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INTRODUCTION Many branded products command premium prices from

consumers; however, generic products, formulated to mimic the

premium brands, offer cost effective ways to purchase near-

identical products. This practice is prevalent in the personal care

marketplace, where competition for consumer loyalty is fierce.

In this work we present our analysis of premium brand and generic

hair care creams typically used for hair styling. Many analytical

methods for analysing cream-based cosmetics have lengthy

extraction or sample preparation requirements.1,2 In contrast, the

atmospheric solids analysis probe (ASAP) enables direct sampling

and analysis that allows rapid surveying of samples compared with

other, typical, cosmetics analysis techniques such as GC-MS1,2,3 or

HPLC.2,3 This is particularly useful in troubleshooting formulation

failures, such as product discoloration, or precipitation, or product

shelf-life problems, when prompt reporting of results might be

required.

ASAP-IM-MS was used to investigate the cause of a generic hair

cream separating and demulsifying after prolonged exposure to

higher temperatures. This phenomenon caused reduced shelf-life

for the product when sold in hot countries. The use of IM-MS

enabled ion mobility driven comparisons between the failed hair

cream and a correct hair cream formulation, to help isolate the

causes of the product demulsification.

TROUBLESHOOTING A HAIR CREAM PRODUCT FAILURE USING ASAP-ION MOBILITY-MASS SPECTROMETRY

Sarah Dowd1, Eleanor Riches2, Jonathan Fox2

1Waters Corporation, 100 Cummings Centre - Suite 407N, Beverly, MA 01915-6101, USA; 2Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow, Cheshire, SK9 4AX, UK

CONCLUSION

Hair cream samples were rapidly analysed using ASAP-SYNAPT HDMS with limited sample prep

IM data comparison using HDMS Compare software enabled isolation of regions of the data that were different between the emulsified product and demulsified product

Comparisons between the hair cream samples and standards of key ingredients enabled qualitative understanding of the key differences highlighted by the HDMS Compare software

Investigation of the differences indicated that the product deformulation could be caused by

- differences in the mineral oil content

- differences in the rapeseed oil content

- the use of natural beeswax in cream 01 and synthetic beeswax in cream 02

References 1. Desmedt, et al., Talanta 2015, 131 444-451

2. De Vaugelade, et al., J Chromatogr A 2017, 1517 126-133

3. H.-Y. Shen, et al., J Sep Sci 2007, 30 48-54

4. Garnier, et al., Anal Chem 2002, 74 4868-4877

Full spectra for standards of ingredients typically used in hair cream formulations are shown in Figure 7. The relationship between significant ions in the standards and significant ions in the two hair cream samples are illustrated in Figures 8, 9, 10, and 11.

METHODS

Sample preparation:

Hair cream samples (Figure 1) were dissolved in toluene at a

concentration of approximately 0.5 mg/mL and sampled directly onto the

glass insert of an ASAP probe with no further sample preparation

(Figure 2).

SYNAPT G2-Si HDMS conditions:

An Atmospheric Solids Analysis Probe (ASAP) was installed on a

SYNAPT G2-Si HDMS instrument (Waters Corporation) (Figure 2).

ASAP and ion mobility-MS conditions were optimized as follows:

Ionization mode: ASAP+

Corona current: 12 µA

Cone voltage: 50 V

Source temperature: 150 °C

Desolvation temperature: 150 °C - 650 °C ramped over 4 minutes

Desolvation gas flow: 600 L/Hr

Cone gas flow: 100 L/Hr

IMS Wave velocity: 900 m/s

IMS Wave height: 40 V

IMS cell pressure: 3.3 mbar

Mass Resolution: 40K

Mass range: 50—1000 m/z

Data Acquisition and Processing:

Data were acquired using MassLynx v4.1 reviewed in MassLynx v4.1

and DriftScope v2.8, and processed using HDMS Compare v1.1.

Figure 1. The hair cream samples.

Figure 2. [Left] The ASAP ionisation source installed on a SYNAPT G2-Si HDMS instrument. [Right] A simple “dip and analyse” sampling technique.

Figure 4. Spectra for two different hair creams, generated at the time points highlighted in Figure 3.

Figure 3. ASAP Total Ion Chromatograms (TICs) for the analysis of two different hair cream products. Highlighted time sections indicate regions that were combined to produce the spectra shown in Figure 4.

RESULTS & DISCUSSION ASAP is a thermal desorption, direct analysis technique that, while it lacks chromatographic separation, offers some degree of component separation based on boiling points. Ion mobility provides an additional, orthogonal dimension of separation and affords increased peak capacity that simplifies the analysis of highly complex samples.

Boiling point profiles of two sample creams are shown in Figure 3, while Figure 4 shows the spectra generated at different time points. The low boiling point species from 0.00 to 0.50 minutes are similar, whereas there are significant differences between the species observed at higher temperatures between 1.25 to 1.75 minutes and 3.25 to 3.75 minutes.

Ion mobility data and an ion mobility driven comparison are shown in Figure 5 and Figure 6 respectively.

Acknowledgements The authors would like to thank Justin Shard for providing hair cream samples and authentic standards of : natural beeswax, synthetic beeswax, castor oil, mineral oil, and rapeseed oil.

Figure 5. The full spectrum combined across the entire TIC from 0.00 to 4.00 minutes for each hair cream sample, along with the 3D ion mobility data, shown in DriftScope software.

Figure 6 An ion mobility driven comparison of five replicates of each hair cream sample, shown in HDMS Compare software. This highlights regions of significant difference between the two samples.

Figure 7. Full spectra for various standards of components typically used in hair cream formulations.

Figure 8. Significant regions in the spectra of natural beeswax, synthetic beeswax, and rapeseed oil showing that synthetic beeswax contains significant amounts of components also present in rapeseed oil.

Figure 9. Spectra from sample cream 01 and mineral oil, at the same temperature, showing the presence of light components of mineral oil in cream 01, as indicated by the HDMS Compare software.

Figure 10. Higher m/z regions of cream 01, natural beeswax, cream 02, and synthetic beeswax showing that cream 02 has more higher mass ions than cream 01, as indicated by the HDMS Compare software. Cream 01 contains key ions from natural beeswax, m/z 847 and m/z 875, which have been identified as protonated diester (16:0/22-diol/16:0) and protonated diester (hexacosanediol-1,15-dipalmitoyl)[ref. 4].

Figure 11. Spectra from sample cream 02 and rapeseed oil, at the same temperature, showing significant levels of components of rapeseed oil in cream 02