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

Probe orientation needle 265*2980 needle head diameter is 6.0 end probe needle

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Kaixin micro test

Instrument Introduction

The ICP2060T Inductively Coupled Plasma Emission Spectrometer from Tianrui Instrument offers exceptional performance in petrochemical oil analysis, with several notable features:

1. A semiconductor refrigeration sample introduction device enhances the stability and sensitivity of the injection process, leading to more accurate and reliable results.

2. A specialized torch for gasoline ensures long-term plasma stability and minimizes background interference from the substrate.

3. An oxygen-assisted injection system helps maintain plasma stability and prevents carbon buildup during analysis.

4. The self-developed RF solid-state generator provides automatic matching, making it suitable for samples like organic compounds and high-matrix materials.

5. The plasma observation height is automatically adjusted to ensure precise positioning at the optimal measurement point.

6. High resolution allows for accurate separation of critical spectral lines such as P at 213.618nm, Cu at 213.598nm, and P at 214.911nm.

Experimental Section

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

BS224S – One ten-thousandth electronic balance, Sartorius

1.2 Instrument Working Conditions

High-frequency 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

Phosphorus analysis line: 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 enters the nebulizer and is introduced into the plasma. Once stable, blank solution, standard solution, and diluted sample solution are measured. The content of each element is derived based on the calibration curve.

2. Results and Discussion

2.1 Optimal Analysis Line Selection

Due to molecular bands in the spectrum, a deep background was observed. Three commonly used analytical lines were tested, and after considering sensitivity, background, and interference, the following lines were selected: Phosphorus at 213.620nm, Silicon at 251.611nm, Iron at 538.204nm, Manganese at 257.610nm, and Lead at 220.353nm. The detection limits and linear range are summarized in Table 1.

Table 1: Determination of linearity and detection limit of elements in gasoline samples

2.2 Sample Analysis According to Test Method

Gasoline standard samples were analyzed 10 times, and repeated data were calculated. The results are shown in Table 2.

Table 2: Gasoline Sample Analysis Results

2.3 Recovery Experiment

Organic standards were added to the gasoline sample, and recovery tests were conducted according to the method. Results are presented in Table 3.

Table 3: Recovery Experiment Results

As seen in Table 3, the recovery rates for phosphorus, silicon, iron, manganese, and lead are all within acceptable ranges, indicating that the method is accurate and reliable.

3. Conclusion

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