April 23rd 2024
To improve the robustness and accuracy of logistic regression identification method, a new Raman spectroscopy identification method was proposed that combines a distributionally robust optimization technique and fused lasso technique with logistic regression. Then, Raman spectroscopy was used to analyze two types of dairy products that were collected for anti-jamming identification testing to verify the effectiveness of the new method.
December 1st 2023
Effect of Azimuthal Angle on Infrared Diffuse Reflection Spectra of Fabrics
Infrared spectroscopy is an appealing technique for application to forensic samples because it offers the benefits of being non-destructive and non-hazardous, fast, reasonably sensitive, and resistant to some of the interferences of many commonly used techniques. Our research team has been focusing on detecting biological fluids on fabrics, which are inherently anisotropic substrates for spectroscopy. The work presented here investigates the effect of azimuthal angle of the sample on the infrared diffuse reflection spectra of fabrics with a goal of removing sampling differences as a source of analytic variation.
Lineshapes in IR and Raman Spectroscopy: A Primer
November 1st 2015Infrared and Raman bands are typically described in terms of peak location and peak height. The shape of the peak-its form, width, and asymmetry-is less well understood. Bandshapes largely depend upon interactions between vibrating molecules and their environment. An understanding of this relationship may enhance spectral interpretation and can explain unexpected behaviors, in both qualitative and quantitative analyses. This paper presents basic concepts that influence line shapes and shows the complex lineshape changes in an apparently simple system of acetone and water.
VT-DRIFTS Investigations of Interactions Between Benzoic Acid and Montmorillonite Clay
October 1st 2015High stability Fourier transform-infrared (FT-IR) interferometers make it possible to conduct experiments designed to identify subtle sample structure changes resulting from external perturbations. In particular, IR spectrum measurements obtained while heating samples can be used to associate specific structure changes with incremental additions of thermal energy. This paper describes the application of variable temperature diffuse reflection infrared Fourier transform spectroscopy (VT-DRIFTS) for analysis of benzoic acid adsorbed on montmorillonite clay. The technique described here is generally applicable for soil adsorbate characterization studies, and therefore should be useful for elucidating soil transport mechanisms for selected contaminants.
Agricultural and Environmental Management with Raman Spectroscopy
September 1st 2015Raman spectroscopy is applied to quality control of agricultural products with greater frequency, and can also be used to refine regulatory criteria for both agricultural and environmental monitoring. It is now integrated into everything from hand held SERS detectors to unmanned aerial vehicles to monitor the gamut from genetic variation to soil and water content. Development opportunities, particularly with bundled technologies, continue to emerge as demand for quality assurance increases.
Application of SERS to the Determination of Butylated Hydroxyanisole in Edible and Essential Oils
July 1st 2015Surface-enhanced Raman scattering (SERS) has been applied to the determination of the antioxidant butylated hydroxyanisole (BHA), commonly used in fatty foods and oils to prevent their oxidation. The use of SERS-Raman microscopy with an inexpensive homemade silver substrate allowed the direct determination of BHA in oils without any sample handling. Several edible and essential oils (used as flavorings) have been considered for this purpose.
A method for the multielemental determination of metals and nonmetals in goji berries (Lycium barbarum L.) by axially and radially viewed inductively coupled plasma-optical emission spectrometry (ICP-OES) is presented.
Sequentially Shifted Excitation Raman Spectroscopy
November 1st 2014A method for removing fluorescence-induced backgrounds from Raman spectra using sequentially shifted excitation (SSE) is described. The method uses a temperature-tuned, distributed Bragg reflector diode laser to produce the multiple excitation spectra required to implement the SSE algorithm. Examples applying the SSE method to analysis of motor oils and edible oils are given.
Macro ATR-FT-IR Spectroscopic Imaging of Dynamic Processes
October 1st 2014Macro attenuated total reflection FT-IR spectroscopic imaging is a powerful and underutilized tool. This article presents an overview of approaches and opportunities for using this method to study dynamic processes such as diffusion, sorption, crystallization, and dissolution.
How Trace Elemental Analysis Provides Important Insight into Wine Chemistry
September 1st 2014Examples are shown that highlight how elemental fingerprinting could provide valuable information about the geographical origin of a food or beverage as well as how different steps in the production of wines impact their elemental composition.
Rapid Determination of Trace Metals in Oil Using Handheld X-Ray Fluorescence Spectroscopy
July 1st 2014Determination of trace metals in oil and petroleum typically is based on ICP-OES methods, requiring signficant sample preparation and expensive instrumentation. This article presents an alternative method, based on the use of a handheld energy-dispersive X-ray fluorescence analyzer, that involves minimal sample preparation, uses authentic standards for calibration, gives low parts-per-million detection limits, and provides significant time and cost savings.
Label-Free Chemical Detection in Micro-Fabricated Devices Using FT-IR Spectroscopic Imaging
October 1st 2012Fourier transform infrared (FT-IR) spectroscopic imaging is a highly versatile technique that can be applied to a wide range of systems. This article summarizes some of the recent efforts developing applications of FT-IR imaging for microfluidics. The main advantage of FT-IR imaging compared to traditional imaging methods is that it is a label-free imaging technique.
Label-Free Chemical Detection in Micro-Fabricated Devices Using FT-IR Spectroscopic Imaging
October 1st 2012Fourier transform infrared (FT-IR) spectroscopic imaging is a highly versatile technique that can be applied to a wide range of systems. This article summarizes some of the recent efforts developing applications of FT-IR imaging for microfluidics. The main advantage of FT-IR imaging compared to traditional imaging methods is that it is a label-free imaging technique.