Method for detecting trace N-nitrosamine compounds in water

Abstract

The invention belongs to the technical field of environment detection and analysis, and particularly relates to a method for detecting trace N-nitrosamine compounds in water. According to the method, a headspace solid-phase microextraction device with a dehydration and heat insulation device is used for extraction, the dehydration and heat insulation device is installed between a to-be-detected sample container and an extraction handle, the dehydration and heat insulation device comprises a double-layer quartz tube, degreasing cotton and a dehydrating agent, and the degreasing cotton with the dehydrating agent is placed at the top end of a ventilation connecting pipe of the dehydration and heat insulation device; and the bottom end of the ventilation connecting pipe is arranged above the to-be-tested sample. After the dehydration and heat insulation device is additionally arranged, the extraction temperature and the stirring speed can be increased, the extraction time is saved, and the problems of damage to an extraction head and a gas chromatographic column and desorption caused by water vapor adsorption possibly caused by too high temperature are solved; and the gas space above the liquid level is reduced by using the dehydration and heat insulation device, the adsorption of an object to be detected in a gas environment is promoted, the detection limit reaches 0.05-0.1 ng / L, and the recovery rate is 90-103.2%.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental detection and analysis, and particularly relates to a method for detecting trace N-nitrosamine compounds in water. Background Art

[0002] N-nitrosamine compounds are a new type of small molecule nitrogen-containing disinfection by-products, which are highly water-soluble, stable in nature, and highly mutagenic and carcinogenic to humans. Among them, N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosomethyl ethylamine (NMEA), N-nitrosopyrrolidine (NPYR), N-nitrosomorpholine (NMOR), N-nitrosopiperidine (NPIP), N-nitrosodipropylamine (NDPA) and N-nitrosodibutylamine (NDBA) are listed as possible carcinogens for humans by the International Agency for Research on Cancer (IARC).

[0003] N-nitrosamine compounds can cause liver cancer, lung cancer and damage to the nervous system. Once formed in water, they are difficult to remove and have a serious impact on the environment. In recent years, the presence of N-nitrosamine compounds has been frequently detected in water, which has attracted people's attention to a series of problems such as the content, distribution, source of nitrosamines in water bodies and the harm to human health. At present, the analysis of N-nitrosamines in water has become a major research hotspot in the field of global environmental science, and many countries and regions have formulated relevant water quality standards. For example, the World Health Organization's concentration limit for NDMA is 100 ng / L.

[0004] At present, there is no unified standard for the detection of N-nitrosamines in China. The commonly used analysis method is mainly Method 521 developed by the US Environmental Protection Agency (EPA), which uses solid phase extraction-gas chromatography-mass spectrometry to analyze NDMA. Some researchers have also developed solid phase extraction-high performance liquid chromatography-mass spectrometry to analyze N-nitrosamines. However, the traditional solid phase extraction method has a complex operation process and a long time consumption. It is necessary to enrich a large volume of samples (200-1000 mL), resulting in a large loss of N-nitrosamines during the pretreatment process, and the enrichment column cannot be reused, with a high analysis cost. Some researchers have developed a method to directly determine N-nitrosamines in water by high performance liquid chromatography, but its detection limit is relatively high, higher than 100 ng / L, which cannot meet the current detection requirements.

[0005] Headspace solid-phase microextraction combines extraction, concentration, desorption, and injection into one. Through headspace suspension, the analytes are enriched on a solid support to establish an adsorption equilibrium, completing the pretreatment process. Its analysis steps are simple, time-consuming is short, and the extraction head can be reused. It is a simple, feasible, and relatively low-cost pretreatment enrichment method for new sample analysis. During the extraction process, temperature is an important condition affecting the extraction effect. Within a certain temperature range, as the extraction temperature increases, the detection limit decreases and the recovery rate increases. However, too high a temperature will also have adverse effects. For example, the evaporation of water in the solution will damage the extraction head and the gas chromatography column; too high a temperature will promote the desorption of the analyte to be measured, which is not conducive to improving the extraction efficiency. The above two problems limit its use in the analysis of compounds with poor volatility. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a detection method for trace N-nitrosamine compounds in water. By using a headspace solid-phase microextraction-gas chromatography-mass spectrometry with a dehydration and heat insulation device to determine 9 N-nitrosamine compounds in water, it not only avoids complex pretreatment steps, is easy to operate, but also avoids the influence of water vapor and the desorption process caused by too high a temperature. The technical solution adopted is as follows:

[0007] A headspace solid-phase microextraction device with a dehydration and heat insulation device, including an extraction head for headspace solid-phase microextraction, an extraction handle, a dehydration and heat insulation device, a sample container to be measured, a water bath cup, a heatable magnetic stirrer, and an iron stand. A dehydration and heat insulation device is installed between the extraction handle of the headspace solid-phase microextraction device and the sample container to be measured. The dehydration and heat insulation device includes a double-layer quartz tube, absorbent cotton, and a dehydrating agent;

[0008] The extraction handle of the headspace solid-phase microextraction device with the extraction head inserted into the inner tube cavity of the quartz tube at the top of the dehydration and heat insulation device, and the bottom end of the dehydration and heat insulation device is inserted into the top port of the sample container to be measured;

[0009] The inner tube of the double-layer quartz tube is divided into three parts. The upper part is a wide section connected to the extraction handle, and the lower part is reduced to a thin tube, which is an air vent connecting tube. Absorbent cotton is placed at the connection part between the middle and the lower part. The dehydrating agent is fixed on the absorbent cotton. The bottom end of the air vent connecting tube is above the sample to be measured; among them, the diameters of the three parts of the inner tube of the quartz tube from small to large are the lower part, the middle part, and the upper part;

[0010] The sample container to be measured is placed in the water bath cup, the water bath cup is placed on the heatable magnetic stirrer, the heatable magnetic stirrer is installed on the bottom plate of the iron stand, and the iron clamp of the iron stand fixes the quartz tube of the dehydration and heat insulation device.

[0011] Preferably, a sealing ring is installed at the connection between the top end of the dehydration and heat insulation device and the extraction handle. The bottom end of the dehydration and heat insulation device is adapted to the top end of the sample container to be measured, and a ground glass joint is used for connection to form a closed system up and down.

[0012] Preferably, the dehydrating agent is any one of anhydrous calcium chloride, soda lime, and quicklime.

