Extraction and Analysis of Polycyclic Aromatic Hydrocarbons in Infant Formula (ASMS)

Significance of the topic

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants formed during incomplete combustion. Dietary intake represents a major route of human exposure, and infant formula is of particular concern due to the vulnerability of infants and strict regulatory limits imposed by the European Commission. Accurate determination of PAHs at trace levels in complex, high-fat matrices is essential for food safety compliance and public health protection.

Objectives and Study Overview

This study aimed to develop and validate a robust analytical workflow for the extraction and quantitation of priority PAHs in infant formula. Key goals included achieving limits of quantitation below 1 µg/kg for benzo[a]pyrene and the sum of four marker PAHs (PAH4), while replacing helium carrier gas with hydrogen for sustainability and cost effectiveness.

Methodology and Instrumentation

The sample preparation combined aqueous dissolution of formula powder (2 mL water per 2 g sample) with ethyl acetate/acetonitrile extraction. A Captiva EMR–Lipid pass-through cleanup removed co-extracted lipids, followed by isooctane back-extraction to enhance GC compatibility and partial concentration.
Instrumental analysis employed an Agilent 8890 GC coupled to a 5977C Inert Plus MSD equipped with a HydroInert source, using a J&W DB-EUPAH capillary column. Hydrogen served as the carrier gas at 0.9 mL/min. Injection was performed in pulsed splitless mode with a two-layer sandwich internal standard protocol. Detection was by selective ion monitoring for 16 priority PAHs.

Main Results and Discussion

Method recoveries for eight target PAHs ranged from 60 % to 95 % with relative standard deviations below 20 % at spiking levels of 10 and 50 ng/g. At 1 ng/g, benzo[k]fluoranthene showed slightly lower recovery (54 %) and benzo[ghi]perylene higher variability (34 % RSD) due to low signal intensity and matrix effects. Matrix-matched calibration from 0.1 to 20 ppb in vial (equivalent to 0.5–100 µg/kg in formula) yielded correlation coefficients >0.994.

Benefits and Practical Applications

• The EMR–Lipid pass-through cleanup efficiently removed fatty interferences, simplifying sample preparation.
• Hydrogen carrier gas used with the HydroInert source provided stable ionization without hydrogenation or dechlorination artifacts.
• The workflow met EU Regulation (EU) 835/2011 requirements for PAH monitoring in infant formula.

Future Trends and Potential Applications

Emerging trends include coupling supercritical fluid extraction with high-resolution mass spectrometry to further reduce solvent use and improve sensitivity. Implementation of automated on-line cleanup and novel sorbents may accelerate throughput. Expanding the analyte scope to include alkylated PAHs and other semi-volatile contaminants will enhance comprehensive dietary exposure assessment.

Conclusion

The combination of Captiva EMR–Lipid cleanup, hydrogen carrier gas, and the Agilent HydroInert source on an 8890/5977C GC/MS platform provided a robust, sensitive, and sustainable method for quantifying priority PAHs in infant formula at regulatory levels. The approach balances analytical performance with operational efficiency and cost savings.

Used Instrumentation

• Agilent 8890 Gas Chromatograph
• Agilent 5977C Inert Plus GC/MSD with HydroInert source
• J&W DB-EUPAH GC column (20 m × 0.18 mm, 0.14 µm)
• Captiva EMR–Lipid sorbent cartridges

References

1. Agilent Technologies. Inert Plus GC/MS System with HydroInert Source; Technical Overview; Publication 5994-4889EN; 2022.
2. Sampaio, G. R.; et al. Polycyclic Aromatic Hydrocarbons in Foods: Biological Effects, Legislation, Occurrence, Analytical Methods, and Strategies to Reduce Their Formation. Int. J. Mol. Sci. 2021, 22, 6010.
3. European Commission. Commission Regulation (EU) No 835/2011 Amending Regulation (EC) No 1881/2006 as Regards Maximum Levels for Polycyclic Aromatic Hydrocarbons in Foodstuffs. Off. J. Eur. Union 2011, L 215, 4–8.