Dry Extraction System Research Articles

Detection of Profenofos in Chinese Kale, Cabbage, and Chili Spur Pepper Using Fourier Transform Near-Infrared and Fourier Transform Mid-Infrared Spectroscopies.

Different types of quantitative technology based on infrared spectroscopy to detect profenofos were compared based on Fourier transform near-infrared (FT-NIR; 12,500–4000 cm–1) and Fourier transform mid-infrared (FT-MIR; 4000–400 cm–1) spectroscopies. Standard solutions in the range of 0.1–100 mg/L combined with the dry-extract system for infrared (DESIR) technique were analyzed. Based on partial least-squares regression (PLSR) to develop a calibration equation, FT-NIR–PLSR produced the best prediction of profenofos residues based on the values for R2 (0.87), standard error of prediction or SEP (11.68 mg/L), root-mean-square error of prediction or RMSEP (11.50 mg/L), bias (−0.81 mg/L), and ratio performance to deviation or RPD (2.81). In addition, FT-MIR–PLSR produced the best prediction of profenofos residues based on the values for R2 (0.83), SEP (13.10 mg/L), RMSEP (13.00 mg/L), bias (1.46 mg/L), and RPD (2.49). Based on the ease of use and appropriate sample preparation, FT-NIR–PLSR combined with DESIR was chosen to detect profenofos in Chinese kale, cabbage, and chili spur pepper at concentrations of 0.53–106.28 mg/kg. The quick, easy, cheap, effective, rugged, and safe technique coupled with gas chromatography–mass spectrometry was used to obtain the actual values. The best FT-NIR–PLSR equation provided good profenofos detection in all vegetables based on values for R2 (0.88–0.97), SEP (5.27–11.07 mg/kg), RMSEP (5.25–11.00 mg/kg), bias (−1.39 to 1.30 mg/kg), and RPD (2.91–5.22). These statistics revealed no significant differences between the FT-NIR predicted values and actual values at a confidence interval of 95%, with agreeable results presented at pesticide residue levels over 30 mg/kg. FT-NIR spectroscopy combined with DESIR and PLSR should be considered as a promising screening method for pesticide detection in vegetables.

Preliminary Study on the Determination of ppm-Level Concentration of Histamine in Tuna Fish Using a Dry Extract System for Infrared Coupled with Near-Infrared Spectroscopy.

Rapid and simple methods to determine histamine in tuna fish have been examined. A dry extract system for infrared (DESIR) was coupled with near-infrared spectroscopy in order to obtain the absorption of histamine in tuna fish at the ppm level. The result showed that the optimal extraction solvent for preparing DESIR samples was 75% methanol and boiling water (100 °C). Calibration equations were developed and tested by independent validation set samples. The calibration equation developed from boiling water as solvent extraction was slightly better than the equation developed from 75% methanol solvent with a coefficient of determination (R2) of 0.79, a standard error of calibration of 2.45 ppm, a standard error of prediction of 2.94 ppm, and a bias of 0.10 ppm. Furthermore, the predicted values from both equations were not significantly different from the reference values obtained from the standard method at the 95% confidence interval. Compared to the current AOAC fluorometric official method, the proposed technique simplified and reduced the preparation time.

Fat color and reflectance spectra to evaluate the β-carotene, lutein and α-tocopherol in the plasma of bovines finished on meadows or on a dry total mixed ration

An experiment was conducted to analyze the evolution of carotenoids and α-tocopherol during the fattening period of beef cattle that were fed with different diets to check the feasibility of using these compounds to trace grass-feeding in the visible and near-infrared spectra. A group of Parda de Montaña and a group of Pirenaica steers were finished on mountain meadows, and another group of Pirenaica steers was finished with a dry total mixed ration (50 alfalfa hay:10 straw:40 maize grain, as-such basis). Plasma samples were obtained throughout the fattening period to determine the β-carotene, lutein and α-tocopherol concentrations via high performance liquid chromatography (HPLC) and plasma visible-near infrared (VIS-NIR) spectra; the samples were collected using the dry-extract system for infrared (DESIR) method. Additionally, after slaughter, the carcass subcutaneous fat color was measured, and a spectrophotometric estimation of the carotenoid content was calculated. Feeding systems had a great effect on the plasma concentrations of β-carotene, lutein and α-tocopherol, which increased sharply when the animals were grazing. In the same way, when the animals were switched over to the dry total mixed ration, their concentrations sharply decreased to quite low concentrations. Both the VIS-NIR spectra of the plasma and the subcutaneous fat color are useful in discriminating steers fed with finishing diets, but neither method is not suitable for discriminating between the Pirenaica and Parda de Montaña breeds. The calibrations that were developed to estimate the lutein and α-tocopherol concentrations could be classified as poor. The calibration used to estimate the β-carotene plasma concentration was useful for analytic purposes, but it should still be improved. The DESIR method can be interesting to monitor the plasma concentrations of carotenoids and tocopherol in live animals, whereas the measurement of the subcutaneous fat color of the carcass is a simple and fast method for discriminating, post-mortem, animals that were fed diets with different carotenoid contents.

