Classification of methamphetamine seized in different regions of Iran using GC–MS and chemometrics

According to the intensive physical and mental risk of methamphetamine (crystal) on human, it is important to focus on the prevention of distribution and decrease of the usage of methamphetamine. In the current study, attempts was on the application of GC–MS analysis combined with chemometrics to present a classification model for methamphetamine samples seized in different regions of Iran. In this work, principal component analysis was not able to discriminate samples from different geographic regions. For the discrimination goal, partial least squares discriminant analysis (PLS-DA) and extended canonical variate analysis (ECVA) were utilized and a classification model was constructed to differentiate methamphetamine samples seized in three regions of Iran, i.e., south, west and central. PLS-DA showed good performance in calibration step; however, ECVA indicated better prediction ability. The difference of the classified samples can be because of difference in the synthetic root used in each of three investigated regions. Class sensitivity and selectivity for all three regions were excellent in ECVA model with nonsignificant misclassifications. Cross-validation and external validation using a test set confirmed the obtained classification model. Statistical results indicated a regional production/distribution pattern in the country.     

Structural and thermal behavior of polystyrene thin films using ATR–FTIR–NanoDSC measurements

Most studies report a depression of the glass transition temperature in thin polymer films. To gain insight into this behavior, we have simultaneously investigated the structure of materials and their thermal behavior by developing an ATR–FTIR–nano-differential scanning calorimeter (nanoDSC) hybrid instrument consisting of a ZnSe ATR crystal upon which the sample and a DSC-on-a-chip rests. FTIR spectra showed property changes with film thickness; nanoDSC did not. The relative absorbance of an IR peak at 797 cm⁻¹ was found to correlate with aging time in thin films, suggesting that conformational structure of thin films is critical to their thermal behavior.     

Gamma radiolytic degradation of fluoranthene and monitoring of radiolytic products using GC–MS and HPLC

Removal of priority pollutant fluoranthene in methanol by gamma-irradiation under varied conditions has been optimized. The influence of applied dose and dose rate on the degradation of fluoranthene under nitrogen has been investigated. The preliminary radiolytic degradation efficiency has been monitored by spectrophotometry. HPLC and GC–MS have been used to study the nature of degradation pattern. It is found that four main degradation products are formed and detected by HPLC. Different reversed phase columns have been used for the separation of degraded products under optimum chromatographic conditions. For 2 kGy dose ⩾80% fluoranthene has been degraded at dose rate 200 Gy/h. However, a dose of 370 Gy/h was more effective and it produces for less degradation products. Radiolytic degraded fluoranthene was also analyzed to detect various degradation products using GC–MS. It was proposed that major products were hydrocarbons and methoxy group containing organic compounds after comparing their mass spectra with the installed NIST mass spectral library.     

Rapid and Efficient Synthesis of Diaryl Carbazones using Microwave Technology

Diaryl carbazone is an important organic analytical reagent normally prepared by the oxidation of diaryl carbazine, but in literatures’ methods, the yields were low and the procedures were trouble1,2. Recently, our laboratory reported some new methods for the preparation of diaryl carbazone from diaryl carbazine3,4. Generally, these methods have drawbacks such as tedious operation3, using large amounts of volatile and poisonous solvent which will pollute the environment inevitably3, long reac…     

Evaluation of the application of attenuated total reflectance–Fourier transform infrared spectrometry (ATR–FTIR) and chemometrics to the determination of nutritional parameters of yogurt samples

A critical evaluation of the application of attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR) and partial least squares (PLS) to the determination of several nutritional parameters, such as the energetic value and the carbohydrate, protein and calcium contents, in commercially available yogurt samples was carried out. To this end, a highly heterogeneous population of 48 samples covering a wide range of yogurts obtained from the Spanish market was used. After correcting the spectra, hierarchical cluster analysis was performed in order to select a representative calibration set and the corresponding validation sample set. Different PLS models and several spectral windows were tested in order to evaluate their prediction capabilities for the validation set. For all nutritional parameters, with the exception of fat content, the procedure developed here provided good precision; the values obtained complied with the statutory values declared by the US FDA.     

