The Determination of Lead in Unleaded Gasoline Using the Agilent 55 AA Atomic Absorption Spectrophotometer

Význam tématu

Determination of trace levels of lead in unleaded gasoline is critical for environmental monitoring and compliance with regulations restricting lead additives. Ensuring low residual lead content helps protect public health and reduces pollution.

Cíle a přehled studie / článku

This study evaluates the performance of the Agilent 55B atomic absorption spectrophotometer for quantifying lead in unleaded gasoline. The method is based on ASTM D3237-79 with modification of the extraction solvent from methyl isobutyl ketone (MIBK) to di-isobutyl ketone (DIBK). Accuracy and precision were verified using NIST SRM 2712 reference fuel, and both regular and premium gasoline samples were analyzed.

Použitá metodika a instrumentace

Sample preparation follows a liquid-liquid extraction protocol:

• Aliquot 30 mL DIBK and 5 mL gasoline into volumetric flasks
• Add 0.1 mL iodine/toluene solution and allow to react
• Introduce 1 % (v/v) Aliquat 336 in DIBK as phase-transfer agent
• Dilute to volume with DIBK and mix thoroughly

Calibration standards at 0, 20, 50 and 100 mg Pb/USgal were prepared similarly. Measurements were performed under air/acetylene flame with D2 background correction, at wavelengths 217.0 nm and 283.3 nm, using integration mode and three replicates per reading.

Hlavní výsledky a diskuse

• Calibration was linear across the range with detection limits of approximately 0.0006–0.0007 g Pb/USgal.
• Measured SRM 2712 value of 0.0302 ± 0.0001 g/USgal matched the certified 0.0297 ± 0.0010 g/USgal.
• Regular gasoline showed levels near the detection limit, while premium grade exhibited higher readings.
• Both 217.0 nm and 283.3 nm lines produced comparable results; the 283.3 nm line offered higher signal intensity and lower background.

Přínosy a praktické využití metody

The method delivers high precision and accuracy in routine fuel analysis. Automation and software control allow LIMS integration and data archiving. The substitution of DIBK reduces solvent volatility compared to MIBK.

Budoucí trendy a možnosti využití

Future advancements may include coupling with advanced data analysis tools, miniaturized extraction systems, adoption of greener solvents, and integration into online monitoring platforms. Alternative atomic spectrometry techniques, such as graphite furnace AAS or ICP-OES, may provide complementary sensitivity.

Závěr

The Agilent 55B AA spectrophotometer, using a modified ASTM D3237 extraction with DIBK and Aliquat 336, provides a reliable, accurate, and precise approach for trace lead determination in unleaded gasoline. The 283.3 nm wavelength is recommended due to enhanced sensitivity.

Reference

ASTM D3237-79 (Re-approved 1984); current version ASTM D3237-97