Vol. 47, No. 8
August, 1998
*Shiseido Research Center, 1050, Nippacho, Kohoku-ku, Yokohama 223-8553
(Received 20 February, Accepted 25 May 1998)Attempts to miniaturize columns for liquid chromatography (LC) have been reported since the late 70's. A series of advantages were repeatedly claimed in the use of microcolumns, whose inner diameters were less than 1 mm. However, several requirements and limitations have kept microcolumn LC within a very limited area of applications. On the contrary, semi-microcolumn LC (inner diameter: 1~2 mm) has been widely accepted in academia and industry, possessing both advantages shown by microcolumn LC and the reliability of conventional LC. Although certain modifications, such as miniaturizing dead volumes of components, are required in instrumental arrangements, it became possible to easily obtain highly efficient separation with a semi-microcolumn, even under isocratic conditions. The benefits of semi-microcolumn LC seem most pronouncing when a column-switching system is arranged. A tremendous concentrating effect could be earned by first injecting a sample solution into a short conventional-bore precolumn, and then transferring an analyte-containing fraction to a semi-microcolumn connected into a detector. This analytical format was applied to the analysis of various substances contained in biological liquids at very low concentrations. The later sections of the article discuss some of these applications, including forensic analysis and diagnosis in clinical chemistry.
Hideo Noguchi, Shigeaki Matsutani, Shoichi Tanaka, Yasunobu Horiguchi* and Toshiyuki Hobo**
*Analytical Research Center, Lion Corporation, 7-13-12, Hirai, Edogawa-ku, Tokyo 132-0035
**Department of Industrial Chemistry, Faculty of Engineering, Tokyo Metropolit
an University, 1-1, Minami-Ohsawa, Hachioji-shi, Tokyo 192-0397
An alkyl homologue distribution analysis of surfactants contained in household detergents or toiletries involved intricate work. A rapid analysis method using a two-dimensional (2D) HPLC has been developed. In the case of anionic surfactants, each surfactant, such as carboxylates or sulfates, is separated from matrices according to the type of anionic group by an anion exchange column (1D), and eluted as a single peak. The eluted surfactant is trapped on a C8 short column and then transferred to a C18 analysis column (2D) by a switching technique. The alkyl homologs can be analyzed in this a time of less than 40 min. In the case of cationic or amphoteric surfactants, a cation exchange column was used as an 1D column. The method was successfully applied for the analysis of carboxylates, sulfates, sulfonates, quaternary ammonium salts, alkyl pyridinium salts, amidobetains, and other surfactants in household formulations.
Keywords: HPLC; two-dimension; surfactants; detergents; column switching.
Akiko Tanabe, Hideko Mitobe, Kuniaki Kawata and Masaaki Sakai*
*Niigata Prefectural Research Laboratory for Health and Environment, 314-1, Sowa, Niigata 950-2144
(Received 23 March 1998, Accepted 6 May 1998)A gas chromatography-mass spectrometry (GC/MS) was applied to the determination of 90 pesticides and 10 transformation products in the particulate matter (PM) of river water. The pesticides investigated were 18 fungicides, 30 insecticides and 42 herbicides. After a water sample was filtered through a glass-fiber filter (1 µm of pore size), the filtrate was filtered with a hydrophilic polytetrafluoroethylene (PTFE) filter (0.5 µm of pore size). The target compounds on the PM on each filter were extracted ultrasonically with acetone. The extracts were concentrated under reduced pressure for GC/MS determination. The overall recoveries of the compounds were 74% to 104% from PM. Thirteen compounds, such as etofenprox, benfluralin and trifluralin, spiked to a river-water sample distributed to the PM at rates from 4.0 to 72%. This method has been successfully applied to monitoring compounds in river water.
Keywords: pesticide; particulate matter; river water; monitroing; GC/MS.
Ken Matsumoto and Mayumi Kitagawa*
*Department of Chemistry, Faculty of Science, Kanazawa University, Kakuma-machi, Kanazawa-shi, Ishikawa 920-1192
(Received 19 March 1998, Accepted 6 May 1998)A simple and rapid method for the decomposition of refractory cerium compounds has been proposed. Cerium samples (CeO2, CeTiO4, CeZrO4 and ore) were decomposed by fusion with ammonium hydrogen sulfate, which was found to be a suitably powerful flux for dissolving various refractory cerium compounds. An accurately weighed sample (ca. 30~100 mg) was placed in a dry Pyrex glass test-tube(16 mm o.d., 180 mm length). Ammonium hydrogen sulfate(ca. 3 g) was added to the tube and mixed with the sample by agitating the tube. The bottom of the test tube was gently heated along with a swirling motion over a small gas flame of a Bunsen burner with a fish-tail at a temperature of ca. 350~450°C.
Heating was continued until the yellow melt changed into a colorless, clear and translucent form. The cooled melt was dissolved in water. Cerium(IV) oxide was dissolved by heating for about 6 min; for cerium(IV) titanate and cerium(IV) zirconate it was about 10 min. Finally, the concentration of the cerium in the resulting solution was determined by absorption spectrophotometry or a redox titrimetric method. This method was successfully applied to various cerium compounds and ore. The cerium, titanium and zirconium in the samples were determined.
