Determination of formic acid, acetic acid and oxalic acid in ambient air particles by ion chromatography with self-produced chromatographic column
There are two main aspects of fine particulate matter produced by human activities in the ambient air:
① The first is the direct release of fine particles into the air from various pollution sources, including smoke, dust, fugitive dust, oil fume, etc.;
② The second is the fine particulate matter generated after some chemically active gaseous pollutants (precursor pollutants) react in the air. These precursor pollutants include sulfur oxides, nitrogen oxides, volatile organic compounds, and ammonia.
As a component of PM2.5, organic acids play a very important role in photochemical reactions. However, there is currently no international limit on the content of organic acids in ambient air particles. Domestically, the "Comprehensive Emission Standard of Air Pollutants" (GB16297-1996) did not see the limit statement on the concentration of organic acid pollutants in particulate matter, and the "Ambient Air Quality Standard" (GB3095-2012) only covers The requirements are made as a whole, and no limit is specified for organic acids. At present, the determination methods of organic acid content mainly include potentiometric titration, spectrophotometry, enzymatic analysis, capillary electrophoresis, gas chromatography, liquid chromatography, mass spectrometry and ion chromatography.
In order to implement the Environmental Protection Law of the People’s Republic of China and the Air Pollution Prevention and Control Law of the People’s Republic of China, prevent and control environmental pollution, improve the quality of the ecological environment, and standardize the determination methods of formic acid, acetic acid and oxalic acid in ambient air particles, the Ministry of Ecology and Environment organizes The draft of the National Ecological Environment Standard "Ion Chromatography for the Determination of Formic Acid, Acetic Acid and Oxalic Acid in Ambient Air Particles" for comments was compiled.
1 Chromatography equipment
Ion chromatograph: IC6200, equipped with conductivity detector
Eluent generator: EG6100, OH-type
|Column||Wayeal HS-5A-P2 4.6x250mm|
|Eluent||KOH Gradient elution|
|Column temperature||40℃||Pond temperature||40℃|
3 Interference test
|No.||Compound name||Retention time||Peak height||Peak area||Signal-to-noise ratio||Degree of separation|
Note: It can be seen from the test chromatogram and injection information that there is no interference between the target ion and the conventional 7 kinds of anions, and the resolution meets the test requirements, and the chromatographic conditions are available.
4 Standard curve test
|Standard curve series concentration gradient table (μg/L)|
5 Repeatability test
|No.||Acetic acid||Formic acid||Oxalic acid|
|Retention time||Peak area||Retention time||Peak area||Retention time||Peak area|
Note: In this test, the qualitative repeatability and quantitative repeatability of formic acid, acetic acid, and oxalic acid are all less than 1%.
6 Detection limit test
The test results are as follows:
(Formic acid—8.64μg/L, acetic acid—28.8μg/L, oxalic acid—28.8μg/L, low-concentration standard solutions for this test (formic acid—5μg/L, acetic acid—10μg/L, oxalic acid—10μg/L ), the detection limit is calculated by the signal-to-noise ratio.