1、 Sample pretreatment requirements
1. Acid base neutralization: Liquid samples should be neutralized to neutral (pH 6-8) to avoid corrosion of instrument pipelines by strong acids (such as sulfuric acid, phosphoric acid) or strong bases (pH ≤ 2 or ≥ 12).
2. Salt control: Total dissolved solids (TDS) should be ≤ 5000 ppm, and high salt samples should be diluted to below 2000 ppm to prevent detection errors or blockages.
3. Filtration treatment: Use a 0.45 μ m filter membrane to filter until clear and transparent, removing suspended particles and emulsion.
2、 Operating environment and instrument status
1. Temperature control: The recommended ambient temperature is 10-40 ℃ (fluctuation ≤ 5 ℃/day), and the sample temperature is 0-95 ℃.
2. Power supply and grounding: A stable 220V/50Hz power supply is required, and it is recommended to equip UPS to prevent data loss.
3. Reagent inspection: Before use, it is necessary to confirm the remaining amount of desiccants, dehalogenants, phosphoric acid and other reagents, as well as the status of the combustion tube.
3、 Testing process specification
1. Concentration range: The conventional detection range is 4 μ g/L-40000 mg/L, and samples exceeding the limit need to be diluted.
2. Sample volume: A single test should be ≥ 15 mL, and multiple tests should be proportionally increased (such as ≥ 35 mL for three tests).
3. Calibration and maintenance: Regularly calibrate with standard solution and clean the injector and multi way valve.
4、 Security and Storage
1. Hazard avoidance: It is strictly prohibited to analyze samples containing explosive gases, toxic substances, or high concentrations of organic solvents.
2. Sample preservation: Fresh water samples should be tested first. If refrigeration is required, they should be sealed in the dark (4 ℃).
3. Shutdown process: After detection, wait for the furnace temperature to drop below 100 ℃ before turning off the carrier gas and power.
5、 Interference and Limitations
1. Interference substances: Halides and hydrocarbons may affect the results, and it is recommended to choose anti-interference techniques (such as NDIR).
2. Particle limitation: Large suspended particles cannot be detected, and the results only reflect dissolved organic carbon.