Specific Peak Area Research Articles

High-throughput assessment of soil carbonate minerals in urban environments

As urbanization expands, interest in understanding soil properties and functions in urban environments has also increased. Urban soils play an important role in the global carbon (C) cycle. Due to natural and human influences on various forms of C, quantifying soil inorganic carbon (SIC) becomes critical in urban areas. In this study, the suitability of diffuse reflectance mid-infrared Fourier-transform spectroscopy (mid-DRIFTS) to rapidly estimate calcite and dolomite concentrations was tested. Also, the effectiveness of HCl acid pre-treatment to remove carbonates to enable proper estimation of soil organic carbon (SOC) in urban soils was evaluated. Specific mid-infrared frequencies known to be associated with carbonates, i.e. dolomite and calcite, were identified, and specific peak areas were measured and calibrated with results obtained with the volumetric calcimeter method. Multiple linear regression was used to estimate total carbonates with peaks areas at 2930 cm−1, 2515 cm−1 and 730 cm−1 resulting in a 3.72% root mean squared error of an independent validation set (RMSEV). Greater prediction accuracy of calcite (875 cm−1) and dolomite (875 cm−1 and 730 cm−1) were achieved using single peaks in bivariate relationships resulting in RMSEV of 1.27% and 4.22%, respectively. Soil samples were treated with 1 M HCl for 24 h to remove carbonates, and total carbonate, dolomite, and calcite contents were estimated again using both volumetric calcimeter and mid-DRIFTS. The reduction in carbonate concentrations post-acid treatment was considerable (97% for dolomite, and 96% for calcite and total carbonates), but was not complete. Thus, this could compromise quantification of other soil carbon fractions such as total SOC. Using mid-DRIFTS peak areas of CO3−2 functional groups represents a robust alternative for rapid, fast, and low-cost laboratory measurements of soil carbonates, and this high-throughput approach may be used in assays aiming to minimize carbonate interference in SOC estimations.

Rapid screening of zeolite acidity by thermal response measurements using InfraSORP technology

Thermal response measurements using the recently developed InfraSORP technology are nowadays established as a versatile and rapid screening tool for the estimation of physicochemical properties of porous materials, such as adsorption capacity, surface area and porosity. In the present work, InfraSORP experiments are explored for fast screening of zeolite acidity especially for test samples available only in small quantity. Twelve MFI and beta type zeolite samples with varying molar Si/Al ratios were examined using ammonia as test gas (0.5% NH3 in nitrogen). Caused by the exothermic adsorption of ammonia on acidic sites of the zeolite samples, a characteristic temperature response curve (temperature vs. time) is observed. The specific peak area under the curve reflects the total NH3 amount adsorbed. In two consecutive adsorption/desorption runs the contributions of physisorbed and chemisorbed NH3 are distinguished. The difference between the first integral of the thermal response (caused by physisorption and chemisorption of NH3) and a second adsorption cycle (reflecting only weakly adsorbed NH3) correlates directly with the sample acidity determined by conventional temperature-programmed desorption of ammonia (TPD). Calibration of the signal versus established TPD techniques results in excellent correlation and renders the new technique as a promising high-throughput screening tool for zeolite acidity assessment in industrial process and product quality control requiring less than 30 min per sample.

Inter-comparative study of quantitative methods of industrial clinker

Impurities from the raw materials, the grinding and the homogenization of the raw materials, the kiln instability and the complexity of the cooling step, all these factors make it difficult to obtain a perfect evaluation of the mineralogical composition of Portland clinker. We studied the limitations of the most commonly used quantitative methods and recommend some procedures to obtain reliable and reproducible results of quantitative analyses. Different clinker samples (provided by the Bizerte Cement Company (Tunisia)) were subjected to an elemental analysis by X-ray fluorescence and the mineralogical composition was determined by the Bogue calculation and by X-ray powder diffraction combined with the Rietveld method (Different softwares were used: XPert High Score Plus version 2.0 and TOPAS version 4.2). We then compared the results obtained by the Rietveld method and the Bogue calculation to the specific peak areas of each phase. The content of each phase, determined by the Rietveld method, varied proportionally to the change in peak area; a significant difference in these results was found by using the elementary Bogue calculation.

Overcoming carbonate interference on labile soil organic matter peaks for midDRIFTS analysis

Mid-infrared spectroscopy has been used with various degrees of success in quantitative and qualitative analysis of soil organic matter (SOM). This study evaluated the spectral interference caused by soil carbonates on the feasibility of using the specific peak area approach obtained by diffuse reflectance infrared Fourier transform spectroscopy in mid-range (midDRIFTS) as an indicator of SOM quality and composition. A midDRIFTS peak area corresponding to more labile SOM compounds (2930 cm−1) was related to microbial biomass carbon and nitrogen (Cmic, Nmic) and hot water extractable carbon and nitrogen (CHWE, NHWE) across two contrasting agroecological regions (Kraichgau (K) and Swabian Alb (SA), Germany) with soils containing carbonates up to 41 g kg−1 soil. Although, the 2930 cm−1 peak showed its potential use as an index for representing labile soil carbon, a poor regression performance between the relative peak area at 2930 cm−1 (rPAnt 2910 cm−1) and labile SOM fractions (R2 = 0.31–0.45) was attributed to inorganic carbon (IC) potentially interfering with this particular peak. To avoid carbonate interference, a spectral-based coefficient was developed using a multiple linear regression model consisting of TOC and TIC as predictors of the difference between peak areas at 2930 cm−1 of non-acid and acid treated spectra (ΔPA 2930 cm−1) of bulk soils. Peak areas at 2930 cm−1 of non treated spectra (PAnt 2930 cm−1) were corrected using a coefficient of 0.21 for carbonates (PAcorr 2930 cm−1), which greatly improved relationships with Cmic, Nmic, CHWE and NHWE (R2 = 0.68–0.75; P < 0.0001). We further developed a regression equation to correct PAnt 2930 cm−1 for future application using the relationship between PAnt 713 cm−1 (assigned for carbonates (mainly calcite)) and PA at 2930 cm−1 (ΔPATIC 2930 cm−1) (R2 = 0.98). We concluded that PA 2930 cm−1 has a high potential to be used as an indicator of SOM composition once carbonate interference is corrected for in carbonated containing soils. The proposed approach is free of multivariate calibration and the spectral index developed (PAcorr 2930 cm−1) is suited to predict accurately labile SOM without the need of additional laboratory measurements. For general applicability of the approach, it should be tested on additional soil types of varying TOC and TIC contents.

