Use of ATR-FTIR spectroscopy coupled with chemometrics for the authentication of avocado oil in ternary mixtures with sunflower and soybean oils.

Avocado oil is a high-value and nutraceutical oil whose authentication is very important since the addition of low-cost oils could lower its beneficial properties. Mid-FTIR spectroscopy combined with chemometrics was used to detect and quantify adulteration of avocado oil with sunflower and soybean oils in a ternary mixture. Thirty-seven laboratory-prepared adulterated samples and 20 pure avocado oil samples were evaluated. The adulterated oil amount ranged from 2% to 50% (w/w) in avocado oil. A soft independent modelling class analogy (SIMCA) model was developed to discriminate between pure and adulterated samples. The model showed recognition and rejection rate of 100% and proper classification in external validation. A partial least square (PLS) algorithm was used to estimate the percentage of adulteration. The PLS model showed values of R(2) > 0.9961, standard errors of calibration (SEC) in the range of 0.3963-0.7881, standard errors of prediction (SEP estimated) between 0.6483 and 0.9707, and good prediction performances in external validation. The results showed that mid-FTIR spectroscopy could be an accurate and reliable technique for qualitative and quantitative analysis of avocado oil in ternary mixtures.

Automated acid and base number determination of mineral-based lubricants by fourier transform infrared spectroscopy: commercial laboratory evaluation.

The Fluid Life Corporation assessed and implemented Fourier transform infrared spectroscopy (FTIR)-based methods using American Society for Testing and Materials (ASTM)-like stoichiometric reactions for determination of acid and base number for in-service mineral-based oils. The basic protocols, quality control procedures, calibration, validation, and performance of these new quantitative methods are assessed. ASTM correspondence is attained using a mixed-mode calibration, using primary reference standards to anchor the calibration, supplemented by representative sample lubricants analyzed by ASTM procedures. A partial least squares calibration is devised by combining primary acid/base reference standards and representative samples, focusing on the main spectral stoichiometric response with chemometrics assisting in accounting for matrix variability. FTIR(AN/BN) methodology is precise, accurate, and free of most interference that affects ASTM D664 and D4739 results. Extensive side-by-side operational runs produced normally distributed differences with mean differences close to zero and standard deviations of 0.18 and 0.26 mg KOH/g, respectively. Statistically, the FTIR methods are a direct match to the ASTM methods, with superior performance in terms of analytical throughput, preparation time, and solvent use. FTIR(AN/BN) analysis is a viable, significant advance for in-service lubricant analysis, providing an economic means of trending samples instead of tedious and expensive conventional ASTM(AN/BN) procedures.

[Direct identification of Ophiogon japonicus (Thunb.)Ker-Gawl. from its confusable varieties by second derivative FTIR spectroscopy combined with statistics].

In order to establish the theory and method for the identification of Ophiogon japonicus (Thunb.)Ker-Gawl. of traditional Chinese herbal medicines and its confusable varieties, second derivative FTIR spectroscopy was used combined with statistics. Samples were collected directly by Fourier Transform Infrared (FTIR) spectra with OMNI-Sampler. Then through converting FTIR spectra of the samples into second derivative spectra by derivative spectra software, Ophiogon japonicus (Thunb.)Ker-Gawl. could be identified from the confusable varieties with statistics. The result shows that the second derivative FTIR of Ophiogon japonicus (Thunb.)Ker-Gawl. and its confusable varieties are different, which differ greatly in 2 000-650 cm(-1) range in second derivative FTIR spectroscopy. The Ophiogon japonicus (Thunb.)Ker-Gawl. and its confusable varieties can be identified by identifying the inner layer parts of the cuticles of samples by second derivative FTIR spectroscopy with statistics directly, rapidly and accurately.