BUNSEKI KAGAKU Abstracts

Nineteen polycyclic aromatic hydrocarbons (PAHs) containing 2 to 7-rings were determined in oil mist emitted during fish grilling. The oil mist was collected depending on the particles size, and the concentration of each PAH was measured by GC/MS. PAHs having 4 to 6 rings were dominantly detected in particle size ranges below a diameter of 3.3 μm, whereas PAHs with 2 to 4-rings accounted for over 90% of total PAHs in ranges over 3.3 μm diameter. In addition, PAHs having 2 and 3 rings showed a bimodal size distribution with peak tops at diameters of 1.1 to 2.1 μm and over 11 μm. On the contrary, PAHs with 5 and 6 rings demonstrated a unimodal size distribution with the peak top at diameters of 1.1 to 2.1 μm. Then, the total concentrations of PAHs were converted into a toxic equivalent (TEQ) of benzo[a]pyrene, depending on the particle size ranges. The obtained size distribution of TEQ was unimodal, having the peak top at diameters of 1.1 to 2.1 μm. TEQ at diameters over 4.7 μm, 1.1 to 4.7 μm and below 1.1 μm corresponds to 8%, 47% and 45% of total TEQ, respectively. This suggest the possibility that around half of the TEQ converted PAHs can reach the pulmonary alveolus region when PAHs containing oil-mists are emitted from fish grilling and inhaled through the respiratory tract.

The analysis of trace elements in cigarettes and cigarette ash using ICP-MS was applied to the forensic discrimination of cigarette samples from different sources. Seven boxes of cigarettes were purchased from 6 different brands; 1 – 5 of 20 sticks in each box were used for experiments. Approximately 50 – 100 mg of cigarette or 20 mg of cigarette ash was taken from a stick, accurately weighed and dissolved into a mixture of 1.5 mL nitric acid and 0.5 mL hydrogen peroxide by heating in a microwave oven. After cooling to room temperature, it was diluted to 20 mL, centrifuged and the supernatant obtained was subjected to elemental analysis using ICP-MS. Rhodium was used as an internal standard for quantitative analysis. The mass spectra of the 7 different cigarettes demonstrated that they contained 11 elements (Cu, Zn, Rb, Sr, Mo, Cd, Ba, La, Ce, Nd and Pb). These elements in NIST 1515 (Apple Leaves) could be determined with RSDs (relative standard deviations) from 0.8% for Cu to 6.0% for Mo and with satisfactory good agreement with the certified or reference values except for Cd. Measured values for cigarette samples taken from 5 different positions within cigarette stick provided RSDs from 2.4% for Cu to 12.9% for Ba; these values were much smaller than most of those among cigarettes from different boxes. Comparisons of the elemental concentrations, except for Zn and Pb, made it possible to distinguish all of the 21 possible pairs among 7 different cigarettes. The concentrations of trace elements in cigarette ash were calculated using the weight ratio (0.21 ± 0.01) of ash to the original cigarette and measured values of trace elements in the cigarette. The measured values for cigarette ash showed good agreement with the calculated ones, except for Cd and Pb, which exhibited significantly lower measured values in ash than the calculated ones.

In recent years, some kind of air or pure-nitrogen atmospheric pressure thermal plasma, used as an ionization and excitation source for ultra trace elemental analysis, have been developed. The cost effectiveness will be dramatically improved if high-density and high-temperature air or nitrogen thermal plasma is realized. However, the temperature and analytical performances of air and nitrogen plasma are lower than conventional argon inductively coupled plasma (ICP). In order to improve the plasma properties, air-ICP with a nitrous monoxide gas additive was studied. The rotational temperature was mesured by using a spectroscopic method for nitrous oxide mixed air-IPC from 0 to 100% of the nitrous oxide conditions; the rotational temperature was slightly decreased from 3200 K to 2700 K. Also, it was found that the plasma volume was enlarged by twice, and the atomic and ionic emission intensity values of the analyte were increased up to 1.5 times when 40% of N₂O gas was added compared to our usual air-ICP.

