Prospects and difficulties in TiO₂ nanoparticles analysis in cosmetic and food products using asymmetrical flow field-flow fractionation hyphenated to inductively coupled plasma mass spectrometry.
In this work, we proposed an analytical approach based on asymmetrical flow field-flow fractionation combined to an inductively coupled plasma mass spectrometry (AsFlFFF-ICP-MS) for rutile titanium dioxide nanoparticles (TiO2NPs) characterization and quantification in cosmetic and food products. AsFlFFF-ICP-MS separation of TiO2NPs was performed using 0.2% (w/v) SDS, 6% (v/v) methanol at pH 8.7 as the carrier solution. Two problems were addressed during TiO2NPs analysis by AsFlFFF-ICP-MS: size distribution determination and element quantification of the NPs. Two approaches were used for size determination: size calibration using polystyrene latex standards of known sizes and transmission electron microscopy (TEM). A method based on focused sonication for preparing NPs dispersions followed by an on-line external calibration strategy based on AsFlFFF-ICP-MS, using rutile TiO2NPs as standards is presented here for the first time. The developed method suppressed non-specific interactions between NPs and membrane, and overcame possible erroneous results obtained when quantification is performed by using ionic Ti solutions. The applicability of the quantification method was tested on cosmetic products (moisturizing cream). Regarding validation, at the 95% confidence level, no significant differences were detected between titanium concentrations in the moisturizing cream prior sample mineralization (3865±139 mg Ti/kg sample), by FIA-ICP-MS analysis prior NPs extraction (3770±24 mg Ti/kg sample), and after using the optimized on-line calibration approach (3699±145 mg Ti/kg sample). Besides the high Ti content found in the studied food products (sugar glass and coffee cream), TiO2NPs were not detected.
Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain.
Isabel
I
López-Heras
Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain.
Yolanda
Y
Madrid
Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain. Electronic address: ccamara@quim.ucm.es.
Carmen
C
Cámara
D002138:Calibration; D003358:Cosmetics / Q000737:chemistry*; D004643:Emollients / Q000737:chemistry; D005504:Food Analysis / Q000379:methods*; D031521:Fractionation, Field Flow / Q000379:methods*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry / Q000379:methods*; D053768:Metal Nanoparticles / Q000032:analysis* / Q000737:chemistry / Q000648:ultrastructure; D000432:Methanol / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D015203:Reproducibility of Results; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013473:Sunscreening Agents / Q000737:chemistry; D014025:Titanium / Q000032:analysis* / Q000737:chemistry
D003358:Cosmetics; D004643:Emollients; D013473:Sunscreening Agents; C009495:titanium dioxide; D012967:Sodium Dodecyl Sulfate; D014025:Titanium; D000432:Methanol
Asymmetrical flow field-flow fractionation; Inductively coupled plasma-mass spectrometry; Quantification; Titanium dioxide nanoparticles; Transmission electron microscopy