GB/T 37185-2018 in English

Introduction

This standard (GB/T 37185-2018) specifies the determination method of volatile hazardous organic compounds in indoor air, using SUMMA tanks and silanized tube sampling combined with gas chromatography/mass spectrometry (GC/MS) technology. This method is suitable for the detection of volatile organic compounds in places such as residences, office buildings, and environmental test chambers.

Method principle

Indoor air samples are collected through stainless steel tanks with inert inner walls, and cold trap capture concentration and heating desorption technology are used. After the samples are separated by capillary chromatographic columns, they are qualitatively and quantitatively analyzed by mass spectrometry detectors. The identification of the target is completed by comparing with the standard mass spectrum database and retention time.

Reagents and Materials

Instruments and Equipment

The main instruments include:

• Gas pre-concentration system: used for sample capture and concentration.
• Gas chromatograph/mass spectrometer (GC/MS): with electronic flow controller, program temperature rise function and full scan/selected ion scan mode.
• Capillary column: 6% cyanopropylbenzene/94% methylsiloxane, 60 meters long, 0.32 mm inner diameter, 1.8 microns film thickness.

Sample collection and storage

Sample collection adopts two methods: instantaneous sampling and constant flow sampling:

1. Instantaneous sampling: bring the SUMMA tank to the sampling point, and complete the sampling in about 30 seconds after opening the valve.
2. Constant flow sampling: Set a constant flow rate and start sampling until the scheduled time ends.

Samples must be stored at room temperature. Formaldehyde analysis must be completed within 7 days, and other components must be completed within 15 days.

Analysis steps

Result calculation and presentation

Quantitative analysis is based on the calibration curve. The mole fraction of the target compound is calculated by the peak area and converted into the mass concentration under standard conditions. Qualitative analysis is completed using relative retention time and mass spectrum database matching.

Quality assurance and control

• Parallel sample determination: one parallel sample is analyzed for every 10 samples or each batch, and the relative deviation of the target object is no more than 30%.
• Calibration curve: at least 5 concentration points, and the linear correlation coefficient is not less than 0.995.

Implementation suggestions

To ensure the effective implementation of the standard:

1. The laboratory should be equipped with advanced GC/MS equipment and calibrated regularly.
2. Operators must undergo professional training and be familiar with the specifications for the use of SUMMA tanks and silanized tubes.
3. In data processing, it is recommended to use the NIST database for mass spectrum matching.