Polycyclic aromatic hydrocarbons (PAHs) are a group of chemicals released into the air during the incomplete burning of fossil fuels, such as gasoline and other organic substances. Some PAHs are reasonably anticipated to be human carcinogens. In this study, a high-performance liquid chromatography-tandem mass-spectrometry method has been developed for the simultaneous quantification of eight urinary OH-PAHs, including 1-hydroxynaphthalene (1-OH-Nap), 2-hydroxynaphthalene (2-OH-Nap), 1-hydroxyphenanthrene (1-OH-Phe), 2-hydroxyphenanthrene (2-OH-Phe), 3-hydroxyphenanthrene (3-OH-Phe), 4-hydroxyphenanthrene (4-OH-Phe), 9-hydroxyphenanthrene (9-OH-Phe) and 1-hydroxypyrene (1-OH-Pyr) in human urine. Deuterated 3-OH-Phe-d₉ and 1-OH-Pyr-d₉ were used for quantification of the analyte as an internal standard. Considerable amounts of PAHs are present in the workplace. PAHs exposure is reported to exist high in coke plants, aluminium work and paving work. In order to assess the potential health risks posed by exhaust gas from ships, and to obtain a better understanding of the occupational hazards connected with PAHs exposure, the concentration of OH-PAHs in urine collected from mariners has been analyzed. This method was applied to the analysis of OH-PAHs in 29 urine specimens collected from the crews on a ship. The median concentrations of urinary 1-OH-Nap, 2-OH-Nap, 1-/9-OH-Phe, 2-OH-Phe, 3-OH-Phe, 4-OH-Phe and 1-OH-Pyr were 0.36, 0.57, 0.12, 0.07, 0.14, 0.07 and 0.11 μg/g creatinine in the crews, respectively. The developed method was applied to occupational exposure to urine in order to assess human exposure due to the working environment.

This report describes a novel procedure allowing estimation of total PCB concentration in insulating oil by pattern analysis using selected peaks from gas chromatography with electron capture detection (GC/ECD). Two peaks for each of four Kanechlors (total of eight peaks) were selected on the basis of the signal intensity and orthogonality from the 97 distinct peaks corresponding to PCB congeners on the GC-ECD chromatogram. An algorithm is described to fit the measured eight peak pattern in the sample with a weighted sum of the eight peak pattern from each of the four Kanechlor mixtures. The weighted factors correspond to the concentration of individual Kanechlors in the sample, and their sum gives the total PCB concentration. Estimated concentrations of 14 transformer oil samples by the pattern analysis showed a good correlation with both HRGC-HRMS and the standard GC/ECD (analysis of all peaks from the chromatography) until 1.0 mg-PCB kg-oil⁻¹ total PCBs.

A simple, sensitive and rapid quantitative method for polycyclic aromatic hydrocarbons (PAHs) in sediment samples was developed by using thin-layer chromatography (TLC) and a digital camera (DC). This method (TLC-DC method) has three-parts: 1. Separation of different types of PAHs on a TLC plate impregnated with a 6% (w/v) caffeine solution; 2. Excitation of each PAH on the TLC plate by irradiation of a UV lamp and recording of the fluorescence image from each PAH by DC; 3. Analysis of the image data and making calibration curves of PAHs on a personal computer. Anthracene (Anth), fluoranthene (Flu), pyrene (Pyr), benzo[b]fluoranthene ([b]flu), benzo[a]pyrene ([a]pyr), and perylene (Pery) were selected as target compounds. The calibration curves of each PAH obtained in the concentration of 0.01 to 0.3 ppm showed high linearity (R = 0.977 – 0.999). The detection limits for four PAHs (Flu, [b]flu, [a]pyr and Pery) were from 6.8 – 8.8 ng mL⁻¹ (61 – 88 pg per spot), which were almost at the same levels as those by the GC-MS method. Moreover, sediment samples collected at Yoro tidal flat were pretreated. Their PAH concentrations were measured by TLC-DC and GC-MS methods. The PAH concentrations of the sediment samples were 2 – 8 μg kg-dry⁻¹ by the standard addition TLC-DC method, and the values obtained were in good agreement with the values obtained by the internal standard GC-MS method. These results concluded that the TLC-DC method is useful for the quantification of four kinds of PAHs, benzo[a]pyrene, fluoranthene, benzo[b]fluoranthene, and perylene in sediment samples.