[0013] A method for detecting trace N-nitrosamine compounds in water uses the above headspace solid-phase microextraction device with a dehydration and heat insulation device. The N-nitrosamine compounds include N-nitrosodimethylamine (NDMA), N-nitrosomethyl ethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA), N-nitrosodibutylamine (NDBA), N-nitrosopyrrolidine (NPYR), N-nitrosopiperidine (NPIP), N-nitrosomorpholine (NMOR), and N-nitrosodiphenylamine (NDPhA). The detection method includes the following steps:

[0014] (1) Add the water sample to be measured into the sample container to be measured, add a certain mass of sodium chloride to the water sample to be measured, put the stir bar of the magnetic stirrer into the sample container to be measured, and stir to dissolve the sodium chloride.

[0015] (2) Install and fix them in sequence, and hermetically connect the sample container to be measured to the bottom end of the dehydration and heat insulation device, so that the bottom end of the ventilation connecting pipe is located above the sample to be measured. Turn on the magnetic stirrer for heating and stirring, and use the headspace solid-phase microextraction device with a dehydration and heat insulation device to extract the water sample to be measured.

[0016] (3) Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head from the extraction handle, and use gas chromatography-tandem mass spectrometry for analysis and testing.

[0017] Preferably, in the step (1), the mass ratio of sodium chloride to the volume of the sample to be measured is 4:10 (g / ml).

[0018] Preferably, in the step (2), the extraction head is 75μm CAR / PDMS.

[0019] Preferably, in the step (2), the water bath heating temperature is 25-85°C, the extraction time is 5-15 min, and the stirring rate is 300 r / min.

[0020] As a further preference, in the step (2), the water bath heating temperature is 75°C and the extraction time is 10 min.

[0021] Preferably, in the step (3), the carrier gas for gas chromatography is He, and the flow rate is 1 mL / min;

[0022] The inlet temperature is 250 °C;

[0023] The temperature programming conditions are as follows: hold at 40 °C for 1 min, increase to 200 °C at a rate of 20 °C / min, continue to increase to 260 °C at a rate of 60 °C / min, and hold for 3 min.

[0024] Preferably, in step (3), the mass spectrometry conditions are: EI source, ionization voltage: 70 eV;

[0025] Ion source temperature: 230 °C;

[0026] Solvent delay time: 2 min;

[0027] The detection mode is selected ion mode.

[0028] Preferably, the SIM qualitative characteristic ions are NDMA (42, 74), NMEA (42, 88), NDEA (44, 57, 102), NDPA (70, 113, 130), NDBA (84, 99, 116, 141, 158), NPIP (55, 114), NPYR (41, 42, 100), NMOR (56, 86, 116), NDphA (169, 168, 167), and the quantitative characteristic ions are NDMA (74), NMEA (88), NDEA (102), NDPA (130), NDBA (158), NPIP (114), NPYR (100), NMOR (116), NDphA (169). The types of nitrosamines are determined by the qualitative characteristic ions and the peak emergence time, and the content of nitrosamines is determined by the quantitative ions.

[0029] Preferably, the detection limit of N-nitrosamine compounds is 0.05 - 0.1 ng / L, and the recovery rate is 90% - 103.2%.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] The present invention uses a headspace solid-phase microextraction device with a dehydration and heat insulation device for microextraction, and then detects trace N-nitrosamine compounds in water, shortening the pretreatment time and pretreatment steps, avoiding secondary pollution that may be caused by the large use of organic solvents, and reducing the use costs of solid-phase extraction columns, headspace devices, and organic solvents;

[0032] The present invention adds a dehydration and heat insulation device, which can increase the extraction temperature and stirring speed, save the extraction time. At the same time, after adding the dehydration and heat insulation device, it avoids the damage and desorption problems of the extraction head and gas chromatography column caused by water vapor adsorption that may be caused by too high temperature; moreover, the use of the dehydration and heat insulation device reduces the gas space above the liquid surface, promoting the adsorption of analytes in the gas environment;

[0033] Due to the increase in extraction temperature and the reduction of the gas space above the liquid surface, the types of N-nitrosamine compounds that can be analyzed are increased, extended to 9 kinds, the detection limit of N-nitrosamine compounds is reduced, the detection limit is 0.05-0.1 ng / L, and the recovery rate is 90%-103.2%. Description of the Drawings

[0034] Figure 1 It is a schematic structural diagram of a headspace solid-phase microextraction device with a dehydration and heat insulation device used in the present invention;

[0035] Figure 2 It is a schematic structural diagram of the dehydration and heat insulation device of the present invention;

[0036] Figure 3 It is a comparison diagram of the microextraction effects of 4 extraction heads in the embodiment of the present invention;

[0037] Figure 4 It is a comparison diagram of the effects of different addition amounts of NaCl in the embodiment of the present invention;

[0038] Figure 5 It is a comparison diagram of the extraction effects at different extraction temperatures in the embodiment of the present invention;

[0039] Figure 6 It is a comparison diagram of the extraction effects at different extraction times in the embodiment of the present invention;

[0040] Figure 7 It is a comparison diagram of the extraction effects with and without the dehydration and heat insulation device in the embodiment of the present invention;

[0041] Figure 8 It is the NDMA standard curve established in Example 12 of the present invention;

[0042] Figure 9 It is the NEMA standard curve established in Example 13 of the present invention;

[0043] Figure 10 It is the NDEA standard curve established in Example 14 of the present invention;

[0044] Figure 11 It is the NDPA standard curve established in Example 15 of the present invention;

[0045] Figure 12 It is the NDBA standard curve established in Example 16 of the present invention;

[0046] Figure 13 NPIP standard curve established for Example 17 of the present invention;

[0047] Figure 14 NPYR standard curve established for Example 18 of the present invention;

[0048] Figure 15 NMOR standard curve established for Example 19 of the present invention;

[0049] Figure 16 NDphA standard curve established for Example 20 of the present invention.

[0050] In the figure: 1 - iron stand; 2 - heatable magnetic stirrer; 3 - magnetic stir bar; 4 - water bath solution; 5 - container for sample to be measured; 6 - absorbent cotton and dehydrating agent; 7 - extraction handle for headspace solid-phase microextraction, 71 - extraction head; 8 - dehydration and heat insulation device; 9 - iron clamp; 10 - ventilation connecting pipe. Detailed implementation manners

[0051] The attached drawings are only for illustrative purposes; for better explaining this embodiment, some components in the attached drawings will be omitted, enlarged or reduced, and do not represent the dimensions of the actual product. Some well-known structures and their descriptions in the attached drawings may be omitted. Therefore, it cannot be construed as a limitation to the present invention.

