Yasuyuki Hoshika

Sensitive gas chromatographic determination of phenols as bromophenols using electron capture detection

Abstract Eight phenols, phenol, o -, m - and p -cresol, 2,3-, 2,5-, 3,4- and 3,5-xylenol, were converted into the corresponding bromophenols by reaction with bromine. The optimum conditions for the bromophenol derivative formation of 10 -8 mol of each phenol in 1 ml of ethanol were as follows: mol ratio (bromine/phenols), greater than 400; reaction temperature, room temperature; reaction time, 4 h. The minimum detectable amount of the bromophenols with an electron capture detector was about 0.01 ng, which is about 100 times less than the minimum detectable amount of the non-bromine-containing phenols.

Gas—liquid—solid chromatographic determination of phenols in air using Tenax-GC and alkaline precolumns

Abstract A simple and rapid gas—liquid—solid chromatograhic method for the determination of trace concentrations (at ppb * levels) of 11 phenols in air has been developed, using a Tenax-GC precolumn and a Tenax-GC plus alkaline precolumn. The phenols were identified and quantitated from the differences between the chromatogram obtained using the Tenax-GC precolumn and that obtained using the Tenax-GC plus alkaline precolumn. Complete separation was achieved within ca . 7 min. No evidence was found for the interference of certain acidic compounds, such as lower fatty acids (C 2 C 7 ) and mercatans (C 5 C 7 . The method was applied to specimens of ambient air near a phenolic resin factory, and of urban air in the Nagoya area.

Simultaneous gas-chromatographic analysis of lower fatty acids, phenols and indoles in faeces and saliva using a fused silica glass capillary column

The simultaneous gas-chromatographic separation of a mixture of 14 lower fatty acids, 11 phenols and 7 indoles was performed by using a fused silica glass capillary column of Carbowax 20M (50 m × 0.2 mm i.d., Carbowax 20M deactivated). Complete separation of the mixture was obtained, except for the peaks of phenols and o-cresol, o-ethylphenol and 3,5-xylenol and pelargonic acid, 2,3-xylenol and 1,2-dimethylindole, whose peaks overlapped, and 2- and 3-methylindoles, which were poorly separated. The optimum conditions are as follows: column temperature, held for 1 min at 100 °C; column oven, heated at 4 °C min–1 from 100 to 220 °C, maintained at 220 °C for 9 min for standard compounds or 29 min for sample specimens, then cooled to 100 °C; and carrier gas (nitrogen) flow-rate, 0.97 ml min–1. The method was applied to the analysis of the lower fatty acids, phenols and indoles in cat and human faeces and non-smoker saliva.

Pattern display for characterisation of trace amounts of odorants discharged from nine odour sources

The odorants discharged from nine odour sources were classified into eight compound groups and were analysed by a systematic gas-chromatographic technique. The characterisation of trace amounts of the odorants was carried out by using the values for new proposed units (pOUm, pOUa, logOU, OUt and OU; all terms are dimensionless) based on the ratio of the detected concentration to the odour recognition threshold concentration. The graphical representation of these data is effective for rapid recognition of the whole state. A polar co-ordinate pattern display was also proposed for the explanation of the relationship between odour characteristics (odour quality and intensity) and chemical analysis data of the odorants responsible for each odour discharged from nine odour sources. The calculated pOUm and pOUa values of eight odorant groups were plotted on polar co-ordinate circular odour charts. These charts illustrated a characteristic pattern and it was found that the shapes and sizes of each odour chart could characterise the quality and intensity of each odour from the nine odour sources. This was confirmed by investigating examples of processes or factories belonging to the nine odour sources.

Gas-chromatographic determination of trace amounts of lower fatty acids in ambient air near and in exhaust gases of some odour sources

The gas-chromatographic determination of trace amounts of the lower fatty acids (C2—C5) in ambient air near and in the exhaust gases of some odour sources was investigated. The sample for the gas-chromatographic determination was prepared by trapping in a pre-column packed with FFAP + orthophosphoric acid (H3PO4) on Carbopack C at 25 and 30 °C. The lower fatty acids were identified and quantitated from the difference between the chromatograms obtained using the FFAP + H3PO4 pre-column and that obtained using the FFAP + H3PO4 plus an alkaline pre-column. The method has been applied to the analysis of lower fatty acids in practical specimens, namely the ambient air near accumulated poultry manure, in a pig pen and a fish meal factory, and in the exhaust gases from a corn starch manufacturing factory and from a poultry manure dryer. The sample volume is as low as about 0.4 l and the method is sensitive (detection limit about 0.5 p.p.b.) and rapid (including the concentration and analysis of one sample, about 15 min are required). The coefficient of variation is less than 6%. This sensitivity and precision are adequate for use in odour pollution analysis.