Ethanol diluted (1 wt%) ionic liquid 1-ethyl-3-methylimidazolium acetate is used in order to avoid the charge-up of insulator specimen for scanning electron microscope (SEM) analysis. SEM-EDX analysis is additionally performed for the specimen treated by the ethanol diluted ionic liquid. As an example of the insulator specimen, we analyze volcanic ash particles, and succeed to discriminate the elemental composition difference of a specimen surface within 10 μm² micro area. Though a clear secondary electron image of the volcanic ash particle of which diameter is less than 10 μm can be obtained without electric conductive treatment, particles of diameter larger than 20 μm are needed to be treated by the diluted ionic liquid to avoid the charge-up effects.

Acid distillation is commonly carried out before the determination of total cyanide in aqueous samples to decompose metal-cyano complexes into HCN. We designed the miniature distillation apparatus, which consists of a 20 mL distillation tube, a 30 mL outer tube as a receiver, and an inner tube for air cooling. This apparatus (16 cm in width, 40 cm in height, and 27 cm in depth) was equivalent to about one-tenth of a standard distillation system in size. Sample and reagent solutions used were reduced to one-fiftieth of those used in the standard method. The proposed procedure is as follows: 5 mL of a sample, 0.2 mL of phosphoric acid (85%), and 0.2 mL of EDTA (100 g L⁻¹) were added to the distillation tube. Then, 2 mL of NaOH (20 g L⁻¹) was added to the outer tube, in which the inner tube was covered. A maximum of 8 sets were heated by a dry block bath at 150℃ for 20 min. The CN⁻ in the distillate was determined by FIA. Under the distillation conditions, potassium hexacyanoferrate as well as KCN was converted into HCN, whereas thiocyanate was not. The CN⁻ was completely recovered from a KCN solution (0.05 mg L⁻¹ as CN) in the presence of Fe(III) (≤1000 mg L⁻¹), Mn(II) (≤100 mg L⁻¹), and Zn(II) (≤100 mg L⁻¹). Satisfactory recoveries of CN⁻ were found for a recovery test using the leaching solution from soils. The proposed distillation method is easier to operate, and reduces the distillation time, space, and consumption of chemicals and energy.

The quantitative analysis of amino acid is widely used in many analysis fields. Purity evaluations of amino acids are essential to prepare accurate calibration solutions for amino acid analysis. In this paper, the purity determination of L-lysine hydrochloride with using neutralization titration is discussed. Removing hydrogen chloride from a sample solution of L-lysine hydrochloride is important to determine the purity by neutralization titration. For an accurate purity determination of L-lysine hydrochloride, the condition in sample preparation was optimized. Under the optimized conditions, the purity of L-lysine hydrochloride could be determined with 0.03% to 0.07% of repeatability. The uncertainty of the measurement could be estimated at about 0.1%. Moreover, the determined purity value was in good agreement with the purity value from nitrogen analysis. The optimized condition is valid for the purity analysis of lysine hydrochloride.

Nuclear magnetic resonance (NMR) spectra have mainly been used for qualitative analysis, such as molecular structure analysis. In the present work, the analytical parameters were considered to apply to accurate quantitative analysis. In optimizing the analytical parameter, the influences for results on baseline correction and integral range were considered. In this result, optimized analytical conditions for quantitative NMR were determined. The purity of 17β-estradiol (NMIJ CRM) was measured under optimized conditions. The result of a purity analysis corresponded within the range of a certified value, and verified the use of NMR for accurate quantitative analysis.

Gas chromatographic analysis with atomic emission detection (GC-AED) was performed for 17 chemical warfare agents (CWAs) and their 17 related compounds. Specific hetero elements in all CWAs and their related compounds were clearly detected, and their detection limits, linearity of their calibration curve, and within-day variability were evaluated. Some CWAs could be identified with respect to their peak area ratios of their hetero elements and their retention indices. GC-AED can be a powerful tool for screening CWAs in a complex matrix.