Interfering and enhancing effects of various acids and metal salts matrices were studied for the flameless atomic absorption determination of total arsenic [As (III), As (V) and dimethyl arsinic acid (DMAA) ] in water samples. The limit of the ashing temperature for arsenicals was dependent on the nature of anions in the matrix. With changing anions, the limit temperature increased in the following order : chloride<nitrate<sulfate. Phosphate in the matrix seemed possible to form an easily atomizable compound with arsenic at nearly 1150°C, although serious interference was observed less than 1000°C as reported by the others. All arsenicals were vaporized together with alkali halides at high ashing temperature. The sensitivities for the determinations of arsenicals were almost same in the presence of the same cation. High sensitivities were observed in the presence of calcium, magnesium or nickel salts matrices and the sensitivity of DMAA was greatly improved. The presence of nitric acid (0.1 N) and calcium sulfate is recommended for the determination of total arsenic in water samples to obtain the same sensitivity.

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In recent years, several investigators have reported the feasibility of using a silicon photodiode array as a multi-wavelength detector for liquid chromatography. Although these reports indicate that the ability of recording complete UV spectra of each component in LC effluent can greatly facilitate identification of the components, the problem of data processing represents a major obstacle to acceptance of this detection system. In principle, all absorption data during an LC run are once stored in the computer memory. Then, at the completion of the LC run, UV spectra of components are traced. Such post-run data processing is too time consuming and require a large volume of computer memory. In our study, a novel technique that permits the continuous recording of three dimensional chromatogram (absorbance, wavelength and time) in real time was developed. All absorption data obtained from each pixcel of the silicon photodiode array with a sampling rate of 5.8 nm/ms were processed by a microcomputer and complete UV spectra in the (210430) nm wavelength range were displayed instantaneously with a repetition rate of one spectrum/6 s during the chromatographic experiment. The system has the advantage of continuous use without requiring a large volume of computer memory. The capability of the detection system has been demonstrated with an experiment on the gel chromatography of an effluent from a sewage treatment plant.

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A continuous foam separation-extraction-spectro-photometric measurement system has been constructed and evaluated through applying it to the measure-ment of ppb level of Cu (II) ions in water. The flotation conditions were chosen as follows : 0.5 % potassium butylxanthate solution supply rate, 67 ml h^-1; 0.075% cetyltrimethylammonium bromide solution supply rate, 114 ml h^-1; sample solution supply rate, 1100 ml h^-1; pH 9.0; nitrogen gas flow rate, 1000 ml min^-1. The foam comming out of the separator is pricked and subsided by the vapor of 1- butanol which was fed continuously through the lower end of the extractor at the flow rate of 19.1 mlh^-1.The 1-butanol layer is carried to the flow cell of a spectrophotometer through a Teflon tube at the flow rate of 19.9 ml h^-1, which is effected by a peristaltic pump linked behind the flow cell. The extractant which is supposed to be a ternary complex has a characteristic absorbance at 360 nm. Experiments, in which the concentration of Cu (II) in the sample was changed stepwise, showed that it took (3040) min to get a constant absorbance level, that a linear relationship existed between the absorbance and the concentration, and further that minimum concentration to be determined was 3.8 ppb (at S/N=2). Further, experiments where Cu (II) ions were introduced intermittently into the separator showed the constant extraction efficiency. Though it has many points to be improved, it is concluded that the applicability of the proposed system to the determination of low ppb level of Cu (II) ions in water has been confirmed.

