The properties of RTP (room temperature phosphorescence) on pharmaceutical compounds, salicylic acid, acetyl salicylate, and phenyl salicylate, have been studied from the analytical viewpoint. These salicylic acid derivatives adsorbed on filter paper show two bands of long-lived emission at room temperature, which bands can be attributed, respectively, to tripletsinglet radiative transition (RTP) and to delayed fluorescence arising from triplet-upper singlet thermal activation (TADF). A dominant characteristic emission is RTP (salicylic acid : Ex. 300 nm/Em. 475 nm, τ_RTP =31.6 ms; phenyl salicylate : 350 nm/495 nm, τ_RTP =84.5 ms; acetyl salicylate : 300 nm/475 nm, τ_RTP =31.9ms), which is enhanced with sodium hydroxide and heavy-atom solvent such as sodium iodide. Especially, in the case of phenyl salicylate, no RTP signal was observed in the absence of sodium hydroxide. The use of sodium iodide as a heavy-atom perturber was found to be very effective in enhancing RTP emission intensity of these salicylates going up over 1.7 times that of free from external heavy-atom ion. The procedure for the determination of these compounds was established as follows : 1.0μl of 1 mol dm^-3-NaOH aqueous solution and -NaI aqeous solution, respectively, was spotted on the filter paper (TOYO, No. 51) with a microliter syringe. Then, a (13)μl portion of the alcoholic sample solution was spotted on the spot. Care was taken to mauntain the spot size (5 mm diameter) as constant as possible. The filter paper was dried for ca. 30 min at 50°C with an infrared lamp. The sample was then directly mounted on a sample holder, and the holder was fit into the phosphoroscope accessory instead of the normal cap and cylinder used for the dewar flask assembly. The RTP intensity of the spot was measured at 30°C. The sensitivity of the phosphorometer was regulated by setting up the emission of a YVO₄/Eu phosphor plate at an appropriate position of the reading (60 div.). The relationship between the intensity of RTP and the concentration of salicylates is linear over a wide range from 3 ng to 630 ng for salicylic acid and acetyl salicylate, and 1.5 ng to 700 ng for phenyl salicylate (spot size : 5 mmφ). The coefficient of variation of the measurements for samples containing 300 ng per spot is less than 3% (5 determinations). This RTP method is very sensitive, rapid and simple, and would be quite suitable for salicylate microanalysis.

View full abstract

The potentiometry with an ion-selective electrode composed of silver chloride membrane was studied to determine successively chloride ions and hypochlorous acid. Using hydrogen peroxide at pH 8 as the reductant of hypochlorous acid enabled determination of amounts of two species. The procedures are as follows: Total ionic strength adjustment buffer of N/30 KH₂PO₄-Na₂HPO₄ containing 15 % KNO₃ is added one tenth of the sample volume to the sample water, and potential difference (E₁) is measured after it has stabilized. Then sufficient amounts of 2% hydrogen peroxide are added dropwise to sample water to reduce hypochlorous acid, and potential difference (E₂) is measured again. Chloride ions (C₁) are evaluated from E₁ with the calibration graph of chloride ions, and total chloride ions (C₂) of the sum of chloride ions and hypochlorous acid are done from E₂. Hypochlorous acid (C', as chloride ion) is calculated by using the following equations: C'= C₂-C₁ or C'=C₁{antilog (ΔE/S)-1}. Where ΔE=E₁-E₂(mV), S: sensitivity for chloride ions (mV/decade). It is possible to determine hypochlorous acid with the precision and accuracy equal to those for chloride ions when potential difference is measured with the digital millivolt meter discriminating till 0.1 mV and the extents of hypochlorous acid are as follows: C'/C₁>1/20, C'<200μg/ml, C₁>4 μg/ml.

