BUNSEKI KAGAKU Abstracts

Recent developments in packing materials for high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) have been discussed. Silica gel and its derivatives have been used predominantly as column packing materials for HPLC owing to their high resolution and mechanical strength. The fact that silica gel matrixes are chemically unstable under acidic and basic conditions facilitated the developments of silica matrixes with stable polymer-coating and organic- and inorganic-hybrid silica matrixes, which were used for the preparation of reversed-phase sorbents. Studies on titania and zirconia have progressed especially due to their extreme robustness and unique chemo-affinity for organic phosphates. Titania and zirconia also play important roles in phosphoproteome analysis. Various intelligent materials such as temperature- and photo-sensitve stationary phases, bio-affinity sorbents, molecular imprinting polymers and molecular shape-selective packing materials were reported. The invention of monolith columns is a major innovation in column technology. However, our description about monolith columns was shortened because the related topics were reviewed previously by many authors.

Novel methods for the direct analysis of small amounts of organic components in various polymeric and/or biomaterials were developed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) using solid sampling techniques while avoiding troublesome solvent extraction. At first, a trace amount of oligomeric hindered amine light stabilizer (HALS) in polypropylene (PP) materials was directly analyzed by solid sampling MALDI-MS. In addition, using an internal standard material, the HALS contents in PP could be determined. Moreover, the light-stabilizing action of the HALS component was also discussed through solid sampling MALDI-MS measurements of UV-irradiated PP samples. Next, the condensed tannin components in wood powder samples were analyzed by solid sampling MALDI-MS. The obtained mass spectra showed a series of peaks corresponding to the sodium ion adducts of the condensed tannin oligomers up to around m/z 3000. Then, the intact lipids in a single zooplankter individual at the level of a few tenths of a microgram were analyzed by a direct sampling MALDI-MS. The observed mass spectra of the single zooplankter samples showed a series of ions generated from phospholipids and neutral lipids; this means that the relative quantity between “structural lipids” (phospholipids) and “storage lipids” (neutral lipids) can be estimated for an individual zooplankter, which should give us a good clue to elucidate the roles of each class of lipids during growth. Finally, phospholipids in whole bacteria were characterized by solid sampling MALDI-MS using a so-called “on-probe” sample pretreatment. By this method, a series of peaks derived from phospholipids in gram-negative bacteria were readily observed in the mass spectra. Furthermore, even for gram-positive bacteria with a thicker peptidoglycan, the phospholipid components in whole bacteria were able to be clearly detected by this method using trifluoroacetic acid as an additional reagent for the promoted decomposition of the bacterial cell wall.

A rapid simultaneous assay was developed for determining 63 veterinary drugs in bovine, porcine, and poultry muscles by on-line solid phase extraction (on-line SPE)/high-performance liquid chromatography/tandem mass spectrometry (MS/MS). The drugs were extracted from muscle samples with acetonitrile-methanol (4 : 1, v/v). The extracts were evaporated, and the residues were dissolved with acetonitrile-water (1 : 1, v/v). The samples were injected into an on-line SPE column packed with Oasis HLB using 0.1％ formic acid as a mobile phase, to separate drugs from interfering substances and retain them on it. The drugs were introduced onto an analytical column using 0.1％ formic acid- acetonitrile in a gradient mode by column switching and directed into MS/MS. Under the optimal analytical conditions, the repeatability of the retention time and the peak area of standard compounds were less than 1％ and 12％, respectively. The recoveries of 63 drugs from muscle spiked at 20 ng/g were 45.8〜153％. The detection limits were less than or equal to10 ng/g.