Keywords: decomposition of cerium(IV) oxide; fusion with ammonium hydrogen sulfate; determination of cerium, titanium and zirconium in cerium compounds and ore.
Kazuyuki Nara and Takashi Saito*
*Department of Applied Chemistry, Kanagawa Institute of Technology, 1030, Shimoogino, Atsugi-shi, Kanagawa 243-0292
(Received 31 October 1997, Accepted 8 May 1998)The determination of copper ion by flow injection analysis using a polyvinyl chloride (PVC) membrane containing 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline (bathocuproine) as a detection port has been developed. The PVC membrane containing bathocuproine and o-nitrophenyloctylether was synthesized and set in a flow-through cell; the flow-through cell was then attached in the cell holder of a spectrophotometer. A carrier solution consisting of 5×10-2 mol dm-3 of hydroxyl ammonium sulfate, 5×10-2 mol dm-3 of sodium chloride and sodium hydroxide was prepared, and pumped at 0.5 ml min-1. The sample volume was 100 µl. The injected copper ion formed a complex with bathocuproine on the PVC membrane surface in the flow-through cell; the absorbance of the colored membrane was then measured by the spectrophotometer at 481.5 nm. The determinable concentration of copper ion on the proposed method was over the range of 5×10-6~1×10-4 mol dm-3. The reproducibility of the determined values of copper ion was 3.8% with a relative standard deviation on repeatable experiments of seven times for a 5×10-5 mol dm-3 copper ions sample. Coexisting metalions had no effect on the determined value of copper ions when their concentrations were equal to or less than the copper-ion concentration. A linear correlation between the determined values by the proposed method and AAS was obtained at a concentration range of 1×10-5~1×10-4 mol dm-3.
Keywords: determination of trace copper ion; spectrophotometry using a membrane, polyvinyl chloride membrane; bathocuproine; flow injection analysis; optical sensing.
Nobuaki Ogawa, Ryoei Kikuchi*, Hiroshi Goto**, Masahiro Kajikawa* and Toru Ozeki***
*Faculty of Engineering and Resource Science, Akita University, 1-1, Tegata Gakuencho, Akita 010-8502
**Yuzawa Senior High School, 27, Shinmachi, Yuzawa-shi, Akita 012-0853
***Hyogo University of Teacher Education, Yashiro-cho, Kato-gun, Hyogo 673-1415
The validity of the classification of sea-salt and non-sea-salt origins of pollutants in precipitation was evaluated using a constrained oblique rotational factor analysis. The precipitations used for this analysis were collected from April, 1993 to March, 1995 in Akita and from January to March of 1994 and 1995 in Yuzawa on a day-after-day basis. The chemical compositions in these precipitations were analyzed and their four sub-data-sets (a two-year data-set of Akita, a data-set of winter season in Akita, a data-set of seasons except for winter in Akita and a data-set of winter season in Yuzawa) were analyzed using the factor analysis. Three or four pollutant sources were quantitatively extracted for each data-set. The factor analysis has extracted a factor ascribed to the sea-salt (ss) component without using any information concerning its composition. However, a part of the sodium and chloride ion is also involved in another acidic factor, which contains sulfuric acid. This means that part of sea-salt particles suffered a chemical reaction while coming to the precipitation place from the Sea of Japan.
Keywords: constrained oblique rotational factor analysis; classification of sea-salt/non-sea-salt origins; acid precipitation in Akita; seasonal changes; pollutant sources.
Mitsuko Oshima, Takashi Ohsaki and Shoji Motomizu*
*Department of Chemistry, Faculty of Science, Okayama University, 3-1-1, Tsushimanaka, Okayama 700-8530
(Received 6 April 1998, Accepted 20 May 1998)Ultra-trace amounts of lead were determined by graphite-furnace AAS (GF-AAS) after miniature-membrane filter (MF) concentration/dissolution. Lead was concentrated as a pyrrolidinedithiocarbamate (APDC) chelate on a miniature MF, which was 5 mm in diameter, 2 mm in effective filtering diameter and 0.2 µm in pore size. After collection of the lead chelate on MF, the MF was cut so as to be 3 mm in diameter using a punch. This tiny MF was dissolved in 100 µl of a dissolution solvent (methyl cellosolve), which resulted in a high concentration efficiency. When 10 ml of a sample was used, the concentration ratio was 100. The addition of 5×10-5 M Zephiramine to the sample solution before chelation was effective for collecting lead; the recovery was almost 100%. The filtering time was 15 min for a 10 ml sample solution. The detection limit was 10 ppt when a 10 ml of sample solution was concentrated in 200 µl of methyl cellosolve. Measurements by GF-AAS were carried out using 40 µl of a methyl cellosolve solution. The relative standard deviation for 40 ppt of lead was 4.51% (n=4). This method was applied to both river- and tap-water samples.