View full abstract

A simple and rapid method for determination of PCBs in river water, butter, and soil has been developed utilizing gas chromatography-chemical ionization mass spectrometry (GC/CIMS) or direct chemical ionization mass spectrometry (direct-CIMS). The procedure is as follows. Pretreatment: [river water] 25 ml of acetone are added to 500 ml of a sample, and the solution is extracted with two 25 ml portions of hexane; [butter or soil] 3 g of butter or 10 g of soil are heated in 50 ml of a 1 N-KOH ethanolic solution under reflux for 1 h, and 50 ml of hexane is added. The mixture is transferred into a separatory funnel with 20 ml of hexane-ethanol (1 : 1), and washed with 25 ml of water. Each hexane extract is concentrated to about 1 ml with a Kuderna-Danish(KD) concentrator. Measurement : 1 μl to 5 μl of the concentrated solution is introduced into a Finnigan 3300EGC/QMS instrument equipped with a 1.5 m×2 mm i. d. glass column packed with 1.5 % OV-17 (GC/CIMS) or a 0.5 m glass tube packed with glass beads (direct-CIMS). Methane is used as both a carrier and a reagent gas. The mass fragmentograms are recorded by monitoring specific peaks due to MH⁺, which are m/z 189, 223, 257, 293, 325, 361, 395, 431, and 465 for mono-, di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, and nona-chlorinated compounds, respectively. A mixture of equal amounts of Kanechlor (KC-) 300, 400, 500, 600 is used as a calibration standard. The content of each chlorinated compound in this mixture was accurately determined by FID after identification by the GC/CIMS using a 20 m capillary column of OV-101. Because of high selectivity of the proposed method, satisfactory results for each chlorinate were obtained without preseparation of pesticides and phthalic acid esters. Determination limits for GC/CIMS and direct-CIMS were 10 pg to 50 pg with relative standard deviation of about 3 %, and 1 pg to 5 pg with about 6 %. The direct-CIMS was especially suitable for samples containing less pesticides.

View full abstract

The HPLC separation of Isomers of dihydroxydiphenyl sulfone (DDS) was applied with Zorbax sil column (25cm×2.1 mm i. d.) by mean of a step gradient elution (pressure 170 kg/cm², at 254 nm and 290 nm). Thus at 1 st step, 2, 2'-, 2, 3'-, and 2, 4'-DDS isomers were eluted with hexane-CHCl₃ (40 : 60 v/v). After above 3 isomers were detected (21 min after), then the elute was changed to CHCl₃-2-PrOH (99 : 1 v/v) and 3, 3'-, 3, 4'-, and 4, 4'-DDS isomers were separated. By this method, 6 kind of DDS isomers were eluted in the following order; 2, 2'-, 2, 3'-, 2, 4'-, 3, 3'-, 3, 4'-, and 4, 4'-DDS isomer. The coefficients of variations in the calibration of 2, 2'-, 2, 3'-, 2, 4'-, 3, 3'-, 3, 4'-, and 4, 4'-DDS isomer analysis by this HPLC method at 254 nm, were 2.10, 1.65, 1.59, 1.64, 1.74, and 1.53, respectively.

View full abstract

The extraction of ion-associates of alkylsulfonate ions (carbon number : 213) with eight cationic dyes is described. Distribution between aqueous and organic phase were determined. A linear relationship was obtained between the log K_ex and the number of carbon atoms in the alkylsulfonate ions, and the contribution of a methylene group to the extraction constant, a so-called group contribution value (π value), was on average 0.62. The order of the extractability of the ion-associates was ethyl violet> brilliant green> Hofmann's violet> crystal violet> malachite green> new fuchsin> methylene blue> para rosaniline, and the difference of the log K_ex between two successive dyes averaged 1.17, 0.60, 0.59, 0.85, 2.69, 0.47, and 1.50, respectively. These differences are in good agreement with those deduced from the group contribution values of amino-, dimethylamino-, and diethylamino-groups and the resonance effect. The order of the extractability of the ion-associates was isobutylmethylketone> 1, 2-dichloroethane> dichloromethane> chloroform>ο-dichlorobenzene> chlorobenzene> benzene> toluene> carbontetrachloride, and the difference of the log K_ex between two successive solvents averaged 1.3, 0.6, 0.7, 1.1, 2.5, 2.3, 0.8, and 1.0, respectively. The plot of the average values of Δ log K_ex (solvent-benzene) against E_T parameters shows a good linearity.

View full abstract

The effects of baseline drift on a peak maximum point (apex) and apparent peak height are estimated from mathematical models, assuming that the peak shape is a normal or a gamma (so called Poisson) type and that the drift is straight. The inclination of baseline drift is expressed in the ratio of the apparent peak height (h) and the difference (d₁) of two points (C and E) on the vertical axis (detector response) ; where C and E are the intersections in the baseline with the tangent line at the inflection point in the leading half of a peak, and with the perpendicular from the apparent apex to the horizontal axis (time), respectively. The shift of a peak apex and the decrease of apparent peak height increase with d₁/h and with the skewness of the peak shape. The peak apex moves about the region between the two inflection points which are half of the peak width. The decrease rate {(h_o/-h)/h_o} of peak height exceeds 10 % in d₁/h> 0.7 (upward drift) or in d₁/h> 0.6 (downward), where h_o is the true peak height in no drift. However, the rate is less than 1 % in d₁/h<0.2, which is negligible in most cases.