A speciation method for sulfur in petroleum liquids by gas chromatography/inductively coupled plasma mass spectrometry (GC/ICP-MS) was developed. From an investigation of the effects of the ICP-MS operating conditions on the background intensities at m/z 32 and 34, the origin of the contaminated sulfur and the interference of the oxygen molecular ion O₂^＋ with the background were clarified, and countermeasures, such as an alternative GC/ICP-MS interface without using silver brazing, purification of Ar gas by a getter, and alternate cone materials, were quantitatively evaluated for decreasing this contamination and interference. The dependence of the sensitivity and the matrix effect on the ICP output power were also examined, and high sensitivity and low matrix effects were obtained at higher output power. The detection limit was around 0.6 ng S mL^-1, corresponding to 0.05 pg at the ICP-MS detector, taking account of the GC split ratios, which were 2 or 3 orders of magnitude superior to those with GC/FPD and GC/AED and equivalent, or 10 times superior to those with GC/pulsed FPD and GC/SCD. The detector response to sulfur is considered to be essentially equimolar for all sulfur species, but in practice, the sensitivity decreased slightly for a species with a high boiling point. It was speculated that the reason for the low sensitivity was not due to an inefficient ionization in ICP, but due to discrimination at the GC injection port, or decomposition in the GC column. The present method was successfully applied to petroleum liquids, such as naphtha, gasoline, kerosene and light oil. These results were also compared with those by GC/AED and GC/SCD, and showed satisfactory agreement. Although the quenching effects by concomitant hydrocarbons were found to be slightly larger than those observed with SCD, the present method was superior in sensitivity to other conventional methods, and is expected to contribute to the development of low-sulfur gasoline for automobiles and fuels for fuel cells.

The quantitative analysis of different calculation method of regression analysis (DCR) is performed without a calibration curve and separation process. Also, the mixture ratio of an unknown sample is determined from the coefficient of the multiple regression equation using the measured values of two or more known samples and one unknown sample. In the present work, the mixture ratio of small component in food dye mixture was calculated from 431 absorbance data of known and unknown samples measured by a spectrophotometer. As a result of calculations, a small component in a food dye mixture in an unknown sample was determined very correctly by DCR. The detection limit of the small component in the food dye mixture by this method was about 1％. The reproducibility of the purple dye mixture ratio was examined using a test sample (red dye : purple dye＝99.01 : 0.99), and the relative standard deviation from the calculated result was 3.63％. Also, the relative standard deviations of PCR and PLS were 26.36％ and 12.9％, respectively. Furthermore, the existence judgment of a non-recognized small component in an unknown sample of food dye was performed based on the difference in the corrected value and the calculated value.

The detection performance of Dräger safety gas detection tubes for chemical-warfare agents was investigated using authentic compounds. “Phosphoric esther” tubes gave limit of detection (LOD) values of 0.002 (sarin), 0.02 (soman), 0.5 (tabun) and 2.0 (VX) mg/m³ with about 5 min of operation. “Thioether” tubes gave an LOD value of 1.2 mg/m³ (mustard gas) after about 2 min of operation. “Organic arsenic compounds and arsine” tubes gave an LOD of 3.8 mg/m³ (lewisite 1) after about 2 min of operation. “Hydrogen cyanide” tubes gave an LOD of 0.3 mg/m³ (HCN) with less than 1 min of operation. “Cyanogen chloride” tubes gave an LOD of 0.75 mg/m³ (ClCN) with about 3 min of operation. False positive detection was also observed for various simulants.

The Japan Society for Analytical Chemistry has developed plastic certified reference materials (CRMs) for the X-ray fluorescent analysis of four hazardous elements: Pb, Cd Cr and Hg in plastics. Disk samples were prepared by filling Al-cylindrical molds with the raw material liquid of polyester resin mixed with hardener and organometallic compounds. Thus 360 candidate reference materials of JSAC 0631 and 0632 were obtained. Both surfaces on prepared disks obtained after 12 h of hardening at room temperature were ground and polished by a milling machine at 4.00±0.05 mm thick. The homogeneity of the prepared disks was shown excellently. An interlaboratory comparison study was performed by 24 laboratory’s participants. In a statistical evaluation for the interlaboratory study, z-scores in the “robust method” were applied in order to reject outlier. The certified uncertainties for prepared CRMs were determined at in the confidence levels of 95％.

The Japan Society for Analytical Chemistry carried out a sixth proficiency testing for the determination of dioxins (polychlorodibenzo-p-dioxins, polychlorodibenzofurans and dioxin-like polychlorobiphenyls) in wastewater. This proficiency testing of analytical laboratories was based on ISO/IEC Guide 43-1, “Proficiency testing by interlaboratory comparisons”. The testing was carried out from February ’05 to May ’05, with the participation of 105 laboratories. As a result, 93 laboratories (88.5％) were estimated as “satisfactory”, 5 laboratories (4.8％) as “questionable” and 7 laboratories (6.7％) as “unsatisfactory”. Dioxins in wastewater were classified in two groups: existing in SS particulates, and dissolved in water. It was shown from the results that those compounds with a high dissolved state ％, such as many CoPCBs, gave a high CV％ in their analytical results.