Keywords: lead; miniature membrane filter concentration/dissolution; ammonium pyrrolidinedithiocarbamate; graphite furnace AAS.
Zhidong Chen, Takahiro Kiyonaga and Tsutomu Nagaoka*
*Department of Applied Chemistry, Faculty of Engineering, Yamaguchi University, 2557, Tokiwadai, Ube-shi, Yamaguchi 755-8611
(Received 20 April 1998, Accepted 29 May 1998)The authors have prepared colloidal dispersions of polypyrrole-poly(vinylalcohol) composites doping carbobenzoxy-L-aspartic acid, using the oxidative polymerization technique. The colloid was used to resolve the enantiomers of glutamic acid (glu) and valine (val). When 15 mg dm-3 colloid was added to a solution containing 1.0×10-4 mol dm-3 D-glu or L-glu and 2.0×10-4 mol dm-3 cupric ion, about 50% and 10% of D- and L-glu were extracted into the colloid, respectively.
Keywords: conducting polymer; polymer colloid; amino acid; optical isomer; extraction.
Toshihide Ihara, Akiko Takatsu and Akira Nomura*
*National Institute of Materials and Chemical Research, 1-1, Higashi, Tsukuba-shi, Ibaraki 305-8565
(Received 7 April 1998, Accepted 20 May 1998)The Comité Consultatif pour la Quantité de Matière (CCQM) was established by the Comité International des Poids et Mesures (CIPM) in response to the issue of international comparability and traceability of chemical measurements. At its second meeting, in 1996, the CCQM working group on metrology in chemistry decided upon international comparisons for organic compounds using isotope dilution mass spectrometry (IDMS). The first CCQM inter-comparison concerning the determination of a solution of (p,p'-dichlorodiphenyl) dichloroethylene using IDMS was carried out by eight national laboratories, including our institute. Two-level (low and high) sample solutions were provided by the pilot laboratory. Our results for high-level samples showed good agreement within 1% of the reference values. Further, we had attempted an IDMS measurement using three different types of mass spectrometers: a magnetic sector, a quadrupole and an ion trap for comparing the sensitivity or reproducibility among these instruments.
Keywords: (p,p'-dichlorodiphenyl) dichloroethylene; isotope dilution mass spectrometry; international comparison.
Takashi Yarita
National Institute of Materials and Chemical Research, 1-1, Higashi, Tsukuba-shi, Ibaraki 305-8565
(Awarded by Chiba University dated September 20, 1996)Separation and quantification methods using supercritical fluids have been developed in terms of separation, detection and hyphenation techniques as well as an application to real sample analyses. For sensitive and selective detection in supercritical fluid chromatography (SFC), an electron-capture detector was used as a detector; small quantities of organochlorine pollutants could be determined. A novel deactivation method of silica-based column packings using supercritical fluid carbon dioxide as a reaction medium was also reported. The effectiveness of this method was higher than that of the classical method using organic solvents. On the other hand, the use of a modifier in supercritical fluid extraction (SFE) of small quantities of triazine herbicides in soil was investigated; the addition of methanol as a modifier increased the recoveries of the herbicides. Regarding the hyphenated system, on-line SFC/GC and SFE/SFC systems were investigated; a type analysis of essential oils and residue analysis of thiolcarbamate herbicides could be rapidly performed using these systems. The results obtained in this study indicate that the proposed methods are useful for the sensitive and rapid determination of organic compounds.
(Received April 4, 1998)Keywords: supercritical fluid; supercritical fluid chromatography; supercritical fluid extraction; separation technique.
Shinji Yoshiyagawa
Forensic Science Laboratory, Criminal Investigation Department, Hokkaido Prefectural Police Headquarters, Nishi-7, Kita-2, Chuou-ku, Sapporo 060-8520
(Awarded by Hokkaido University dated March 25, 1997)Cation permselectivity at the phase boundary of ionophore-incorporated liquid membranes was studied by optical phenomena as probes for phase-boundary potentials in order to understand the response mechanism of liquid membrane-type ion-selective electrodes (ISEs) at the molecular level. In the first study, optical second-harmonic generation (SHG) at various plasticized poly(vinyl chloride) (PVC)-based ion-selective membranes was observed, and the existence of SHG-active, oriented cation complexes at the membrane surface was shown. By examining the correlation between the SHG and potentiometric responses, the observed SHG intensity was assumed to be a measure of the charge density at the very membrane surface. In the second study, lipophilic derivatives of photoresponsive azobis(benzo-15-crown-5) were used as a molecular probe and the photoinduced changes in the potentiometric responses were observed. As a result, it was found that the photoinduced change in the potentiometric response behavior depends on the change in the number of primary cations permselectively extracted into the membrane side of the interface. These studies proved the necessity to investigate the interfacial phenomena which arise at the membrane surface in addition to thermodynamic considerations in order to understand the response mechanism of liquid membrane-type ISEs.
(Received 11 May, 1998)Keywords: liquid membrane-type ion-selective electrode; phase boundary potential; optical second harmonic generation; photoresponsive ionophore.
Copyright (c) The Japan Society for Analytical Chemistry