Determination of captopril in pharmaceutical preparation and biological fluids using two- and three-way chemometrics methods

Spectrophotometric method has been developed for the direct quantitative determination of captopril in pharmaceuticalpreparation and biological fluids(human plasma and urine)samples.The method was accomplished based on parallel factoranalysis(PARAFAC)and partial least squares(PLS).The study was carried out in the pH range from 2.0 to 12.8 and with aconcentration from 0.70 to 61.50 μg mL~(-1)of captopril.Multivariate calibration models such as PLS at various pH and PARAFACwere elaborated from ultraviolet spectra deconvolution and captopril determination.The best models for this system were obtainedwith PARAFAC and PLS at pH 2.0.The applications of the method for determination of real samples were evaluated by analysis ofcaptopril in pharmaceutical preparations and biological fluids with satisfactory results.The accuracy of the method,evaluatedthrough the RMSEP,was 0.5801 for captopril with best calibration curve by PARAFAC and 0.6168 for captopril with PLS at pH 2.0model.     

SPMMTE and Q-TOF–UPLC–MS for monitoring of atenolol and atorvastatin in human plasma using pentafluoro phenyl column

Iron nanocomposite adsorbent was prepared by green technology with 90% yield. The prepared iron nanocomposite adsorbent was used in solid-phase micromembrane tip extraction (SPMMTE) sample preparation technique. Analysis of atenolol and atorvastatin was performed in human plasma using SPMMTE and Q-TOF–UPLC–MS methods. New generation Acquity UPLC HSS penta fluoro phenyl (2.1?×?75?mm²; 1.8?µm) column was used with acetonitrile–0.1% formic acid in water (50:50 v/v) as mobile phase. The flow rate was 0.2?mL?min^?1 with electrospray mass detection. The limits of detection were 0.2 and 0.4?ng active mass for atenolol and atorvastatin, while the limits of quantification were 1.0 and 2.0?ng active mass, respectively. The values of the retention times were 3.224 and 3.907 for atorvastatin and atenolol. The values of the separation and resolution factors were 1.31 and 1.71, respectively. The peaks were sharp with base lined separation within 4.2?min. The developed SPMMTE and Q-TOF–UPLC–MS methods were reproducible, fast, precise, robust, rugged, and economic for the analyses of atenolol and atorvastatin in human plasma. The reported methods can be applied for monitoring of the reported drugs at trace level.     

Rapid solidification of cryolite and cryolite–alumina melts

Abstract  

Rapid solidification processing (with a cooling rate in the interval 10⁵–10⁶ K s⁻¹) was used to prepare deeply undercooled cryolite–alumina melts. These samples were analyzed by XRD, infrared, and Raman spectroscopy. Besides cryolite, the amorphous phase and a low amount of ι-Al₂O₃ were detected. Annealing of the quenched sample revealed the transformation of metastable amorphous phases into different products depending on the annealing conditions. The results obtained showed that all of the elements (Na, Al, O, and F) are probably present in the amorphous parts of the quenched samples.     

Experimental study of the influence of solvent and asphaltenes on liquid–solid phase behavior of paraffinic model systems by using DSC and FT-IR techniques

This experimental work presents the results of a study about the liquid–solid phase behavior of high molecular weight n-paraffins (C₂₄–C₂₈ mixture and C₃₆ pure) in aliphatic (n-decane and squalane) and aromatic (xylene and 1-phenyl dodecane) solvents. The effect of asphaltenes of different chemical nature over the liquid–solid behavior of heavy n-paraffins is also studied. Differential Scanning Calorimetry (DSC) was used to obtain the phase transitions onsets and enthalpies as well as the wax solubility curves. Crystallinity was studied by using both DSC and Infrared Spectroscopy (FT-IR) techniques. The results obtained and presented in this study showed that both, solvent and asphaltenes as well as their chemical nature have a significant effect on paraffin crystallization process.     

