The detection method of N-methylaniline
In this study, a gas chromatography/mass spectrometry (GC/MS) method was developed for the detection of N-methylaniline in textile products. N-methylaniline is an amine substance for which there is currently no detection method. However, the currently promulgated and implemented safety performance testing methods, especially footwear testing, have testing requirements for N-methylaniline.
N-methylaniline; gas chromatography/mass spectrometry; detection method;foreword
N-methylaniline is often used as a rubber accelerator in industrial production [1, 2], but it has certain toxicity, can enter the skin and cause poisoning, causing damage to the nervous system, immune system and other systems , N- Methylaniline is an amine substance for which there is currently no detection method. However, the currently promulgated and implemented safety performance testing methods, especially footwear testing, have testing requirements for N-methylaniline. Therefore, it is necessary to establish corresponding methods to meet the needs of detection.
1.1 Instruments and Reagents
Agilent 7890 gas chromatograph equipped with 5977B mass detector (Agilent); KQ-250DB ultrasonic generator, power 100W (Kunshan Ultrasonic Instrument Co., Ltd.); BUCHI automatic concentrator (Vacuum Controller V-850 Rotavapor R-215) .
N-methylaniline (99.0%, Dr. Ehrenstorfer, Germany) ethyl acetate, n-hexane and methanol were chromatographically pure (Tedia, USA); dichloromethane was analytically pure (Sinopharm Chemical Reagent Co., Ltd.)
1.2 Sample preparation
Take a representative sample, cut it into pieces below 5mm × 5mm, and mix well. Weigh 1.0g (accurate to 0.01g) sample, put it in a 100mL conical flask with stopper, add an appropriate amount of methanol, remove the sample with methanol, and extract in an ultrasonic generator for 30min. Filter the extract into a 50mL volumetric flask. The residue was then ultrasonically extracted with an appropriate amount of methanol for 10 min, and the filtrates were combined, concentrated to near dryness with a rotary evaporator, and made up to 1.0 mL with methanol for gas chromatography-mass spectrometry and sample injection analysis.
1.3 Instrumental Analysis
Analysis conditions: DB-5MS capillary column (30.0m×0.25mm×0.25μm); inlet temperature 250°C; GC and MS interface temperature 300°C; heating program: initial temperature 60°C, then 25°C/min The rate was heated to 300 °C for 5.00 min; carrier gas: high-purity helium (> 99.999%). EI ion source temperature 250°C, 70eV; quadrupole temperature 150°C; injection volume 1.0 μL. N-methylaniline chromatogram.
2.1 Linear range and detection limit
The limit of detection was calculated according to the signal-to-noise ratio of 3 times, and the limit of quantification was calculated according to the signal-to-noise ratio of 10 times. The detection line of this method was 0.15mg/kg, and the limit of quantification was 0.5mg/kg. Standard work for N-methylaniline Curve, obtain the equation and correlation coefficient of linear correlation, the correlation coefficient reaches 0.9992.
2.2 Precision and recovery
0.5, 2, and 4 mg/kg of N-methylaniline were added to the negative leather samples, respectively. Gas chromatography-mass spectrometry instrument analysis, 6 parallel experiments were performed for each level of addition, and the recovery and precision were calculated, and the data results in Table 1 were obtained. Table 1 shows that the recovery rate is between 91.4% and 98.7%, and the RSD value is 5.79% to 7.89%, which meets the requirements of the promulgated and implemented safety performance testing methods, especially the testing requirements for N-methylaniline in footwear testing.
Table 1 Spiked recovery and precision of 2,4-diaminotoluene (n=6)
The identification of N-methylaniline in textile products by gas chromatography/mass spectrometry (GC/MS) was established. Results The N-methylaniline showed a good linear relationship with the chromatographic peak area within the range, and the correlation coefficient was greater than 0.999. The recovery range of different addition levels was between 91.4% and 98.7%. The concern about the measurement operation status of gas color measurement equipment provided in this paper, the publicity of the corresponding measurement management technology in the industry is not enough, because the technology promotion is not timely, the effective use of the detection equipment in the industry cannot be guaranteed, which is not conducive to the better measurement of water transportation projects. develop.
4.Analysis of the current situation of measurement management
Judging from the current situation of measurement of water transportation engineering testing equipment at home and abroad, foreign countries pay more attention to the investment in water transportation engineering measurement equipment. Local governments and national quality inspection agencies have a strong guiding role, which can give water transportation engineering testing equipment measurement work. attention and attention. However, the domestic quality inspection agencies do not pay enough attention to the water transportation measurement work, especially the water transportation engineering testing equipment cannot take effective measures to strengthen the measurement management in time, and the management personnel cannot play their functions  . There are also certain differences between foreign and domestic water transportation engineering testing equipment measurement management technology. It is necessary to actively improve domestic testing equipment measurement management technology, and further explore innovative strategies for testing equipment measurement management.
5.Strategies for optimizing the measurement management of water transportation engineering testing equipment
5.1 Strengthen system construction
In the development process of water transportation projects, in order to improve the standardization and unity of measurement management, it is necessary to effectively grasp the current status of measurement of testing equipment, actively optimize the measurement management system, and vigorously promote the construction of the system, which provides an excellent working environment for the measurement of water transportation engineering testing equipment. In a good atmosphere, strengthen the timely supplement and improvement of the current measurement management system, and timely find system defects, so as to timely fill and deal with them  . Build a standard system for measurement management of water transportation engineering testing equipment, attract more technical talents, set up a special measurement management agency, and further strengthen the measurement management function. During the construction of the system, the measurement awareness and safety awareness of the measurement staff have been greatly improved. An excellent metrology work environment has been created to promote the initiative and enthusiasm of the staff. Under the favorable environment of system construction, the Company consciously follows the standard operation of metrology management of testing equipment, strictly implements metrology management measures, and formulates rules and regulations. Effectively improve the current systems such as the regular maintenance system for equipment, work specifications for measurement departments, and personnel inspection specifications. On the basis of a sound management system, the efficiency of measurement management will be greatly improved.
5.2 Strengthen measurement supervision
Strictly manage and supervise the measurement work, and effectively play its own role in supervision. According to the implementation of the established supervision system for the measurement of water transportation engineering testing equipment, actively carry out strict inspections on the operation status of the testing equipment, and timely discover the technical problems of the measuring instruments. Effectively check the safety hazards in the measurement work, and actively improve the supervision level of the measurement work . Establish and improve the measurement work supervision mechanism, comprehensively analyze and consider the problems arising in the measurement supervision, and improve the supervision awareness of the department personnel. Introduce modern measurement methods, innovate measurement work supervision modes, especially further improve measurement supervision methods, and strictly supervise and manage measurement work by adopting new methods.
In summary, in order to improve the measurement management level of water transportation engineering testing equipment, it is necessary to vigorously promote modern measurement technology, actively play the guiding role of government departments, strictly follow the standardization system to carry out measurement management, and conduct regular maintenance and measurement of existing equipment. The department’s work norms, personnel supervision and inspection mechanism and other systems have been effectively improved, and the management system has been improved. Strengthen the post-event supervision of the measurement of water transportation engineering testing equipment, and provide strong technical support for the construction of the water transportation industry.