[0052] The technical solutions of the present invention will be further described below in conjunction with the embodiments.

[0053] Prepare several portions of 10 mL of a mixed solution of the above 9 N-nitrosamine compounds (the concentration of each of the 9 N-nitrosamines is 50.0 ng / L) for multiple experimental determinations and analyses.

[0054] Example 1

[0055] A headspace solid-phase microextraction device with a dehydration and heat insulation device, comprising an extraction head 71 for headspace solid-phase microextraction, an extraction handle 7, a dehydration and heat insulation device 8, a container 5 for the sample to be measured, a water bath cup, a heatable magnetic stirrer, and an iron stand. A dehydration and heat insulation device 8 is installed between the extraction handle 7 of the headspace solid-phase microextraction device and the container 5 for the sample to be measured. The dehydration and heat insulation device 8 includes a double-layer quartz tube, absorbent cotton, and a dehydrating agent 6.

[0056] The extraction head 71 of the headspace solid-phase microextraction device is inserted into the inner tube cavity from the top of the dehydration and heat insulation device 8. A sealing ring is installed at the connection between the top of the dehydration and heat insulation device 8 and the extraction handle. The bottom end of the dehydration and heat insulation device 8 is inserted into the top port of the container 5 for the sample to be measured. The bottom end of the dehydration and heat insulation device 8 is adapted to the top end of the container 5 for the sample to be measured and is connected by a ground glass joint to form a closed system up and down.

[0057] Above the ventilation connecting pipe of the dehydration and heat insulation device 8, absorbent cotton is placed, and a dehydrating agent is fixed on the absorbent cotton. The dehydrating agent is anhydrous calcium chloride. The inner tube of the double-layer quartz tube is divided into three parts. The upper part is a wide section connected to the extraction handle, and the lower part is reduced to a thin tube, which is the ventilation connecting pipe 10. Absorbent cotton is placed at the connection part between the middle and the lower part, and a dehydrating agent is fixed on the absorbent cotton. The bottom end of the ventilation connecting pipe 10 is above the sample to be measured.

[0058] When in use, the sample to be measured is loaded into the sample container 5 to be measured, a certain amount of sodium chloride (NaCl) is added, the stirrer 3 of the heatable magnetic stirrer 2 is placed into the container, the container is placed in the water bath cup containing the water bath solution 4, the water bath cup is placed on the heatable magnetic stirrer 2, the heatable magnetic stirrer 2 is placed on the bottom plate of the iron stand 1, and the iron clamp 9 of the iron stand 1 fixes the quartz tube of the dehydration and heat insulation device 8.

[0059] A method for detecting trace N-nitrosamine compounds in water uses the above headspace solid-phase microextraction device with a dehydration and heat insulation device. The N-nitrosamine compounds include N-nitrosodimethylamine (NDMA), N-nitrosomethyl ethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA), N-nitrosodibutylamine (NDBA), N-nitrosopyrrolidine (NPYR), N-nitrosopiperidine (NPIP), N-nitrosomorpholine (NMOR), N-nitrosodiphenylamine (NDPhA).

[0060] Qualitative analysis is carried out by retention time and characteristic fragment ions. The analysis parameters of different N-nitrosamine compounds are shown in Table 1.

[0061] Table 1 GC-MS analysis parameters of N-nitrosamines

[0062] N-nitrosamine Retention time / min Quantitative ion Qualitative ion NDMA 2.832 74 42,74 NMEA 4.293 88 42,88 NDEA 4.917 102 44,102 NDPA 6.778 130 70,113,130 NDBA 7.329 158 84,99,116,141,158 NPIP 8.012 114 55,114 NPYR 9.381 100 41,42，100 NMOR 10.378 116 56,86,116 NDphA 12.837 169 169,168,167

[0063] The steps of the detection method include:

[0064] (1) Add 10 mL of a mixed solution of N-nitrosamine compounds to the sample container to be measured, add 4 g of sodium chloride to saturation, and place the stirrer of the magnetic stirrer into the sample container to be measured.

[0065] The purpose of adding NaCl: Since the extraction head adsorbs N-nitrosamine compounds volatilized from the solution into the closed container, adding sodium chloride can enhance the ionic strength, reduce the solubility of N-nitrosamines in water, that is, play a salting-out role, reduce the concentration of N-nitrosamines in the water sample, increase the concentration of N-nitrosamines in the air above the liquid surface, and improve the sensitivity and precision of detection.

[0066] (2) Install and fix the headspace solid-phase microextraction device with a dehydration and heat insulation device in sequence. Connect the sample container to be measured airtight to the bottom end of the dehydration and heat insulation device, making the bottom end of the connecting pipe above the mixed solution of N-nitrosamine compounds. Place the sample container to be measured into a water bath cup filled with water bath solution, and place the water bath cup on a magnetic stirrer. Insert the extraction handle with an extraction head into the inner tube cavity from the top end of the dehydration and heat insulation device and connect it airtight. Clamp the tube diameter of the dehydration and heat insulation device with an iron clamp of an iron stand to better fix the entire extraction device.

[0067] Turn on the magnetic stirrer to heat and stir, expose the extraction head covered with an adsorption material, heat and stir in a 75°C water bath for 10 min, with a stirring rate of 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction. The extraction head used is 100 μm PDMS.

[0068] (3) Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head from the extraction handle. Use gas chromatography-tandem mass spectrometry for analysis and testing. The headspace solid-phase microextraction enriches the samples in water, and then uses the analytical method of gas chromatography-tandem mass spectrometry (GC-MS / MS).

[0069] Among them, the GC-MS test conditions are as follows:

[0070] Analyze 9 kinds of N-nitrosamines by GC-MS, and the ion source is an EI source;

[0071] The ionization voltage is 70 eV, and the ion source temperature is 230°C;

[0072] The chromatographic column is an Agilent capillary chromatographic column VF-WAXms with a specification of 30 m × 0.25 mm and 1.0 μm. He is used as the carrier gas, with a flow rate of 1 mL / min, an injection port temperature of 250°C, and splitless injection;

[0073] The programmed temperature rise conditions are as follows: maintain at 40°C for 1 min, rise to 200°C at a rate of 20°C / min, continue to rise to 260°C at a rate of 60°C / min, and maintain for 3 min.

