Determination of phosphorus, silicon, iron, manganese and lead in gasoline by direct injection method

Probe orientation needle with a head diameter of 6.0mm and length of 2980mm

Test - lowercase jpg file

Kaixin micro test sample

Instrument Introduction

The ICP2060T Inductively Coupled Plasma Emission Spectrometer from Tianrui Instrument is a powerful tool for petrochemical oil analysis, offering exceptional accuracy and performance. Here are some of its key features:

• Equipped with a semiconductor cooling sample introduction system that enhances stability and sensitivity, ensuring more accurate and reliable results.
• Features a specialized gasoline torch that ensures long-term plasma stability and reduces background interference from the matrix.
• Includes an oxygen-assisted injection system to maintain plasma stability and prevent carbon buildup during analysis.
• Uses a self-developed RF solid-state generator with automatic matching, ideal for handling organic and high-matrix samples.
• Automatically adjusts the plasma observation height to locate the optimal measurement position for maximum precision.
• Offers high resolution, capable of accurately separating closely spaced spectral lines such as P at 213.618nm, Cu at 213.598nm, and P at 214.911nm.

Experimental Part

1.1 Instruments and Reagents

• Tianrui Instrument ICP2060T – Inductively Coupled Plasma Emission Spectrometer
• CONOSTANS-21 – Mixed standard oil (300 ppm, 100g)
• CONOSTAN Co – Standard solution (5000ppm, 50g)
• CONOSTANICP – Special thinner (one gallon)
• Pipette (0–5ml), Prand, Germany
• Electronic balance (BS224S, Sartorius, one ten thousandth precision)

1.2 Instrument Working Conditions

• RF Generator: 27.12MHz, center channel 0.6mm
• Quartz Torch, High Frequency Power: 1100W, Reflection Power ~50W
• Plasma Gas Flow: 15L/min
• Auxiliary Gas Flow: 1.0L/min
• Carrier Gas Flow: 0.4L/min
• Oxygen Flow Rate: 30ml/min
• Spray Chamber Temperature: -10°C
• Peristaltic Pump Speed: 3ml/min
• Analysis Lines: Phosphorus (213.620nm), Silicon (251.611nm), Iron (538.204nm), Manganese (257.610nm), Lead (220.353nm), Cobalt (228.616nm)

1.3 Experimental Method

After the instrument is automatically ignited and parameters are set according to working conditions, the diluent is introduced into the nebulizer and enters the plasma. Once the system stabilizes, blank solution, standard solution, and diluted sample solution are measured. The element content in the final sample is derived using the calibration curve.

2. Results and Discussion

2.1 Optimal Analysis Line Selection

In ICP analysis, many molecular bands can appear in the spectrum, creating a deep background that affects metal element analysis. Three commonly used analytical lines were tested, and after considering sensitivity, background, and interference, the following lines were selected: Phosphorus (213.620nm), Silicon (251.611nm), Iron (538.204nm), Manganese (257.610nm), Lead (220.353nm).

Table 1: Linearity and Detection Limit of Elements in Gasoline Samples

2.2 Sample Analysis

Gasoline standard samples were analyzed 10 times according to the test method, and repeated data was calculated. The results are shown in Table 2.

Table 2: Gasoline Sample Analysis Results

2.3 Recovery Experiment

Organic standards were added to gasoline samples, and recovery tests were performed. The results are shown in Table 3.

Table 3: Recovery Experiment Results

The recovery rates for phosphorus, silicon, iron, manganese, and lead in gasoline samples are all within acceptable limits, indicating that the method is accurate and reliable.

3. Conclusion

The multi-element direct determination method using ICP-AES in gasoline offers higher accuracy, better reproducibility, and faster testing speeds. It significantly improves work efficiency and reduces labor and material costs. Compared to imported ICP systems, the Tianrui Instrument ICP2060T provides a cost-effective, high-speed, and high-accuracy solution for analyzing phosphorus, silicon, iron, manganese, and lead in gasoline samples, meeting the needs of petrochemical industry customers effectively.