Standardization of analytical methods

This is the basis and central link of environmental analysis. The formulation and implementation of environmental quality assessment and environmental protection planning should be based on environmental analysis data, so it is necessary to study and formulate a set of standard analysis methods to ensure the reliability and accuracy of the analysis data.

Continuous automation of analytical technology

Environmental analytical chemistry has gradually changed from classical chemical analysis to instrumental analysis, and from manual operation to continuous automatic operation. Since 1970s, there have been automatic analytical instruments that can continuously measure dozens of samples per hour, and they have been officially designated as standard analytical methods. At present, there are automatic analytical methods and corresponding instruments such as colorimetric analysis, ion-selective electrode, X-ray fluorescence spectrum, atomic absorption spectrum, polarography, gas chromatography, liquid chromatography and flow injection analysis. In particular, the flow injection analysis method, with the analysis speed of more than 200 samples per hour, low reagent and sample consumption, simple instrument structure and easy popularization, is one of the methods with rapid development.

Application of electronic computer

The application of electronic computer in environmental analytical chemistry has greatly improved the analytical ability and research level. In modern analytical laboratories, many analytical instruments have used computers to control operating procedures, process data, display analysis results and interpret various charts. The application of electronic computer can realize the automation of analytical instruments and the continuous determination of samples. For example, a γ -ray spectrometer equipped with an electronic computer can determine various elements in hundreds of samples at the same time, and Fourier transform can be calculated on the computer, which can not only improve the sensitivity and accuracy of analysis, but also enable a nuclear magnetic resonance oscillator to measure 13C signals, making it possible to determine the organic skeleton structure, which opens up a prospect for studying the ecological and physiological mechanisms caused by environmental pollutants at the molecular level.

Joint use of various methods and tools

This can effectively give full play to the advantages of various technologies and solve some complex problems, and with the help of electronic computers, the analysis effect can be greatly improved and the analysis results can be given in time. For example, GC-MS-computer can quickly determine various volatile organic compounds. This method has been applied to wastewater analysis and can detect more than 200 kinds of pollutants. In environmental pollution analysis, spark source mass spectrometry-computer, gas chromatography-microwave plasma emission spectrum, gas chromatography-infrared spectrum, gas chromatography-atomic absorption spectrum, emission spectrum and plasma source, and mass spectrometry-ion microscope are often used as direct imaging ion analyzers.

Application of laser technology

Using laser as the light source of analytical chemistry, laser spectroscopy techniques and analytical methods such as absorption spectrum, Raman spectrum, atomic and molecular fluorescence spectrum, laser photoacoustic spectrum and high resolution spectrum have been developed. Laser analysis is characterized by high resolution, high sensitivity, long distance and short time. With the further development of laser basic theory research, laser technology will further change the face of environmental analytical chemistry.

Study on Trace and Ultra-trace Analysis

With the development of environmental science research, a new requirement is put forward for environmental analysis, that is, it is often necessary to detect as low as 10-6 ~ 10-9 g (trace level) and10-9 ~12 g (trace level). For example, it has been determined that the lead content in the air over the center of the Pacific Ocean is 1 ppb, while that in the north and south poles is lower than 0.5ppb, and that in the Antarctic ice is 0.04ppb；. The average content of mercury in rainwater is 0.2ppb；; The average content of uranium in human body is 1ppb. These results are obtained by micro or ultra-micro analytical techniques. Strengthening the research on new methods of trace and ultra-trace analysis with high sensitivity, good selectivity and rapidity has become one of the development directions of environmental analytical chemistry in the future.

Pretreatment of environmental analysis samples

Sample pretreatment method in environmental analysis

Because environmental samples have the characteristics of low concentration of tested substances, complex components, many interfering substances, and the same element exists in multiphase form and is easily affected by the environment, it usually needs complex pretreatment before analysis and determination. Classical pretreatment methods, such as precipitation, complexation, derivation, adsorption, extraction, distillation, drying, filtration, dialysis, centrifugation, sublimation, etc. Rely on manual operation, poor reproducibility, high working intensity, long treatment cycle, and use a lot of organic solvents. Therefore, sample pretreatment and pre-separation are the weakest links in environmental analysis, and also the important key links in environmental analytical chemistry and even analytical chemistry. It includes two aspects: the research of new pretreatment methods and technologies and the research of on-line combination equipment of these technologies and analysis methods.