Gas-chromatographic determination of concentrations of trace amounts of 46 odorants prepared in air in a 10-m3 stainless-steel odour test room

The determination of the concentrations of trace amounts of 46 odorants prepared at odour threshold levels (in parts per billion) in air in a 10-m3 stainless-steel odour test room was investigated by gas chromatography using two pre-concentration methods, namely cold trapping with liquid oxygen and room-temperature adsorption trapping with porous polymer beads, such as Tenax-GC or graphitised carbon black coated with a small amount of stationary phase (SP-1000 + orthophosphoric acid)(0.3 + 0.3% on Carbopack B, 60–80 mesh). The 46 odorants tested were four sulphur compounds, ten lower aliphatic carbonyl compounds, an aromatic hydrocarbon, seven lower aliphatic mono-alcohols, eleven phenols, six lower aliphatic carboxylic acids and seven indoles. The recoveries of the odorants having boiling-points of less than about 150 °C were quantitative, but those having boiling-points of more than 160 °C gave recoveries of about 50%, except for the phenols, which had much lower recovery levels.

Gas chromatographic determination of trace amounts of β-methylmercaptopropionaldehyde (methional) in the free form using flame photometric detection

Abstract The gas chromatographic (GC) determination of trace amounts of β-methylmercaptopropionaldehyde (methional) in the free form using a flame photometric detector (FPD) was investigated. The GC conditions were as follows: stationary phase, 6% DEGS; support, Chromosorb W HP (80–100 mesh); glass column, 2 m X 3 mm I.D., column temperature (programming), holding for 1 min at 100°C, heating the column oven at a rate of 10°C/min from 100 to 190°C, maintaining this temperature for 20 min and then cooling to the initial temperature; carrier gas, nitrogen, flow-rate, 60 ml/min; flow-rates of hydrogen and air for the FPD, each 40 ml/min. The minimum detectable amounts for the methional were ca. 0.3 ng; the repeatabilities of retention times and peak areas (measured as intergrator counts) at 1-ng level of the compound were less than ca. 1.5% and ca. 15%. The percentage recovery in the concentration method by bubbling the nitrogen carrier gas (0.2 1/min, at 28°C) through the standard solution of methional (at 1 ng per μl ethanol) from 10 to 0.5 ml was ca. 72%; however, the percentage recovery of the standard solution (at 10 ng/μl ethanol) after 10 l of the laboratory air had been passed through the impinger containing the standard solution at a rate of 0.5 l/min was 97.5%. The method was applied to the determination of methional in air over waste water from a corn starch factory.

A Case Study of Olfactory Fatigue to an Odorant (Tertiary-Butyl-Mercaptan) in Town Gas in the Matsumoto City Area of Japan

It is important that town gas possess a smell, so that accidental carbon monoxide poisoning can be avoided as far as possible. Tetrahydrothiophene (THT) has been used for this purpose. In the United States, three types of odorant have been used: mercaptans, aliphatic sulfides, and THT, which is chemically stable, economical, and easily added to town gas. In the Matsumoto City area in Japan, tertiary-butyl-mercaptan is added as an odorant to the town gas; however, there is little practical information regarding the constituents and the olfactory fatigue of the odorant in the town gas.

International Comparison of Odor Threshold Values of Several Odorants in Japan and in The Netherlands1

The purpose of this paper is to compare the published odor threshold values of six odorants. In Japan, all of the odor threshold values used in the Offensive Odor Control Law (enacted in 1972) were determined in an odor-free room (4 m3) by a trained panel (20 men, ages 30–45 years who were perfumers) who sniffed the odors directly and made absolute judgments of odor quality and intensity. In The Netherlands, sensorial odor concentration measurements were made with an olfactometer in a mobile sniffing car with eight panelists, four men and four women, ages 18–40 years. Such presentations are repeated with different dilution ratios. Comparison of the threshold data for the six different compounds given as the barely perceptible concentration level revealed striking similarities for hydrogen sulfide (in Japan 0.0005 ppm/in The Netherlands 0.0003 ppm), phenol (0.012/0.010), styrene (0.033/ 0.016), toluene (0.92/0.99), and tetrachloroethylene (1.8/1.2) but not for m-xylene (0.012/ 0.12). Such a similarity was not found with any other literature sources.

A Case Study of Characterization and Continuous Monitoring of Trace Odorants in the Shinshu University School of Medicine Hospital ICU Room Air

Characterization of trace amounts of odorants in the Shinshu University School of Medicine Hospital ICU room (ca.257m2) air was carried out by gas chromatography and API-Mass spectrometry. The main component of the oxygenates in the ICU air was ethanol, 3.53ppm, however, the data was less than the odor recognition threshold value (6.1ppm).