Evaluation of a Dry Extract System Involving NIR Spectroscopy (DESIR) for Rapid Assessment of Pesticide Contamination of Fruit Surfaces

The dry-extract system for (near) infrared (DESIR) technique was implemented using reflectance near-infrared spec-troscopy in context of detection of contact pesticide residues on fruit. Based on chemical structure, spectra features and regression statistics for PLSR models, a product containing metiram and pyraclostrobin was chosen from six pesticides for further consideration. Regression models based on spectra of dry extracts of aqueous solutions and either acetone or water washes of contaminated fruit were encouraging (RMSECV of approximately 0.03 - 0.06 mg a.i.). This level of analytical performance would support the use of the technique as a rapid screening tool, with suspect samples then subject to the reference GC-MS analysis method. However, the PLSR model performance was poor across populations of fruit, suggesting that matrix changes in the solvent wash between sets of fruit is problematic. Further work is required to establish whether sufficient variation can be built into a calibration set to overcome this issue, without degrading model performance to the point where it loses practical application.

Simultaneous stable isotope analysis of methane and nitrous oxide on ice core samples

Abstract. Methane and nitrous oxide are important greenhouse gases which show a strong increase in atmospheric mixing ratios since pre-industrial time as well as large variations during past climate changes. The understanding of their biogeochemical cycles can be improved using stable isotope analysis. However, high-precision isotope measurements on air trapped in ice cores are challenging because of the high susceptibility to contamination and fractionation. Here, we present a dry extraction system for combined CH4 and N2O stable isotope analysis from ice core air, using an ice grating device. The system allows simultaneous analysis of δD(CH4) or δ13C(CH4), together with δ15N(N2O), δ18O(N2O) and δ15N(NO+ fragment) on a single ice core sample, using two isotope mass spectrometry systems. The optimum quantity of ice for analysis is about 600 g with typical "Holocene" mixing ratios for CH4 and N2O. In this case, the reproducibility (1σ ) is 2.1‰ for δD(CH4), 0.18‰ for δ13C(CH4), 0.51‰ for δ15N(N2O), 0.69‰ for δ18O(N2O) and 1.12‰ for δ15N(NO+ fragment). For smaller amounts of ice the standard deviation increases, particularly for N2O isotopologues. For both gases, small-scale intercalibrations using air and/or ice samples have been carried out in collaboration with other institutes that are currently involved in isotope measurements of ice core air. Significant differences are shown between the calibration scales, but those offsets are consistent and can therefore be corrected for.

A Method for Determining Organophosphorus Pesticide Concentration Based on Near-Infrared Spectroscopy

The traditional methods for determining pesticide concentrations are time-consuming, complicated, and require extensive pretreatment processes. In this study, near-infrared (NIR) spectroscopy was used to determine trace chemicals. The dry-extract system for infrared (DESIR) technique was used to prepare samples. Filter paper was used as the substrate. Pesticide solutions were prepared by dissolving a commercial pesticide in distilled water at different concentrations (1.25 to 400 mg kg-1). Samples were prepared by pipetting the solution onto the filter paper and then evaporating it in a vacuum drying oven. Spectral curves of the samples were acquired in the range of 10000 to 4000 cm-1 using an NIR spectrometer. Partial least squares regression (PLSR) was used to establish prediction models. The best prediction result was obtained using PLSR with multiplicative scatter correction (MSC) and first derivation as the pretreatment procedure. The process was able to predict the concentrations of chlorpyrifos with R = 0.899. A support vector machine (SVM) was used to establish a classification model. The result showed that 89.286% of samples were correctly predicted when the sample set was divided into three classes of chlorpyrifos content (<100, 100 to 300, >300 mg kg-1).

