The determination method of the fluorescence sulfur content analyzer (taking UV fluorescence method as an example) is based on the excitation of specific wavelength fluorescence of sulfides under UV light irradiation, and the quantitative analysis of sulfur content is achieved by measuring the fluorescence intensity. The core steps are as follows:
1、 Measurement principle
Sulfides (such as hydrogen sulfide, thiols, organic sulfides, etc.) absorb energy and transition to an excited state under specific wavelength (usually 254nm) ultraviolet light irradiation, and then release fluorescence of another wavelength (usually 300-400nm) when returning to the ground state. The fluorescence intensity is directly proportional to the sulfur content in the sample. By measuring the fluorescence intensity and comparing it with the standard curve, the sulfur content can be calculated.
2、 Measurement steps
Instrument preparation and calibration
Check the status of the instrument: Confirm that the UV light source, photodetector, gas flow path, and other components are working properly, clean the light path system and sample chamber to avoid interference from dust or stains.
Calibration instrument: Use standard samples with known sulfur content (such as GBW series standard substances) for calibration. Introduce standard samples into the instrument and establish a calibration curve for fluorescence intensity and sulfur content (correlation coefficient ≥ 0.999). If the deviation of the calibration result exceeds 5%, the standard sample or parameter settings need to be rechecked.
Sample processing
Liquid sample:
Petroleum, gasoline, etc. can be directly injected;
Liquids containing particulate impurities need to be filtered through a 0.45 μ m filter membrane to ensure uniformity and no precipitation;
Solid samples (such as coal and ore) need to be ground into powder form (particle size ≤ 0.1mm) and pressed into uniformly thick samples using a tablet press (pressure 10-20MPa, maintained for 30 seconds).
Gas sample: Introduce the instrument through a gas sampling system to control the stable gas flow rate.
Sample injection and measurement
High temperature cracking oxidation: The sample is sent to a high-temperature cracking furnace (usually 700-1050 ℃) to quantitatively convert sulfides into sulfur dioxide (SO ₂).
Dehydration treatment: The reaction gas is dehydrated by a membrane dryer to avoid interference with fluorescence detection.
Ultraviolet excitation: SO ₂ enters the reaction chamber and emits fluorescence upon exposure to ultraviolet light. The photodetector (such as a photomultiplier tube) receives the signal and converts it into an electrical signal.
Data processing: The instrument converts the fluorescence signal intensity into sulfur content based on the calibration curve, and the results are displayed in units of mg/kg or%.
Result output and recording
After the measurement is completed, the instrument automatically generates a detection report, including the sample number, measurement time, sulfur content value, and standard deviation.
For non-conforming samples or abnormal results, repeated measurements or consultation with technical support are required.
3、 Key precautions
Environmental control:
The instrument should be placed in a constant temperature (20 ± 5 ℃), dry (humidity<70%) environment, away from electromagnetic interference sources.
Avoid temperature, humidity, and airflow fluctuations during testing to ensure the stability of the results.
Security protection:
It is strictly prohibited to open the hatch when the instrument is working to prevent X-ray (X-ray fluorescence method) or ultraviolet light leakage; Operators are required to wear personal dosimeters.
Wear protective gloves when operating the high-temperature cracking furnace to avoid burns.
Instrument maintenance:
Regularly clean the sample chamber, optical system, and injection port to prevent residue contamination.
Check and replace consumable components (such as UV lamps, filters, membrane dryers) to ensure long-term stable operation of the instrument.
Record maintenance logs, including usage time, fault conditions, and maintenance content, for easy traceability.
4、 Application Fields
The fluorescence sulfur content analyzer is widely used in the following scenarios:
Petrochemical industry: Determine the sulfur content in petroleum products such as gasoline, diesel, kerosene, and lubricants to ensure compliance with environmental standards.
Natural gas monitoring: detecting trace sulfide content in natural gas and other gases to control industrial emissions.
Environmental monitoring: Analyze sulfur pollutants in industrial waste gas and wastewater to assist in environmental protection.
Materials Science: Evaluating the sulfur content in alloys, ores, and other materials to optimize production processes.