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Determination of trimethylselenonium ion (TMSe⁺) and total selenium in human urine by graphite furnace atomic absorption spectrometry (GFAA) was studied. It is necessary to separate TMSe⁺ from other selenium compounds in urine and to digest TMSe⁺ to inorganic selenium completely without any loss of selenium, so that ion exchange column chromatograph and pressure decomposition technique were applied prior to the analysis by GFAA. Method: (1) Separation of TMSe⁺; ml of urine was placed on an ion exchange column (1×20 cm) containing Dowex 50 W-X8(H⁺) resin suspended in 1 N NH₄OH. The column was washed with 50 ml of 1 N NH₄OH, distiled water, and HC1(0.05 N, 0.1 N, 0.5 N, 1.0 N and 4.0 N). TMSe⁺ was eluted with 4.0 N HCL and the first 5 ml of the eluent was discarded and then 40 ml was collected as TMSe⁺ fraction. A 10 ml aliquot of the TMSe⁺ fraction was transferred into the pressure decomposition vessel and heated for 80 min at 200 °C. After cooling the vessel in water, 2 ml of 20 % hydroxylamine hydrochloride was added to the digested solution and the whole was boiled for 10 min. The selenium in the solution wan extracted with 1 ml of 0.02 % dithizone in carbon tetrachloride.(2) Ashing for the determination of total selenium; 1 ml of urine was taken into a pressure decomposition vessel containing 5 ml of 5 N HNO₃ and heated for 80 min at 200 °C. Hydrochloric acid was added to the digested solution to be adjusted with ca. 4 N of HC1 concentration and the selenium was extracted with dithizone in carbon tetrachloride. (3) Analysis; A 20μl aliquot of the extract was injected into the carbon tube with a microsyringe. The carbon tetrachloride was evaporated by heating for 20 s at 100 °C.Then 50 μl of 0.1% nickel solution to the residue and the selenium was determined according to the operating conditions in Table 1. The proposed method could determine TMSe⁺ in human urine with a recovery of (82102) %, and with a variation coefficient of (3.76.2) %, and total selenium in urine a recovery of (94101)0/0. Detection limits of TMSe⁺ in urine was 1.0 ng/ml and total selenium was 0.5 ng/ml.

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An atmospheric pressure ionization mass spectrometric (API-MS) method was studied for the determination of residual NO in high purity N₂ gas. The API-MS is very sensitive to NO, but the presence of O₂ interferes with the NO measurement. Nitrogen gas in cylinders as sample gas was mixed with NO standard gas (971 ppm) and/or O₂ standard gas (1050 ppm) by a standard gas diluter and the gas was introduced into API-MS. The calibration curves of NO and O₂ had linearity in the region of 02 ppm but the slopes changed at every cylinder. Effect of O₂ on NO⁺ peak was additive and proportional to O₂ concentration in the range of 00.5 ppm (O₂).The increase in NO⁺ intensity due to O₂ was (0.070.13) %/O₂, 1 ppm. Determination of NO and O₂ was carried out by standard addition method to eliminate the influences of variation of slopes. The interference due to O₂ was estimated from the product of the O₂ conentration and the ratio of slope "A" to slope "B". The slope "A" is the change in the NO⁺intensity with O₂ concentration. The slope "B" is the change in the NO⁺ intensity with NO concentration. The analytical values obtained were about 50 ppb for O₂, (0.61.3) ppb for interference of O₂, and (913) ppb for NO (error due to interference of O₂ was subtracted). The analytical value for O₂ is considered to be adequate to estimate the interference of O₂, still it requires further examination.

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The interference of chloride with the determination of lead by flameless atomic absorption spectrometry was studied when the tube was made by graphite, molybdenum and tantalum. The tubes used were as follows. Graphite tube : diameter 8.0 mm, inside diameter 6.0 mm, and length 32 mm, supplied by Nippon Carbon Corp. (type EG-36 H). Molybdenum tube: purity 99.99 %, diameter 6.8 mm, inside diameter 6.0 mm, and length 32 mm. Tantalum tube : purity 99.99 %, diameter 7.0 mm, inside diameter 6.0 mm, and length 32 mm. The interference was smaller when tantalum tube was used than when graphite tube was used. In order to study the reason for this interference, the liberated gas from the heated tube was analysed by mass spectrometry as follows. Argon gas was supplied at a flow rate of 1.2 1/min, a 10 μl portion of a lead solution was injected into the atomizer and then the tube was heated (the temperature range of 5002400°C). The exhausting gas was collected in a cell and supplied to the mass spectrometer. It was found from the analysis that hydrogen was detected prominently when the tantalum tube was heated above 550°C and when the graphite tube above 1000°C. The atomization of lead was carried out at 2000°C and at this temperature, the amount of hydrogen from the former tube is fifteen times as much as that from the latter. This effect of hydrogen was further studied by supplying argon containing 10 % of hydrogen and a decrease of the interference by chloride was always found with the graphite, molybdenum and tantalum tubes. From these results, the smaller interference by the chloride in the tantalum tube than in the graphite tube was estimated to be due to the reducing action of the hydrogen in the atmosphere.