[0074] The mass spectrometry conditions are as follows:

[0075] EI source, ionization voltage: 70 eV;

[0076] Ion source temperature: 230°C;

[0077] Solvent delay time: 2 min.

[0078] The detection method is the selected ion mode:

[0079] The SIM qualitative characteristic ions are NDMA(42,74), NMEA(42,88), NDEA(44,57,102), NDPA(70,113,130), NDBA(84,99,116,141,158), NPIP(55,114), NPYR(41,42,100), NMOR(56,86,116), NDphA(169,168,167), and the quantitative characteristic ions are NDMA(74), NMEA(88), NDEA(102), NDPA(130), NDBA(158), NPIP(114), NPYR(100), NMOR(116), NDphA(169). The types of nitrosamines are determined by the qualitative characteristic ions and the peak emergence time, and the content of nitrosamines is determined by the quantitative ions.

[0080] Example 2

[0081] Turn on the magnetic stirrer for heating and stirring, expose the extraction head coated with the adsorbent material, heat and stir in a water bath at 75 °C for 10 min, and the stirring rate is 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction. The extraction head used is 30 μm DVB / CAR / PDMS.

[0082] Other parts not mentioned are the same as in Example 1.

[0083] Example 3

[0084] Turn on the magnetic stirrer for heating and stirring, expose the extraction head coated with the adsorbent material, heat and stir in a water bath at 75 °C for 10 min, and the stirring rate is 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction. The extraction head used is 75 μm CAR / PDMS.

[0085] Other parts not mentioned are the same as in Example 1.

[0086] Example 4

[0087] Turn on the magnetic stirrer for heating and stirring, expose the extraction head coated with the adsorbent material, heat and stir in a water bath at 75 °C for 10 min, and the stirring rate is 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction. The extraction head used is 70 μm CW / DVB.

[0088] Other parts not mentioned are the same as in Example 1.

[0089] As Figure 3 shown, the peak areas of 9 N-nitrosamine compounds determined by headspace solid-phase microextraction-gas chromatography-mass spectrometry using different extraction heads in Examples 1-4 were compared. From Figure 3It can be seen that the peak areas detected by the extraction head with 75μm CAR / PDMS are larger, and are all better than those detected by the other three extraction heads, with obvious detection effects.

[0090] Example 5

[0091] Add 10 mL of a mixed solution of N-nitrosamine compounds to the sample container to be tested. Do not add sodium chloride to the mixed solution. Place the stir bar of the magnetic stirrer into the sample container to be tested. Place the dehydration and heat insulation device on the water sample container to be tested, connect it with a ground glass joint to ensure airtightness, and install the headspace solid-phase microextraction handle on the dehydration and heat insulation device. The extraction head used is 75μm CAR / PDMS to form a closed system.

[0092] Expose the extraction head covered with the adsorption material, heat and stir in a 75°C water bath for 10 min, with a stirring rate of 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction. Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port and screw out the extraction head for analysis and testing.

[0093] Other parts not mentioned are the same as in Example 1.

[0094] Example 6

[0095] Step (1): Add 10 mL of a mixed solution of N-nitrosamine compounds to the sample container to be tested, and add 2 g of sodium chloride to the mixed solution to dissolve.

[0096] Other parts not mentioned are the same as in Example 5.

[0097] As Figure 4 shown, compare and analyze Examples 3, 5, and 6. Different amounts of NaCl were used in these three examples, and other test conditions were the same. Compare the peak areas of 9 N-nitrosamine compounds determined by headspace solid-phase microextraction-gas chromatography-mass spectrometry with different amounts of sodium chloride in Examples 3, 5, and 6. It can be seen from Figure 4 that when the NaCl concentration is 0.4 g / mL (saturated), the peak areas of the 9 N-nitrosamine compounds detected are larger, and are all better than those detected at the other two NaCl concentrations, with obvious detection effects. Therefore, the extraction effect is the best when the NaCl concentration is 0.4 g / mL (saturated).

[0098] Example 7

[0099] The volatility of N-nitrosamine compounds increases continuously with the increase of temperature. Select a 75μm CAR / PDMS extraction head, add 4g of sodium chloride to saturation in a mixed solution, place the dehydration and heat insulation device on the container of the water sample to be measured, connect it with a ground glass joint to ensure airtightness, install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system. Expose the extraction head covered with the adsorption material, then heat it in a water bath at 25°C, stir for 10 minutes, and the stirring rate is 300r / min. After the adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction. Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port and screw out the extraction head for detection and analysis.

[0100] Other parts not mentioned are the same as in Example 1.

[0101] Example 8

[0102] The volatility of N-nitrosamine compounds increases continuously with the increase of temperature. Select a 75μm CAR / PDMS extraction head, add 4g of sodium chloride to saturation in a mixed solution, place the dehydration and heat insulation device on the container of the water sample to be measured, connect it with a ground glass joint to ensure airtightness, install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system. Expose the extraction head covered with the adsorption material, then heat it in a water bath at 45°C, stir for 10 minutes, and the stirring rate is 300r / min. After the adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction. Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port and screw out the extraction head for detection and analysis.

[0103] Other parts not mentioned are the same as in Example 1.

[0104] Example 9

[0105] The volatility of N-nitrosamine compounds increases continuously with the increase of temperature. Select a 75μm CAR / PDMS extraction head, add 4g of sodium chloride to saturation in a mixed solution, place the dehydration and heat insulation device on the container of the water sample to be measured, connect it with a ground glass joint to ensure airtightness, install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system. Expose the extraction head covered with the adsorption material, then heat it in a water bath at 85°C, stir for 10 minutes, and the stirring rate is 300r / min. After the adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction. Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port and screw out the extraction head for detection and analysis.

[0106] Other parts not mentioned are the same as in Example 1.

[0107] As Figure 5As shown, Examples 3, 7, 8, and 9 were compared and analyzed. In these four examples, microextraction was carried out by water bath heating to different temperatures, while other test conditions were the same. The peak areas of 9 N-nitrosamine compounds determined by headspace solid-phase microextraction-gas chromatography-mass spectrometry at different extraction temperatures in Examples 3, 7, 8, and 9 were compared. From Figure 5 it can be seen that when the water bath temperature was 75°C, the peak areas of the 9 N-nitrosamine compounds detected were relatively large, and a good extraction effect had been achieved at 75°C. The improvement of the extraction effect was not obvious at 85°C. Therefore, 75°C was selected as the optimal temperature.

