Abstract:

Addressing the cumbersome and technically challenging pre-treatment steps involved in the graphite furnace atomic absorption spectrometry method specified in the National Food Safety Standard for Determination of Lead in Foods（2023 edition），this study proposed a simplified and improved protocol. The standard-recommended palladium nitrate-ammonium dihydrogen phosphate ［Pd（NO?）?］ matrix modifier was replaced with ammonium dihydrogen phosphate （NH?H?PO?） or ammonium nitrate （NH?NO?），with ashing temperatures set at 600 and 500 ℃， respectively，eliminating the need for additional solid-phase extraction column purification. Method accuracy was validated through quality control samples and addition recovery tests. The results demonstrated that both matrix modifiers maintained a good linear relationship between lead concentration（0-25.0 μg·L^-1）and absorbance. When NH₄H₂PO₄ was used as the modifier，the addition recovery rates for salt and hot pot base were 99.1% and 97.6%，respectively；whereas with NH₄NO₃，the recovery rate for salt reached 99.2%，but was lower at only 84.3% for hot pot base. Furthermore，when NH₄H₂PO₄ was employed as the modifier at a calcination temperature of 600 ℃，the simulated high-salt samples exhibited lead concentrations of 0.126 and 1.083 mg·kg^-1，both within the specified limits of the control samples. These findings confirm that the modification method was simple to implement，accurate，and reliable，effectively reduces pre-treatment complexity，is suitable for rapid lead determination in high-salt foods，and is well-suited for widespread application.

Key words: graphite furnace atomic absorption spectrometry, matrix modifier, high-salt foods, lead