Determination of Halogens in Petroleum Products by SDXNS200 Combustion Ion Chromatography System (CIC)

Abstract

This application note describes the simultaneous determination of fluorine, chlorine, and bromine in aviation fuel using the SDXNS200 High-Temperature Combustion Ion Chromatography System. Duplicate analyses showed excellent agreement, while the resulting ion chromatograms exhibited clearly defined peaks, stable baselines, and good separation from adjacent components.

Multiple elements can be quantified in a single analytical run, providing a simple, efficient, and reliable solution for determining halogens in petroleum and petrochemical products.

Application Note No.: SD-XNS-001-01003

Introduction

The petrochemical industry is a fundamental part of the modern economy. Its products are used throughout numerous industrial sectors, ranging from synthetic fibers for textiles and synthetic rubber materials to coatings, piping systems, and transportation equipment.

Through crude-oil refining and processing, the petrochemical industry supplies essential fuels such as gasoline, kerosene, and diesel. It also converts crude oil into basic chemical feedstocks, including ethylene, propylene, butadiene, benzene, toluene, and xylenes. These basic chemicals serve as the starting materials for tens of thousands of downstream chemical products.

Fluorine, chlorine, bromine, sulfur, and other elements may be present in crude oil, intermediate streams, and finished petroleum products. Their concentrations directly affect product quality, operational safety, equipment service life, and environmental compliance.

Chlorine and sulfur compounds can corrode process piping, furnace components, and other production equipment. Even ppm-level halogen contamination may irreversibly deactivate reforming and hydrotreating catalysts. Sulfur emissions affect atmospheric environmental quality, while residual halogens may influence the safety and regulatory compliance of exported products.

As product specifications and environmental regulations become increasingly stringent, the analysis of halogens and sulfur in petroleum products is shifting from general monitoring to precise concentration control. Selected limits for halogens and sulfur in petroleum products and related materials are shown below.

Table 1. Selected Limits for Halogens and Sulfur in Petroleum Products and Related Materials

Existing Analytical Methods and Their Limitations

Current methods for determining halogens and sulfur in petroleum and petrochemical products mainly include the following.

1. GB/T 40111-2021: Combustion–Ion Chromatography

This method is applicable to petroleum products with boiling ranges from approximately 30 to 380°C, including solvent oils, liquefied petroleum gas, and fuel oils.

The method provides a measurement range of approximately 0.3–15 mg/kg, with good sensitivity and precision. However, it requires relatively high capital investment and trained laboratory personnel.

2. NB/SH/T 0977-2019: Monochromatic Wavelength-Dispersive X-Ray Fluorescence Spectrometry

This method is suitable for light petroleum products such as gasoline, liquefied petroleum gas, and aromatic hydrocarbons. It provides rapid results and is suitable for high-throughput routine testing.

However, it cannot determine fluorine, and its accuracy may be insufficient for samples containing very low analyte concentrations.

3. GB/T 18612-2011: Microcoulometric Method

The microcoulometric method is applicable to crude oil, petroleum coke, and heavy petroleum products. It is suitable for samples containing low concentrations of chlorine.

However, the analytical procedure is relatively complicated and time-consuming, and only one element can normally be determined in each analysis.

Overall Limitations of Conventional Methods

Conventional analytical methods may involve one or more of the following limitations:

• Complicated sample preparation that may cause analyte loss or contamination
• Separate analyses for individual elements
• Insufficient sensitivity for increasingly stringent concentration limits
• Multiple manual operations that increase the risk of cumulative errors
• Low analytical throughput
• Limited support from internationally recognized standard methods in certain applications

High-temperature combustion ion chromatography provides an effective alternative for overcoming these limitations.

Table 2. Comparison of Combustion Ion Chromatography and Conventional Methods

Analytical Principle

High-temperature combustion ion chromatography is based on the complete combustion of a sample in a high-temperature, oxygen-rich atmosphere.

Organic halogens and sulfur compounds in the sample are converted into gaseous hydrogen halides—including HF, HCl, HBr, and HI—and sulfur dioxide. The combustion products are subsequently condensed and captured in an absorption solution. The resulting ionic species are then introduced into the ion chromatography system for chromatographic separation and conductivity detection.

A major advantage of the method is that fluorine, chlorine, bromine, iodine, and sulfur can be quantitatively determined in a single analytical run. The organic matrix is completely decomposed during high-temperature combustion, significantly reducing matrix interference during chromatographic separation.