Among the new methods and technologies, the more mature ones are:

1, solid phase extraction, SPE)

The principle is to separate the tested component from other components according to the strength of different components acting on the solid filler in the sample. It is mainly used to treat environmental water samples and soluble solid environmental samples, and can also be used to capture trace organic matter and aerosol in gas. The composition of eluent, the type of packing and other parameters are changed to achieve different separation purposes. In the early days, columnar solid filler was the main filler, but recently, a new type of film filler with a thickness of about 1mm appeared. They have large cross-sectional area and high flow rate, and are especially suitable for on-site treatment of samples.

2. Supercritical fluid extraction (SLM)

This method uses the supercritical fluid with high density similar to liquid, high solubility and high diffusivity similar to gas, so it can effectively extract the measured solute from solid. It is especially suitable for treating various solid environmental samples. By changing the composition, temperature and pressure of supercritical fluid, different components can be selectively extracted and separated continuously from the sample. It is not only used for sample pretreatment, but also for solid waste treatment.

3. Solid phase microextraction (SPME)

It takes the fused Shi Ying optical fiber in the syringe needle as the carrier, and the surface is coated with organic fixing liquid. When it is immersed in the sample solvent, the detected substance is adsorbed on its surface by diffusion, and then transferred to the injection port of the gas chromatograph for injection. After thermal desorption, the measured substance enters the chromatographic calibration with the carrier gas for separation and determination. This method can be used to treat various gases and liquids in environmental samples, such as solid samples of volatile substances in HPLC. By changing the type of stationary liquid and the thickness of liquid layer, the selectivity of the method can be changed, the adsorption capacity can be increased, and it is easy to be automated, and it can be directly treated below 650. Table-1 lists several representative pretreatment methods of solvent-free and solvent-free samples.

Table-1 Several main pretreatment methods of solvent-free and solvent-free samples

Pretreatment method

principle

Analysis

Analysis object

Extraction stage

disadvantaged

Headspace method (static headspace method, capture and purge method)

Using the volatility of the object to be measured

Directly extract the headspace gas of the sample for chromatographic analysis; Blow out the tested substance in the sample as much as possible with carrier gas, and collect the tested substance by freezing capture or adsorption collection.

Volatile organic compound

gas

Static headspace method can't concentrate the sample, and the quantification needs to be corrected. Blow-grab method is easy to form foam, and the instrument is too cut.

Supercritical fluid extraction

Using the characteristics of high density, low viscosity and sensitivity to pressure change of supercritical fluid

Extract the sample to be tested in supercritical state, and analyze it after decompression, cooling or adsorption collection.

Hydrocarbons and nonpolar compounds, as well as some moderately polar compounds.

Carbon dioxide, ammonia, ethane, ethylene, propylene, water, etc.

The extraction device is expensive and not suitable for analyzing water samples.

Membrane extraction

Adsorption of substances to be detected by membrane

The substance to be detected in the sample is extracted by polymer membrane, and then the substance to be detected in the membrane is extracted by gas or liquid.

Volatile and semi-volatile substances support liquid membrane extraction of compounds that can be ionized at different pH values.

Polymer film, hollow fiber

The change of the concentration of the substance to be measured is lagging behind with the age of the membrane, and the substance to be measured is greatly limited by the membrane.

Solid phase extraction

Adsorption of solid adsorbent on measured object

Firstly, the substance to be detected is adsorbed by adsorbent, and then eluted by solvent.

All kinds of gases, liquids and soluble solids

Keywords disk membrane, filter, solid phase extraction

The recovery rate is low, and the solid adsorbent is easy to block.

Solid microphase extraction

Distribution equilibrium of analyte between sample and extraction coating

Expose the extracted fibers to articles or their headspace for extraction.

Volatile and semi-volatile organic compounds.

Selective adsorption coating

The extraction coating is easy to wear and has a limited service life.

4. Accelerate solvent extraction

This is a brand-new extraction method, which can significantly improve the speed of sample pretreatment. After the solvent is pumped into the extraction tank containing the sample, it is heated and pressurized. After a few minutes, the extract was transferred from the heated extraction tank to the collection bottle for analysis. The extraction step is automatic, and it can be extracted for many times, which is fast, time-saving and less solvent consumption. Taking the analysis of organochlorine pesticides in soil as an example, a large number of organic solvents should be used to extract them from the matrix. Recently promulgated and about to be promulgated environmental protection laws and regulations strictly restrict the use of solvents in laboratories in many aspects. In order to adapt to this change, accelerated solvent extraction came into being as a solid sample pretreatment technology to reduce solvent consumption. Compared with traditional methods, accelerated solvent extraction is more convenient, faster, less solvent consumption, and the reproducibility is equivalent to that of ultrasonic extraction. Avoiding the problem of multiple cleaning caused by ultrasonic extraction.

