/min; substance (order of derivative, n; increment in differentiation, Δλ); BaP (n = 4; Δλ=3 nm); Chry, BkF, Py, and BghiP(n=4; Δλ=2 nm); BaA(n=4; Δλ=4nm); Pery(n=2; Δλ=2nm). The detection limits were 0.04 ng/ml for BaP, 0.05 ng/ml for Chry, 0.07 ng/ml for BkF, 0.05 ng/ml for BaA, 0.04 ng/ml for Pery, 0.2 ng/ml for Py, and 0.04 ng/ml for BghiP. The derivative-spectrofluorometric method gave the analytical results which were in good agreement with the narrow base line method, and offered the following advantages over the latter method: 1) lower interference from the impurities, 2) at least twice as high detection sensitivity, 3) simplified data treatment. The proposed method is useful for the routine analysis of PAH in river sediments.

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A rapid method has been established for the potentiometric determination of N-acetyl-L-cysteine, glutathione, and D-penicillamine by argentimetric titration using an iodide-selective electrode. The reaction involved was (1), and the iodide ion produced by the reaction with iodine in methanol was determined.
R-SH+3I₂+ 3H₂O = R-SO₃H+6HI…(1)
In a typical example, a sample containing (0.0088.6) mg N-acetyl-L-cysteine or (0.01515) mg glutathione or (0.0086.2) mg D-penicillamine was taken into a 100 ml amber-glass titration cell, 8 ml of 5 M sulfuric acid (except D-penicillamine) was added and operated with excess of an 0.05 M iodine-methanol solution. After the solution was made up to 50 ml with redistilled water, it was then titrated potentiometrically with a (0.00010.1) M standard silver nitrate solution at room temperature. All operations of the titration procedure were performed at 10 min. N-Acetyl-L-cysteine {(0.088.6)mg}, glutathione {(0.615)mg}, and D-penicillamine {(0.36.2)mg} were determined with a relative error and relative standard deviation of less than 1 %. The best results with a relative error and relative standard deviation of less than 0.3 % were obtained using 8.6 mg of N-acetyl-L-cysteine, 15 mg of glutathione, and 6 mg of D-penicillamine. The commercial samples of N-acetyl-L-cysteine, glutathione, and D-penicillamine were determined by this method.

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To avoid the influence due to dissolved oxygen, tin (II) ion was treated with iodine-methanol and the iodide ion produced was titrated with potassium iodate. The 2.0 cm³ of tin (II) solution involved concentrated hydrochloric acid was cooled to ca. 10°C and then was added an excess of 10 % (w/v) iodine-methanol. The mixture was immediately diluted to ca. 50 cm³ with distilled water and then was titrated potentiometrically with 0.05 mol dm^-3 potassium iodate. Blank test was carried out similar fashion. All procedure were performed in air. Amounts of tin (II) { (50150) mg} was determined simply and the analytical results were in good agreement with those obtained by the iodometric method (oxygen-free).

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A rapid and simple method for determining nitrogen oxides (NO_x), sulfur oxides (SO_x), and hydrogen chloride (HCl) in exhaust gases has been investigated. A mixture of 5 ml of 0.5 N sodium hydroxide and 25 ml of 1.0 % hydrogen peroxide was placed in a 1l flask, and about 800 ml of sample gas and 200 ml of oxygen were introduced. The NO_x, SO_x, and HCl in the sample gas were absorbed in 5 min and converted to nitrate, sulfate, and chloride ions, respectively, which were then determined by ion chromatography. Only about 20 min were required for the determination. The analytical data of NO_x, SO_x, and HCl in municipal refuse incineration exhaust gases by the present method were in fair agreement with those obtained by Zn-reduction NEDA method, precipitation titration method, and Hg(SCN) method, respectively.

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Thermal lens spectrophotometry was examined using the CO₂ laser as an exciting source for trace analysis of benzene in air. Thermal lens signal was recorded by a digital lock-in amplifier system. The sample gas of benzene was generated continuously by the Permeater (Kitazawa, diffusion tube). The detection limit was 500 ppb for benzene with the 9.639 μm line of the CO₂ laser (output power : 20 W). This method is useful for the determination of the substances which have no absorption band at the visible region.

