Molybdenum disulfide-graphene oxide composites as dispersive solid-phase extraction adsorbents for the enrichment of four paraben preservatives in cosmetics.

Molybdenum disulfide-graphene oxide composite (MoS2/GO) was synthesized and used as the adsorbent in dispersive solid-phase extraction. Four paraben preservatives, namely, methylparaben, ethylparaben, propylparaben, and butylparaben, were enriched with MoS2/GO and determined by ultra-high-performance liquid chromatography. Molybdenum disulfide was intercalated into graphene oxide layers to reduce self-aggregation by using the solvothermal method. The experimental results indicated that the as-prepared MoS2/GO composite exhibited great enrichment capability toward those four paraben preservatives, and the adsorption time was 10 min and the elution time was as short as 1 min. The mechanism of MoS2/GO composite and parabens is attributed to hydrogen bonding and electrostatic attraction. The relative standard deviation (RSD, n = 9) of this method was below 7.6%. Limits of detection and limits of quantification were in the range 0.4-2.3 ng/mL and 1.4-7.6 ng/mL, respectively. The recoveries obtained from the parabens of cosmetic sample were in the range 91.3-124% with RSDs below 10%. The developed method has great potential for the determination of emerging contaminants with low cost and high sensitivity.