A semi-online apparatus for analyzing an atmospheric sample of trace nitrogen-containing organic fine particles PM2.5 (particle size smaller than 2.5 micrometer), comprising:
- a collision-type PM2.5 filter (1), a transparent window (2), a resistive heating rod (3) which includes a temperature sensor, a sealed water tank (4), a condenser (5), an external condensation coil (6), an internal condensation tube (7), a thermal insulation layer (8), a virtual concentrator (9), a high-flow volume flow controller (10), a high-flow vacuum pump (11), a particulate matter collection bottle (12), a low-flow volume flow controller (13), a low-flow vacuum pump (14), dimethylacetamide organic reagent (15), an ultrasonic bath (16), a fraction automatic supply/collect integrated pump (17), a vacuum parallel concentrator (18), a micro-injection pump (19) equipped with a micro-injection needle, and a liquid chromatography time-of-flight mass spectrometer (20);
- wherein the collision-type PM2.5 filter (1) is connected to an intake of the sealed water tank (4) through a matching management system;
- wherein the sealed water tank (4) comprises a transparent window (2) located at a first side the sealed water tank (4) near the intake for observing a level of ultrapure water added to the tank;
- wherein the resistive heating rod (3) with the temperature sensor is positioned inside the sealed water tank (4), wherein the resistive heating rob (3) is inserted into the sealed water tank (4) at a depth of 20-30 cm and arranged above a bottom of the sealed water tank (4) in a range of 3-4 cm;
- wherein the temperature sensor is connected to the resistive heating rod (3) via a data cable which is arranged at a minimum distance of 30 cm from the temperature sensor, and wherein the temperature sensor is inserted parallel to the resistive heating rod (3) at a position about 5-10 cm along a length of the resistive heating rod (3) and about 3-4 cm above the bottom of the sealed water tank (4);
- wherein the resistive heating rod (3) heats the ultrapure water in the sealed water tank (4), and the temperature sensor measures a temperature of the ultrapure water;
- wherein the internal condenser tube (7) is connected to an outlet on a second side of the sealed water tank (4) opposite to the first side through a first custom flange;
- wherein the external condenser coil (6) is wrapped around an external surface of the internal condenser tube (7), and the condenser (5) is connected to both ends of the condenser coil (6);
- wherein the condenser coil (6) is wrapped with the thermal insulation layer (8) for thermal insulation;
- wherein the condenser (5) generates an ethanol coolant which passes through the condenser coil (6) to produce cooling effects;
- wherein the virtual concentrator (9) is coaxially connected to a lower end of the internal condenser tube (7) through a second custom flange, wherein the virtual concentrator (9) divides an airflow into two paths:
- an exhaust gas path at a first outlet of the virtual concentrator (9), and a concentrated gas path at a second outlet of the virtual concentrator (9), wherein the concentrated gas path is connected to a particulate matter collection bottle (12) via a fixed pipeline, and the exhaust gas path is connected to the high-flow volume flow controller (10) and the high-flow vacuum pump (11) via pipes;
- wherein the high-flow vacuum pump (11) generates an airflow for a main sampling suction force in the semi-online analytical apparatus, and wherein the high-flow volume flow controller (10) controls the airflow generated by the high-flow vacuum pump (11);
- wherein the ultrasonic bath (16) is filled with ultrapure water to a height in a range of 10-15 cm;
- wherein the particulate matter collection bottle (12) is suspended in a cavity of the ultrasonic bath (16), with a distance of about 2-3 cm between a bottom of the particulate matter collection bottle (12) and a bottom of the ultrasonic bath (16);
- wherein an upper outlet of the particulate matter collection bottle (12) is connected to the low-flow volume flow controller (13) and the low-flow vacuum pump (14) in sequence;
- wherein the low-flow vacuum pump (14) extracts concentrated gas from the concentrated gas path into the particulate matter collection bottle (12), wherein the low-flow volume flow controller (13) controls a flow rate of the concentrated gas extracted into the particulate matter collection bottle (12) by the low-flow vacuum pump (14);
- wherein middle and bottom positions of the particulate matter collection bottle (12) are connected to the fraction automatic supply/collect integrated pump (17) via pipelines;
- wherein the fraction automatic supply/collect integrated pump (17) injects a dimethylacetamide solvent (15) into the particulate matter collection bottle (12) through one pipeline, and collects atmospheric fine particulate matter (PM2.5) samples dissolved in the dimethylacetamide solvent (15) from the particulate matter collection bottle (12) through another pipeline;
- wherein the fraction automatic supply/collect integrated pump (17) is connected to the vacuum parallel concentrator (18) and the micro-injection pump (19) in sequence via pipelines;
- wherein the fraction automatic supply/collect integrated pump (17) transfers a specified volume of a collected sample solution to the vacuum parallel concentrator (18) to be concentrated, and then the concentrated sample solution of the specified volume is transferred to the micro-injection needle on the micro-injection pump (19), wherein a remaining solution is diverted to an exhausted liquid bucket;
- and
- wherein the micro-injection needle on the micro-injection pump (19) is connected in series with a liquid phase injection port of the liquid chromatography-time-of-flight mass spectrometer (20) via a pipeline, wherein the liquid chromatography-time-of-flight mass spectrometer (20) analyzes organic components in the concentrated sample solution.