[0108] Example 10,

[0109] A 75-μm CAR / PDMS extraction head was selected. 4 g of sodium chloride was added to a mixed solution until saturation. The dehydration and heat insulation device was placed on the container of the water sample to be measured, and the ground glass joints were connected to ensure airtightness. The headspace solid-phase microextraction handle was installed on the dehydration and heat insulation device to form a closed system.

[0110] The extraction head covered with the adsorption material was exposed, and the water bath was heated to 75°C. The magnetic stirrer was used to stir for 5 min at a stirring rate of 300 r / min. After adsorption was completed, the extraction head was retracted into the extraction handle to complete the adsorption extraction. The headspace solid-phase microextraction handle was inserted into the gas chromatography injection port, and the extraction head was screwed out for detection and analysis.

[0111] Other parts not mentioned were the same as in Example 1.

[0112] Example 11

[0113] A 75-μm CAR / PDMS extraction head was selected. A mixed solution was added to the container of the sample to be measured, and then 4 g of sodium chloride was added until saturation. The dehydration and heat insulation device was placed on the container of the water sample to be measured, and the ground glass joints were connected to ensure airtightness. The headspace solid-phase microextraction handle was installed on the dehydration and heat insulation device to form a closed system.

[0114] The extraction head covered with the adsorption material was exposed, and the water bath was heated to 75°C. The magnetic stirrer was used to stir for 15 min at a stirring rate of 300 r / min. After adsorption was completed, the extraction head was retracted into the extraction handle to complete the adsorption extraction. The headspace solid-phase microextraction handle was inserted into the gas chromatography injection port, and the extraction head was screwed out for detection and analysis.

[0115] Other parts not mentioned were the same as in Example 1.

[0116] As Figure 6 shown, the extraction effects at 5 min, 10 min, and 15 min of extraction were compared respectively. From Figure 6It can be seen that for the 9 N-nitrosamine compounds, a good extraction effect has been achieved at 10 minutes of extraction. The enrichment amount of N-nitrosamine compounds does not increase significantly at 15 minutes. Considering the time cost, the optimal extraction time is selected as 10 minutes.

[0117] Comparative Example 1

[0118] A 75μm CAR / PDMS extraction head was selected. A portion of the mixed solution was added to the sample container to be measured, and then 4 g of sodium chloride was added until saturated. Without using a dehydration and heat insulation device, the headspace solid-phase microextraction handle was installed on the sample container to be measured to form a closed system.

[0119] The extraction head covered with the adsorption material was exposed, and it was heated in a water bath to 75°C and stirred with a magnetic stirrer for 10 minutes at a stirring rate of 300 r / min. After adsorption, the extraction head was retracted into the extraction handle to complete the adsorption extraction. The headspace solid-phase microextraction handle was inserted into the gas chromatography injection port, and the extraction head was screwed out for detection and analysis.

[0120] As Figure 7 shown, Example 3 and Comparative Example 1 were compared and analyzed, and the extraction effects with and without a dehydration and heat insulation device were compared. From Figure 7 it can be seen that when using a dehydration and heat insulation device, the peak areas of the 9 N-nitrosamine compounds determined by headspace solid-phase microextraction-gas chromatography-mass spectrometry are significantly larger than those detected without using a dehydration and heat insulation device. Therefore, the dehydration and heat insulation device significantly improves the extraction effect.

[0121] Example 12

[0122] NDMA standard curve drawing:

[0123] 10 mL of NDMA solutions with concentrations of 0.02, 0.05, 0.10, 0.20, 0.50, 1.00, 2.00, 5.00, 10.00, and 20.00 ng / L were respectively prepared. The solutions were respectively placed in the sample containers to be measured, 4 g of sodium chloride was added to each, the dehydration and heat insulation device was placed on the sample container to be measured, and the ground glass joints were connected to ensure airtightness. The headspace solid-phase microextraction handle was installed on the dehydration and heat insulation device to form a closed system.

[0124] The extraction head covered with the adsorption material (the extraction head is an Agilent 75μm CAR / PDMS extraction head) was exposed, heated and stirred in a 75°C water bath for 10 minutes at a stirring rate of 300 r / min. After adsorption, the extraction head was retracted into the extraction handle to complete the adsorption extraction.

[0125] Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head for detection and analysis. Detection was performed using GC-MS, and the peak areas at each concentration are shown in Table 2.

[0126] Table 2 NDMA Concentration and Peak Area

[0127] NDMA concentration (ng / L) Peak area 0.02 0 0.05 0 0.1 110 0.2 257 0.5 612 1.0 1290 2.0 2619 5.0 6653 10.0 14289 20.0 27108

[0128] Taking the concentration of NDMA as the abscissa and the peak area of NDMA as the ordinate, establish the standard curve of NDMA, as Figure 8 shown. The standard curve is y = 1369.78x - 30.53, and R 2 is 0.999, and the detection limit is: 0.1 ng / L.

[0129] Other parts not mentioned are the same as in Example 1.

[0130] Example 13

[0131] Drawing of the NMEA standard curve:

[0132] Prepare 10 mL of NMEA solutions with concentrations of 0.02, 0.05, 0.10, 0.20, 0.50, 1.00, 2.00, 5.00, 10.00, and 20.00 ng / L respectively. Place the solutions in the sample containers to be measured, add 4 g of sodium chloride to each, place the dehydration and heat insulation device on the sample containers to be measured, connect with a ground glass joint to ensure airtightness, and install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system.

[0133] Expose the extraction head coated with the adsorption material (the extraction head is an Agilent 75 μm CAR / PDMS extraction head), heat and stir in a 75 °C water bath for 10 min, with a stirring rate of 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction.

[0134] Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head for detection and analysis. Detection was performed using GC-MS, and the peak areas at each concentration are shown in Table 3.

[0135] Table 3 NMEA Concentration and Peak Area

[0136] NMEA concentration (ng / L) Peak area 0.02 0 0.05 85 0.10 129 0.20 255 0.50 586 1.00 1086 2.00 2175 5.00 5753 10.00 12089 20.00 22098

[0137] Taking the concentration of NMEA as the abscissa and the peak area of NMEA as the ordinate, establish the standard curve of NMEA, as Figure 9 shown. The standard curve is y = 1121.76x + 65.31, and R2 is 0.999, and the detection limit is: 0.05 ng / L.