View full abstract

Linear parameter estimation in spectrophotometry (LPES), least squares calculation to extract the maximum possible information from the spectra, is simulated by means of a computer. In simulation, the standard and sample spectra are synthesized with Gauss function. After adding random noise to the spectra, regression analysis is done to estimate the linear parameter which represent the ratio of standard and sample spectra. Some conditions related to the measurement, such as noise magnitude, reproducibility of wavelength, and spectra characteristics, such as band width at half height, proximity of spectra are varied and the effect of those conditions to the precision of measurement are investigated. In the case of single component system, LPES improves the precision of measurement, and the errors due to noise and impurity spectra are reduced as compared with usual single wavelength measurement. In multicomponent system, LPES can be used to determine the composition of mixture conveniently, but some limitations to the system, such as proximity of spectra, absorbance ratio, are found.

View full abstract

Some improvements were given on the method for the nonaqueous titrimetric microdetermination of carbon in metals. An automatic photoelectric titrator and a circulating titration cell were introduced to lower the limit of the determination. The cell equipped a small valve was satisfactory to reduce the disturbance of the back pressure caused by violent combustion of metallic samples. The standard solution of tributylmethylammoniumhydroxide (TBMAH) was introduced instead of tetrabutylammoniumhydroxide (TBAH). The stability of the former solution was much better than that of the latter especially at low concentrations. Carbon dioxide liberated by the combustion of a sample was absorbed with N, N-dimethylformamide containing 2-aminoethanol and then the absorbent was titrated with the standard (water plus t-butanol) solution of TBMAH standardized against pure benzoic acid. End-point was located photometrically by using thymolphthalein as an indicator. Microamounts of carbon in sucrose were determined by the improved method. Down to 0.22μg of carbon could be determined with relative standard deviation of 4.5%. The results were one order of magnitude lower than the previous reports. Microamounts of carbon in various metals weredetermined by the proposed method under the different surface treatments of the samples. They were tin {(46)ppmC}, high purity iron (10.2 ppmC), various kinds of copper {(24) ppmC}, stainless steels {(2040) ppmC}, various zircaloys {(1O0200) ppmC}. The results were satisfactory compared with those of some reference materials and of other methods. Metallic samples were usually contaminated with carbonaceous compounds in atmosphere. And it was difficult to remove the contaminators thoroughly by washing with some organic solvents under super-sonic radiation.However, they could be removed effectively by washing under super-sonic radiation with nitric acid, water, acetone, and petroleum benzine in order, and then dried in vacuo at 80°C.

View full abstract

The determination of copper in sea water was studied by the coprecipitation with zirconium hydroxide and subsequent square-wave polarographic method. A square-wave polarograph of Shimadzu type PR-50 and Shimadzu type SWP-50 was used and anode was mercury pool in electrolytic cell. To sea water 1000 ml is added 30mg zirconium and pH is adjusted to 8.5 with ammonia water (1:2). The precipitate is separated by filtration and then dissolved in 25 ml of 4M hydrochloric acid. The solution is diluted to 50ml with distilled water. A portion of this solution is submitted to the polarographic determination. The polarogram is recorded over the range from (-0.10 to-0.45) V vs. Hg-pool. Copper is determined by the peak current at-0.26 V. The results are as follows; (1) It was found that coprecipitation could be carried out quantitatively when the pH was adjusted to 8.5 for copper in sea water. (2) The analytical result for copper in sea water was 0.0025 ppm and the determination of copper in sea water could be carried out with good accuracy.

View full abstract

Quantitative analysis of oxidative pyrolysis pyoducts of polyethylene was tried by applying the sampling system which had been developed previously by auther. One milligram of high-density polyethylene was pyrolyzed at various temperatures (300-, 400-, 500-, 600-, 700-, and 800°C) in air (flow rate : 25ml/min). The pyrolysis products were collected in two cold traps of glass tubing (inner diameter : 3mm) packed with Porapak Q in 1 cm length. The traps were connected in series and were cooled in a Dry ice-acetone bath and a liquid nitrogen bath, respectively. The products which were collected fractionally in these traps were released by heating the traps and were analyzed with gas chromatograph and gas chromatography-mass spectrometry. Following components were analyzed quantitatively : alkanes, alkenes, and alkadienes of carbon number from 1 to 11, acethylene, cyclopentadiene, benzene, and other aromatic hydrocarbons, saturated aliphatic aldehydes of carbon number from 1 to 9, acrylic aldehyde, acetone, methyl ethyl ketone, saturated fatty acids of carbon number from 2 to 4, acrylic acid, carbon monoxide, and carbon dioxide. Among these products, yields of alkenes and aldehydes were remarkably large compared with other products at every pyrolysis temperature. The yield of hydrocarbons increases and that of carbonyl compounds decreases with increasing pyrolysis temperature.

