ASTM D5623 - Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography
ASTM D5623: Standard Test Method for Sulfur Compounds in Light Petroleum Liquids by Gas Chromatography and Sulfur Selective Detection
Introduction
ASTM D5623 outlines a standardized approach for determining volatile sulfur-containing compounds in light petroleum liquids using gas chromatography coupled with sulfur-selective detection. This methodology caters to a range of petroleum products, including distillates, gasoline motor fuels, and other liquids that boil at approximately 230°C (450°F) or lower at atmospheric pressure. The method is precise enough to detect sulfur concentrations ranging from 0.1 mg/kg to 100 mg/kg.
Scope
1.1 Applicability
The test method is designed for light petroleum liquids, including those with oxygenates, providing a broad applicability within the petroleum industry. It offers a means to quantify individual sulfur species within the specified concentration range, although it does not aim to identify all sulfur compounds present.
1.2 Limitations
While the detector response is linear and equimolar for all sulfur compounds, reactive sulfur species like hydrogen sulfide and mercaptans may alter in concentration during sampling and analysis, affecting the accuracy for these specific compounds. Moreover, the method estimates total sulfur content but isn't the preferred choice for total sulfur determination.
1.3 Standard Units
The test method adopts SI units as the standard, with non-SI units provided for informational purposes only.
1.4 Safety Considerations
Users are responsible for adhering to safety and health guidelines and understanding regulatory constraints relevant to the test method.
1.5 International Standard Compliance
Developed in accordance with global standardization principles, this test aims at facilitating international commerce and technological compatibility.
Referenced Documents
The methodology references several ASTM standards and other documents, ensuring a comprehensive approach to sulfur detection in petroleum liquids.
Test Method Summary
The process involves gas chromatography with a sulfur-selective detector to analyze the sample. Calibration is achieved using internal or external standards, assuming equivalent sulfur responses across compounds.
Significance and Use
This method allows for rapid identification and quantification of sulfur compounds, aiding in the control of sulfur levels in petroleum products. Given the impact of sulfur compounds on product quality and processing, detailed knowledge of these compounds is critical.
Apparatus and Conditions
Chromatograph Specifications: The gas chromatograph must support linear temperature programming and constant flow control of gases, with a detector capable of equimolar sulfur response.
Column and Operating Conditions: A specified column type and dimensions are recommended, along with particular settings for sample size, injector and column oven temperatures, and carrier gas pressure.
Detector Requirements: The sulfur-selective detector should meet specific sensitivity and linearity criteria, ensuring accurate detection without interference.
Data Acquisition and Processing
Data should be captured and analyzed using devices capable of presenting chromatograms, displaying peak areas, and performing calculations with response factors and standardization methods.
Reagents and Materials
High purity reagents are required, with specific recommendations for solvents, carrier and detector gases, and standards. The selection of internal standards is crucial, with emphasis on their purity and relevance to the sample being analyzed.
Conclusion
ASTM D5623 provides a robust framework for analyzing sulfur compounds in light petroleum liquids, offering significant benefits for quality control and product development within the petroleum industry. By adhering to this standardized test method, companies can ensure consistent and reliable sulfur analysis, contributing to product integrity and regulatory compliance.