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C₁₈-Bonded glass beads are applied to the preconcentration and spectrophotometric determination of traces of iron as the bathophenanthroline complex. Iron (II) is treated with bathophenanthroline at pH 3.0 and the solution is passed through the column packed with the glass beads. Next, a mixture of ethanol and dimethylsulfoxide is passed through the column to elute the adsorbed complex. 1.5 ml of the colored fraction in the eluate is collected and is made up to 2 ml with ethanol. And the absorbance is measured at 534 nm. Iron involved from 0.6 to 5μg in 150 ml of sample solutions is determined with satisfactory precision. Large amounts of Zn(II), Cr(III), Mg(II), Ca(II), Pb(II) and Mn(II) do not interfere with the determination. More than ten-fold of Cd(II), Ni(II), Co(II) and Cu(II) somewhat interfere for determining 3 μg of iron. Addition of thiourea is effective to eliminate the interference from large amounts of copper. Other popular adsorbents such as Amberlite XAD-2 and XAD-7 are tested for the same purpose. In the case of XAD-7, the adsorbed complex is not eluted at all. When XAD-2 is used, more than 2 ml of the eluent is needed for complete elution of the complex.

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A rapid and precise method for the determination of _L-cysteine in the presence of L-cystine was developed by amperometric titration using a rotating (2000 rpm) platinum indicator electrode at the potential of + 0.6 V vs. SCE._L-Cysteine could be titrated at ca. 45°C by adding 0.025 ml portions of potassium iodate solution at intervals of (25) s in the presence of 0.4 M potassium bromide and 0.5 M sulfuric acid. _L-cysteine {(0.21) mg} was determined with a relative error and a coefficient of variation of less than 0.2 %._L-Cysteine in ten-times excess amounts of L-cystine could be determined with a relative error of less than 1 %. The titration required only 3 min. The recommended procedure is as follows. Place 5 ml of sample solution containing (0.21) mg of L-cysteine into the titration cell. Add 5 ml of 5 M sulfuric acid, 5 ml of 4 M potassium bromide and 35 ml of water. Titrate the resultant solution with (10^-35 × 10^-3) M potassium iodate standard solution amperometrically.

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In general, injection of an overloaded amount of a sample into a separatory column gives rise to a tailing peak for an eluted component of short retention time, whereas a leading asymmetric peak for the one of long retention time. Induction of tailing peak has been explained to be due to the increase in the flow velocity of carrier gas at high concentration zone of the component. In the present study, it is assumed for the leading peak that leading is caused by that increased part of liquid phase by absorbing the sample vapour also acts as liquid phase : if these increased parts of liquid mixture were eliminated, the distribution ratio of the sample over two phases would be almost independent of the sample concentration. Under these conditions, higher concentration zone will move more slowly than low concentration zone. The validity of the assumption is experimentally verified, using decane-squalane system, by comparing experimental elution curves with calculated ones using plate model, assuming the sample concentration in the gas phase is proportional to the molar fraction of sample in the liquid phase. For tailing peaks, using hexane-squalane system, it is shown that both an increase in flow velocity of carrier gas and an increase in the amount of liquid phase caused by introduction of a sample must be taken into account to explain asymmetry of chromatographic peaks.

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Iodide ion in acidic solution reacted with the copper electrode of a piezoelectric quartz crystal to form copper (I) iodide. As the frequency of the crystal decreased with increasing the weight of the electrode adsorbed the copper (I) iodide, iodide ion could be determined using the piezoelectric quartz crystal. Copper (I) iodide on the electrode could be washed out with ammonium hydroxide solution for the successive experiments. All solutions were placed in a thermostat (25°C) and flowed on the electrode at the rate of 2.2 ml/min. The iodide sample solution was flowed in the cell after the shift in the frequency of the crystal attained a constant rate in the flow of blank solution. The frequency change resulted from the iodide was obtained from the difference between the maximum and minimum frequency obtained before and after the flow of the sample solution. Iodide of (15) × 10^-5 M could be determined by the calibration curve prepared by the same method.

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The sensitizing effect of DTMAB (dodecyltrimethylammonium bromide) on the spectrophotometric determination of germanium(IV) with phenylfluorone was studied. Under the optimum conditions the sensitivity was about twice as high as that in the absence of this salt, the molar extinction coefficient of the complex formed being 1.72×10⁵ dm³ mol^-1 cm^-1 at 503 nm. The calibration curve was linear up to 0.40 ppm of germanium(IV). PVA (polyvinylalcohol) was not necessary, which has been commonly used as a stabilizer. Metal ions such as As³⁺, AS⁵⁺, Pb²⁺, Hg²⁺, Cu²⁺, Al³⁺, Cd²⁺, and Zn³⁺ did not interfere with the determination, while Sb³⁺, Sn²⁺, Sn⁴⁺, and Mo⁶⁺ gave positive errors.

