BUNSEKI KAGAKU Abstracts

Vol. 53 No. 8

August, 2004

Accounts

Qualitative and quantitative analysis using multivariate analysis

Toshiyuki Mitsui¹, Shuji Okuyama² and Minesada Hida²

(Received 20 February 2004, Accepted 10 April 2004)

Multivariate analysis was applied to the determination of a mixed compound, and each component was accurately measured without a separation procedure. Two or more data from measuring one sample for analysis were used for a multivariable analysis. The qualitative analysis for identification is evaluated as follows. First, the principal component analysis is examined for removing the outlier samples. Next, the cluster analysis is examined for the formation of a cluster to unknown samples, or the determination of a belonging cluster of an unknown sample. Finally, the relations between the unknown samples are calculated by soft independent modeling of the class analogies method (SIMCA method) based on the result of the cluster analysis. The principal component analysis (PCS), the principal component regression analysis (PCR), and the different calculation method of regression analysis (DCR) were examined for quantitative analysis. When PCS or PCR were examined using two or more measured data, the accuracy of the determination improved as compared with the calibration-curve method. DCR was unnecessary for a calibration curve for the determination, and but was applied for a determining the content of each compound from samples in which three or more kinds of compounds had been mixed.

Keywords : cluster analysis; principal component analysis; SIMCA analysis; different calculate method of regression analysis.

Low-pressure helium ICP-MS for trace analysis

Hideo Hayashi¹ and Masataka Hiraide¹

(Received 2 March 2004, Accepted 23 April 2004)

Inductively coupled plasma mass spectrometry (ICP-MS) offers a powerful multielement analytical method. Polyatomic interferences, however, are a major problem for the analysis of some elements. For example, ⁴⁰Ar¹⁶O⁺, ⁴⁰Ar³⁵Cl⁺and ⁴⁰Ar₂⁺cause overlap interferences when detecting ⁵⁶Fe⁺, ⁷⁵As⁺and ⁸⁰Se⁺, respectively. To address this issue, we studied low-pressure helium-ICP-MS, where a highly energetic helium plasma was generated with an rf power of 500 W in a water-cooled plasma torch. A sampling orifice was fabricated from an aluminum metal to minimize the background spectra. Different sample-introduction techniques were also developed for extending the scope of the proposed method. A liquid sample, for example, was first converted into tiny droplets with an ultrasonic nebulizer and then desolvated in a heater. The resulting dry aerosol was successfully introduced in the low-pressure helium plasma through a PTFE capillary tube. A small amount of sample was transported to the plasma after electrothermal vaporization on a tungsten filament. Other sampling techniques examined include hydride generation and laser ablation. The detection limits were measured based on 3σ for a large range of elements in the periodic table. Improved lower detection limits were obtained for halogens, C, Cr, Fe, Se, and so on. The diagnosis of helium plasma with a Langmuir probe indicated that the plasma temperature was higher than the conventional argon plasma, which may contribute to an enhancement of the detectability. The analytical capability of the proposed ICP-MS was demonstrated by analyzing different types of certified reference materials.

Keywords : ICP-MS; helium plasma; trace analysis; electrothermal vaporization; laser ablation.

Development of highly potent chiral discrimination methods that have solved the Intrinsic Problem of the diastereomer method

Hiroshi Ohrui¹

(Received 7 January 2004, Accepted 26 April 2004)

Since the discovery of enantiomerism by L. Pasteur in 1848, studies concerning to the discrimination of enantiomers have been among the important subjects in science. A recent finding that the relationship between the optical purity and the biological activity of biologically active compounds is very important, has stimulated the development of a highly potent chiral-discrimination method. The most widely used diastereomer method for the discrimination of enantiomers has a problem in that it is very difficult, or even impossible, to discriminate diastereomers having chiral centers separated by more than four bonds. The problem has been assumed to be intrinsic to the diastereomer method, and has been left unsolved. The author has proposed a solution to this problem by developing several fluorescent chiral labeling reagents.

Keywords : highly potent chiral discrimination method; a solution to the Intreinsic Problem of the diastereomer method; discrimination of remote chirality; fluorescent chiral labeling reagents; reversed-phase HPLC; ¹H NMR.

Research Papers

Evaluation of cooling gas for argon/helium compatible ICP

Hidekazu Miyahara¹, Takayuki Doi¹, Youichi Mizusawa¹, Eiki Hotta¹ and Akitoshi Okino¹

(Received 23 January 2004, Accepted 2 April 2004)

In a new argon/helium compatible ICP torch designed to reduce plasma gas consumption, a cooling gas is exhausted in the same direction as the plasma, which causes concern about an immixture of both gases and air. In this study, the effect of a cooling gas difference and the flow rate on the emission properties of Ar and He ICP were investigated by measuring the emission intensities of OH, N₂ and Ar. When an appropriate cooling gas and flow rate were chosen, the background emission caused by the air immixture was reduced.

