Targeting Efficiency: A Database and Optimized Method for Sensitive and Reliable Targeted LC/MS Analysis of Extractables and Leachables

Significance of the topic

Targeted extractables and leachables (E&L) analysis is essential for assessing chemical safety of medical devices, drug delivery systems, consumer goods and food contact materials. Routine regulatory and quality-control workflows demand methods that are sensitive, selective, reproducible and easy to implement across many compound classes and concentration ranges. This study addresses practical challenges in targeted LC/MS E&L work: broad chemical diversity, large target lists, isobaric/isomeric interferences and matrix-driven variability in ionization.

Objectives and study overview

The poster describes development and validation of an optimized targeted LC/TQ (triple quadrupole) workflow and an accompanying MRM database for routine E&L monitoring. Main goals were to:

• Compare stationary phases, mobile phase additives and ion source parameters to maximize sensitivity and minimize adduct formation;
• Establish robust chromatography capable of resolving common isomers/isobars;
• Automate MRM and source parameter optimization and build a database of optimized transitions and retention times for routine dMRM use;
• Demonstrate applicability using food contact material extracts (vacuum sealer bags) with time-course extraction.

Methodology

A comprehensive E&L standard kit (350 LC‑MS amenable compounds) guided method development. Key experiment components included:

• Columns compared by chemistry and dimensions to optimize separation of isomers/isobars;
• Systematic evaluation of mobile phase additives (formic acid, ammonium formate and low µM ammonium fluoride) to improve ionization and suppress undesired adducts;
• Automated optimization of MRM transitions, collision energies and fragmentor voltages using the MassHunter Optimizer tool;
• Application of the optimized dMRM method to solvent extracts of consumer food contact materials to assess real-sample performance.

Used instrumentation

• LC: Agilent 1290 Infinity III LC system
• MS: Agilent 6475 triple quadrupole with dual AJS ESI source
• Columns: Agilent Poroshell 120 Aq-C18, 2.1 x 150 mm, 2.7 µm (analytical) and Poroshell 120 EC-C18 4.6 x 50 mm, 2.7 µm (delay column)
• Software: Agilent MassHunter Acquisition with Optimizer for automated MRM/source optimization
• Standard set: AChemTek E&L kit (350 LC-MS amenable standards)

Key LC and source settings: 0.35 mL/min flow, 40 °C column temperature, 29.1 min total run time (26.0 min gradient to 100% B), autosampler 5 °C, needle wash (50% isopropanol/25% methanol/25% acetonitrile). Mobile phases: A = water with 2.5 mM ammonium formate, 0.05% formic acid and 100 µM ammonium fluoride; B = methanol with identical modifiers. Source conditions included gas temperature 250 °C, sheath gas 300 °C and capillary voltage 4000 V.

Main results and discussion

• Mobile phase additives: Low concentrations of formic acid and ammonium formate increased sensitivity, especially in positive mode. Addition of 100 µM ammonium fluoride reduced sodium-adduct formation, promoted production of informative fragment ions and further improved sensitivity.
• Chromatography and gradient: A 150 mm Aq‑C18 column with a 26-min gradient provided optimal separation for many common isomeric and isobaric E&L pairs (phthalate isomers, benzotriazole UV stabilizers, bisphenol isomers, etc.), addressing a major source of false positives/quantitation errors.
• Automated optimization and database building: Using MassHunter Optimizer, at least two MRM transitions were optimized for 303 E&L compounds (resulting database contained >1000 transitions). Forty-seven compounds from the original mixes required APCI or GC/MS and were excluded from the ESI-LC-MS database.
• Analytical performance: The dMRM method produced reproducible retention times, peak areas and qualifier/quantifier ion ratios across replicate extracts. Calibration curves prepared from 0.5 to 200 ppb displayed wide linear dynamic ranges (many with R2 > 0.998), enabling quantification of both trace and higher-level extractables.
• Application to food-contact extracts: Ethanol extractions of three vacuum sealer bag types at 70 °C for 10, 20 and 60 min revealed fatty acid amides, phthalates, antioxidants, diethylene glycol and tris(2,4‑di‑t‑butylphenyl)phosphate among prominent analytes. Concentrations generally increased with extraction time, demonstrating the method's ability to monitor temporal release behavior.

Benefits and practical applications of the method

• Turnkey targeted workflow: The combination of optimized chromatography, tuned source parameters and a curated MRM database enables routine, reproducible targeted screening for common E&L compounds.
• High sensitivity and reduced adduct artifacts: The methanol-based mobile phase with ammonium formate and low-level ammonium fluoride boosts signal and reduces sodium adducts, improving quantifier and qualifier ion responses.
• Broad applicability: Coverage of 303 LC‑MS amenable E&L compounds with wide calibration ranges supports regulatory testing, QC monitoring, product development and failure/root-cause investigations.
• Efficient updates: MassHunter Optimizer allows rapid addition of new targets and one‑click saving of optimized transitions into the database and dMRM methods, facilitating method maintenance and expansion.

Future trends and potential applications

• Expansion of target libraries: Integrating APCI-amenable and GC-volatile targets into companion workflows (GC/MS, LC/APCI) will offer more comprehensive E&L coverage across regulatory scopes.
• Hybrid workflows: Coupling sensitive dMRM screening with HRMS suspect/untargeted follow-up (LC/Q-TOF) for unknown identification will improve confidence in assignments and characterization of novel leachables.
• Automation and informatics: Further automation of optimization, retention-time prediction and integration into LIMS will reduce operator burden and accelerate routine testing throughput.
• Method standardization: Adoption of curated transition libraries and common chromatographic conditions across laboratories would facilitate inter-lab comparability for regulatory submissions.

Conclusion

An optimized LC/TQ method combined with an automated, curated MRM database provides a sensitive, reproducible and practical solution for targeted E&L analysis by ESI-LC-MS. Key enablers were careful chromatography selection, low‑level ammonium fluoride to suppress adducts, and automated MRM/source tuning. The approach successfully quantified hundreds of E&L compounds at real-world extract concentrations and demonstrated applicability to food contact material extracts, supporting routine QC, safety assessments and method scalability.

Reference

Agilent Technologies. Targeting Efficiency: A Database and Optimized Method for Sensitive and Reliable Targeted LC/MS Analysis of Extractables and Leachables. ASMS 2026 Poster WP306. Published June 10, 2026. DE-014648.