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A simple and rapid method for measuring tar inriver sediment has been developed. Two grams of a dried sample passed through a screen of 28 mesh was extracted with a mixed solution of ethanol and benzene (1 : 4, v/v) for 10 min by using a ultrasonic apparatus. After centrifugation, a known volume of the extract was transferred into a short-neck kjeldahl flask, and the extract was evaporated to less than one ml under a reduced pressure. The concentrate was transferred to a test tube of a known weight, evaporated near dryness under a reduced pressure, and dried up by standing it in room temperature. After standing the test tube in a desiccator for 24 hrs, the residue was weighed on a balance. Tar contents of 25 river sediments obtained by this method were in good agreement with those by a soxhlet extraction method. Coefficient of variation of tar contents in this method was from 1.3 % to 4.7 %. This method shows the following advantages over a soxhlet extraction method : extraction time is short; tar is extracted with a small volume of solvent; and many samples can be treated simultaneously.

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A method is described for the mutual determination of orthophosphate and arsenate by the use of a dual-wavelength spectrophotometer. It is based on the difference in the optical absorption between heteropoly blue formed from orthophosphate and that from arsenate. The difference in absorbances at 825.0 nm and 855.2 nm is proportional to the concentration of orthophosphate in the range from 1.00 × 10^-6 M (1 M = 1 mol dm^-3) to 9.00 × 10^-6M in the presence of 2.00 × 10^-5 M arsenate with less than 6% relative error. Arsenate in the presence of 2.00 × 10^-5 M orthophosphate can also be determined over the range from 1.00 × 10^-6 M to 9.00 × 10^-6 M with less than 5% relative error. The effect of various ions on the determinations of orthophosphate and arsenate was examined.

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A review has been made on the interlaboratory comparison study on the reliability of environmental analyses conducted by the Environment Agency through 1978-80 FY. Data on Cd, Zn, Pb, Cu, As, total-N and -P in soil and sediment obtained by ca. 200 laboratories including prefectural, municipal and commercial ones were analyzed statistically. Evaluation of data was made in terms of the coefficient of variation (CV) after the rejection of outlying results. The rejection was made according to the combination of Dixon's and Grubbs' methods. Zn, Pb and Cu present in soil in an order of 100 ppm can easily be determined by direct atomic absorption, while Cd in an order of 1 ppm requires solvent extraction. In all of these cases CV was around 10 %. The CV for As was larger than for heavy metals by a factor of about two. Distribution of data showed negative skewness that indicates lower values being liable to be obtained, suggesting the complete decomposition and extraction are a key point for obtaining good results. This is valid also in the determination of total-Cr.

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Programmed temperature operation using a constant-frequency electron capture detector (ECD) has been investigated. There are two causes of the base line drift with the elevation of column temperature. One is the bleed of volatile matter from an injection septum made of silicone polymer, and the other from a packed column. The former was removed by using the septum treated as follows : soaked in toluene, cleaned with ultrasonic wave, and dried at 250°C under reduced pressure of 1 mm Hg. The latter decreased by repeating temperature programing operation. After repeating 20 times of the programing operation, the temperature of a column {1.5 % Silicone OV-17 on Chromosorb W (AW-DMCS), (6080) mesh, 1 m × 3 mm I. D., aged at 300 °C for 20 h} could be raised up to 300 °C without any significant base line drift under the pulse period (t_P) below 200 μs. The peak heights of samples and the degree of the base line drift increased with increasing t_P. It was thus important for programmed temperature operation using a constant-frequency ECD to select t_P appropriately, depending on the temperature range programmed and the sensitivity required.

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Ion flotation followed by a spectrophotometric determination of sulfide ion in water is reported. It is based on the formation of methylene blue from sulfide ion through the reaction with N, N-dimethyl-p-phenylenediamine in the presence of ferric ion, and on the flotation of methylene blue by using an anionic surfactant, sodium lauryl sulfate. Influences of various experimental parameters on the formation and the flotation of methylene blue were examined. Under the optimum conditions established, down to 2 μg of sulfide ion in 1000 ml of sample could be determined. Calibration curve obtained was linear in the range of 2-40 μg 1^-1.

