Determination of UV filter in sun cream using TLC-MS

Abstract

The analytical verification of cosmetic products can be a challenging task. Formulations like creams, balms or lotions are complex matrices with respect to chromatography, so low-level sample preparation and a direct analysis method is appreciated. TLC-MS (thin layer chromatography – mass spectrometry) is such an analytical technique. The determination of the UV filter Eusolex® 9020 in sun cream is presented as an example. After chromatographic separation, the analyte is eluted with the TLC-MS Interface from Camag, transferred and finally detected with an ESI mass detector.

Results

Eusolex® 9020 was detected under UV light (254 nm) at an hRf value of 50. The quantification using peak areas by triple determination of the sun cream and a 4 point calibration was done for Eusolex® 9020. An average amount of 33 ppm in sun cream 1 and 35 ppm in sun cream 2, based on the amount of sun cream matrix was determined. Figure 2 shows the developed plate under UV light at 254 nm and Figure 3 the appendant scan. The mass spectrum (Fig. 1) shows the protonated molecule of Eusolex® 9020 at m/z 311.2.

Mass spectrum and structure of Eusolex

Figure 1: Mass spectrum and structure of Eusolex® 9020, recorded at hRf value of 50 at track 5.

 

Developed plate at 254 nm. Chromato-graphic data shown on next page

Figure 2: Developed plate at 254 nm. Chromato-graphic data shown on next page.

 

Scan at 254 nm

Figure 3: Scan at 254 nm.

 

Conclusion

These results demonstrate that UV filter can easily be analysed by TLC-MS with a minimum of sample preparation even in a complex matrix like sun cream.

Application data

Chromatography
Plate HPTLC RP-18 F254s MS-grade, 20x10 cm
Sample preparation 1 g sun cream stirred in 10 mL 2-Propanol, filtration
Sample application ATS 4 sample applicator (Camag), 6 mm bandwise
Application volume 0.5 - 5 μL
Mobile phase Methanol / Acetonitrile 9/1 (v/v)
Migration distance 5 cm
Migration time 11 min
Extraction
Extraction equipment “TLC-MS Interface” from Camag
Extraction solvent Acetonitrile / Water 95/5 (v/v) + 0.1% Formic acid
Extraction flow 0.2 mL/min
Detection
Documentation equipment documentation unit Reprostar / Digistore (Camag)
Wavelength scan under UV-light at 254 nm and 366 nm
Staining none
MS equipment single-quadrupole mass spectrometer
MS detection ESI (+/-) mode MS (m/z 50 - 350)

Chromatographic data

Track Compound Conc. [mg/mL] Application volume [μL] hRf Detected mass m/z
1-4 Eusolex® 9020 standard 0.1 2, 3, 4, 5 50 311.2
5-7 sun cream 1 - 0.5 50 311.2
8-10 sun cream 2 - 0.5 50 311.2

Ordering information

Description Product No.
HPTLC RP-18 F254s MS-grade, 20x10 cm 1.51161
Acetonitrile hypergrade for LC-MS LiChrosolv® 1.00029
2-Propanol gradient grade for liquid chromatography LiChrosolv® 1.01040
Methanol hypergrade for LC-MS LiChrosolv® 1.06035
Formic acid for analysis EMSURE® 1.00264
Water for chromatography (LC-MS Grade) LiChrosolv® 1.15333
Millex®-FH filter, 0.45 μm hydrophobic PTFE, 25 mm, non-sterile SLFH025NS

 

Materials