[0138] Other places not mentioned are the same as in Example 1.

[0139] Example 14

[0140] Drawing of the NDEA standard curve:

[0141] Prepare 10 mL of NDEA solutions with concentrations of 0.02, 0.05, 0.10, 0.20, 0.50, 1.00, 2.00, 5.00, 10.00, and 20.00 ng / L respectively. Place the solutions in the sample containers to be measured, add 4 g of sodium chloride to each, place the dehydration and heat insulation device on the sample containers to be measured, connect with a ground glass joint to ensure airtightness, install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system.

[0142] Expose the extraction head coated with the adsorption material (the extraction head is an Agilent 75 μm CAR / PDMS extraction head), heat and stir in a 75 °C water bath for 10 min, with a stirring rate of 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction.

[0143] Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head for detection and analysis. Detect with GC-MS, and the peak areas at each concentration are shown in Table 4.

[0144] Table 4 NDEA concentration and peak area

[0145] NDEA concentration (ng / L) Peak area 0.02 0 0.05 0 0.10 120 0.20 361 0.50 1151 1.00 2362 2.00 5001 5.00 13683 10.00 24552 20.00 49021

[0146] Taking the concentration of NDEA as the abscissa and the peak area of NDEA as the ordinate, establish the NDEA standard curve, as Figure 10 shown, the standard curve is y = 2461.01x + 59.17, R 2 is 0.999, and the detection limit is: 0.10 ng / L.

[0147] Other places not mentioned are the same as in Example 1.

[0148] Example 15

[0149] Drawing of the NDPA standard curve:

[0150] Prepare 10 mL of NDPA solutions with concentrations of 0.02, 0.05, 0.10, 0.20, 0.50, 1.00, 2.00, 5.00, 10.00, and 20.00 ng / L respectively. Place the solutions in the sample containers to be measured, add 4 g of sodium chloride to each, place the dehydration and heat insulation device on the sample containers to be measured, connect with a ground glass joint to ensure airtightness, install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system.

[0151] Expose the extraction head coated with the adsorbent material (the extraction head is an Agilent 75-μm CAR / PDMS extraction head), heat and stir it in a 75 °C water bath for 10 min, with a stirring rate of 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction.

[0152] Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head for detection and analysis tests. Detect with GC-MS, and the peak areas at each concentration are shown in Table 5.

[0153] Table 5 NDPA Concentrations and Peak Areas

[0154] NDPA concentration (ng / L) Peak area 0.02 0 0.05 0 0.10 229 0.20 469 0.50 1209 1.00 2401 2.00 4670 5.00 12087 10.00 22934 20.00 49021

[0155] Using the concentration of NDPA as the abscissa and the peak area of NDPA as the ordinate, establish the standard curve of NDPA, as Figure 11 shown. The standard curve is y = 2,428.93x - 139.26, with R 2 being 0.999 and the detection limit being: 0.05 ng / L.

[0156] Other parts not mentioned are the same as in Example 1.

[0157] Example 16

[0158] Drawing of the NDBA Standard Curve:

[0159] Prepare 10 mL of NDBA solutions with concentrations of 0.02, 0.05, 0.10, 0.20, 0.50, 1.00, 2.00, 5.00, 10.00, and 20.00 ng / L respectively. Place the solutions in the sample containers to be measured, add 4 g of sodium chloride to each, place the dehydration and heat insulation device on the sample containers to be measured, connect with a ground glass joint to ensure airtightness, and install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system.

[0160] Expose the extraction head coated with the adsorbent material (the extraction head is an Agilent 75-μm CAR / PDMS extraction head), heat and stir it in a 75 °C water bath for 10 min, with a stirring rate of 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction.

[0161] Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head for detection and analysis tests. Detect with GC-MS, and the peak areas at each concentration are shown in Table 6.

[0162] Table 6 NDBA Concentrations and Peak Areas

[0163]

[0164]

[0165] Taking the concentration of NDBA as the abscissa and the peak area of NDBA as the ordinate, a standard curve of NDBA was established. As Figure 12 shown, the standard curve was y = 1620.65x + 59.55, and R 2 was 0.999, and the detection limit was: 0.05 ng / L.

[0166] Other places not mentioned are the same as in Example 1.

[0167] Example 17

[0168] Drawing of the NPIP standard curve:

[0169] 10 mL of NPIP solutions with concentrations of 0.02, 0.05, 0.10, 0.20, 0.50, 1.00, 2.00, 5.00, 10.00, and 20.00 ng / L were respectively prepared. The solutions were respectively placed in the sample containers to be measured, 4 g of sodium chloride was respectively added, the dehydration and heat insulation device was placed on the sample containers to be measured, and the ground glass joints were connected to ensure airtightness. The headspace solid-phase microextraction handle was installed on the dehydration and heat insulation device to form a closed system.

[0170] The extraction head covered with the adsorption material (the extraction head is an Agilent 75 μm CAR / PDMS extraction head) was exposed, and it was heated and stirred in a 75 °C water bath for 10 min, and the stirring rate was 300 r / min. After the adsorption was completed, the extraction head was retracted into the extraction handle to complete the adsorption extraction.

[0171] The extraction handle of the headspace solid-phase microextraction device was inserted into the gas chromatography injection port, and the extraction head was screwed out for detection and analysis. Detection was carried out using GC-MS, and the peak areas of each concentration are shown in Table 7.

[0172] Table 7 NPIP concentration and peak area

[0173]

[0174]

[0175] Taking the concentration of NPIP as the abscissa and the peak area of NPIP as the ordinate, a standard curve of NPIP was established. As Figure 13 shown, the standard curve was y = 2573.51x + 88.38, and R 2 was 0.999, and the detection limit was: 0.05 ng / L.

[0176] Other places not mentioned are the same as in Example 1.

[0177] Example 18

[0178] Drawing of the NPYR standard curve:

[0179] Prepare 10 mL of NPYR solutions with concentrations of 0.02, 0.05, 0.10, 0.20, 0.50, 1.00, 2.00, 5.00, 10.00, and 20.00 ng / L respectively. Place the solutions in the sample containers to be measured, add 4 g of sodium chloride to each, place the dehydration and heat insulation device on the sample containers to be measured, connect with a ground glass joint to ensure airtightness, and install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system.

[0180] Expose the extraction head coated with the adsorption material (the extraction head is an Agilent 75 μm CAR / PDMS extraction head), heat and stir in a 75 °C water bath for 10 min, with a stirring rate of 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction.