Table -2 shows the 600 series standard analytical methods for preferentially detecting organic pollutants in water. After appropriate pretreatment steps, they can be developed into standard analytical methods for corresponding pollutants in drinking water (500 series) and solid waste (8000 series). These methods actually correspond to their respective pretreatment steps.

Table 2 Comparison table of 500, 600 and 8000 series method numbers of US Environmental Protection Agency

Pollutant name

500 series

(drinking water)

600 series

(wastewater)

8000 series

(solid waste)

Main analytical methods

Volatile halogenated hydrocarbons

502. 1

60 1

80 10

GC/OHD，ECD

Volatile organic compound

502.2

80 15

Volatile aromatic hydrocarbons

503. 1

60 1

8020

GC/PID

vinyl cyanide

603

8030

GC/FID

Dibromoethylene, propane dichloride

504

phenols

604

8040

GC/FID '，EC

Organic halide and pesticide emergency polychlorinated biphenyls

505

benzidine

605

phthalic acid ester

506

606

8060

Nitrogen and phosphorus pesticides

507

Nitrosamines

607

GC/NPD tea

Organochlorine pesticides and polychlorinated biphenyls

508/508A

608

8080

GC/ECD

Nitroaromatic hydrocarbons and isophorone

609

1980s and 1990s; Octogenarians and the 1990s

GC/EC，FID

polycyclic aromatic hydrocarbon

6 10

8 100

Liquid chromatography/ultraviolet, fluorescence, gas chromatography/flame ionization detector

Halogenated ether

6 1 1

GC/OHD

halogenated hydrocarbon

6 12

8 120

GC/ECD

2，3，7，8-TCDD

6 13

Gas chromatography/mass spectrometry

organophosphor

8 140

Organochlorine herbicide

5 15

8 150

Volatile organic compound

524-2(60 weight)

624

8240

Gas chromatography/mass spectrometry

Semivolatile organic compounds

525

625

8250

GS/MS

Progress of various chromatographic techniques

1, continuous development and application of capillary gas chromatography technology

The development of high sensitivity and high selectivity gas chromatography detector, GC and MS laid the foundation for the four analytical methods of priority detection of organic pollutants in water published by USEPA 1 14 at the end of 0979. The application of capillary gas chromatography greatly improves the separation efficiency and analysis speed, simplifies the method and reduces the purification loss. In recent 20 years, the capillary changed from metal to glass, and then developed into melting time. The development of capillary column stationary phase, polymer liquid crystal stationary phase, polymer crown ether new stationary phase, column surface deactivation treatment (such as radiation treatment), especially the successful development of chemically bonded cross-linked stationary phase, makes a large number of important pollutants (including many isomers) have reliable determination methods. Non-split sampling and on-column sampling technology have solved the problems of small column capacity and decomposition of thermally unstable samples. In recent years, the development of large-diameter capillary columns with internal diameters of 0.53 mm and 0.75 mm has further solved the problem of small column capacity, and directly connected it with stripping equipment, which simplifies the analysis steps of volatile compounds and is more conducive to matching with detectors with low sensitivity. Combined column technology, chemical derivatization technology (including pre-column and post-column), etc. , not only can improve the resolution or sensitivity, but also can solve the monitoring of some chemicals with poor volatility to some extent. Detectors with high sensitivity and selectivity are still under development, such as chemiluminescence detector, TEA, ionization detector, enzyme inhibitor fluorescence monitor and so on. Coupled with the application of multidimensional chromatography and the combination of various monitors, especially GC, MS and other instruments. Xu et al. summarized the research status of air pollution chromatography in China, studied and discussed the potential carcinogens in the environment, such as polycyclic aromatic hydrocarbons and nitropolycyclic aromatic hydrocarbons, and studied the greenhouse effect of trace elements and harmful and toxic particles in the air of several cities in China. EPA has adopted capillary gas chromatography as a routine monitoring technology, and GC-TID (ion trap detector) has its own characteristics in improving sensitivity. In this respect, both the production of instruments and the development of capillary columns in China have a good foundation, and it may make more contributions in developing new chromatographic technologies, improving quality, reducing prices and serializing prescription solids in the future. 1More than 350 papers were published in the 7th National Symposium on Chromatography held in 1998, among which 1/6 was related to environmental samples, which also reflected the important role of chromatographic analysis in environmental analytical chemistry in China.