View full abstract

Photoacoustic spectroscopy (PAS) has been applied to the determination of microamount of aluminum by measuring PAS intensity of aluminum oxinate after precipitation in the form of a mixture of aluminum oxine complex and naphthalene. The analytical procedure is as follows: take weakly acidic sample solution containing less than 20μg of aluminum in a 50-ml Erlenmeyer flask, add 1.0 ml of 1% oxine solution and 2.0 ml of acetate buffer (pH 5.2). Mix the solution well, and digest for a while, add rapidly with constant stirring 2.0 ml of 20% naphthalene solution in acetone. Filter under suction through filterpaper, wash with water, and dry in a vacuum desiccator for a few hours. Photoacoustic spectrum of the dried mixture is composed of peaks of aluminum oxinate at 395 nm and naphthalene at 320 nm. Determination of aluminum was performed by measuring the intensity ratio of the aluminum oxinate peak to the naphthalene signal. The calibration curve obtained by plotting the normalized intensity against the aluminum amount was linear in the range from 40ng to 20μg (sample solution: 20 ml). The method was successfully applied to the analysis of aluminum in the standard sample, Pepperbush (NIES SRM No. 1)

View full abstract

A method for the determination of sodium nitroprusside by diazo-coupling reaction was established. Sodium nitroprusside was quantitatively derived to nitrite in strong alkaline medium. The following procedure is recommended; To 0.5ml of a sample solution, 1.0ml of 0.2M sodium hydroxide was added, and this reaction mixture was stood for 15 min under the room light. Then, 1.0ml of 1% sulphanilamide reagent (1.2M hydrochloric acid solution) was added to the reaction mixture. After mixing and standing for 2 min to 6 min, 1.0 ml of 0.1% N-(1-naphthyl) ethylenediamine solution was added to the reaction mixture, and the absorbance of the reaction mixture was measured at 540 nm against the reagent blank. The calibration curve for sodium nitroprusside is rectilinear in the range of (1200)μM. Sodium nitroprusside present in the sample was calculated from the increase in nitrite measured in the alkaline treated sample compared to that obtained without alkaline treatment. The photo-stability of sodium nitroprusside was also investigated.

View full abstract

Atomic absorption spectrometry using graphite furnace for the determination of minute amounts of tellurium was developed from our previous method for tin, antimony, and arsenic. For the atomization, nitric acid solution are preferable and they should be free from hydrochloric acid and sulfuric acid. Interferences induced potentially chromium, iron, manganese, tartaric acid, and tin could be prevented by an addition of 2000 ppm of lanthanum as nitrate. Less than 10μg of tellurium was coprecipitated with 10 mg of lanthanum and 1 mg of iron from an aqueous ammonia solution and was separated from unexpected interfering materials. The method is applied to the determination of tellurium in crude copper and crude selenium.

View full abstract

A fundamental study on the determination of rare earth metals (La, Ce, Pr, Nd, and Sm) by HPLC was carried out. In this study, the detection by postcolumn color reaction with Arsenazo III was researched. Lactic acid, which is one of the most common reagents used for the ion exchange separation of the lanthanides, was found to be available as an eluent, because the rare earth metal ions have strongly formed the colored complexes with Arsenazo III and the effect of a large amount of lactate ion on the color reaction was not recognized. The color reaction proceeds instantaneously at room temperature in lactate solution, and the absorption coefficients of each metal complex were almost similar. These rare earth metal ions could be determined by a single calibration curve showing the relationship between the peak area and the concentration, and each rare earth metal to be contained in Misch Metal alloy will be determined by this method.

