No abstract

The use of portable micro-spectrometers such as a micro near infrared region (microNIR) spectrometer is a promising technique for solving analytical problems in several areas of science. This work evaluated the potential of microNIR in quality control of Arabica coffee. Arabica coffee has a high commercial value product, motivating the development of analytical methods with high sensitivity and accuracy for detection of its adulteration. Herein, microNIR was successfully used to determine the quality of Arabica coffee by identification and quantification of adulterations such as Robusta coffee (in different roasting levels), as well as corn, peels, and sticks. MicroNIR was combined with multivariate calibration by partial least squares (PLS) and principal component analysis (PCA). A total of 125 blends were produced, containing thirteen different concentrations of the adulterants (corn and peels/sticks, and the Robusta coffee) ranging from 1 to 100wt%. Developed PCA and PLS models were also applied to monitor the quality of sixteen commercial coffee samples. The results obtained using microNIR proved the ability of the method to be efficient and capable in the prediction of adulterations with minimum quantification levels (LOQs of 5-8wt%), being able to be applied to quality control of commercial coffee samples. Therefore, microNIR can reduce and simplify the time of analysis and sample preparation step, as well as to guarantee the efficiency of real-time data acquisition owing to its portability.

Paper spray ionization mass spectrometry (PS-MS) technique is a versatile and powerful tool to solve numerous problems in forensic chemistry.

Amaryllidaceae alkaloids are well-known isoquinolines which have demonstrated a wide range of biological activities such as antiviral, anticancer, acetylcholinesterase inhibition, antimalarial, among others. Mass spectrometry (MS) studies based on capillary gas chromatography (CGC), paper spray (PS), and leaf spray (LS) ionization were carried out for alkaloid investigation of the native Brazilian species Hippeastrum aulicum, along with nuclear magnetic resonance (NMR) techniques. Thirty-one alkaloids were identified including the new compound haemanthamine N-oxide. The results from PS-and LS-MS techniques were consistent with those observed in CGC-MS analysis. To the best of our knowledge, it is the first study combining NMR, CGC-MS and the ambient ionization-mass spectrometry (PS-and LS-MS) on Amaryllidaceae plants.

The influence of temperature (110 and 120 °C) on the ageing of piping made from polyamide 11 (PA‐11) containing 10–12% of plasticizer was studied using deionized water (pH ≈ 7.0). A clean analytical methodology has been employed for quality control of polymeric materials: energy‐dispersive X‐ray fluorescence spectrometry (ED‐XRF). It provides a fast and suitable technique to characterize chemical elements because of its multielemental capability, good sensitivity, high precision, short analytical time, and nondestructive nature. Herein, the content of additive in PA‐11 was monitored from ED‐XRF measurements where the abundance of the S line is directly related to the ageing time, agreeing with the thermogravimetric analysis. The XRF data were allied to chemometric treatment to classify PA‐11 samples according to the amount of additive and weight average molar mass change, predicting the ageing time, and viscosity values of PA‐11. Therefore, the XRF can be used as a clean analytical methodology to monitor the PA‐11 degradation, thus eliminating the use of toxic organic solvents (necessary to viscosity measurements) and reducing the working time. Also, the effect of hydrolysis on the structure over time and the material morphology were monitored through measurements of dynamic mechanical analysis and differential scanning calorimetry. Copyright © 2012 John Wiley & Sons, Ltd.

Paper Spray Ionization and Leaf Spray were compared by detection and quantification of agrochemicals.

Fuel quality control has gained interest in many countries owing to the potential damage of low-quality fuel to engines, the environment, and economy. Thus, the application of analytical techniques to verify quality control of fuels has become crucial. The portable micro-spectrometer in the near infrared region (microNIR) has gained credibility as a successful analytical technique in several quality control sectors. The possibility of real-time analysis using a nondestructive and reliable method is the main advantage of this methodology. In this work, chemometric models (PLS) were developed using microNIR data to determine the amount of biodiesel in diesel (LOD = 0.5wt%; LOQ = 1.8wt%; and RMSEP = 1.8wt%); sulfur in diesel (LOD = 2.4mgL; LOQ = 8.0mgL; and RMSEP = 13.2mgL); gasoline, ethanol, and methanol in C-type gasoline (LOD = 0.55wt%; LOQ = 1.84wt%; and RMSEP = 0.81wt%; LOD = 0.75wt%; LOQ = 2.5wt%; and RMSEP = 3.81wt%; and LOD = 0.85wt%; LOQ = 2.84wt%; and RMSEP = 1.80wt%); and water, methanol, and ethanol in ethanol-hydrated fuel (EHF) (LOD = 0.04wt%; LOQ = 1.29wt%; and RMSEP = 1.05wt%; LOD = 0.52wt%; LOQ = 1.73wt%; and RMSEP = 2.78wt%; and LOD = 1.22wt%; LOQ = 4.07wt%; and RMSEP = 4.41wt%). A total of 181 blends were prepared, with biodiesel and sulfur contents ranging from 0 to 100wt% and 10-500mgL, respectively. For gasoline blends, the gasoline, ethanol, and methanol contents ranged from 0.0 to 75.0wt%, 25.0-75.0wt%, and 0.0-50.0wt%, respectively. In the EHF control, the ethanol, water, and methanol contents ranged from 0.0 to 100.0wt%, 0.0-50.0wt%, and 0.0-50.0wt%, respectively. The proposed method presented high precision and accuracy in all cases, and the results showed that the microNIR technique had excellent performance in fuel quality control.

Near infrared (NIR) spectroscopy using a portable instrument (microNIR) associated with chemometrics models analysis was applied to quantify cocaine, and to classify synthetic drugs by their functional chemical composition.