[Detection and analysis of several kinds of oils with Raman spectrum].

Applying Raman spectrometry to detect several kinds of oils such as petrol, diesel oil, naphtha and KHF (aviation fuel hydro treating), the authors can explore the regular laws existing among these oils. The authors detected 150 cases of oils using Raman spectrometer developed by ourselves with 785 nm excitation wavelength miniature portable, and dealed with these spectra-paragraphs of the oils on level and SNV (normalization method) methods. The spectrograms of four categories of oils including petrol, diesel oil, naphtha and KHF and also the additives of them have different characteristics and rules. According to the alkenes peak's location and intensity we can distinguish petrol and naphtha, and then screen out some unqualified petrol. Raman spectrometry is very simple and has advantages that it needs a small amount of oil samples, at the same time, it also has no damage to test samples. The spectra-paragraphs show that different kinds of samples have different character on location and intensity of Raman peak. The Raman spectrometry method has great potential on establishing a rapid oil screening detection and identification method.

[Quality analysis of olive oil and quantification detection of adulteration in olive oil by near-infrared spectrometry and chemometrics].

Discriminant analysis was used to classify 20 olive oil samples based on their near-infrared (NIR) spectra. The samples were successfully classified into two categories which are consistent with extra virgin olive oil and ordinary olive oil defined in the products. The NIR spectra of olive-oil mixtures containing colza oil, corn oil, peanut oil, camellia oil, sunflower oil, and poppy seed oil were collected, respectively. The volume percent of adulterants ranged from 0 to 100%. The best spectrum bands for analysis were selected before developing partial least-squares (PLS) calibration models. The relative errors of prediction ranged from -5.67% to 5.61%. Results showed that the method combined with chemometrics methods and near-infrared spectrometry is simple, fast and credible for qualitative and quantitative analyses of olive oil samples.

Rapid authentication of olive oil adulteration by Raman spectrometry.

The authentication of olive oil and its adulteration with lower priced oils are still serious problems in the olive oil industry. In this study, a method based on the intensity ratio of the Raman spectroscopy vibration bands, especially on the intensity ratio of the cis ( ==C-H) and cis (C=C) bonds normalized by the band at 1441 cm(-1) (CH(2)), was established to authenticate genuine/fake olive oil. These intensity ratios of the vibration bands given in the form of a two-dimensional chart allow first the discrimination between the various grades of olive oil and the seed oils and then the detection of olive oil fraud by the line of y = 0.7, which is observed under most experiments and dot charts. This method can reliably distinguish the genuine olive oils from the olive oils containing 5% (volume percentage) or more of other edible oils, such as soybean oil, rapeseed oil, sunflower seed oil, or corn oil. Compared to the traditional principal component analysis method, this method is more intuitive, more precise, and easier to use. Moreover, this method also has the advantages of simplicity efficiency and has no need for sample preprocessing, being especially suitable for on-site testing in field applications.