Measurement of pesticide residues in peppers by near‐infrared reflectance spectroscopy

Peppers are a frequent object of food safety alerts in various member states of the European Union owing to the presence in some batches of unauthorised pesticide residues. This study assessed the viability of near-infrared reflectance spectroscopy (NIRS) for the measurement of pesticide residues in peppers. Commercially available spectrophotometers using different sample-presentation methods were evaluated for this purpose: a diode-array spectrometer for intact raw peppers and two scanning monochromators fitted with different sample-presentation accessories (transport and spinning modules) for crushed peppers and for dry extract system for infrared analysis (DESIR), respectively. Models developed using partial least squares-discriminant analysis (PLS2-DA) correctly classified between 62 and 68% of samples by presence/absence of pesticides, depending on the instrument used. At model validation, the highest percentage of correctly classified samples-75 and 82% for pesticide-free and pesticide-containing samples respectively-were obtained for intact peppers using the diode-array spectrometer. The results obtained confirmed that NIRS technology may be used to provide swift, non-destructive preliminary screening for pesticide residues; suspect samples may then be analysed by other confirmatory analytical methods.

Effect of Moisture Uptake on the Repeatability of near Infrared Spectroscopy Analyses of Ewe Milk Using the Dry Extract System for Infrared (DESIR) Method

This paper reports a study carried out to determine the effect of post-filter-drying moisture uptake on the repeatability of NIR spectroscopy analyses of ewe milk using the dry-extract system for infrared (DESIR). The study assessed the spectral repeatability of the method and the effect of moisture uptake on that repeatability, using graphical representations and root mean squared (RMS) error between spectra, as well as multivariate Mahalanobis distances (GH values) and predicted constituent values (protein, fat and dry matter). The spectral repeatability of this method of dried milk analysis using glass-fibre filters was very high, both spectrally per se [RMS MEAN = 3.914 μlog (1/R) and STD = 4.126 μlog (1/R)] and in terms of NIR spectroscopy prediction of chemical components and of the Mahalanobis distance. Using a single filter per milk sample is thus considered sufficient to guarantee the required accuracy and precision of the DESIR method. Differences between spectra due to the presence or absence of air exposure [STD = 6446 μlog (1/R)] were greater than the method repeatability error. Predictions of protein, fat and dry matter were significantly higher for air-exposed filters, due to moisture uptake; the increase in GH values for air-exposed filters was highly significant, suggesting that milk samples to be analysed using the DESIR method should be stored in a desiccator after drying and before NIR analysis and not left exposed to air.

The Reliability of Pesticide Determinations Using near Infrared Spectroscopy and the Dry-Extract System for Infrared (DESIR) Technique

In a previous article, a pesticide determination system using near infrared (NIR) spectroscopy and the dry-extract system for infrared (DESIR) technique had been developed. In order to evaluate system reliability, a number of tests had been conducted. To reduce time and labour needed for pesticide assays by gas chromatography, artificial solutions of each pesticide in acetone were used in place of sample extract that was used in the previous article. Effects of several factors, such as chemical structure, interference of another reagent in the solution and sample presentation, on the system accuracy were evaluated. A tentative collaborative study was conducted to evaluate the possibility of large scale utilisation. To test the influence of chemical structure, three pesticides— acephate, dichlofluanid and tetrachloro-isophthalonitrile (TPN)—having different numbers of functional groups with strong dipole moment were used. From the range of 0 ppm to 50 ppm active ingredient in acetone, the SEPs obtained were 2.1, 5.3 and 9.3 ppm for acephate, dichlofluanid and TPN, respectively. These results corresponded to the number of strong dipole moment groups in the chemical structure which were four for acephate, two for dichlofluanid and none for TPN. In the case where two kinds of pesticide were presented in the system, the SEP became larger compared to the single pesticide results. The degree of interference differed depending on the relative absorptivity between the target pesticide and the interference. Using the system developed and acephate solution, a tentative collaborative study was conducted using three laboratories and four technicians. The almost similar SEPs of 2.8, 2.8, 3.0 and 2.5 ppm were obtained by the four technicians, indicating that even if the NIR instruments used and the degree of professional skill differed between technicians, satisfactory results could be obtained after a few hours of training and a proper bias correction. Finally, to simplify the system, three kinds of sample presentation were used to develop a calibration equation for acephate. The SEPs obtained differed only minutely. It could be concluded that when using NIR analysis the operator may choose between the highly precise system which requires more time and labour because of the sample preparation involved or a slightly less precise system with simple sample presentation. Based on the Japanese pesticide control level, the developed system could be used for the monitoring of some pesticides in fruits and vegetables.

