Interview by the Head of the Environment Monitoring Division of the Ministry of the Environment on two issues related to environmental protection standards

The Ministry of Ecology has recently issued two environmental protection standards, the Determination of Ambient Air benzo[a] chromatography Law (HJ 956-2018, hereinafter HJ 956-2018) and the Screening of Filters/Fluorinated Ionization of Environmental Air Fluoride Law (HJ 955-2018, hereinafter HJ 955-2018), and the Head of the Environment Monitoring Division of the Ministry of Ecology responded to questions from journalists on the relevant criteria.

Question: Please describe the main context in which these two standards have been developed.

Response: HJ 956-2018 is an amendment to the accompanying analytical method for [a] benzene in ambient air quality standards (GB 3095-2012, hereinafter referred to as GB 3095-2012) - the Environmental Air, benzene [a] benzene determination and efficient liquid chromatography method (GB/T 15439-1995). With advances in monitoring technology, the original standards showed many deficiencies in sample collection, sample extraction and testing methods. For example, the original standard limits the use of large-flow samplers for inhalable particles in ambient air, is limited to acetylene ultrasound, detection methods are UV-detected without the use of sensitivity and selective and better fluorescent detection methods, and the determination of some of the original standard indicators does not meet the requirements of the Revised Technical Guidelines for the Standardized System of Environmental Monitoring and Analysis Methods (HJ 168-2010, hereinafter HJ 168-2010). In view of these circumstances, it is proposed that the original criteria be revised.

HJ 955-2018 is an amendment to the HFC-Ion Selection Optical Method (HJ 480-2009) for GB 3095-2012 fluoride packages. The original criteria show many deficiencies in sample collection, sample preparation, quality control, etc. For example, the original standard uses medium-flow sampling for both hourly and daily average monitoring, which is excessive; At the same time, there are no regulatory requirements for the technical content of sampler head structure, flow stability and the capacity of sample pump negatives to influence effective sampling, such as for double membrane collection; There is a lack of methodological quality assurance and quality control elements to effectively support GB 3095-2012 requirements for fluoride monitoring. In the light of the above, a revision of the original criteria is proposed.

Q: What is the specific content of the standard revision?

Answer: HJ 956-2018 expands the method from benzo[a]pyrene in PM10 to benzo[a]pyrene in all particulate matter. It allows low-, medium- and high-volume sampling; adds conventional and automated Soxhlet extraction, pressurized fluid extraction and ultrasonic extraction; adds extraction solvents and sample cleanup methods; adopts a fluorescence detector with improved sensitivity and selectivity; revises gradient elution conditions and quantification methods; and adds quality assurance and quality control provisions.

HJ 955-2018 modified the flow of samples; supplemented the requirements for sampling head structure and sampler performance in instruments and equipment; simplified the standard curve configuration process; and added elements such as presentation of results, quality assurance and quality control, waste disposal and information attachments.

In addition, to complement the implementation of the Environmental Air Quality Standards (GB 3095-2012) (Ministry of Ecology Bulletin 2018 No. 29), the presentation of the results of the analysis in both criteria is no longer converted to concentrations in the standard state, but is consistent with the requirements of the change orders.

Q: What is the advanced nature of the new standards?

Response: The revised HJ 956-2018 provides users with more choice in sample collection, extraction, etc., the sampling method is consistent with the current main sampling methods, the application of some more advanced extraction, purification and testing techniques, improved intervention resistance to sample analytical measurements, improved accuracy and precision of measurements, standard test limits, precision and accuracy indicators are in line with the relevant standards, and the revised standard technical methods and technical content are aligned with the relevant international standard methods.

HJ 955-2018, as amended, takes full account of the presence of fluoride in gaseous and particulate form in sample collections, using double-layered filters to ensure that monitored fluoride levels accurately reflect the level of total fluoride in ambient air; Clear requirements are given in the criteria for technical elements that affect effective sampling, such as head structure, flow stability and negative pressure capacity of sampling pumps, to ensure the normative character of sampling; In addition, the use of ion selection electrodes, which are common in international methods, with high sensitivity, low detection limits and easy operational mastery, ensures that the standard analytical method is well adapted throughout the country; At the same time, clear quality assurance and quality control requirements are put in place to ensure the scientific and accurate nature of the data being monitored in the use of the methodology.