FT-IR spectroscopic imaging microscopy of wheat kernels using a Mercury–Cadmium–Telluride focal-plane array detector

A 64×64 Mercury–Cadmium–Telluride (MCT) focal-plane array detector attached to a Fourier transform infrared (FT-IR) microscope was used to spectroscopically image 8-μm-thick cross-sections of wheat kernels in the fingerprint region of the infrared spectrum. After fast-Fourier transformation of the raw image interferograms, the data can be displayed as either a series of spectroscopic images collected at individual wavelengths, or as a collection of IR spectra obtained at each pixel position in the image. Image contrast is achieved due to the intrinsic chemical nature of the sample at each pixel location in the image. Individual cell layers near the outer portion of the wheat kernel, as well as the primary root within the germ, can be clearly differentiated in the IR images as a result of this enhanced chemical contrast.     

Solvent‐Free Rapid Deprotection of Ketone and Aldehyde Oximes using Periodic Acid

Abstract

Ketone and aldehyde oximes can be readily converted to the corresponding carbonyl compounds in high yields under solvent‐free conditions when treated with periodic acid. Oximes bearing aliphatic C?C bonds can be selectively deoximated. The advantages of this protocol include a rapid reaction rate and a simple workup procedure. No volatile organic solvents are required in the reaction processes.     

Rapid and sensitive determination of biphenyl and biphenyl oxide in water samples using dispersive liquid–liquid microextraction followed by gas chromatography

A rapid and sensitive method has been developed for the determination of biphenyl and biphenyl oxide in water samples using dispersive liquid–liquid microextraction followed by gas chromatography. This method involves the use of an appropriate mixture of extraction solvent (8.0?µL tetrachloroethylene) and disperser solvent (1.0?mL acetonitrile) for the formation of cloudy solution in 5.0?mL aqueous sample containing biphenyl and biphenyl oxide. After extraction, phase separation was performed by centrifugation and biphenyl and biphenyl oxide in sedimented phase (5.0?±?0.3?µL) were determined by gas chromatography-flame ionisation (GC-FID) system. Type of extraction and disperser solvents and their volumes, salt effect on the extraction recovery of biphenyl and biphenyl oxide from aqueous solution have been investigated. Under the optimum conditions and without salt addition, the enrichment factors for biphenyl and biphenyl oxide were 819 and 785, while the extraction recovery were 81.9% and 78.5%, respectively. The linear range was (0.125–100?µg L^?1) and limit of detection was (0.015?µg?L^?1) for both analytes. The relative standard deviation (RSD, n?=?4) for 5.0?µg?L^?1 of analytes were 8.4% and 6.7% for biphenyl and biphenyl oxide, respectively. The relative recoveries of biphenyl and biphenyl oxide from sea, river water and refined water (Paksan company) samples at spiking level of 5.0?µg?L^?1 were between 85.0% and 100 %.     

Multi-mycotoxin analysis of animal feed and animal-derived food using LC–MS/MS system with timed and highly selective reaction monitoring

Mycotoxins have the potential to enter the human food chain through carry-over of contaminants from feed into animal-derived products. The objective of the study was to develop a reliable and sensitive method for the analysis of 30 mycotoxins in animal feed and animal-derived food (meat, edible animal tissues, and milk) using liquid chromatography–tandem mass spectrometry (LC–MS/MS). In the study, three extraction procedures, as well as various cleanup procedures, were evaluated to select the most suitable sample preparation procedure for different sample matrices. In addition, timed and highly selective reaction monitoring on LC–MS/MS was used to filter out isobaric matrix interferences. The performance characteristics (linearity, sensitivity, recovery, precision, and specificity) of the method were determined according to Commission Decision 2002/657/EC and 401/2006/EC. The established method was successfully applied to screening of mycotoxins in animal feed and animal-derived food. The results indicated that mycotoxin contamination in feed directly influenced the presence of mycotoxin in animal-derived food.

