BUNSEKI KAGAKU Abstracts

In this article, novel methods based on reaction gas chromatography are proposed to give SI-traceable characteristic values to compounds of interest in an organic standard material. In order to the assure reliability of an analytical value, its traceability is indispensable. Usually, in that case, standard materials whose characteristic values have their own uncertainties are needed to prepare the calibration curve. It is, however, difficult to obtain such standard materials. To prepare such a standard material, it costs a lot of money, and is time consuming. Therefore, a limited number of standard materials are available, and they are expensive. A study was carried out in order to prepare SI-traceable standard materials more simply. The systems that connected one or two parts using a technique for chemical conversion by reactions between a column and a detector were developed. Especially, the system that connected an oxidizing part and a reducing part in series between the column and the flame ionization detector (FID) showed excellent results. In this system, components to be evaluated were separated by the column, changed to carbon dioxide by oxidation, then reduced to methane, and detected with FID as methane. Both reaction efficiencies in the two reaction parts, oxidation to carbon dioxide and reduction to methane, were proved to be 100%. The proposed method was validated using SI-traceable standard materials. Verification of the reaction efficiencies of the two reaction parts were established using SI-traceable standard materials, too. In this verification, the relation between the atomic concentration of carbon measured as methane and the chromatographic peak area, namely the linear regression was, obtained. At first the system was calibrated using SI-traceable standard materials that did not contain ethane; then, an ethane standard material whose characteristic value was determined by gravimetry was measured. The obtained value was SI-traceable. This value and the characteristic value were in agreement with each other. The proposed method can be applied to organic compounds that consist of three elements: carbon, hydrogen, and oxygen. SI-traceable values of the compounds of interest in the organic standard materials can be obtained without each target compounds' standard materials by this method.

An atomic emission detector (AED) equipped with an in-tube micro plasma torch (in-tube MPT) using helium radio-frequency plasma (RFP) was prepared for gas chromatography (GC). An in-tube MPT was prepared by inserting a platinum tubular electrode for ground (0.3 mm i.d., 0.5 mm o.d.) in that for high-voltage RF applications (0.8 mm i.d., 1.0 mm o.d.) at 0.5 mm depth. The head of an optical fiber was inserted and fixed in the electrode for high voltage, and the end was connected to a compact CCD spectrometer. The electrode for ground was connected to a quartz capillary for GC in order to introduce the mixture of the make-up gas, carrier gas and analyte vapors. The prepared AED was set on a conventional GC for measurement. When thioanisole was used as a sulfur compound for the GC-AED measurement, the detection limit of sulfur was estimated to be 4 pg s⁻¹ by a calculation. This calculation used the standard deviation (σ) obtained by a blank measurement and the slope of the calibration curve (a) (D = 3.3 σ/a) at a detection wavelength of 921.3 nm with an applied power of 2 W, applied frequency of 230 kHz and a flow rate of make-up gas of 14 mL min⁻¹. In the case of triethyl phosphate as a test phosphorus compound, when the detection wavelength, applied power and frequency, and the flow rate of the make-up gas were set at 253.4 nm, 3 W, 230 kHz and 12 mL min⁻¹, respectively, 22 pg s⁻¹ was obtained to be the detection limit for phosphorus by the same estimation method.

Within a house, there are usually small amounts of drifing odors. Certain chemical compounds, such as methyl mercaptan, trimethylamine and indole, are generally known as the key compounds of the feces-and-urine odor of restrooms and the garbage odor of the kitchen. However, details about the odor ingredients of the bedroom have not yet been reported, and such an odor is often mentioned with "the feeling of a muffled odor" according to the words of most people questioned. In this study, we utilized four kinds of passive-type solid-phase micro extractions (SPME) that would be easy for the subjects of this research. We also combined those devices with a gas chromatography spectrometer (GC-MS) to analyze the actual situation of the odors in some family bedrooms. As a result, we identified C_2-9 fatty acids, C_9-10 aldehydes, and methyl ketone as common components of the odor in all family bedrooms. Since these components were also detected from pillow cases and underwear that had been used by a family, we assumed that the actual situation of the odor in the bedroom was caused by compounds formed by the oxidative decomposition of unsaturated sebum attached to the used bedclothes.

A method for the simultaneous determination of 1,4-dioxane, epichlorohydrin, 2-methylisoborneol (2-MIB) and geosmin in water by headspace solid-phase microextraction (SPME)-gas chromatography–mass spectrometry (GC/MS) is described. A carboxen (CAR)/polydimethylsiloxane (PDMS) SPME fiber was chosen. The small pores in carboxen particles make this carbon molecular sieve particularly effective for extracting small molecules, like 1,4-dioxane and epichlorohydrin. This method achieved one tenth of the regulated concentration values required in Japanese water regulation, and provided good repeatability with RSD values of between 2.0 and 7.7% at the concentration. The method provided linear ranges from 1 to 100 μg L⁻¹ for 1,4-dioxane, 40 to 4000 ng L⁻¹ for epichlorohydrin, and 1 to 100 ng L⁻¹ for 2-MIB and geosmin. The extractabilities of 1,4-dioxane, epichlorohydrin, 2-MIB and geosmin from a tap-water sample spiked at 10 μg L⁻¹, 400 ng L⁻¹, 10 ng L⁻¹ and 10 ng L⁻¹, respectively, were between 95.7 and 104.6% with RSD values of between 1.4 and 2.4%.

