Gold nanorods for in-drop colorimetric determination of thiomersal after photochemical decomposition
- 65 Downloads
This work reports on the implementation of gold nanorods (AuNRs) in headspace solvent microextraction for colorimetric determination of volatile analyte derivatives in a single drop. The exposure of AuNRs to both H2Se and elemental mercury (Hg0) results in a shift of the longitudinal plasmonic band, unlike a number of volatiles. Accordingly, a method is reported for the determination of Hg0 with potential applicability to the determination of thiomersal (sodium ethylmercurithiosalicylate). It is based on the photochemical decomposition of thiomersal into Hg(II) and subsequent exposure of AuNRs-containing microdrop to in situ generated Hg0. Colorimetric analysis of the enriched drop was carried out without dilution by means of a cuvetteless microvolume UV-vis spectrometer. Under optimal conditions, the limit of detection was 0.5 ng mL−1 (as Hg). The repeatability, expressed as relative standard deviation, was 8.4% (for n = 10). AuNRs exposed to increasing concentrations of the analyte were characterized by means of transmission electron microscopy and UV-vis spectrophotometry to ascertain the mechanism of detection. The method was finally applied to the determination of thiomersal in various pharmaceutical samples and showed quantitative recoveries.
KeywordsCentral composite design Mercury Microextraction Microvolume spectrometry Miniaturization Nanoparticles Pharmaceuticals Plackett-Burman design Sample preparation Thiomersal
Financial support from the Spanish Ministry of Economy and Competitiveness (Project CTQ2015-68146-P) (MINECO/FEDER) is gratefully acknowledged. F. Pena-Pereira thanks Xunta de Galicia for financial support as a post-doctoral researcher of the I2C program. The CACTI facilities (University of Vigo) are also acknowledged for obtaining TEM and SEM images and performing EDS analyses.
Compliance with ethical standards
The author(s) declare that they have no competing interests.
- 1.Campanella B, Onor M, Mascherpa MC, D’Ulivo A, Ferrari C, Bramanti E (2013) Determination of thiomersal by flow injection coupled with microwave-assisted photochemical online oxidative decomposition of organic mercury and cold vapor atomic fluorescence spectroscopy. Anal Chim Acta 804:66–69CrossRefGoogle Scholar
- 2.Rowe RC, Sheskey PJ, Quinn ME Handbook of pharmaceutical excipients, 6th ed. APhA Pharmaceutical Press, LondonGoogle Scholar
- 3.FDA (2018) Thiomersal and vaccines. https://www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/VaccineSafety/UCM096228. Accessed 27 Feb 2018
- 4.Gil S, Lavilla I, Bendicho C (2007) Greener analytical method for determination of thiomersal (sodium ethylmercurithiosalicylate) in ophthalmic solutions using sono-induced cold vapour generation-atomic absorption spectrometry after UV/H2O2 advanced oxidation. J Anal At Spectrom 22:569–572CrossRefGoogle Scholar
- 8.Acosta G, Spisso A, Fernández LP, Martinez LD, Pacheco PH, Gil RA (2015) Determination of thimerosal in pharmaceutical industry effluents andriver waters by HPLC coupled to atomic fluorescence spectrometrythrough post-column UV-assisted vapor generation. J Pharm Biomed Anal 106:79–84CrossRefGoogle Scholar
- 11.Pena-Pereira F (2014) From conventional to miniaturized analytical systems. In: Pena-Pereira F (ed) Miniaturization sample prep. De Gruyter open, Berlin, pp 1–28Google Scholar
- 24.Gil S, de Loos-Vollebregt MTC, Bendicho C (2009) Optimization of a single-drop microextraction method for multielemental determination by electrothermal vaporization inductively coupled plasma mass spectrometry following in situ vapor generation. Spectrochim Acta Part B At Spectrosc 64:208–214CrossRefGoogle Scholar