Rapid Determination of Fungicide Contaminated on Tomato Surfaces Using the DESIR-NIR: A System for ppm-order Concentration

A system for rapid fungicide determination using near infrared spectroscopy was developed using the dry-extract system for infrared (DESIR) technique. Glass microfibre filter paper was used as the substrate. Fungicide solutions were prepared by dissolving the commercial dichlofluanid-carrying fungicide, Euparen, into acetone at concentrations of 2 ppm to 90 ppm of the active ingredient. Some techniques for adding the fungicide solutions onto the filter paper were examined. It was found that by adding 2 mL of the fungicide solution to the filter paper held in an identical size Petri dish made of polysyrene, a sufficiently accurate calibration result with SEP of 6.58 ppm could be obtained. In the following step, the technique was applied to the determination of fungicide on tomato surfaces. The fungicide was extracted from the fruit by washing with acetone. Then, the acetone solution was used for the DESIR embedding instead of the fungicide solution in the first experiment. A satisfactory result, with an SEP of 7.89 ppm for the washed solution that was equivalent to approximately 1.58 ppm per gram fruit weight, could be obtained.

Increase in the atmospheric nitrous oxide concentration during the last 250 years

In order to estimate the concentrations of atmospheric nitrous oxide (N2O) during the last 250 years, air samples were extracted from an Antarctic ice core, H15, using a dry extraction system and were then analyzed with a precision of ±2 ppbv. The results obtained were clearly less scattered and much tighter than those of the previous studies. Our data showed that the concentrations of atmospheric N2O in the 18th century were about 276 ppbv on average. It was also obvious that the N2O concentration began to increase in the mid‐19th century and reached approximately 293 ppbv around 1965, the trend of the concentration increase correlating quite well with the direct atmospheric measurements at the South Pole. Such an increase in the atmospheric N2O concentration is thought to be of anthropogenic origin.

Measurements of CO2 and CH4 concentrations in air in a polar ice core

AbstractDry and wet air-extraction systems and precise analysis systems of the CO2 and CH4 concentrations for a polar ice core were developed to reconstruct their ancient levels. A dry-extraction system was capable of crushing an ice sample of 1000 g into fine powder within 2 min, and its air-extraction efficiency was found to be 98%. The CO2 and CH4 concentrations of extracted air were determined using gas chromatography with a flame-ionized detector. The overall precision of our measurements, including air extraction, was estimated to be better than ± 1 ppmv for CO2 and + 10 ppbv for CH4. Preliminary analysis of the ice core drilled at Mizuho Station, Antarctica, showed that the CO2 and CH4 concentrations at 3340–3700 year BP were about 280 ppmv and 700ppbv, respectively. The Yamato core drilled at the terminus of the glacial flow near the Yamato Mountains, Antarctica, yielded concentrations of 230–240 ppmv for CO2 and 520–550 ppbv for CH4, suggesting that the core had formed during the glacial period.

Measurements of CO2 and CH4 concentrations in air in a polar ice core

AbstractDry and wet air-extraction systems and precise analysis systems of the CO2and CH4concentrations for a polar ice core were developed to reconstruct their ancient levels. A dry-extraction system was capable of crushing an ice sample of 1000 g into fine powder within 2 min, and its air-extraction efficiency was found to be 98%. The CO2and CH4concentrations of extracted air were determined using gas chromatography with a flame-ionized detector. The overall precision of our measurements, including air extraction, was estimated to be better than ± 1 ppmv for CO2and + 10 ppbv for CH4. Preliminary analysis of the ice core drilled at Mizuho Station, Antarctica, showed that the CO2and CH4concentrations at 3340–3700 year BP were about 280 ppmv and 700ppbv, respectively. The Yamato core drilled at the terminus of the glacial flow near the Yamato Mountains, Antarctica, yielded concentrations of 230–240 ppmv for CO2and 520–550 ppbv for CH4, suggesting that the core had formed during the glacial period.

A New Dry Extraction System for Gases in Ice

AbstractA new extraction system has been designed and constructed which allows the extraction of gases from air bubbles in ice without melting it. The ice sample of about 500 g is crushed an evacuated container by a milling cutter, and the gas escaping from the opened bubbles is collected by condensation at 15K. Results of CO2analyses of extracted gases are discussed with respect to possible contamination risks by the system.

A New Dry Extraction System for Gases in Ice

AbstractA new extraction system has been designed and constructed which allows the extraction of gases from air bubbles in ice without melting it. The ice sample of about 500 g is crushed an evacuated container by a milling cutter, and the gas escaping from the opened bubbles is collected by condensation at 15K. Results of CO2 analyses of extracted gases are discussed with respect to possible contamination risks by the system.