View full abstract

The polarographic reduction current of 1, 2-cyclohexanediaminetetraacetato-vanadium (IV) complex {V (IV)-CyDTA} in NH₄Cl-NH₃ buffer solution increased with adding nitrate or nitrite to this solution, that is, a catalytic wave appeared. When the concentration of V(IV)-CyDTA is five times larger than that of nitrate or nitrite ion, the catalytic current is proportional to the concentration of the oxidant. This phenomenon was utilized for the determination of nitrate and nitrite ions. Nitrate or nitrite ion in NH₄Cl-NH₃ buffer solution was determined at pH 8.6 by this method. Nitrite ion in the mixture of nitrate and nitrite ions could be determined without the influence of nitrate ion by using V(IV)-CyDTA of less than 0.5 mM. However, as the determination of nitrate ion in the mixture was affected by nitrite ion, a calibration curve for nitrate ion in the presence of a known amount of nitrite was obtained by using V(IV)-CyDTA in (110) mM and nitrate ion in the mixture could be determined. This method is useful for the determination of nitrate ion and/or nitrite ion in the mixture of both ions.

View full abstract

A new technique of on-line electrochemical derivatization using glassy carbon column electrode as a reactor is established. Materials eluting from a separation column are converted in the reactor to form fluorescent or intensely UV-absorbing products, the products being monitored by a suitable detector. An example of the use of this technique is the detection of homovanillic acid (HVA) in urine. HVA is applied to the column (Hitachi #3011-N, 250×4mm i.d.) of HPLC and derivatized to the fluorescent dimer (2, 2-dihydroxy-3, 3-dimethoxybiphenyl-5, 5-diacetic acid) by electrochemical oxidation in the reactor. The intensity of the fluorophore is measured with a spectrofluorometer (λ_ex325nm, λ_em420 nm) and recorded graphically. Linearity of the relationship between peak hight and amount of HVA is obtained between 5 ng and 120 ng. The reproducibility, expressed in terms of coefficient of variation, is 1.6% (20ng, n=10). As none of the derivatizing reagent need to be added to eluent stream, this technique has a little or no effect on the dilution of eluate, back ground noise based on the derivatizing reagent and peak broadening. This technique will extend to many substances.

View full abstract

Though ESR signal intensity can be measured quantitatively by the two-step integral method, floating of the 0-level of the output signal from the ESR apparatus makes the measurement difficult. The intensity variation caused by reinsertion of the sample into the cavity resonator also reduces the precision of the measurements. To improve these two faults, the PSD circuit was refashioned and a sample adapter was constructed for inserting the sample at a fixed position in the cavity. With these improvements fairly good results were obtained. The signal intensities of several types of copper compounds were measured with the reconstructed apparatus and compared with each other. The results revealed that binuclear complexes which had the stronger interaction between the two copper atoms showed the weaker signal intensities.

View full abstract

The fast response ESR spectrometer with 2 MHz magnetic field modulation was constructed for the study of photochemical process involving free radicals or triplet species. The output S/N with 2 MHz modulation was about 1/4 of that attained at 100 kHz for equal modulation amplitude and output time constant for standard magnetic field-sweep experiments. The kinetic response test of the spectrometer was performed by employing pin diode as a pulse modulator of microwave power while sitting on a first derivative peak of strong ESR signal. The resonance was seen to follow closely the microwave power excitation with the 2 μs time constant. As an indication of the utility of the spectrometer, photo-CIDEP signals were shown which were obtained after extensive signal averaging from durosemiquinone exposed to nitrogen gas laser.

View full abstract

The distribution coefficients of alkaline earth metal ions were measured on crystalline hydrous titanium dioxide fibers at 298K. The adsorption behavior of these ions was well explained by their ion-exchange reaction with hydrogen-ions in the fibers. The distribution coefficients of alkaline earth metals were determined as a function of pH. Separation of strontium(II) from barium(II) was achieved by using a column of this ion-exchanger with hydrochloric acid solutions as an eluent.

View full abstract

A laboratory model study was made for the characterization of organic compounds in the waste water from coal depots. Finely powdered coal samples were suspended in water and steam-distilled. The organic compounds in the distillate were systematically analyzed by silica-gel column chromatography and gas chromatography mass spectrometry. Alkanes, polycyclic aromatic hydrocarbons (PAHS) and oxygen- or sulfur-containing aromatic hydrocarbons were found in ppb to ppm levels on the coal basis. A field sample from a coal depot contained nitrogen-containing PAHs in much higher level than in the model study.

View full abstract

Nanogram quantities of lead and copper are electrodeposited together with mercury on a silver-plated glassy carbon electrode from 100μl of 0.6M hydrochloric acid, and then anodically stripped by the linear scan technique. This method is applied to the simultaneous determination of lead and copper at the low ppm level in 0.5 to 1mg of sponge nickel.

View full abstract