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The losses of elements in marine biological samples during dry ashing were evaluated on 34 elements by neutron activation analysis. Following biological samples were employed : Eisenia bicyclis (phaeophyceae), Sargassum tortile (phaeophyceae), Zostera marina (phanerogamae), small dried sardines (marine fish), and leaves of Crinum asiaticum (angiospermae). Before ashing, samples were freeze-crushed with liquid nitrogen, These samples were ashed at 100 °C in low temperature plasma ashing and at 500 °C in high temperature ashing. Both the dried and the ashed samples were irradiated simultaniously by thermal neutrons of a KUR reactor for activation analysis. Radioactivity measurements were carried out with a 63 cm₃ well type Ge (Li) detector and a Canberra-2048 channel pulse-height analyser over one year after the irradiation. Chlorine, arsenic, selenium, bromine, iodine, gold, and mercury were obviously lost during high temperature ashing. Low temperature plasma ashing was effective for reducing the losses of arsenic and selenium. Depending on the kind of biological samples, there were remarkable differences in losses of halouen elements.

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A simple and rapid method for determination of atmospheric ammonia has been investigated. The method is based on preconcentration with alkalized Porasil A and on analysis with a chemiluminescent nitrogen detector-gas chromatography(CLD-GC). Collection on and thermal release from the adsorbent are almost quantitative. From temperature dependence of retention volumes, it is possible to make a sampling of 5 liters at 20 °C, which allows to determine 10 ppb of ammonia in air. Results with the present method are in good agreement with those by the acid collection and the Indophenol method.

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2, 2'-Dipyridyl-2-quinolylhydrazone(DPQH) is used for the spectrophotometric determination of traces of cadmium after the extraction as the iodide complex. Cadmium is extracted as the coordinationally solvated iodide complex with tributyl phosphate (TBP) in benzene from an aqueous buffered solution containing iodide and tartrate ions. The cadmium is converted to a strongly colored complex by the subsequent treatment of the extract with a DPQH solution in benzene in the presence of an ammonia-sodium hydroxide solution. The analytical species of interest has an absorption maximum at 510 nm and obeys Beer's law over the range 5 ×10^-7-9 ×10^-6 M cadmium in the organic phase. The effective molar absorptivity is 8.94×10⁴ 1 mole^-1 cm^-1 at 510 nm. The interfering metal ions can be effectively masked by thiosulfate, ascorbate, oxalate, thiourea, or cyanide.

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A computer search system has been proposed whose characteristic consists in the high efficiency of search due to the use of peak intensity data in the matching process and in the reduction of search time due to the use of a subfile system. A test search using 100 measured spectra as a sample proved the excellent performance of the present search system.

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A thiocyanate-selective electrode prepared from a new matrix, Urushi, and tri-n-octylmethylammonium thiocyanate ion exchanger is described. The electrode shows linear potential-activity curve within the range 1.0×10^-5-0.56×10⁰mol dm^-3 ammonium thiocyanate and the slope is about 59mV per decade change in thiocyanate activity. The electrode has a fast response. Conditions for the preparation of the electrode such as ratio of the liquid ion exchanger and Urushi, amount of water in the Urushi and temperature for hardening the membrane are studied. The electrode characteristics of pH dependence and selectivity coefficient are also examined. The Urushi matrix membrane is hard, lustrous and smooth.

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The separation of mutagen, ethyl N-ethyl-N-nitrosocarbamate (EENC), from an acidic mixture (pH 1.2) of urethane and sodium nitrite is described, which employs micro high-performance liquid chromatography on a reversed-phase column (LiChrosorb RP-18). Ethyl N-nitrosocarbamate was characterized as an intermediate to EENC.

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Chlorophyll c adsorbed on filter paper emits strong thermally activated delayed fluorescence (τ=37±1 msec at 31°C). This emission was utilized for the determination of chlorophyll c of phytoplankton in matural waters.

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The dissociation and homoconjugation constants of 2, 5-dichlobenzenesulfonic, p-toluenesulfonic, methanesulfonic and picric acids have been determined at 25°C in acetylacetone by conductometry and potentiometry, and compared with those in other solvents. The autoprotolysis constant (K_s) of acetylacetone was estimated potentiometrically with a glass electrode (pK_s = 19.3).

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