Nutech Atmospheric Pre ConcentratorUsed to enrich trace volatile organic compounds (VOCs) in the atmosphere and provide high concentration samples for subsequent detection, the operation needs to follow the "pretreatment parameter setting operation post-treatment" process, with the following core points.
Pre processing before operation is the foundation. Firstly, check the pressure of the carrier gas (nitrogen/helium) to ensure it is stable at 0.8-1.0MPa. Open the gas valve to remove impurities from the pipeline for 30 seconds; Confirm that the temperature of the cold trap meets the standard. Routine testing requires pre cooling to -180 ℃ (low boiling point VOCs can be reduced to -200 ℃). After the temperature stabilizes, calibrate the flow meter and set the sampling flow rate to 50-500mL/min. At the same time, clean the sampling pipeline to avoid cross contamination, and the sampling port should be kept away from the source of pollution, with a height of 1.5-2m above the ground.
The parameter settings need to accurately match the detection requirements. Select "manual mode" or "automatic mode" through the touch screen. The automatic mode can preset the sampling time (usually 30-120min), concentration times (1-3 times), and desorption temperature (200-250 ℃); The manual mode needs to be set step by step: first start the sampling pump to collect the sample. After the sample is preliminarily enriched through the adsorption tube, it enters the cold trap for deep concentration. After reaching the preset time, the sampling will automatically stop. Attention: Different types of VOCs need to be matched with corresponding adsorbents, such as using Tenax adsorption tubes for benzene derivatives.
The operation and post-processing are critical and rigorous. Real time monitoring of cold trap temperature, carrier gas flow rate, and system vacuum during operation. If there are flow fluctuations or temperature anomalies, immediately suspend operation to investigate leaks. After concentration is completed, the desorption program is started, and the cold trap is rapidly heated to the set temperature. The high concentration sample after desorption is pushed by the carrier gas to the detection equipment (such as GC-MS). After the operation is completed, execute the "empty run" program to clean the cold trap and pipelines, close the carrier gas valve, and turn off the power after the cold trap returns to room temperature.
Operation taboos must be kept in mind: it is strictly prohibited to start the equipment without a carrier gas to avoid damaging the cold trap; Do not touch the sampling port during sampling to prevent human contamination; Regularly record operating parameters and faults, and replace adsorption tubes and filters every quarter.