Detection of fentanyl in binary mixtures with cocaine by use of surface-enhanced Raman spectroscopy

Abstract

The ongoing epidemic pertaining to overdose deaths has been attributed to the synthetic opioid fentanyl due to its use as an adulterant in other, less potent drugs of abuse. Detection of low quantities of fentanyl would, therefore, be extremely useful in a forensic science laboratory. While Raman spectroscopy is particularly effective at distinguishing between classes of drugs, weak signatures can prove difficult when dealing with microscopic samples. Surface-enhanced Raman scattering spectroscopy provides the enhancement necessary to make Raman a viable approach for the detection of small amounts of fentanyl. This work explores the use of a paper-based substrate loaded with silver nanoparticles for the recovery of small quantities of fentanyl in cocaine, where it was identified at a lower limit of 500?ng (～65?ppm) in mixtures. Linear relationships were investigated between intensity and concentration for diagnostic peaks associated with fentanyl and cocaine, which in turn sheds light on the attenuation of the enhancement intensity as a result of competitive binding to silver nanoparticles. This work demonstrates a potentially simple and qualitative pathway for the forensic analysis of fentanyl as an adulterant in cocaine.     

Semiconductor Emitters in Entropy Sources for Quantum Random Number Generation

Random number generation (RNG) is needed for a myriad of applications ranging from secure communication encryption to numerical simulations to sports and games. However, generating truly random numbers can be elusive. Pseudorandom bit generation using computer algorithms provides a high random bit generation rate. Nevertheless, the reliance on predefined algorithms makes it deterministic and predictable once initial conditions are known. Relying on physical phenomena (such as measuring electrical noise or even rolling dice) can achieve a less predictable sequence of bits. Furthermore, if the physical phenomena originate from quantum effects, they can be truly random and completely unpredictable due to quantum indeterminacy. Traditionally, physical RNG is significantly slower than pseudorandom techniques. To meet the demand for high-speed RNG with perfect unpredictability, semiconductor light sources are adopted as parts of the sources of randomness, i.e., entropy sources, in quantum RNG (QRNG) systems. The high speed of their noise, the high efficiency, and the small scale of these devices make them ideal for chip-scale QRNG. Here, the applications and recent advances of QRNG are reviewed using semiconductor emitters. Finally, the performance of these emitters is compared and discuss their potential in future technologies.     

Simple and Convenient Synthesis of 21‐Thioalkylether Derivatives of Methyl 16‐Prednisolone Carboxylates

The antedrug approach for corticosteroids has been described as a fundamentally sound approach for the development of safer anti‐inflammatory and anti‐asthmatic therapy. However, the derivatization of prednisolone and its congeners have been considered to be major pitfalls, because their syntheses are complicated by the presence of numerous carboxylate esters and hydroxyl functions in the steroid nucleus. A simple and direct synthesis of 21‐thioalkylether derivatives of methyl 16‐prednisolonecarboxylates is described. The 21‐mesylate of the methyl 16‐prednisolonecarboxylate and 9‐fluoro‐17‐dehydro methyl 16‐prednisolonecarboxylate were reacted with Na‐thioalkoxides to furnish the desired thioethers in good yields. A previously published method for the methanolysis of 16‐cyanoprednisolone to methylcarboxylate has been reexamined, and the conditions are explained clearly. The reaction conditions for all these reactions were critical.     

Anderson localization of expanding Bose-Einstein condensates in random potentials

We show that the expansion of an initially confined interacting 1D Bose-Einstein condensate can exhibit Anderson localization in a weak random potential with correlation length sigma(R). For speckle potentials the Fourier transform of the correlation function vanishes for momenta k>2/sigma(R) so that the Lyapunov exponent vanishes in the Born approximation for k>1/sigma(R). Then, for the initial healing length of the condensate xi(in)>sigma(R) the localization is exponential, and for xi(in)相似文献   

Effect of mating delay on the ovary of Melipona quadrifasciata anthidioides (Hymenoptera: Apidae) queens

The effect of mating delay on the ovary structure of virgin queens of Melipona quadrifasciata anthidioides (Hymenoptera: Apidae) was investigated. Virgin queens 15, 20, 25 and 30 days old were dissected to analyze their degree of ovary degeneration. To verify whether the degeneration would cause permanent sterility, virgin queens of the same ages (15, 20, 25 and 30 days) were mated and accompanied for at least 14 days to verify whether there was physogastry and then dissected. The ovaries were analyzed by histology, histochemical tests and TUNEL to verify programmed cell death. The results showed that mating delay interrupted oogenesis preventing vitellogenesis. Mating delay results in ovary degeneration which increased with queen age. However, even when there was ovariole degeneration, 25-day-old virgin queens after mating presented normal ovariole activation.     

Flow-through amperometric methods for detection of the bioactive compound quercetin: performance of glassy carbon and screen-printed carbon electrodes

Journal of Solid State Electrochemistry - Rapid methods using batch injection analysis (BIA) with amperometric detection were developed for the determination of quercetin extracted from the...     

Estimation of the surface energetic heterogeneity of fillers by inverse gas chromatography

The surface properties of the fillers are determining for obtaining high performance filled polymers. Yet, their determination is most difficult. This paper proposes to use inverse gas chromatography, either at infinite dilution or finite concentration conditions, to estimate surface energy and nanomorphological characteristics, but also surface heterogeneity of different clays, talcs of various origins and ground muscovites.     

Direct determination of glyphosate using hydrophilic interaction chromatography with coulometric detection at copper microelectrode

A simple, rapid, and low-cost coulometric method for direct detection of glyphosate using hydrophilic interaction chromatography is presented. The principle of detection is based on the enhancement of the anodic current of copper microelectrode in the presence of complexing agents, such as glyphosate, with the formation of a soluble Cu(II) complex. Under optimized conditions, the limit of detection (S/R = 3) for glyphosate was 0.1 mg L⁻¹ (0.59 μM) without any preconcentration method. The calibration curve has been found linear in all concentration range tested (from limit of detection to 34 mg L⁻¹) with an excellent correlation coefficient (0.9999). The present method was successfully applied for the determination of glyphosate in fruit juices without any kind of extraction, clean-up, or preconcentration step, with recoveries of 92 and 90% for apple and grape juice, respectively.     

High-temperature heat capacity,thermodynamic properties and debye temperature of CuGe2P3

The heat capacity at constant pressure of CuGe₂P₃ is measured in the temperature range from 180 to 550 K. Standard enthalpies and entropies relative to 298.15 K are calculated from the heat capacity data. The Debye temperature in the high-temperature limit is estimated to be about 710 K.