Study On Detection Of Banned Azo Dyes In Textiles

In view of the current situation of banned azo dye detection in China, the pretreatment of prohibited azo dyes detection is carried out in the operation described in GB/T1759 - 2006 "determination of prohibited azo dyes in textiles".

Therefore, without affecting the final test results, it is necessary to study a new efficient and accurate pre-processing method.

1 test part

1.1 instruments and reagents

Instrument: GC/MSD (7890A/5975C, Agilent Technology Co., Ltd.); constant temperature water bath oscillator; rotary evaporator;

Reagents (all analytically pure): sodium hydroxide, citric acid, sodium hydroxide and ethyl ether.

The sodium citrate buffer solution (0.06 mol/L, pH= "6") was allocated: 12.526 g citric acid and 6.320 g sodium hydroxide, dissolved in water, and fixed capacity to 1000 mL.

It contains two sodium sulfite solution: 200 mg/mL aqueous solution.

When used, the solid is prepared with two sodium sulfite (content equal to 85%) fresh.

1.2 test method

1.2.1GB/T17592 - 2006 method

1) sample preparation and treatment: according to the regulations of GB18401 2003, the samples are cut into 5 mm * 5 mm pieces and mixed evenly, and 1 g (accurate to 0.01 g) is selected, placed in the reactor, 16 mL is added to the sodium citrate solution at 70 degrees Celsius, the reactor is sealed, and the force is shaken, so that all the samples are soaked in liquid, placed in a constant temperature water bath oscillator at 70 degrees Celsius, and heat preservation at 70 (70 + 2) centigrade min, so that all fabrics are fully wetted.

Open the reactor, add 3 mL to two sodium sulfite solution, and immediately close the shake, then reposition the reactor at (70 + 2) centigrade, holding the heat for 30 min, and then cool it to room temperature at 2 min.

2) extraction and concentration: using glass rods to squeeze the sample into the extraction column, the reaction solution was absorbed into the extraction column for 15 min, and the samples were washed with 80 mL ether for four times. The samples were mixed with ether and sample each time, then the ether solution was poured into the extraction column to control the flow rate, and the ether extract was collected in the flask.

The above cylindrical bottomed flask containing ether extract was placed on a vacuum rotary evaporator, concentrated at low temperature of 35 degrees and reduced to nearly 1 mL, and then the ether nitrogen solution was deactivated by nitrogen slow flow to concentrate near dry.

1.2.2 centrifugation

1) sample preparation and treatment: 1 with 1.2.1).

2) extraction and concentration: add 5 mL ether to the reactor, shake it vigorously, then put the reactor into centrifuge, centrifuge at 1500 r/s, centrifuge 2 min, separate the solution in the reactor, absorb the upper ether in the bottom flask, repeat the above operation 2 times.

The above round bottomed flask containing ether extract was placed on a vacuum rotary evaporator, concentrated at low temperature of 35 degrees and reduced to nearly 1 mL, and then nitrogen ether was used to depress the ether solution and concentrate to near dry.

1.3 qualitative and quantitative analysis by gas chromatography / mass spectrometry

The banned decomposable aromatic amine solution extracted from diatomite solid phase extraction column and centrifugation was qualitatively determined according to the analysis method specified in GB/T17592.6.3.1 - 2006.

According to GB/T17592.6.4.2 - 2006, internal standard method was used for quantitative analysis of banned decomposable aromatic amines.

1.4 standard recovery test

In order to verify the feasibility of centrifugation test, a mixture of aromatic amine was designed.

Table 1 experimental results of centrifuge recovery

Standard sample for aromatic amines / (mg/kg) recovery / (mg/kg) recovery /%

4- chloro - toluidine 23.2823.2699.91

P chloro aniline 20.6520.6299.85

2- methoxy -5 methylaniline 26.5826.5699.92

34.2434.299.88, O - toluidine

2, 4- two amino toluene 31.7826.4683.26

2, 4, 5- three methyl aniline 19.7516.6884.46

24.3524.399.79 anisole

2, 4- two methyl aniline 44.2243.0897.42

2- naphthalene 18.3915.8185.97

2, 4- two amino anisole 19.7716.3282.55

4- amino biphenyl 24.4420.0482.00

O amino azo toluene 24.2123.0595.21

4, 4 '- two amino two benzyl methane 26.321660.79

3, 3 '- two chloro - aniline 23.3523.399.79

3, 3 '- two methoxy benzidine 28.5913.5747.46

3, 3 '- two methyl benzidine 19.9511.859.15

3, 3 '- two methyl -4, 4' two amino two benzyl methane 27.5916.5559.99

4, 4 '- methylene two - (2- chloraniline) 22.92296.07

4, 4 '- two amino two phenyl ether 19.713.669.04

4, 5 '- two amino two phenyl sulfide 25.4413.7153.89

5- nitro - O - toluidine 31.9623.7474.28

4- amino azobenzene 22.5118.9984.36

1.5 comparison test

In the design test, the detection rates of various aromatic amines were compared with the two methods, as shown in Table 2.

Table 2 Comparison of test results

Methods GB/T17592 - 2006 centrifugation

Number of aromatic amine concentration / / (mg/Kg) matching concentration / (mg/Kg) matching number detected

1 para chlorobenzene 6.5796%8.0696%

25- nitrotoluidine 24.7794%20.7294%

32, 4- two amino toluene 90.8296%88.6496%

42- methoxy -5- methylaniline 333.0278%333.5278%

54- amino biphenyl 595%7.4695%

6 benzidine 75495%68195%

73, 3 'two methyl benzidine 22598%284.598%

83, 3 'two methoxy benzidine 234098%182098%

9 o toluidine 18394%18194%

2 Result Analysis

From table 1, we can see that the two methods have good consistency in the detection of aromatic amines, and their concentration differences are within the standard requirements. Combined with the advantages of centrifugation, centrifugation can be used instead of standard methods to do experiments.

From table 2, it is known that the recovery rate of banned aromatic amine dyes in 23 of the GB/T18401 2003 regulations is over 70%, and the test reliability is high.

3 conclusion

1) in the testing of prohibited azo dyes in textiles, under the premise of ensuring the accuracy of the results, centrifugation can omit the extraction process through the extraction column, save the experimental time and save the test cost, so the centrifugal method can significantly improve the experimental efficiency.

2) the centrifugation method requires a high degree of experimenter. In the liquid-liquid extraction process, the ether must be completely sucked into the flask, and the lower layer of water should not be taken in to ensure the accuracy of the results.

3) for some fabrics with good water absorption, the lamination is not obvious after centrifugation. It is easier to suck water into the flask. Therefore, this method is not suitable for strong absorbent samples. It is suggested that this method be selected according to the actual situation.

4) the standard method is recommended for the identification of samples with banned aromatic amine dyes.