[0181] Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head for detection and analysis. Detect with GC-MS, and the peak areas at each concentration are shown in Table 8.

[0182] Table 8 NPYR concentration and peak area

[0183] NPYR concentration (ng / L) Peak area 0.02 0 0.05 89 0.10 268 0.20 596 0.50 1688 1.00 3786 2.00 6618 5.00 16855 10.00 31989 20.00 66268

[0184] Taking the NPYR concentration as the abscissa and the NPYR peak area as the ordinate, establish the NPYR standard curve, as Figure 14 shown. The standard curve is y = 3294.69x + 9.25, and R 2 is 0.999, and the detection limit is: 0.05 ng / L.

[0185] Other parts not mentioned are the same as in Example 1.

[0186] Example 19

[0187] Drawing of the NMOR standard curve:

[0188] Prepare 10 mL of NMOR solutions with concentrations of 0.02, 0.05, 0.10, 0.20, 0.50, 1.00, 2.00, 5.00, 10.00, and 20.00 ng / L respectively. Place the solutions in the sample containers to be measured, add 4 g of sodium chloride to each, place the dehydration and heat insulation device on the sample containers to be measured, connect with a ground glass joint to ensure airtightness, and install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system.

[0189] Expose the extraction head coated with the adsorption material (the extraction head is an Agilent 75-μm CAR / PDMS extraction head), heat and stir in a 75 °C water bath for 10 min at a stirring rate of 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction.

[0190] Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head for detection and analysis tests. Detection is carried out using GC-MS, and the peak areas at various concentrations are shown in Table 9.

[0191] Table 9 NMOR Concentration and Peak Area

[0192] NMOR concentration (ng / L) Peak area 0.02 0 0.05 0 0.10 196 0.20 477 0.50 1268 1.00 2399 2.00 5152 5.00 12668 10.00 26009 20.00 50688

[0193] Taking the concentration of NMOR as the abscissa and the peak area of NMOR as the ordinate, establish the standard curve of NMOR, as Figure 15 shown. The standard curve is y = 2,548.38x - 19.86, with R 2 being 0.999 and the detection limit being 0.1 ng / L.

[0194] Other parts not mentioned are the same as in Example 1.

[0195] Example 20

[0196] Drawing of the NDphA standard curve:

[0197] Prepare 10 mL of NDphA solutions with concentrations of 0.02, 0.05, 0.10, 0.20, 0.50, 1.00, 2.00, 5.00, 10.00, and 20.00 ng / L respectively. Place the solutions in the sample containers to be measured, add 4 g of sodium chloride to each, place the dehydration and heat insulation device on the sample containers to be measured, connect with a ground glass joint to ensure airtightness, and install the headspace solid-phase microextraction handle on the dehydration and heat insulation device to form a closed system.

[0198] Expose the extraction head coated with the adsorption material (the extraction head is an Agilent 75-μm CAR / PDMS extraction head), heat and stir in a 75 °C water bath for 10 min at a stirring rate of 300 r / min. After adsorption is completed, retract the extraction head into the extraction handle to complete the adsorption extraction.

[0199] Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head for detection and analysis tests. Detection is carried out using GC-MS, and the peak areas at various concentrations are shown in Table 10.

[0200] Table 10 NDphA Concentration and Peak Area

[0201] NDphA concentration (ng / L) Peak area 0.02 0 0.05 0 0.10 108 0.20 266 0.50 568 1.00 998 2.00 1988 5.00 5016 10.00 9869 20.00 21131

[0202] Using the concentration of NDphA as the abscissa and the peak area of NDphA as the ordinate, a standard curve of NDphA was established. As Figure 16 shown, the standard curve was y = 1,045.45x - 69.26, and R 2 was 0.999, and the detection limit was: 0.1 ng / L.

[0203] Other places not mentioned are the same as in Example 1.

[0204] Example 21

[0205] Determination of the recoveries of 9 N-nitrosamines

[0206] Prepare 9 N-nitrosamine mixed solutions at 3 concentration gradients (1.0, 10.0, and 100.0 μg / L respectively), and directly inject them using GC-MS to analyze 9 N-nitrosamines. The ion source is an EI source, the ionization voltage is 70 eV, and the ion source temperature is 230 °C.

[0207] The chromatographic column is an Agilent capillary chromatographic column VF-WAXms with a specification of 30 m × 0.25 mm and 1.0 μm. He is used as the carrier gas, the flow rate is 1 mL / min, the inlet temperature is 250 °C, splitless injection is used, and the injection volume is 1 μL.

[0208] The programmed temperature rise conditions are as follows: hold at 40 °C for 1 min, rise to 200 °C at a rate of 20 °C / min, rise to 260 °C at a rate of 60 °C / min, and hold for 3 min. Qualitative analysis is performed using the retention time and characteristic fragment ions.

[0209] Prepare 10 mL of 9 N-nitrosamine mixed aqueous solutions at 3 concentration gradients (0.1, 1.0, 10.0 ng / L respectively), perform headspace solid-phase microextraction (the extraction method is as described above), and perform GC-MS analysis (the analysis conditions are as in Example 1). Calculate the recoveries of N-nitrosamines based on the above two detection results. The recoveries of 9 N-nitrosamines are shown in Table 11 and are between 81.1 - 103.2%.

[0210] Table 11 Recoveries of each N-nitrosamine

[0211]

[0212] Example 22

[0213] Determination of the simulation of precursor chloramination

[0214] DMA is an important precursor of NDMA in the chloramine treatment process. Prepare 150 mL of a 50 μg / L DMA solution using ultrapure water. Prepare a 0.1 mol / L monochloramine solution. Add 3 mL of the monochloramine solution to 150 mL of the DMA solution, react in the dark for 3 days, then add a quenching agent to terminate the reaction, and then analyze NDMA in the system according to the headspace solid-phase microextraction procedure and the GC-MS analysis method. The operation and analysis method are the same as in Example 1. Calculate the content of NDMA and the molar conversion rate of DMA in the water sample to be tested based on the detection results and the standard curve of N-nitrosamines. Three groups of parallel experiments were set up, and the results are shown in Table 12.