Recently, Jiang Guibin's Shi Ying Surface-Induced Photometry (FPD) applied QSIL principle pioneered by timely surface to quantitative analysis for the first time in the world, which attracted high evaluation from academic circles and won a national invention patent. This research work provides a highly sensitive flame photometric detector. Compared with the existing commercial instruments, it has three advantages: (1) chromatographic column is directly inserted into the top of the burner, which avoids the phenomenon of chromatographic peak broadening caused by sample diffusion. (2) The traditional combustion mode of hydrogen flame is changed, and the stability of the flame is fundamentally improved. (3) By changing the emission medium of the flame, the emission mechanism is fundamentally changed, and the strong emission spectrum is obtained. Compared with common gas chromatography flame photometry, the sensitivity is improved by100-1000 times. The system can well separate and determine organotin compounds with different forms in various media, and the minimum detection limit is 30 fg-2.3 pg. In addition, this principle can also be applied to the quantitative analysis of sulfur, phosphorus compounds, organic selenium, organic lead and other compounds.

1997 After the 2nd1century seminar was held in the United States, the design and research of field monitoring and mobile laboratory showed a new development direction. For example, portable chromatograph has been applied to field environmental analysis. 1998 commodities appeared at the Pittsburgh conference, and China is also developing a capillary portable chromatograph. In the process of miniaturization, the miniaturization technology of conventional chromatographic detectors is the limiting factor in this field.

Chromatographic sampling technology: rapid development, on-column sampling, split/non-split flow sampling, purging and trapping sampling and other technologies have become routine methods in the laboratory. The development of chromatographic calibration is also changing with each passing day. Many organotin compounds were successfully separated and determined by using a parallel multi-capillary system developed in France (including 900 capillaries with length 1m, inner diameter of 40μm and coating thickness of 0.2μm). The separation time is shortened from 5- 10 min of conventional capillary column to 30 s.

2. Wide application of high performance liquid chromatography.

Since 1980s, the growth rate of HPLC instruments has been the first, and it is estimated that in 1983, the global sales of HPLC has surpassed that of GC. This is because GC is mainly used for the determination of volatile pollutants, but more than 70% of the compounds are low volatility, high molecular weight or thermally unstable, so they cannot be directly determined by GC without derivatization, and HPLC just makes up for this deficiency, so the latter is increasingly used for environmental analysis. Jin Zuliang once counted the articles cited in Analytical Abstracts. In 1980, the number of articles using HPLC is only 1/5 of GC, but it is reduced by nearly half in 1989. Although the resolution of high performance liquid chromatography is not as good as that of capillary gas chromatography (HRGC), it is also useful to directly analyze 32 kinds of pollutants at one time. Reducing the column diameter and using 3μm packing can improve the resolution. The column efficiency of 3-7 cm commercial column can reach 5000- 10000 theoretical plate/m. When used for routine analysis of environmental samples, the post-column reaction of HPLC can be completed within 1min, and the detection sensitivity can reach pg level, which is a rapidly developing field. In addition, more general detectors similar to those used in gas chromatography have been developed, such as HPLC-FPD and HPLC-.

The application of microporous column promotes the development of LC-MS. Due to the decrease of solvent, the interface problem with MS is solved, and routine detection can be carried out. However, due to the slow analysis speed of microporous column, other interface technologies such as thermal spray, electrospray and particle beam are more ideal. If HPLC is used for classification and pre-separation, the number of pollutants detected can be increased several times in system analysis.

3. Development of supercritical fluid chromatography.

The application of supercritical fluid in chemical separation and the successful combination of computer technology have made modern supercritical fluid chromatography instruments and aroused the interest of analytical circles. In recent years, the appearance of commercial capillary SFC has attracted more and more attention in environmental analytical chemistry. Because this method is characterized by using supercritical fluid as mobile phase, it can fill the gap between GC and HPLC, and is suitable for the separation and determination of complex mixtures such as polar compounds, thermal instability, chemical activity, high molecular weight and volatile compounds. Theoretical calculation shows that the separation efficiency of capillary SFC is similar to that of GC, but higher than that of HPLC. Therefore, SFC has the advantages of both GC and HPLC.

The common mobile phase of SFC is CO2, but now there are more fluids to choose from. The combination of different fluids and different composition ratios can also be used, so the analysis methods can be quite diversified and can also play the role of selective extraction and pre-separation. This can not only save solvent, shorten the extraction time, but also reduce the pollution caused by pretreatment.

