Spectral Analysis Review
ISSN / EISSN : 2331-2092 / 2331-2106
Published by: Scientific Research Publishing, Inc. (10.4236)
Total articles ≅ 22
Latest articles in this journal
Spectral Analysis Review, Volume 06, pp 12-32; doi:10.4236/sar.2018.61002
This paper reviews the studies of using FTIR to investigate the components of aerosols produced in smog chamber experiments and collected in atmosphere. The fact that aerosols are mixture of small amount of countless individual compounds makes the analysis of aerosol constituents very challenging. Although a number of advanced instruments have been applied to the chemical characterization of aerosol components, the majority of aerosol components, particularly the organics, remain unknown. Being supplemental to the traditional quantitative instruments, FTIR has been recently used either individually or combining with other analytical instruments to characterize the components of aerosol particles. This paper aims to show how FTIR is applied to analysis of organic aerosols in current literature and to summarize the FTIR characteristic peak frequencies that are widely seen in the FTIR measurement of organic aerosols. It will be greatly helpful to researchers whose studies are focused on the analysis of aerosol components.
Spectral Analysis Review, Volume 06, pp 1-11; doi:10.4236/sar.2018.61001
It is known that the presence of protein aggregates in biological samples is associated with natural aging processes and age-related diseases. The objective of this technical study was to evaluate the potential of Fourier Transform Infrared Spectroscopy to identify the presence of protein aggregates in Saccharomyces cerevisiae containing high levels of protein aggregates. We acquired ATR-FTIR spectra at mid-infrared range (between 4000 and 600 cm-1) and used multivariate analysis to analyze the data. Significant differences between spectra of wild type and mutant strains in the spectral range assigned to proteins were observed. In particular, an increase in β-sheet structures in mutant strains (spectral signals at 1683 and 1628 cm-1) was observed, indicating the putative presence of protein aggregates. These results prove the capacity of FTIR to evaluate changes in protein conformation, mainly protein aggregation, in a fast, simple and non-expensive way, producing insights on the possible application of this technique to the detection of protein aggregates in human biological samples.
Spectral Analysis Review, Volume 06, pp 43-52; doi:10.4236/sar.2018.62004
The hyperfine (hf) structure constants of three atomic niobuim energy levels in the energy range around 23000 cm-1 (at 22936.90, 23010.58, and 23048.58 cm-1) are known with only limited accuracy, and the constants of combining levels are sometimes even unknown. Thus we performed laser spectroscopic investigations in the wavelength range between 5600 and 6500 Å, and we excited altogether 16 transitions in which these lower levels are involved. Beside a more precise determination of the hf structure constants of the three lower levels (which were determined on several lines sharing a common upper level), these experiments led to the knowledge of the hf constants of nine levels with previously unknown constants. Beside these results, also the hf constants of 13 further energy levels are reported. For six of these levels, the constants were previously unknown.
Spectral Analysis Review, Volume 06, pp 33-42; doi:10.4236/sar.2018.62003
The potential of Near Infrared Spectroscopy (NIRS) in quality control of Traditional Chinese Medicine has been evaluated. This study focuses on a rapid and non-destructive quantitative method for the determination of schaftoside acid content in Desmodium styracifolium by near-infrared spectroscopy. The schaftoside acid contents of 103 samples were determined by HPLC. The NIRS quantitative model of the ethanol extracts content was performed by partial least-squares (PLS) regression as linear regression with analysis values as calibration reference using 2nd derivative method as spectral preprocessing options. The model was verified by internal cross validation and external predictive validation with 22 Desmodium styracifolium samples. The correlation coefficients (r), the root-mean-square error of calibration (RMSEC), the root-mean-square error of prediction (RMSEP) and the root-mean-square error of cross-validation (RMSECV) of the calibration model for ethanol extracts content were 0.97201, 0.147, 0.162 and 0.433, respectively. The average recovery was 99.82%, and t-test showed that P > 0.5. Precision and repeatability RSD were 1.75% and 1.17%, RPD > 2.5. The data obtained from results showed that calibration model of NIRS was verified to be reliable, suggesting that the quantitative NIR models can be qualified to accurately quantify the ethanol extracts content of Desmodium styracifolium rapidly.