Keywords : Ar ICP; He ICP; gas-cooled ICP; ICP torch.

Cyclic flow injection system for iodide ion determination using a temperature-regulated colorimetric switching mechanism of iodine and starch reaction

Yumi Kato¹, Yui Ishii¹, Ryohei Wakao², Yoshikazu Amano², Mikita Ishii^1,2 and Masaaki Yamada³

(Received 25 November 2003, Accepted 5 April 2004)

A cyclic FIA system was designed for a determination of iodide ion with considering both environmental protection and a rapid, easy, economical and convenient operation. The proposed system consisted of the most simplified one line by popular colorimetric detection. A coloring switching system depending on the reaction temperature between iodine and starch was used for the proposed cyclic FIA. The present cyclic system by a 100 µl sample injection method under operating conditions of a 30°C to 60°C switching temperature and a reagent flow rate of 2.5 ml min^-1 was available for 50 repeated runs with the 100 ml reagent solution. The calibration for the determination of iodide ion was linear between 1.0×10^-5 M and 5.0×10^-4 M in 100 µl sample injection. The reproducibility of the proposed method in a 100 µl sample injection was less than 1% in terms of relative standard deviation in 5 repeated runs with the 5.0×10^-4 M iodide ion standard solution. The analytical time required was 30 s for one sample. The selectivity of the present method was good, and two Cr₂O₇^2- and SO₄^2- anions giving the next larger absorbance signal to that of the iodide ion had a negligibly small interference in a (1+1) mixed solution of 5.0×10^-4 M iodide ion standard with their foreign ions tested.

Keywords : cyclic FIA; iodide ion; zero emission; temperature-regulated colorimetric switching mechanism; colorimetric detection.

Extraction behavior of environmental organic pollutants in supercritical fluid extraction

Azusa Yamamoto¹, Kazuaki Nagai², Tetsuo Sakamoto², Masanori Owari^2,3 and Yoshimasa Nihei¹

(Received 27 January 2004, Accepted 18 April 2004)

Aiming at the development of a rapid-analysis technique for environmental organic pollutants on suspended particulate matter (SPM) in air, a supercritical fluid extraction (SFE) technique was studied. The extraction efficiencies of typical organic pollutants spiked in alumina particles were first examined at various combinations of the extraction temperatures and pressures. The recovery of polyaromatic hydrocarbons (PAHs) showed strong dependence on both the extraction temperature and the pressure. This result was disscussed in terms of the enhanced solubilities and desorption/diffusion rates at a higher temperature and pressure. As for n-octadecane and tetrachlorobenzene, they showed little dependence on the fluid conditions. This implied that solubility has little effect on the recovery in case of these compounds with relatively high vapor pressures. The extraction behavior was also investigated using real SPM. Phthalates and Phenanthrene showed the maximum recovery at the highest temperature and pressure among three-step extraction, whereas n-alkanes and polysiloxanes were effectively extracted in the medium temperature and pressure step. The apparent difference in the extraction behavior implies the possibility of the selective extraction of the aimed analytes from real environmental samples.

Keywords : SFE; supercritical fluid; extraction; environmental analysis; PAHs.

Solid-phase extraction of lead and copper by chelating cellulose functionalized with thioglycollic acid

Shigeo Takemori¹, Kouji Yamada², Osamu Itoh³, Nobuyoshi Nanbu³ and Yoshifumi Akama¹

(Received 1 March 2004, Accepted 20 April 2004)

A chelating cellulose (SRY-Cell) containing thioglycollic acid as the chelating group was synthesized and studied for its sorption efficiencies with respect to Pb and Cu from an aqueous solution in both batch and column experiments. The influence of the pH on the adsorption, 250 mg each of Pb and Cu on SRY-Cell (0.1 g) from a 100 ml solution was studied in the pH range of 1.2~10.8 by a batch process. Pb and Cu were quantitatively retained on the proposed adsorbent at pH>5. The effects of the flow rate of the sample solution through a column (polypropylene syringe, 78×16 mm i.d., 1.0 g of SRY-Cell was packed) were studied over the range of 10~30 ml min^-1. The retention of these metals on the SRY-Cell was not affected by the flow rate of the sample solution up to 30 ml min^-1. Based on these results, the solution passed through the column at a flow rate of about 15 ml min^-1. The extracted metals were stripped from the column using 20 ml of 1 M HCl at a flow rate of 5.0 ml min^-1. The maximum sorption capacities were found to be 0.89 mmol g^-1 and 0.64 mmol g^-1 for Pb and Cu, respectively. The adsorbent was chemically stable and the adsorption-desorption cycles could be repeated at least 20 times. The method was applied to the concentration and determination of Pb and Cu in solar salt and water samples.