Experimental

Instrumentation

The analysis was performed using the SDXNS200 High-Temperature Combustion Ion Chromatography System.

The combustion furnace has a maximum operating temperature of 1,250°C and a 14 cm high-temperature constant-temperature zone with a temperature variation of ±20°C. Temperature control accuracy is ±5°C.

The combustion atmosphere can be accurately configured using oxygen, argon, and water vapor. The system supports direct introduction of:

• Solid samples: 0–100 mg
• Liquid samples: 0–100 μL
• Gaseous samples

The system supports the simultaneous determination of fluorine, chlorine, bromine, iodine, and sulfur. It is equipped with 49-position small-volume and 78-position large-volume sample trays.

The analysis time is no more than 20 minutes per sample. The method limit of quantification is 0.2 mg/kg, making the system suitable for ppm-level determination of halogens and sulfur in petroleum and petrochemical products.

Combustion Furnace Conditions

Combustion temperature: 1,100°C
Oxygen flow rate: 450 mL/min
Argon flow rate: 150 mL/min
Argon flow for steam transfer: 60 mL/min
Water-vapor flow rate: 0.1 mL/min

Sample Introduction Program

Stage 1

• Insertion distance: 130 mm
• Insertion time: 60 s
• Hold time: 250 s

Stage 2

• Insertion distance: 20 mm
• Insertion time: 200 s
• Hold time: 100 s

Stage 3

• Insertion distance: 15 mm
• Insertion time: 200 s
• Hold time: 100 s

Stage 4

• Insertion distance: 165 mm
• Insertion time: 300 s
• Hold time: 100 s

Ion Chromatography Conditions

Analytical column: AS19, 2 × 250 mm
Guard column: AG19, 2 × 50 mm
Eluent concentration: 13 mM
Flow rate: 0.25 mL/min
Column temperature: 35°C
Injection loop: 400 μL
Detector: Suppressed conductivity detector, SDRS 600
Linear range: 0.005–1 mg/L
Eluent source: EGC KOH eluent generator cartridge
Serial number: 230921904017

Results and Discussion

Two aviation fuel samples were analyzed using the SDXNS200 High-Temperature Combustion Ion Chromatography System. Each sample was analyzed twice to evaluate the repeatability of the method.

For Aviation Fuel Sample 1, the measured fluorine concentrations ranged from 0.93 to 0.96 mg/L. Chlorine concentrations ranged from 0.92 to 0.93 mg/L, while both bromine results were 0.92 mg/L. The duplicate results showed excellent agreement.

For Aviation Fuel Sample 2, the fluorine concentrations ranged from 4.49 to 4.52 mg/L. Chlorine concentrations ranged from 4.62 to 4.65 mg/L, and bromine concentrations ranged from 4.71 to 4.72 mg/L. These results also demonstrated good repeatability.

Table 3. Analytical Results for Aviation Fuel Samples

The ion chromatograms of the two aviation fuel samples are shown in Figure 2.

Fluoride, chloride, and bromide were successfully detected at their respective characteristic retention positions. The chromatographic peaks were clearly defined, the baselines remained stable, and good separation from adjacent components was achieved.

These results demonstrate that high-temperature combustion ion chromatography can effectively complete both the combustion conversion and ion chromatographic determination of halogens in aviation fuel, a representative petroleum-based matrix.

Sample 1                                               Sample 2

Figure 1. Ion chromatograms of Aviation Fuel Sample 1 and Aviation Fuel Sample 2.

Conclusion

The analysis of actual aviation fuel samples demonstrates the applicability of high-temperature combustion ion chromatography for determining halogens in petroleum and petrochemical products.

The method offers several important advantages:

• Liquid samples can be introduced directly without complicated sample preparation.
• A single analysis can be completed within 20 minutes.
• The limit of quantification is as low as 0.2 mg/kg.
• The method can meet stringent limits of ≤1.0 mg/kg for products such as petroleum benzene and petroleum p-xylene.
• Fluorine, chlorine, bromine, iodine, and sulfur can be quantitatively determined in a single analytical run.
• Duplicate measurements show good agreement and reliable analytical performance.

With broad sample compatibility, a high degree of automation, low quantification limits, and simultaneous multi-element capability, the SDXNS200 provides an efficient and reliable analytical solution for precise halogen and sulfur determination throughout the petroleum and petrochemical industry.