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Rapid determination of sulfite was carried out by flow injection method. A sulfite solution was mixed with both a phosphonate reagent solution and an acidic molybdenum (V) -molybdenum (VI) reagent solution. In a reaction coil (PTFE, 0.5 mm i. d. 10 m, heated at 140°C), phosphonate was oxidized with sulfite and the resultant orthophosphate allowed to react with the molybdenum reagent to produce a heteropoly blue complex. The absorbance of the heteropoly blue complex was monitored at 800 nm. The standard sample could be measured in a working range of 1 × 10^-4 to 1 × 10^-2 M (NaHSO₃) at a sampling rate of 60 samples h ^-1. Detection limit (S/N=2) was 2× 10^-5 M. The precision (RSD, ten times injection) was 2% for sulfite of 4 × 10^-3 M.

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A microcomputer-controlled electroanalytical system by using two microcomputers (MEK DII, Motorola and H68/TR, Hitachi), potentiostat and current measuring circuit was constructed and programs of the system control and the data processing for differential pulse polarography have been developed. The system control program coded by machine language of MEK DII was almost the same as that of sigmoidal polarography, except for addition of data-averaging and noise-eliminating sub-programs. The outline of the data-processing program coded by BASIC language of H68/TR is as follows: after smoothing of the data transferred from MEK DII, peak potential(E_p), halfpeak width (W_p), and regions of peak and background were determined by comparing currents and the slopes of the i-E curve. Peak current (I_p) was then estimated by the correction of background current, obtained by using the least-squares fitting with the quadratic polynominal for the background regions. Finally, approximate values were utilized for the rigorous calculation of I_p, E_p, and W_p by means of least-squares fitting with Gaussian equation. The results of dataprocessing by computer were in good agreement with those obtained by manual treatment. The overall precision of the system for the determination of 10μM-level depolarizers (pyrazine, Pb²⁺, Cd²⁺, Zn²⁺ etc.) was within ±2 % for I_p, ±1 % for E_p, and ±5 % for W_p and the execution time was about 1 min/peak. Applicability of the fitting functions such as theoretical, Gaussian, and Lorentzian equations was briefly examined.

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Highly sensitive analytical methods of various biological substances developed in the author's laboratory are reviewed. Amino sugarsand amino acids are determined by a fluorophotometric method using pyridoxal-Zn(II) ion. α-Oxo acids are also assayed fluorophotometrically with pyridoxamine-Zn(II) ion. Various oxosteroids are assayed by fluorescence high-performance liquid chromatography using dansyl hydrazine as a pre-labeling reagent. Bile acids are also determined fluorophotometrically with highperformance liquid chromatography after labeling with 1-bromoacetylpyrene. Fluorescence and chemiluminescence reactions are applied to enzyme immunoassays of various hormones and drugs.

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The fundamentals and the present status of titrimetric analysis are briefly discussed. The drying conditions for primary standard reagents recommended previously and some recent works are reviewed. The most advisable conditions and procedures for handling are given.

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The adsorption behavior of chromium(III, VI) onto activated carbon (AC, Merck Co. Ltd.) and oxine-impregnated activated carbon (AC(HOx)) was investigated by use of a column method. The adsorption of chromium(III, VI) onto activated carbon, and of chromium(VI) onto AC(HOx) showed remarkable pH-dependency. The optimum pH for the adsorption of chromium(VI) from 1.00 × 10^-3 mol dm^-3 chromium(VI) solution were about 2.5 for activated carbon and about 3.0 for AC(HOx). The amount of chromium(VI) adsorbed onto adsorbents at the optimum pH was 13.5 mg for 5.0 g of activated carbon and 22.0 mg for 5.0 g of activated carbon impregnated with 0.5 g of oxine. Chromium (VI) adsorbed onto activated carbon at pH 4.9 was completely desorbed with 0.10 mol dm^-3 NaOH solution in the form of chromium(III) (33%) and chromium(VI) (67%). While less than 6% of the total chromium(VI) adsorbed onto AC(HOx) at pH 4.9 was desorbed with 0.10 mol dm^-3 NaOH solution. It seems probable that the chromium(VI) which was adsorbed onto activated carbon in the forms of Cr(OH)(H₂O)₅²⁺ appeared from the reduction of some portion of chromium(VI) with activated carbon, HCrO₄^- and Cr₂O₇^-2. On the other hand, chromium(VI) may be adsorbed onto AC(HOx) mainly in the form of Cr(III)-oxine complex.

