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Determination Of Harmful Components In Adhesives By Gas Chromatography

2008/8/9 10:27:00 41774

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The main toxic and harmful chemical components in adhesives are benzene, toluene, xylene, hexane and trichloroethylene. Unqualified adhesive products can cause skin damage, asphyxia, lung disease, gastrointestinal dysfunction, nervous system damage, reproductive toxicity, cardiovascular diseases, hematopoietic system damage and carcinogenesis.

The limits of harmful substances in adhesives for interior decoration and finishing materials in China have stipulated the limits of benzene, toluene and xylene in solvent based adhesives and water-based adhesives.

Determination of benzene content in existing adhesives and gas chromatography for determination of toluene and xylene in adhesives. However, the content of benzene, toluene and xylene should be determined separately. There is no method for the determination of hexane and trichloroethylene in adhesives.

In recent years, with the widespread use of adhesives, the number of occupational poisoning incidents has increased.

For this purpose, we have established a gas chromatographic method for the determination of benzene, toluene, xylene, hexane and trichloroethylene in adhesives, and verified by gas chromatography-mass spectrometry. It shows that the method can simultaneously qualitatively and quantitatively analyze benzene, toluene, xylene, hexane and trichloroethylene in samples, and is suitable for the content analysis of benzene, toluene, xylene, hexane and trichloroethylene in adhesives.

Materials and methods

1 instruments and conditions: HP6890N gas chromatograph, equipped with FID detector; chromatographic column: key and polyethylene glycol (HPwax), 30m x 0.32mm x 0.5 m; inlet mode: no shunt; column temperature: 30 C (5min) heating, 10 C min, 150 C 5min; vaporization chamber temperature: 200 c; detector temperature: 200 c; carrier gas: nitrogen; flow rate: 2.4mlmin.

2 reagents: benzene, toluene, xylene, hexane and trichloroethylene are chromatographic pure; N, N two methyl formamide (DMF) are analytically pure.

3 methods: (1) standard curve drawing: weighing method, using DMF to prepare benzene, toluene, xylene, hexane and trichloroethylene standard reserve solution respectively.

Before starting the determination, the series of mixed standard solutions was diluted with DMF. The concentration of benzene was 7.33, 14.65, 29.30, 73.25, 146.50mgL, and the concentration of toluene was 7.23, 14.45, 28.90, 72.25 and 144.50mgL. The xylene concentration was 7.21, 14.42, 28.84, 28.84 and 144.20mgL. The concentration of n-hexane was 7.21, 14.42, 7.21, 131.80mgL, and trichloroethylene.

The retention time of benzene, toluene, xylene, hexane and trichloroethylene were 5.738, 8.267, 10.259, 1.539 and 7.227min respectively, respectively. The standard curve was drawn according to the retention time, and the peak area was used to draw the concentration curve respectively. The injection time was 1 L.

(2) sample determination: weigh 0.4 ~ 0.5g adhesive sample, place it in 10ml test tube, dissolve with DMF and scale to scale, shake well.

A 10 L syringe was used to sample 1 L and determine the peak area.

If the component content in the sample is larger than the peak area in the standard series, the sample will be diluted.

The contents of benzene, toluene, xylene, hexane and trichloroethylene in the samples were calculated by the standard curve.

Two, results and discussion

1 choice of dissolved reagents: synthetic adhesives, such as chloroprene rubber, styrene butadiene rubber, phenolic - chloroprene rubber, phenolic - NBR and so on. In general, some organic solvents are used as solvents for adhesives, and there are often toxic and harmful compounds.

When choosing the solvent to dissolve the sample, the commonly used solvent acetone is not suitable for the dissolution of the sample. It is not suitable for the solvent of the sample. The methanol has a good solubility for the adhesive, but when the chromatography is separated, the signal is large, affecting the determination of harmful compounds. According to the characteristics of the adhesive, we choose the DMF which has good solubility and does not interfere with the determination of harmful compounds.

2 selection of chromatographic conditions: according to the physical and chemical properties of the tested compounds, large diameter capillary bonds and polyethylene glycol chromatographic columns can be used to separate non-polar benzene, hexane and polar xylene, toluene and trichloroethylene. The column temperature conditions are very low initial temperature and programmed temperature. The compounds can be well separated and the possible coexistence of ethanol, acetone, ethyl acetate, two chloroethane, chlorobenzene, two methyl sulfoxide, cyclohexanol, acetonitrile and nitrobenzene are not interfered.

3 the determination range and detection limit of the method: using this method, benzene has good linear relationship from 7.33 to 146.50mgL, toluene in 7.23 ~ 144.5mgL, xylene in 7.21 ~ 144.20mgL, hexane in 6.59 ~ 131.80mgL, trichloroethylene in 14.64 ~ 292.80mgL range.

The regression equation of benzene is ^Y=1.21X+1.01, the correlation coefficient is r=0.999; the regression equation of toluene is ^Y=1.14X+0.12 and r=0.999; the regression equation of xylene is ^Y=1.09X-0.28, r=0.999; the regression equation of hexane is ^Y=0.92X+0.82, r=0.999; the regression equation of trichloroethylene is ^Y=0.25X+ 0.50, r=0.999.

The detection limits of benzene, toluene, xylene, hexane and trichloroethylene were 0.20, 0.20, 0.20, 0.20 and 2.00mgL respectively, and the lowest detectable concentrations of benzene, toluene, xylene, hexane and trichloroethylene were 0.005, 0.005, 0.005, 0.005 and 0.040gkg respectively.

4 the accuracy of the method: 4 copies of each 300mg adhesive were added to the 10ml test tube respectively, and 3, medium, and high concentrations of benzene, toluene, xylene, n-hexane and trichloroethylene were added into the 3 test tubes. The standard solution was determined by DMF, then the sample solution and the standard solution were determined respectively. The recovery rate of benzene, toluene, xylene, hexane and trichloroethylene were calculated according to the determination results.

The results showed that the recovery rates of benzene, toluene, xylene, hexane and trichloroethylene were 3, 96.38%, 100.08%, 98.89% to 101.66%, 97.99% to 100.40%, 92.37% to 105.96% and 99.22% to 100.56%, respectively, which all met the requirements of detection (table 100.56%).

5 method precision test: Take 1 l sample for injection, repeat 6 times, calculate the relative standard deviation (RSD) of the peak area, and result the RSD of the two concentration is 1.81% ~ 3.67%, the result is shown in Table 2.

The 6 part is the result of sample determination: by using this method, all kinds of adhesives, such as all-purpose adhesive, strong glue, neoprene adhesive, polyurethane adhesive and instant dry glue, are tested by gas chromatography and gas chromatography-mass spectrometry. Benzene, toluene, xylene, hexane and trichloroethylene are all detected in all kinds of adhesives. The results of two methods are in good agreement, indicating that the method is accurate and feasible for the detection of toxic and harmful compounds in adhesives.