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Graphical abstract Multi-mycotoxin analysis of animal feed and animal-derived food using LC-MS/MS

     

Rapid determination of inorganic elements in airborne particulate matter by using acidified subcritical-water extraction and inductively-coupled plasma–optical-emission spectrometry

A rapid and simple method has been developed for determination of inorganic elements in airborne particulate matter (PM10) by using acidified subcritical water and ICP–OES. Elements such as Al, As, B, Ba, Cd, Cu, Fe, Mn, Pb, Se, and Zn were rapidly and efficiently extracted from PM10 samples with a solution of 0.1 mol L^–1 HNO₃ under subcritical conditions. The method requires approximately 5% of the amount of acid used in the standard microwave extraction procedure. The material selected for the subcritical extraction manifold was poly ether ether ketone (PEEK), to avoid sample contamination with elements present in previously reported stainless-steel manifolds. The extraction temperature, time of static and dynamic extraction, and flow rate of acidified water were studied keeping the pressure controlled at about 1,500 psig. The efficiency of extraction of most of the analytes increased with temperature, tending to quantitative extraction at temperatures near 150°C. After the extraction process the analytes were determined directly in the extract by ICP–OES. When the method was compared with the USEPA counterpart, the results indicate that under optimized conditions (static extraction time: 15 min, dynamic extraction time: 30 min, flow rate: 2 mL min^–1) the analytes were extracted with recoveries between 73 and 158%. Alternatively, by using an extraction time of 15 min, the method could be used to screen for all the elements, with recoveries over 50%. The developed method was applied to the determination of inorganic elements in airborne particulate matter in the atmosphere of Santiago, Chile.     

Rapid and Catalyst‐Free α‐Halogenation of Ketones using N‐Halosuccinamides in DMSO

α‐Halogenation of various carbonyl compounds such as β‐keto‐esters, cyclic ketones, and lactams with N‐halosuccinamides (NBS, NCS, NIS) in the presence of DMSO proceeded very smoothly to give the corresponding α‐monohalogenated products in good to excellent yields with high selectivity under catalyst‐free conditions.     

Rapid LC–TOFMS Separation and Identification of Diarylheptanoids and Gingerol-Related Compounds in Dried Ginger

A tandem liquid chromatographic–time-of-flight mass spectrometric (LC–TOFMS) method has been developed for rapid separation and identification of diarylheptanoids and gingerol-related compounds in aqueous extracts of dried ginger. Total-ion-current chromatograms and mass spectra were acquired. A formula database of known compounds was established, against which components of dried ginger could be rapidly identified by matching their exact masses with theoretical masses of compounds calculated from their empirical formulae. Identification of 20 compounds was accomplished with error of 4 ppm, and further confirmation of elemental composition was obtained from the abundance of the isotope peaks. LC–TOFMS has been shown to be a useful tool for rapid identification of compounds in aqueous extracts of dried ginger.     

Rapid synthesis of highly functionalised α-amino amides and medium ring lactones using multicomponent reactions of amino alcohols and isocyanides

Four-component reactions between amino alcohols, aldehydes, isocyanides and thiols proceed rapidly under microwave or conventional heating at 60 °C in methanol. The reaction is successful with a wide range of components and gives access to potentially drug-like products containing amine, amide and thioether functionality in moderate to excellent yield. The reaction conditions are also applicable to the synthesis of a range of 8-10 membered medium ring lactones via three-component reactions of amino alcohols, isocyanides and acid-aldehydes. Incorporation of L-prolinol as the amino alcohol component in each case gives access to multicomponent products with moderate to high diastereoselectivity.     

Label-free monitoring of the thrombin–aptamer recognition reaction using an array of nanochannels coupled with electrochemical detection

A sensitive and label-free method of monitoring the thrombin–aptamer recognition reaction has been developed using an array of nanochannels coupled with an electrochemical detection technique. Due to the highly amplified ion current produced by an array of nanochannels compared to a single nanochannel/pore, a significant increase in detection sensitivity has been achieved.