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The study on the adsorption behavior of orthophosphate onto activated carbon loaded with molybdenum(VI) (Mo(VI)-AC) or iron(III) (Fe(III)-AC) was carried out by a column method. Orthophosphate adsorbed increases with increasing the amount of molybdenum(VI) loaded onto activated carbon. The optimum pH for the adsorption of orthophosphate onto Mo(VI)-AC was 2.0. As much as 7.7 × 10^-4 mol of orthophosphate was adsorbed onto 5.0 g of activated carbon loaded with 1.1 g of molybdenum(VI) at pH 2.0. The molar ratio of orthophosphate adsorbed onto Mo(VI)-AC to molybdenum(VI) adsorbed onto activated carbon was found to be 1 : 12. Orthophosphate may be adsorbed in the form of phosphomolybdenic acid (H_3-nPO₄Mo₁₂O₃₆^n-) onto Mo(VI)-AC. Orthophosphate adsorbed onto Fe(III)-AC decreases on both sides of the optimum pH 6.0. As much as 3.0 × 10^-4 mol orthophosphate was adsorbed onto 5.0 g of activated carbon with 23.5 mg of Fe(III). The amount of orthophosphate adsorbed increases with increasing Fe(III) loaded onto activated carbon; the molar ratio of orthophosphate adsorbed to Fe(III) adsorbed was less than unity in the pH range over 2.5 to 10.4. Orthophosphate may be adsorbed onto Fe(III)-AC by the coordination of orthophosphate to Fe(III).

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Sulfur in fuels and chlorine, bromine and sulfur in biological samples were quickly determined with a satisfactory accuracy without complicated pretreatments by the combustion flask method coupled with ion chromatography.

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Graphite furnace atomic absorption spectrophotometry(GFAAS) of platinum in urban air and automobile exhaust gas, as well as in biological samples has been studied. Pollution samples collected through a glass fiber filter were treated with aqua regia and the solution was then evaporated to dryness. The residue was dissolved in 3M hydrochloric acid and tin(II) chloride solution was added. The platinum-tin complex formed was extracted with isoamyl acetate(IA) and the extract was centrifuged. Platinum in the IA extract was measured by means of GFAAS. The present method is reproducible and any disturbance has not been observed. The calibration curve was linear in the range of 0.02-0.2 ppm platinum in the solution and the limit of identification was 0.01 ppm platinum.

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The copper(11)-α, β, γ, δ-tetrakis(1-methylpyridinium-3-yl)porphine [T(3-MPy)P or H₂L⁴⁺] complex, a tetra-positive macro-molecule, was extracted quantitatively and selectively into 2-nitropropane from the acidic solution containing a large amount of perchlorate ion in the form of the ion-association complex, CuL(ClO₄)₄, with keeping the excess of T(3-MPy)P in the aqueous phase. On this basis, a highly sensitive and selective method for the determination of copper at ppb levels has been developed. The apparent molar absorption coefficient and the sensitivity for 0.001 absorbance were 4.0 × 10⁵ M^-1·cm^-1 and 0.16 ng·cm^-2, respectively. The interference of 17 cations and 4 anions usually encountered were examined, and found to be minimal. The method developed could be applied successfully to the determination of copper in real samples.

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A rapid preconcentration method for uranium(VI) in seawater based on the extraction-back extraction with capriquat (trioctylmethylammonium chloride) system is described. Uranium(VI) is extracted as the thiocyanate from 400 cm³ of a seawater sample into 30 cm³ of 2 × 10^-2 mol dm^-3 capriquat in benzene and back-extracted into 3 cm³ of 5.5 mol dm^-3 perchloric acid containing Arsenazo III. By using this method, uranium(VI) in seawater with levels below ppb range could be determined by spectrophotometry. Other cations in seawater are found not to cause interferences. A relative standard deviation of 2.4% can be achieved.

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A new spectrphotometric determination of phosphorus is proposed. The method is based on the measurement of color intensity of membrane filters which are colored by the filtration of dilute molybdenum blue solutions. The proposed method is very sensitive as it can determine as low as 0.001 ppm of phosphorus. Coefficient of variation for 8 measurements of 0.1 ppm of phosphorus in 500 ml was 2.46 %. Effects of various analytical conditions were examined. The method was applied to the determination of phosphorus in the sea water samples.

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A leaching technique utilizing ultrasonic waves was applied to leach cations with dilute nitric acid solutions from soils. Resulting from the detailed investigations of the effects of the reaction temperature, the irradiation time and intensity of ultrasonic waves, it was found that the developed leaching method was reproducible, rapid, and easy to control the reaction temperature, compared with the usual leaching by a shaker.

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