DIFFERENTIATING PHTHALATE ISOMERS WITH MULTI-PASS CYCLIC ION MOBILITY AND RAPID SCREENING IN COSMETIC AND PERSONAL CARE PRODUCTS

Significance of the Topic

Phthalates, esters of phthalic acid, are commonly added to plastics, cosmetics and personal care products as plasticizers or solubilizers. Their widespread use and associated health concerns—particularly endocrine disruption and reproductive toxicity—have driven the demand for rapid and reliable analytical methods. Ion mobility separation combined with mass spectrometry offers enhanced selectivity to distinguish structurally similar phthalate isomers and rapidly screen complex consumer matrices.

Objectives and Scope of the Study

This study aimed to develop and demonstrate a dual-mode analytical workflow for cosmetic and personal care products: 1) high-resolution separation of C8 phthalate isomers using multi-pass cyclic ion mobility spectrometry (IMS) coupled to a mass spectrometer, and 2) rapid screening for a broad range of additives via atmospheric solids analysis probe (ASAP) MS with minimal sample preparation. The approach targeted confident identification based on accurate mass and collision cross section (CCS) matching to a reference library.

Methodology and Instrumentation

The analytical strategy comprised two complementary techniques:

• Ion mobility separation: Direct infusion electrospray ionization (ESI+) of a mixture of di-n-octyl phthalate, bis(2-ethylhexyl) phthalate (DEHP), and dioctyl terephthalate (DEHT). The SELECT SERIES Cyclic IMS device performed up to four passes to achieve baseline resolution of protonated [M+H]+ and sodium adduct [M+Na]+ ions.
• ASAP screening: The atmospheric solids analysis probe introduced trace sample directly into the MS source using heated nitrogen desolvation and corona discharge ionization. A temperature ramp (50–500 °C) generated a total ion profile and subsequent mobility-resolved spectra for rapid detection of additives in real-world samples.

Instrumentation Used

• SELECT SERIES™ Cyclic™ IMS Mass Spectrometer (Waters Corporation)
• Atmospheric Solids Analysis Probe (ASAP™) accessory
• Xevo™ G2-XS QTof mass analyzer in V-mode
• UNIFI™ Scientific Information System for data processing and library matching

Key Results and Discussion

• Multi-pass cyclic IMS achieved clear separation of three C8 phthalate isomers: DOP, DEHP and DEHT. Protonated ions required four passes for baseline resolution, while sodium adducts separated fully in three passes.
• Accurate mass measurements (<0.4 mDa error) and CCS determinations (ΔCCS <0.5 %) enabled unambiguous isomer identification against a high-resolution HRMS library.
• ASAP screening of six commercial cosmetics and personal care items detected a range of plasticizers, antioxidants and UV filters with minimal sample handling. Matches were confirmed by m/z (<5 ppm) and CCS deviations (<3 %) relative to library entries.
• Extracted drift time traces provided additional confidence, distinguishing co-eluting compounds in complex matrices such as hand creams, nail polish and sanitizers.

Practical Implications

This workflow delivers two major benefits for quality control and regulatory laboratories:

• Enhanced isomeric separation without chromatographic run times, reducing analysis time and solvent consumption.
• Rapid additive screening with ASAP enables high-throughput profiling of consumer products for compliance monitoring.

Future Trends and Applications

Advancements in cyclic IMS geometry and integration with automated sampling are expected to further increase resolving power and throughput. Expanding CCS libraries for emerging additives and contaminants will enhance screening breadth. Potential future applications include in-line process monitoring in manufacturing and on-site testing for product authentication.

Conclusions

The combined use of multi-pass cyclic IMS and ASAP-MS provides a robust platform for both detailed isomer differentiation and rapid additive screening in cosmetic and personal care matrices. Accurate mass and CCS matching ensures reliable identification, while minimal sample preparation accelerates laboratory workflows.

References

1. Goh, E. and Gay, M. Rapid Screening for Phthalates in Food and Beverages using Atmospheric Solids Analysis Probe (ASAP) with Xevo TQ MS. Waters Application Note 720004066EN 2011.
2. Cooper, J. High Throughput Analysis of Phthalates and Parabens in Cosmetics and Personal Care Products Using UPLC with Mass Detection and Empower 3 Software. Waters Application Note 720005521EN 2015.
3. Cooper, J., Sanig, R., Barkinoxitz, G., and Cabovska, B. Screening Workflow Using Ion Mobility-Mass Spectrometry for the Analysis of Extractables and Leachables. Waters Application Note 720006988EN 2020.