Now people realize that SFC is valuable because it can be combined with a series of detection systems. Generally speaking, GC and HPLC detectors can be used for SFC, such as FID, FPD, ECD, UV and fluorescence. New detectors, such as chemiluminescence sulfur detector, have a sensitivity of several tens to 100pg and a linear range of 103. The combination of SFC with MS and FT-IR is also successful. At present, SFC-FTIR can obtain mass spectra similar to EI and CI, with good sensitivity.

According to reports, SFC is applied to pesticides, dyes, organic acids, surfactants and drugs. Among them, there are many reports about the determination of pesticides and their metabolites.

4, the application of ion chromatography [IC]

With the development of ion chromatography, ion chromatography is gradually applied to environmental analysis because of its advantages of simple operation, high speed, good selectivity, high sensitivity and accuracy, and simultaneous determination of various components. First of all, it has developed rapidly in anion analysis. In recent years, due to the further development of gradient elution, chromatographic column and detector, ion chromatography has been used to determine cations, transition metals and metal complexes. Distinguish different valence states until organic compounds are analyzed.

5. Capillary electrophoresis

In recent years, the application of capillary electrophoresis in environmental chemistry has gradually expanded, including the analysis of pollutants and DNA adducts, the determination of n-octanol-water partition coefficient and the determination of methylmercury in animals. , and published several reviews. Capillary electrophoresis has unique advantages in the separation of environmental pollutants because of its small sample demand, high separation efficiency, low column price, easy cleaning, low reagent consumption, simple method and short analysis time. Yan et al. used packed column capillary electrochromatography to separate 65,438+06 polycyclic aromatic hydrocarbons (PAHs) preferentially detected by EPA within 45min minutes. Using CZE (capillary zone electrophoresis) mode, phenol and its 65,438+02 derivatives can be separated within 24min. By changing the analysis conditions, 65,438+02 phenolic compounds can be quickly separated within 24min. There are also reports on the separation of dioxin TCDD, polychlorinated biphenyl isomers and optical isomers. MEKC (micellar electrokinetic chromatography y) has been successfully used to separate and analyze colloidal compounds. Capillary electrophoresis has been used to separate paraquat, herbicide, sulfonylurea and phenoxy acid. This kind of work involves not only the separation of enantiomers or isomers of herbicides, but also the analysis of herbicide residues in crops and herbicides in water. At present, the research on the separation and analysis of environmental pollutants by capillary electrophoresis is deepening and expanding, but a lot of work focuses on the separation of standard samples, and it is relatively less applied to the analysis of actual environmental samples. The main reason is that the sensitivity of the detector is not enough, and new sample pretreatment methods are needed, but overall, the prospect is still very bright.

coupling technique

Combinatorial technology is a hot spot in analytical chemistry. In environmental analysis, it is difficult to solve problems with a single instrument because of the complexity of samples and the high demand for information. The successful experience of GC/MS in environmental analytical chemistry, especially in environmental organic analysis, need not be described in detail, especially the introduction of four-level mass spectrometry combined with microcomputer system retrieval, which makes its routine detection cost in the US Environmental Protection Agency system comparable to that of GC, and sometimes even lower than that of the latter. With the development of mass spectrometry itself, the on-line application scope is constantly expanding, and the combination of gas chromatography and elemental analysis instruments also extends its power to the analysis of inorganic or organometallic substances. Although it is difficult to remove solvents by replacing gas chromatography with high performance liquid chromatography online, it is convenient to combine with infrared spectroscopy and nuclear magnetic resonance. In addition, the combination of interface technologies such as thermal spraying, electrospray and soft ionization not only solved the main obstacle of LC/MS coupling, but also extended the analysis object to low volatile compounds, and the coupling of SFC, IC and MS was also successful. Table -3 shows several combination technologies in environmental analysis, from which we can see that combination technologies and their combinations are increasing rapidly.

The emergence of triple and quadruple instrument systems and even multi-machine integration is a new trend of environmental analytical chemistry and environmental analytical instruments. In addition, the introduction of injection flow injection (FIA) and other technologies will also make the analysis of environmental samples automatic and rapid to a new height.