Keywords : lead; copper; thioglycolic acid; SRY-Cell; solid phase extraction.

Technical Papers

Detection of trace methamphetamine in dimethylamphetamine hydrochloride as stimulant material

Minemasa Hida¹, Motoyasu Satoh¹ and Toshiyuki Mitsui²

(Received 16 February 2004, Accepted 12 April 2004)

A method has been examined that analyzes whether or not a very small amount of the stimulant methamphetamine hydrochloric acid salt (MA) in dimethylamphetamine hydrochloric acid salt (DMA), which is a stimulant material, exists. The optimization of an extraction system for MA was carried out as a pretreatment process of GC-MS. This method was able to detect 5 µg of MA in 100 mg of DMA as a result. DMA powder was easily recovered by air-drying to remove the extraction solvent.

Keywords : methamphetamine; dimethylamphetamine; extraction.

Ion chromatographic determination of organic acids in vinegar samples using cetyltrimethylammonium ion coated graphite carbon column

Akio Sakuragawa¹ and Miki Nakane¹

(Received 28 January 2004, Accepted 19 April 2004)

From the viewpoint of a graphite carbon column with excellent durability, it was applied to the ion chromatography of several organic acids. The carbon column was permanently coated with the cetylmethylammonium ion, and the elution behaviors of several organic acids and inorganic anions (acetic acid, lactic acid, succinic acid, malic acid, tartaric acid, citric acid, Cl^-, NO₂^-, NO₃^-) were examined according to an ion chromatography that combined conductometric detection using a mobile phase of the salicylic acid system, when an ion-exchange ability was given to the graphite carbon column. Though the peaks overlapped among Cl^-, NO₂^- and malic acid, it was possible that 9 components were separated within 15 minutes. The calibration curve of each ion was over 0.999 with the correlation coefficient (r²), and the relative standard deviations (RSD) by repeated measurements were found tobe 0.53~1.03% (n=6) with good reproducibilities. Analytical results for organic acids, that were contained in food vinegar, were examined using the proposed method. It was possible to get within 1.0% and good values were obtained that comparied with a reversed phase-high performance liquid chromatography (HPLC) using ODS column.

Keywords : graphite carbon column; organic acids; inorganic anions; ion chromatography; vinegar samples.

Analytical Reports

Determination of anionic surfactants in tap water by HPLC-UV detection after solid-phase extraction

Hideaki Kitami¹, Tetsuo Watanabe², Takio Kitahara³, Yoshimi Ishihara³ and Jiro Takano³

(Received 22 January 2004, Accepted 20 April 2004)

A cartridge-type solid-phase extraction method for the determination of anionic surfactants, followed by high-performance liquid chromatography with ultraviolet detector (HPLC-UV) is described. The HPLC-UV measurement method provides good linearity of the calibration curve as well as repeatability. The correlation coefficients of the calibration curve were estimated to be from 0.9989 to 0.9996 for anionic surfactants in the concentration range from 0.1 mg l^-1 to 10 mg l^-1. For anionic surfactants by HPLC-UV, the detection limits were calculated to be 0.031 mg l^-1 for ABS analysis and 0.047 mg l^-1 for synthetic detergent test for laundering, at which the signal-to-noise (S/N) ratio was 3. Methanol was recommended for the elution of anionic surfactants from the cartridge-type solid-phase. The recoveries for anionic surfactants for ABS analysis from distilled water spiked at concentration of 1.0 ng ml^-1 was 93.2%, and the relative standard deviations (RSD) was 6.3% by a cartridge-type solid-phase extraction method. This measurement method could be successfully applied to the determination of anionic surfactants in tap water.

Keywords : HPLC-UV; cartridge-type solid-phase; extraction; anionic surfactants; tap water.

Digests of Doctoral Dissertation

Screening of pesticides using X-ray fluorescence spectroscopy and the determinations of water-soluble herbicide in human blood by capillary electrophoresis

Tetsuya Ishiwata

Scientific Investigation Laboratory, Ibaraki Prefectural Police Headquarters, 978-6, Kasaharacho, Mito-shi, Ibaraki 310-8550

(Awarded by Ibaraki University dated March 23, 2004)