A portable Curie-point probe was developed to use for pyrolysis-GC analysis and VOC analysis. The pyrolyzates or VOC can be injected into the injection port of GC/MS by this probe in the same manner as a micro-syringe injection. Generally, conventional pyrolyzers have been fixed mechanically onto the injection port of GC; its installation requires several hours, when concerning the mechanical setting operation and waiting for the stabilization of GC/MS. However, the developed probe was adopted without any mechanical setting. On the other hand, the furnace temperature in the developed probe can easily rise up and cool down very quickly; also, the maximum heating time is 15 s. Thus, the surface temperature of the probe is almost at room temperature. Thus, the operator can handle the probe without being burned. Cold spots are not found in the probe. Accordingly, higher boiling-point compounds, up to carbon number 72 (seventy two) of hydrocarbons can be detected from the pyrogram of polyethylene. RSD of pyrolysis-GC analysis and VOC analysis were obtained as less than 1% and less than 10%, respectively. Also, both calibration curves for pyrolysis-GC analysis and VOC analysis show a quite linear relation. As an application of VOC analysis, components-analysis was performed for the defense gas of Japanese Kamemushi (Halyyomorpha picus).

A method for determining 305 pesticides by GC/MS using synchronous SIM/Scan acquisition is described; 111 pesticides that could not be detected adequately in the scan mode among the 305 pesticides were selected for SIM acquisition. The other 194 pesticides were acquired in the scan mode. The SIM/Scan method allowed us to detect 301 pesticides at 0.02 ppm (test solution) in a single run. The method dramatically increases the number of compounds in a single run with high sensitivity. The recovery of the method was tested by a replicate analysis (n = 3) of seven agricultural products spiked with standards at 0.05 ppm using sample preparation based on the Ministry of Health, Labour and Welfare. Good recoveries were obtained for about 80% of pesticides with values of between 70 and 120%. Furthermore, screening software with deconvolution (NIST AMDIS) using the database of the mass spectra and retention times of 429 pesticides is also described. Scan data in SIM/Scan acquisition was used for screening. The software was useful for screening 429 pesticides in non-spiked agricultural products by optimizing the AMDIS settings.

A novel system based on continuous gas-liquid counter-current flow extraction has been developed to determinate trace volatile organic components in aqueous samples. Under different conditions, the gas-liquid partition of 2-methylisoborneol and geosmin is theoretically described using this system. The results demonstrate that their mass transfer can be achieved at a level of the theoretical values; therefore, its extraction efficiencies are far higher than those of purge-and-trap (PT). To resolve problems with time-consuming of the headspace having a multi extraction-trapping mode, this methodology is also applied to an on-line monitoring system of musty odor substances in river water. Finally, the novel system is capable of determining musty odor substances in river water with high turbidity, and volatile organic compounds in aqueous samples, such as milk and beverages containing foaming substances, although applying the PT system is difficult for these samples.

Automobile exhaust is considered to be an important emission source of air pollutants; it is thought that measurements of Hazardous Air Pollutants (HAPs) concentrations are important for the reduction of HAPs in atmospheric environment. Proton Transfer Reaction/Mass Spectrometry (PTR/MS) has been applied for measurements of HAPs in the atmospheric environment, because of high sensitivity detection in real time. Then, PTR/MS was investigated concerning a possibility of being used for on-line-real-time measurement of the HAPs exhaust from automobiles. Gasoline was analyzed in combinations of GC and PTR/MS, and it was clearly shown that a few interference ions are generated from other compounds. Moreover, automotive exhaust concentration measurements become difficult due to a reduction of emission concentration, it is very important to know the availability that the sub ppb order compounds can be detected by PTR/MS.

This research examined gas chromatograph/mass spectrometer (GC/MS) measurements for nicotine and 4-ethenylpyridine, which are passive smoking markers of environmental tobacco smoke. Since the object ingredient was a polar compound, a comparison examination was performed using both a non-polar column (DB-5) and a mid-polar column (DB-17) for analysis. Of the two columns, as a result of comparing the peak shape, sensitivity, and linearity, it was found that DB-17 is suitable for measuring nicotine and 4-ethenylpyridine, which is a substitute compound of 3-ethenylpyridine. When the nicotine concentration determined by the GC/MS method was compared with that of the GC/FID method, which was the regulating method, the concentration as determined by the GC/MS method was about 30% lower than that of the GC/FID method. It was suggested that measurements by GC/FID include other organic components. When tobacco smoke (the gaseous and particle components of mainstream smoke and sidestream smoke) was measured using this GC/MS condition, nicotine was detected in all samples, except for the gaseous component of the mainstream smoke, and 3-ethenylpyridine was only detected in the gaseous component of sidestream smoke.