Table 3 Combinatorial Techniques in Environmental Analytical Chemistry

coupling technique

Application example

Gas chromatography-atomic absorption spectrometry

Ethyl lead compounds in petroleum, complexes in fish and mercury compounds.

atomic emission spectrometry

Organotin compounds, silylated alcohols

Microwave plasma emission spectrum

Element selective detection

atomic fluorescence spectrometry

lead tetraethyl

Gas Chromatography-Inductively Coupled Plasma Atomic Emission Spectrometry

Alkyl lead, silicone (manganese, mercury, chromium)

Gas chromatography-mass spectrometry

Universal application (volatile, semi-volatile compounds, derivatives)

Gas chromatography-infrared spectrum

Nitro-polycyclic aromatic hydrocarbons in diesel engine exhaust particulate matter

Gas chromatography-mass spectrometry-infrared spectrum

GX tea

nitrosamine

High performance liquid chromatography-atomic absorption spectrometry

Organotin tetraalkyl lead

High Performance Liquid Chromatography-Inductively Coupled Plasma Emission Spectrometry

Cobalt, protein dielectric metal, iron, arsenic, mercury and copper in VB 12; Chelation state analysis, isotope dilution

High performance liquid chromatography-inductively coupled plasma mass spectrometry; High performance liquid chromatography-infrared spectrum; High performance liquid chromatography-tea

High performance liquid chromatography-mass spectrometry

Thermal spraying, particle beam/magic

High performance liquid chromatography-nuclear magnetic resonance

10-4g, semi-volatile and non-volatile substances in multicomponent electrospray.

HPLC-IR/MS

MS/MS (can be combined with GC or HPLC)

10- 1 1- 10- 12g(PCDF PCDD)

SFC-FID, UV, etc.

Azo, anthraquinone, aniline dyes, polycyclic aromatic hydrocarbons

SFC-MS, FTIR or NMR

Insecticide, etc

IC-ICP

1-100×10-9 surface water

Inductively coupled plasma mass spectrometry

0.1-10×10-9 (the detection limit can reach 0.0 1). Aluminum, manganese, copper, nickel, cobalt, zinc, tin, cadmium, barium, lanthanum, cerium, thorium and uranium in marine life.

Photometric detection of surface emission flame by gas chromatography

Speciation analysis of organotin, lead, mercury, germanium and selenium in water and biological samples, the sensitivity is 0.7-2.3pg (detection limit) organotin.

In the analysis of inorganic substances, the combination of ic and detection instruments, especially the combination of ICP, MS and various injection methods, has become an important frontier in the analysis of trace elements. Because of its high sensitivity (detection limit is 10-60pg/ml), high selectivity, wide linear range, simultaneous determination of multiple elements and online analysis, USEPA has listed ICP-MS as a feasible routine analysis method.

Environmental analytical chemistry combined with biology

1, separation and analysis under the guidance of biological experiments

Separation and analysis under the guidance of biological experiments developed in the early 1980s, which is one of the important development directions of organic pollutant analysis. At present, carcinogenic, teratogenic and mutagenic components in environmental samples are the main concerns. Because medicine can't completely control and cure cancer that seriously threatens human life, and epidemiology points out that 70%-90% of human cancers are caused by carcinogens in the environment, the development of short-term biological experiments (such as Ames test) provides the possibility to preliminarily evaluate the three characteristics of the research object in a short time, with low cost and high sensitivity. It has good selectivity, and combined with chemical separation and identification, it is possible to effectively screen active components from complex environmental samples and obtain new results, such as finding the potential carcinogen nitro polycyclic aromatic hydrocarbons in the environment. Recent studies show that there are not only nitropolycyclic aromatic hydrocarbons, but also hydroxynitropolycyclic aromatic hydrocarbons in atmospheric dust, and the mutagenicity of the latter is sometimes higher than that of the former. Gas research has also achieved corresponding results, which has promoted the study of environmental pollution activities. Bioguided activity discovery is the product of the combination of biology and analysis, which will play a greater role in environmental science research.

2. A new analytical method-biological monitoring: immunoassay.

Conventional environmental analysis sometimes cannot report the results of a large number of complex samples in time and quickly, and some biological monitoring methods can play a very good role in this regard. Immunization test is a good example. The latter has made great achievements in environmental application in recent years and has been applied to regional environmental quality assessment. Immunoassay has many advantages: low price, high sensitivity (such as 1ng), simple pretreatment method, which is beneficial to monitoring a large number of certain objects and real-time analysis, so the prospect is attractive. In the progress of some environmental analysis in the frontier of analytical chemistry, the immunoassay data of pesticides, carcinogens and even DNA adducts are reported, which shows its high sensitivity. EPA, AOAC and IUPAC of the United States have organized many professional meetings, which are expected to be more used for environmental monitoring in the future.

In addition, the development and application of various biosensors and biomarkers will also have broad prospects.