[0215] Table 12. Formation rate of NDMA in the chloramine treatment of DMA

[0216] NDMA concentration μg / L NDMA molar formation rate (%) 1 5.18 6.3 2 4.85 5.9 3 5.10 6.2

[0217] Since nitrosamines are highly mutagenic and carcinogenic to humans, controlling their environmental concentration not only requires controlling their direct release, but also controlling the conversion of their precursors is of great significance. Therefore, determining their precursors and formation potential has been an important task for many researchers in recent years.

[0218] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A headspace solid-phase microextraction device with a dehydration and heat insulation device, comprising an extraction head for headspace solid-phase microextraction, an extraction handle, a dehydration and heat insulation device, a container for the sample to be measured, a water bath cup, a heatable magnetic stirrer, and an iron stand, characterized in that, An anhydrating and heat-insulating device is installed between the extraction handle of the headspace solid-phase microextraction device and the container of the sample to be measured. The anhydrating and heat-insulating device includes a double-layer quartz tube, absorbent cotton, and a dehydrating agent. The extraction handle with an extraction head installed in the headspace solid-phase microextraction device is inserted into the inner tube cavity of the quartz tube at the top end of the anhydrating and heat-insulating device, and the bottom end of the anhydrating and heat-insulating device is inserted into the top port of the container of the sample to be measured. The inner tube of the double-layer quartz tube is divided into three parts. The upper part is a wide section connected to the extraction handle, and the lower part is reduced to a thin tube, which is an air vent connecting tube. Absorbent cotton is placed at the connection part between the middle and the lower part, and the dehydrating agent is fixed on the absorbent cotton. The bottom end of the air vent connecting tube is above the sample to be measured. The container of the sample to be measured is placed in a water bath cup, the water bath cup is placed on a heatable magnetic stirrer, the heatable magnetic stirrer is installed on the bottom plate of an iron stand, and the iron clamp of the iron stand fixes the quartz tube of the anhydrating and heat-insulating device.

2. The headspace solid-phase microextraction device with a dehydration and heat insulation device according to claim 1, wherein A sealing ring is installed at the connection between the top end of the anhydrating and heat-insulating device and the extraction handle. The bottom end of the anhydrating and heat-insulating device is adapted to the top end of the container of the sample to be measured, and a ground glass joint is used for connection to form a closed system up and down.

3. The headspace solid-phase microextraction device with a dehydration and heat insulation device according to claim 1, characterized in that, The dehydrating agent is any one of anhydrous calcium chloride, soda lime, and quicklime.

4. A method for detecting trace N-nitrosamine compounds in water, which uses a headspace solid-phase microextraction device with a dehydration and heat insulation device described in any one of claims 1-3, characterized in that, The N-nitrosamine compounds include N-nitrosodimethylamine, N-nitrosomethyl ethylamine, N-nitrosodiethylamine, N-nitrosodipropylamine, N-nitrosodibutylamine, N-nitrosopyrrolidine, N-nitrosopiperidine, N-nitrosomorpholine, and N-nitrosodiphenylamine. The detection method includes the following steps: (1) Add the water sample to be measured into the container of the sample to be measured, add a certain mass of sodium chloride to the water sample to be measured, put the stir bar of the magnetic stirrer into the container of the sample to be measured, and stir to dissolve the sodium chloride. (2) Install and fix them in sequence, and connect the container of the sample to be measured to the bottom end of the anhydrating and heat-insulating device in a sealed manner, so that the bottom end of the air vent connecting tube is above the sample to be measured. Turn on the magnetic stirrer for heating and stirring, and use the headspace solid-phase microextraction device with the anhydrating and heat-insulating device to perform extraction treatment on the water sample to be measured. (3) Insert the extraction handle of the headspace solid-phase microextraction device into the gas chromatography injection port, and screw out the extraction head from the extraction handle, and perform analysis and testing by gas chromatography-tandem mass spectrometry.

5. The detection method of trace N-nitrosamine compounds in water according to claim 4, wherein, In the step (1), the mass ratio of sodium chloride to the volume of the sample to be measured is 4:10 (g / ml).

6. The detection method of trace N-nitrosamine compounds in water according to claim 4, characterized in that, In the step (2), the extraction head is 75μm CAR / PDMS.

7. A detection method for trace N-nitrosamine compounds in water according to claim 4, characterized in that, In the step (2), the water bath heating temperature is 25 - 85°C, the extraction time is 5 - 15 min, and the stirring rate is 300 r / min.

8. The detection method of trace N-nitrosamine compounds in water according to claim 7, characterized in that, In the step (2), the water bath heating temperature is 75°C, and the extraction time is 10 min.

9. The detection method of trace N-nitrosamine compounds in water according to claim 4, wherein, In the step (3), the carrier gas of the gas chromatography is He, and the flow rate is 1 mL / min; the injection port temperature is 250°C; The programmed temperature rising conditions are: hold at 40°C for 1 min, rise to 200°C at a rate of 20°C / min, continue to rise to 260°C at a rate of 60°C / min, and hold for 3 min.

10. The detection method of trace N-nitrosamine compounds in water according to claim 4, characterized in that, In the step (3), the mass spectrometry conditions: EI source, ionization voltage: 70 eV; Ion source temperature: 230°C; Solvent delay time: 2 min; The detection method is selected ion mode.

11. A method for detecting trace N-nitrosamine compounds in water according to claim 10, characterized in that, The SIM qualitative characteristic ions are N-nitrosodimethylamine (42, 74), N-nitrosomethylethylamine (42, 88), N-nitrosodiethylamine (44, 57, 102), N-nitrosodipropylamine (70, 113, 130), N-nitrosodibutylamine (84, 99, 116, 141, 158), N-nitrosopiperidine (55, 114), N-nitrosopyrrolidine (41, 42, 100), N-nitrosomorpholine (56, 86, 116), N-nitrosodiphenylamine (169, 168, 167), and the quantitative characteristic ions are N-nitrosodimethylamine (74), N-nitrosomethylethylamine (88), N-nitrosodiethylamine (102), N-nitrosodipropylamine (130), N-nitrosodibutylamine (158), N-nitrosopiperidine (114), N-nitrosopyrrolidine (100), N-nitrosomorpholine (116), N-nitrosodiphenylamine (169). The types of nitrosamines are determined by the qualitative characteristic ions and the peak emergence time, and the content of nitrosamines is determined by the quantitative ions.

12. The detection method of trace N-nitrosamine compounds in water according to claim 11, characterized in that, The detection limits of N-nitrosamine compounds are 0.05 - 0.1 ng / L, and the recovery rates are 90% - 103.2%.

Images