Spectral Analysis Review, Volume 05, pp 37-48; doi:10.4236/sar.2017.54004
The aim of this scientific research was to study the influence of various diets (ketogenic, low carb, mixed) on teeth and saliva structure of healthy individuals. The health condition of teeth and the influence of diet (sweets, water intake) were investigated using the questionnaires which were statistically processed by descriptive and inductive statistics. Saliva was examined using synchronous fluorescent fingerprint (SFF) and atomic force microscopy (AFM). The statistical evaluation of answers of respondents using the questionnaires about intake of sweets in their diet showed significant influence of sugars on formation of tooth decay of diet. The intake of water (volume and frequency) did not show significant influence on formation of tooth decay. Endogenous fluorescence and surface structure of saliva differed in healthy subjects with different diet. The most organized surface structure showed low carb diet (without crystals). The least organized surface structure showed ketogenic diet with the big crystals (1 - 2 μm). Untraditional methods (SFF and AFM) enable the new, sensitive and quick analysis of the mixture of saliva. Saliva of individuals with low carb diet showed the most organized structure. Low content of sugar in diet is important possibility of the prevention before dental carries.
Spectral Analysis Review, Volume 05, pp 25-36; doi:10.4236/sar.2017.53003
Near infrared spectroscopy offers advantages in the analysis of vegetable oils such as rapidity, relative cost-effectiveness, and usually no need for sample preparation. Virgin Sunflower oils were used as reference standards to develop spectra library for qualitative identification and validation of the method. This model was validated by correct classification method using positive and negative control samples. Various market samples of virgin sunflower oil were purchased and compared with spectra library. The results of spectral analysis of reference library and market samples were correlated using Mahalanobis distance method. Analysis involved 22 market samples. When these samples were matched against calibration samples, 4 samples out of 22 which are about 18.2% were not matched by the reference model. These market samples had Mahalanobis distance values between 4.2 and 6.7, which are greater than maximum permissible value of 3. Some of adulterants mentioned were Korie oil and pumpkin seeds oil.
Spectral Analysis Review, Volume 05, pp 49-80; doi:10.4236/sar.2017.54005
In this work numerical codes carried out in a multiconfiguration Har-tree-Fock relativistic (HFR) approach for the P IV ion are used to obtain the oscillator strengths of each transition as well as the lifetimes of each energy level. With the existing data from several authors that contributed to the spectrum using different light sources, and optimizing the electrostatic parameters by a least-squares procedure when replacing the theoretical values by the experimental ones in the energy matrices, one obtains closer values and according to the observations for the intensities, and also of the lifetimes closer to those that would be obtained experimentally.
Spectral Analysis Review, Volume 05, pp 11-24; doi:10.4236/sar.2017.52002
Spectral Analysis Review, Volume 05, pp 1-10; doi:10.4236/sar.2017.51001
Streptomyces sp. ZZ035 isolated from a folk medicinal soil sample in China showed remarkable antimicrobial activities. During the isolation of secondary metabolites, a white crystal powder (1) was isolated from the broth of this strain. Its nuclear magnetic resonance (NMR) and infrared (IR) spectra indicated that it was a complex composed of triglycerides. Next, six C15-17 long- chain fatty acids derived from these triglycerides were respectively identified as n-pentadecanoyl, 12-methyltetradecanoyl, 14-methyl pentadecanoyl, palmitoyl, 15-methyl hexadecanoyl and 14-methyl hexadecanoyl using the gas chromatography-mass spectroscopy (GC-MS) technology. Finally, the 13C and 1H assignments of 1 were achieved through the analyses of NMR data. Based on above, their detailed NMR spectroscopic elucidation and meticulous 13C, 1H assignments, especially the split peaks and coupling correlation of protons attached on the glycerol carbons, were performed for distinguishing triglycerides from other glycerides and for the identification of the long-chain fatty acids, and which would be helpful to the qualitative and quantitative analyses of tri-, di-and mono-glycerides.
Spectral Analysis Review, Volume 04, pp 23-40; doi:10.4236/sar.2016.43003
We performed systematic laser spectroscopic investigations of La I spectral lines, using optogalvanic detection. Sixteen previously unknown even parity levels, having energies between 40,300 and 44,300 cm-1, are reported. These levels classify altogether 67 lines, not listed in spectral tables. The new levels were found due to the observation of the depopulation of the lower levels of the excited transitions. We found a remarkable variation of the observed widths of single hyperfine structure components dependent on the energy of the upper excited levels. Some levels having energies higher than 43,000 cm-1 appear to have a very high ionization probability.