In the case of poisoning incidents that occur by pesticide ingestion, it has been required to determine the pesticide. First, screenings of pesticides using X-ray fluorescence spectroscopy (XRF), ion chromatography and gel-permeation chromatography were carried out. By XRF analysis, the elements of the active ingredient were detected in most pesticides, giving a first-step clue for estimating a compound. The proposed method was applied to estimate the pesticide in an actual fatal case. Second, an OASIS® MCX cartridge was used for the extraction of paraquat (PQ) and diquat (DQ) from human blood, and their determination was carried out by capillary electrophoresis (CE). The recoveries of PQ and DQ from human plasma and whole blood were found to be above 87%. The proposed method was successfully applied to the determinations of PQ and DQ in human blood in actual cases. Third, a Titansphere^TM TiO column was used for the extraction of phosphorus-containing amino acid-type herbicides (PAAHs) and their metabolites from human blood, and their determination was carried out by CE. The recoveries for glyphosate, aminomethylphosphonic acid, and glufosinate from human whole blood were found to be above 94%, and that for 3-methylphosphinicopropionic acid was 47%. The present method can be used for the rapid and simple determination of PAAHs in human blood in cases of accidental and suicidal ingestion.

(Received April 6, 2004)

Keywords : X-ray fluorescence spectroscopy; paraquat; diquat; OASIS® MCX cartridge; capillary electrophoresis; phosphorus-containing amino acid-type herbicides; Titansphere^TM TiO column.

Study on the determination and behavior of trace organic compounds and halogenated disinfection by-products in water supplies

Yasuo Takahashi

Division of Water Environment, Department of Environmental Health, Tokyo Metropolitan Institute of Public Health, 24-1-3, Hyakunincho, Shinjuku-ku, Tokyo 169-0073

(Awarded by University of Shizuoka dated March 25, 2003)

Plasticizers (phthalate esters and organophosphate triesters), cyclic sulfur molecules, agricultural chemicals for paddy rice, and phenols were detected at the ng ml^-1 level in water resources; all of these materials were also detected in a water supply at nearly the same concentrations as in river water. We also studied the behavior and kinetics of agricultural chemicals, plasticizers, and phenols in tap water and their sources. Concerning thiobencarb, a herbicide used for paddy rice not detected in a water supply, we clarified its degradation characteristics on the chlorination and degradation pathways to its degradation products, and revealed their concentrations in tap water. We attempted to determine unidentified halogenated disinfection by-products (HDBPs), and established a method for a systematic analysis of 34 HDBPs, including known HDBPs. The concentrations of trihalomethanes (THMs) measured by this method were found not to be overestimated, and to be close to the true concentrations, unlike those obtained by the purge and trap -GC/MS method or head space (HS)-GC/MS method, and part of the materials responsible for the positive errors observed in the HS-GC/MS method could be clarified. Intermediate and final HDBPs were found to increase in tap water that has been stored in a water tank compared with tap water before storage; the increases were particularly notable in haloacetic acids. The level of dichloroacetic acid in tap water, which originated from river water and stored in a water tank, sometime exceeded 40 ng ml^-1 in the summer. In heated tap water, intermediate HDBPs decreased with increases in the water temperature and the duration of heating, and part of them were converted to THMs and dihaloacetic acid, which are final HDBPs. We further clarified part the reaction pathways of HDBPs, and showed that the sources of disinfection by-products can be identified from the compositional ratio of HDBPs.

(Received April 6, 2004)

Keywords : disinfection by-products; river water; water supply; agricultural chemicals; plasticizers; phenols.

Sedimentary photosynthetic pigments as indicators of phototrophs in changing aquatic environment of Lake Hamana

Nobuyasu Itoh

Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba-shi, Ibaraki 305-8569

(Awarded by University of Shizuoka dated March 20, 2003)

This thesis focuses on the potential of photosynthetic pigments of phototrophs in lake sediments as a biomarker that indicates the changes in aquatic environments in the past. Using chlorophyll derivatives formed through grazing of algae by zooplankton, and accumulated in sediments as grazing indicators, difference in the accumulation efficiency of each pigment could be attributed to selective grazing by zooplankton and seasonal variations in algal assemblages. The vertical distributions of photosynthetic pigments and Mo in the ²¹⁰Pb-dated sediment core demonstrated that the anoxic zone has existed in the central basin of Lake Hamana over at least the last~250 years, and that the primary production by algae and phototrophic sulfur bacteria and the extent of anoxia have closely related. The construction of training walls in the Imagire-guchi Channel during 1954~1956 introduced the most dramatic change over a wide extent of Lake Hamana. By comparing the composition of photosynthetic pigments in sediment cores obtained from the central and 4 attached basins of Lake Hamana, it has been found that the exchange of water by seawater intrusion in each enclosed basin has strongly affected the extent of anoxia indicated by the ratio of total bacterial carotenoids to total algal carotenoids in the sediments.

(Received April 7, 2004)

Keywords : photosynthetic pigment; Lake Hamana; sediment; water; anoxia.

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