Rapid Determination of the ‘Legal Highs’ 4-MMC and 4-MEC by Spectroelectrochemistry: Simultaneous Cyclic Voltammetry and In Situ Surface-Enhanced Raman Spectroscopy

The synthetic cathinones mephedrone (4-MMC) and 4-methylethcathinone (4-MEC) are two designer drugs that represent the rise and fall effect of this drug category within the stimulants market and are still available in several countries around the world. As a result, the qualitative and quantitative determination of ‘legal highs’, and their mixtures, are of great interest. This work explores for the first time the spectroelectrochemical response of these substances by coupling cyclic voltammetry (CV) with Raman spectroscopy in a portable instrument. It was found that the stimulants exhibit a voltammetric response on a gold screen-printed electrode while the surface is simultaneously electro-activated to achieve a periodic surface-enhanced Raman spectroscopy (SERS) substrate with high reproducibility. The proposed method enables a rapid and reliable determination in which both substances can be selectively analyzed through the oxidation waves of the molecules and the characteristic bands of the electrochemical SERS (EC-SERS) spectra. The feasibility and applicability of the method were assessed in simulated seized drug samples and spiked synthetic urine. This time-resolved spectroelectrochemical technique provides a cost-effective and user-friendly tool for onsite screening of synthetic stimulants in matrices with low concentration analytes for forensic applications.

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Determination of the Immunoglobulin G Spectrum by Surface-Enhanced Raman Spectroscopy Using Quasispherical Gold Nanoparticles

Journal of Nanomaterials ◽

10.1155/2021/8874193 ◽

2021 ◽

Vol 2021 ◽

pp. 1-6

Author(s):

Alejandra Ortiz-Dosal ◽

Elizabeth Loredo-García ◽

Ana Gabriela Álvarez-Contreras ◽

Juan Manuel Núñez-Leyva ◽

Luis Carlos Ortiz-Dosal ◽

...

Keyword(s):

Gold Nanoparticles ◽

Raman Spectroscopy ◽

Raman Spectrum ◽

Surface Enhanced Raman Spectroscopy ◽

Protein Quantification ◽

Acquisition Time ◽

Sers Substrate ◽

Surface Enhanced ◽

Surface Enhanced Raman

Background. Immunoglobulins (Ig) are glycoprotein molecules produced by plasma cells in response to antigenic stimuli involved in various physiological and pathological conditions. Intravenous immunoglobulin (IVIG) is a compound whose composition corresponds to Ig concentrations in human plasma, predominantly IgG. It is used as a replacement treatment in immunodeficiencies and as an immunomodulator in inflammatory and autoimmune diseases. The determination of IgG concentrations is useful in the diagnosis of these immunodeficiencies. Surface-enhanced Raman spectroscopy (SERS) is a technique that allows protein quantification in a fast and straightforward way. Objective. This study is aimed at determining the Raman spectrum of IgG at physiological concentrations using quasispherical gold nanoparticles as a SERS substrate. Methods. We initially determined the Raman spectrum of IVIG at 5%. Subsequently, for SERS’ characterization, decreasing dilutions of the protein were made by adding deionized water and an equal volume of the 5 nm gold quasispherical nanoparticle colloid. For each protein concentration, the Raman spectrum was determined using a 10x objective; we focused the 532 and 785 nm laser on the sample surface, in a range of 500-1800 cm-1, with five acquisitions and an acquisition time of 30 seconds. Results. We obtained the IVIG spectrum using SERS up to a concentration of 75 mg/dl. The Raman bands correspond to aromatic amino acid side chains and the characteristic beta-sheet structure of IgG. Conclusion. The use of 5 nm quasispherical gold nanoparticles as a SERS substrate allows for detecting the Raman spectrum of IVIG at physiological concentrations.

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Surface Enhanced Raman Spectroscopy for Rapid Determination ofβ-Agonists in Swine Urine

CHINESE JOURNAL OF ANALYTICAL CHEMISTRY (CHINESE VERSION) ◽

10.3724/sp.j.1096.2012.10801 ◽

2012 ◽

Vol 40 (5) ◽

pp. 718

Author(s):

Fu-Li ZHAI ◽

Yi-Qun HUANG ◽

Xi-Chang WANG ◽

Ke-Qiang LAI

Keyword(s):

Raman Spectroscopy ◽

Rapid Determination ◽

Surface Enhanced Raman Spectroscopy ◽

Beta Agonists ◽

Swine Urine ◽

Surface Enhanced ◽

Surface Enhanced Raman

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Multivariate Analysis Aided Surface-Enhanced Raman Spectroscopy (MVA-SERS) Multiplex Quantitative Detection of Trace Fentanyl in Illicit Drug Mixtures Using a Handheld Raman Spectrometer

Applied Spectroscopy ◽

10.1177/00037028211032930 ◽

2021 ◽

pp. 000370282110329

Author(s):

Ling Wang ◽

Mario O. Vendrell-Dones ◽

Chiara Deriu ◽

Sevde Doğruer ◽

Peter de B. Harrington ◽

...

Keyword(s):

Raman Spectroscopy ◽

Principal Component ◽

Surface Enhanced Raman Spectroscopy ◽

Quantitative Detection ◽

Least Squares Regression ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Sers Detection ◽

Current Screening

Recently there has been upsurge in reports that illicit seizures of cocaine and heroin have been adulterated with fentanyl. Surface-enhanced Raman spectroscopy (SERS) provides a useful alternative to current screening procedures that permits detection of trace levels of fentanyl in mixtures. Samples are solubilized and allowed to interact with aggregated colloidal nanostars to produce a rapid and sensitive assay. In this study, we present the quantitative determination of fentanyl in heroin and cocaine using SERS, using a point-and-shoot handheld Raman system. Our protocol is optimized to detect pure fentanyl down to 0.20 ± 0.06 ng/mL and can also distinguish pure cocaine and heroin at ng/mL levels. Multiplex analysis of mixtures is enabled by combining SERS detection with principal component analysis and super partial least squares regression discriminate analysis (SPLS-DA), which allow for the determination of fentanyl as low as 0.05% in simulated seized heroin and 0.10% in simulated seized cocaine samples.

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