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Functionalized Graphene-Coated Cobalt Nanoparticles for Highly Efficient Surface-Assisted Laser Desorption/Ionization Mass Spectrometry Analysis
Hideya Kawasaki, Keisuke Nakai, Ryuichi Arakawa, Evagelos K. Athanassiou, Robert N. Grass and Wendelin J. Stark
(1) high surface area(2) affinity for the specific analytes(3) efficient extraction of analytes(4) easily oxidized in air
IntroductionCoC−NH2 nanomagnets
(1) Graphene has outstanding physical, and chemical properties(2) increase ion yields(3) affinity for the specific analytes
Introductionpolyfluorinated compounds (PFCs)
Compounds in this class were firstproduced in the 1940s and1950s.
By the early 2000s, when it became apparent that PFCs were broadly distributed in the environment.
Perfluorooctanesulfonic acid (PFOS)
PFOS
An increase in hepatocellular adenomas and thyroid follicular cell adenomas was observed in rats exposed to high levels of PFOS in their food
the half-life of PFOS in humans is approximately 5.4 years
EXPERIMENTAL SECTION
Method 1two-layer sample preparation method
CoC−NH2 Nanomagnets sample
EXPERIMENTAL SECTION
Method 2
RESULTS AND DISCUSSION
Characterization of Modified and Unmodified CoC Nanomagnets.
Unmodified CoC Nanomagnets.
Characterization of Modified and Unmodified CoC Nanomagnets.
Functionalization of carbon-coated magnetic nanobeads with chlorobenzene and nitrobenzene and reduction of the nitro groups to amino groups with elemental sulfur. SDS=sodiumdodecylsulfate
Characterization of Modified and Unmodified CoC Nanomagnets.
Affinity SALDI-MS Using Modified and Unmodified CoC−NH2 Nanomagnets.
angiotensin IIm/z: 1047
Affinity SALDI-MS Using Modified and Unmodified CoC−NH2 Nanomagnets.
Graphene oxide (SY = 0.38)
a hybrid film of poly(allylaminehydrochloride)-functionalized graphene oxide and gold nanoparticles(SY = 0.78)
Affinity SALDI-MS Using Modified and Unmodified CoC−NH2 Nanomagnets.
Extraction of PFOS from Water Using CoC−NH2 Nanomagnets and SALDI-MS Detection.
Extraction of PFOS from Water Using CoC−NH2 Nanomagnets and SALDI-MS Detection.
PFOS pKa:−3.27
pH < 7pH 11
Extraction of PFOS from Water Using CoC−NH2 Nanomagnets and SALDI-MS Detection.
Extraction of PFOS from Water Using CoC−NH2 Nanomagnets and SALDI-MS Detection.
LOD
The recovery ratio of PFOS from 1 L of 10 ppt PFOS aqueous solution using CoC−NH2 nanomagnets was more than 99%.
Extraction of PFOS from Water Using CoC−NH2 Nanomagnets and SALDI-MS Detection.
Tap water sample
Extraction of PFCs with Different Chain Lengths from Water Using CoC−NH2 Nanomagnets, Followed by SALDI-MS Detection.
Extraction of PFCs with Different Chain Lengths from Water Using CoC−NH2 Nanomagnets, Followed by SALDI-MS Detection.
CONCLUSIONS1.We have demonstrated that CoC−NH2 nanomagnets work well in tandem with SALDI-MS as a LDI-assisting material and for the extraction/enrichment of analytes from dilute solution.
2.The benzylamine surface modification of the CoC nanomagnets was shown to increase the ion yield of angiotensin II and decrease ion fragmentation of benzylpyridinium ions.
3.SALDI-MS using CoC−NH2 nanomagnets enabled the detection of various small molecule drugs,but the detection of the small acidic drug molecules acetylsalicylic acid and ibuprofen were not achieved with this approach.
4.The detection sensitivities of PFCs were 0.1 ppt for PFOS (C8), 10 ppt for PFHxS (C6), and 10 ppt for PFBS (C4).
5.In future work, it may be interesting to detect aromatic compounds as aqueous environmental samples using affinity SALDI-MS with CoC−NH2 nanomagnets.
CONCLUSIONS
In fact, preliminary experiment indicated that the detection of pentachlorophenol (20 ppb) in water, was accomplished by the use of affinity SALDIMS with CoC−NH2 nanomagnets.