Total elemental analysis of food samples using the Thermo Scientific iCAP TQ ICP-MS with autodilution

Importance of the Topic

Food safety and nutritional quality assessments rely on accurate multielement quantification to monitor toxic contaminants like arsenic and essential nutrients such as selenium. Regulatory bodies such as FAO and WHO mandate standardized testing methods to ensure public health. The presence of contaminants from environmental or industrial sources and the need to measure both trace and macro element concentrations require robust, high-throughput analytical workflows.

Objectives and Overview of the Study

This work evaluates a fully automated approach to simultaneous elemental analysis in food matrices using the Thermo Scientific iCAP TQ ICP-MS in conjunction with an autodilution system. Certified reference materials (NIST 1515 Apple Leaves and NIST 1573a Tomato Leaves) were used to benchmark performance under single quadrupole with helium KED (SQ-KED) and triple quadrupole with oxygen reaction gas (TQ-O2) modes. Key goals include reduction of manual sample preparation time, effective interference removal, and extension of calibration ranges automatically.

Methodology and Instrumentation Used

Sample preparation involved acid digestion of ~0.3 g samples in closed-vessel microwave systems followed by dilution to 10 mL. Calibration curves across major and trace element groups were generated via the Elemental Scientific prepFAST Autodilution System. Internal standards (Sc, Ga, In, Tb) at 5 µg/L were added on-the-fly. The iCAP TQ ICP-MS was configured with a cooled cyclonic spray chamber, PFA nebulizer, quartz torch, and Ni sampler/skimmer. Operating parameters included 1550 W RF power, He KED at 4.3 mL/min, and O2 reaction at 0.3 mL/min. Measurement dwell times were 0.1 s per analyte.

Main Results and Discussion

A complete 24-element analysis, including uptake and washout, was achieved in 2.5 minutes per sample. Instrument detection limits after automatic fourfold dilution ranged from sub-ng/L to a few µg/L, corresponding to MDLs in the µg/kg range. SQ-KED mode showed positive bias for As and Se due to rare earth element doubly charged interferences. TQ-O2 mass shift mode effectively eliminated these interferences by forming AsO+ and SeO+ product ions, yielding results in agreement with certified values. Calibration linearity exceeded R2>0.999 for both high-concentration (e.g., Na up to 1000 mg/L) and trace elements.

Benefits and Practical Applications of the Method

• Automated autodilution minimizes manual handling, consumable use and reagent waste.
• Collision/reaction cell operation in TQ-O2 mode provides comprehensive interference removal, enabling accurate trace contaminant analysis.
• Wide dynamic range covers macro- to trace-level elements in a single run.
• Rapid throughput supports high-volume food safety and quality control laboratories.

Future Trends and Potential Applications

Integration of intelligent method development tools and expanded reaction chemistries may further streamline multielement workflows. The combination of triple quadrupole ICP-MS with advanced autosamplers promises broader application to complex matrices such as supplements, beverages, and environmental samples. Continuous improvements in sample introduction, detection sensitivity, and software-driven automation will drive higher throughput and lower detection limits.

Conclusion

The combination of the iCAP TQ ICP-MS and prepFAST Autodilution System demonstrates a robust, rapid, and fully automated solution for comprehensive multielement analysis in food. Effective interference removal with TQ-O2 mode and dynamic calibration ensure accurate quantification across a wide concentration range, supporting regulatory compliance and routine quality control.