Characterization of Conversion-Coated Aluminum Using Fourier Transform Infrared and Raman Spectroscopies

Fourier transform infrared and Raman spectroscopies have been employed to define the molecular composition of chromium phosphate conversion coatings on aluminum. Attenuated total reflectance at 55° can be employed to probe the structure of conversion coatings present on aluminum at relatively high coating weights (≥23 mg Cr/m2). Both reflection-absorption infrared and surface-enhanced Raman spectroscopic techniques can discern the presence of conversion coatings at coverages as low as 9 mg Cr/m2. On the basis of the vibrational spectra from these techniques, we have determined that hydrated chromium phosphate is the major component in these conversion coatings on aluminum. Reflection-absorption infrared and surface-enhanced Raman spectroscopies also provide a means to determine the molecular structure of the nascent oxide layer on aluminum as a function of processing conditions. Specular reflection, attenuated total reflectance at 35°, diffuse reflectance, and Raman spectroscopic methods, in general, lack the surface sensitivity necessary to probe thin (≤23 mg/m2) inorganic films on aluminum.

Download Full-text

Analysis of ‘legal high’ substances and common adulterants using handheld spectroscopic techniques

Analytical Methods ◽

10.1039/c4ay02169j ◽

2015 ◽

Vol 7 (2) ◽

pp. 736-746 ◽

Cited By ~ 18

Author(s):

S. Assi ◽

A. Guirguis ◽

S. Halsey ◽

S. Fergus ◽

J. L. Stair

Keyword(s):

Fourier Transform ◽

Ir Spectroscopy ◽

Near Infrared ◽

Fourier Transform Infrared ◽

Attenuated Total Reflectance ◽

Spectroscopic Techniques ◽

Total Reflectance ◽

Legal High ◽

Ft Ir ◽

Ft Ir Spectroscopy

Three handheld spectrometers, near-infrared (NIR), Raman and attenuated total reflectance Fourier transform-infrared (ATR-FT-IR) spectroscopy, were used for the identification of ‘legal high’ model mixtures and Internet products.

Download Full-text

Detection of bloodstains using attenuated total reflectance-Fourier transform infrared spectroscopy supported with PCA and PCA–LDA

Medicine Science and the Law ◽

10.1177/00258024211010926 ◽

2021 ◽

pp. 002580242110109

Author(s):

Sweety Sharma ◽

Rito Chophi ◽

Jaskirandeep Kaur Jossan ◽

Rajinder Singh

Keyword(s):

Fourier Transform ◽

Ftir Spectroscopy ◽

Body Fluid ◽

Due Process ◽

Dna Analysis ◽

Fourier Transform Infrared ◽

Body Fluids ◽

Attenuated Total Reflectance ◽

Total Reflectance ◽

Non Destructive

The most important task in a criminal investigation is to detect and identify the recovered biological stains beyond reasonable scientific doubt and preserve the sample for further DNA analysis. In the light of this fact, many presumptive and confirmatory tests are routinely employed in the forensic laboratories to determine the type of body fluid. However, the currently used techniques are specific to one type of body fluid and hence it cannot be utilized to differentiate multiple body fluids. Moreover, these tests consume the samples in due process, and thus it becomes a great limitation especially considering the fact that samples are recovered in minute quantity in forensic cases. Therefore, such limitations necessitate the use of non-destructive techniques that can be applied simultaneously to all types of bodily fluids and allow sample preservation for further analysis. In the current work, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy has been used to circumvent the aforementioned limitations. The important factors which could influence the detection of blood such as the effect of substrates, washing/chemical treatment, ageing, and dilution limits on the analysis of blood have been analysed. In addition, blood discrimination from non-blood substance (biological and non-biological in nature) has also been studied. Chemometric technique that is PCA–LDA has been used to discriminate blood from other body fluids and it resulted in 100% accurate classification. Furthermore, blood and non-blood substances including fake blood have also been classified into separate clusters with a 100% accuracy, sensitivity, and specificity. All-inclusive, this preliminary study substantiates the potential application of ATR-FTIR spectroscopy for the non-destructive identification of blood traces in simulated forensic casework conditions with 0% rate of false classification.

Download Full-text