1H NMR Evaluation of Polar and Nondeuterated Ionic Liquids for Selective Extraction of Cellulose and Xylan from Wheat Bran

Cellulose and xylan, extracted from wheat bran with polar ionic liquids (ILs), were quantified using 1H NMR spectroscopy. Both No-D NMR and solvent suppression techniques were applied to realize direct analysis of extracts in nondeuterated ILs. As models of extracts, mixtures of cellulose and xylan dissolved in ILs were measured with 1H NMR spectroscopy. There was a linear relation between mixing ratio and specific peak area of each polysaccharide. Extracts from bran in ILs were analyzed with the obtained calibration curve. This NMR analysis was confirmed to be applicable to three representative ILs used for extraction of polysaccharides. A relation between extracted amount and extraction conditions was obtained.

Characterization of paraffin oils and petrolatum using LDI‐TOF MS and principle component analysis

AbstractLaser desorption/ionization time‐of‐flight mass spectrometry (LDI‐TOF MS) followed by evaluation of the mass spectra with principal component analysis (PCA) was used for the in‐depth characterization of paraffin oils (mineral oils) and petrolatum (paraffin jelly) samples. These raw materials are liquid and semisolid mixtures of hydrocarbons obtained from petroleum. Mass spectrometric analysis was done using a solvent‐free sample preparation with silver trifluoroacetate. The analysis was carried out on a commercially available matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometer.Mass spectra were evaluated using parameters calculated from the areas of different alkane and cycloalkane species and by PCA. The ratios between specific peak areas were chosen as PCA‐input data instead of the less reproducible absolute peak areas.The principal components enable comparison of a large number of samples and can also be used for visualization of data. In this work, it is clearly demonstrated that combining LDI‐TOF MS and PCA provides a fast and efficient tool for the characterization of paraffin oils and petrolatum. Petrolatum and four different kinds of paraffin oil were analyzed and the results compared with other analytical methods.

O.30 Arginine-enriched total enteral nutrition increaseliver albumin gene expression and does not increase iNOS expression

liver albumin gene expression and does not increase iNOS expression J. Ren, S. Wang, Y. Zhao, J. Li and A. Li Research Institute of General Surgery, Jingling Hospital, Nanjing University, Nanjing, China. Aim: To examine the effects of arginine enriched total enteral nutrition (TEN) on liver albumin, TNF, IL-lcq IL-6R and inducible nitric oxide synthase (iNOS) gene expression. Methods: A 30% burn was applied in 40 rats after 7 days of gastrostomy. The rats received a continuous intragastric infusion of two different diets 2 hours after burn: low arginine (AL, arginine 0.01 g/kg/day) and arginine enriched (AE, arginine 0.264 g/kg/day). The two formulas were isocaloric (1 75 Kcal/kg/day) and isonitrogenous (1.25 gN/kg/day). The animals were sacrificed on day 1 post burn (PBD1) and PBD9. The mRNA of albumin, TNF, IL-l(z, IL-6R and iNOS of the liver were reverse transcribed (RT) into cDNA and the cDNA were amplifed by polymerase chain reaction (PCR). The RT-PCR products of albumin, TNF, IL-lc~, IL-6R and iNOS were determined by capillary electrophoresis (CE) and semi-quantified by the specific peak area of the CE chromatogram. Results: RT-PCR products of albumin, TNF, IL-6R and iNOS (absorbance unit). Albumin TNF IL-6R iNOS AL(PBD1) 869_*:52 1031 _+23 4320_+108 965-+41 AE(PBD1) 813_+34 984+_27 3810+_217 984_+39 AL(PBD9) 1417 -+ 43 ~ 743 _+ 29* 2570 -+ 90* 547 _+ 23* AE(PBDg) 1812_+41** 603_+32** 972-+87 **~: 522_+48* Means -+ SD, t-test: * P < 0.05 vs AL(PBD9), ** P < 0.01 vs AL(PBD9), 1: P < 0.01 vs PBDI.

Unusual signal enhancement in reversed-phase chromatography of polystyrene monitored by UV detector

Gradient elution of polystyrene standards on reversed phase C18 columns by methanol/tetrahydrofuran or methanol/dichloromethane mixtures yielded a strange effect of the molecular weight of the sample on the specific peak are (mAUs per μg sample injected). The effect did not occur when pure dichloromethane was used as an eluent. Further to this, dependence of specific peak area on flow rate was observed in gradient elution with methanol/tetrahydrofuran mixtures. It was found that these effects were due to polymer elution at the verge of precipitation. Depending on the dwell time of the sample in the column, opalescence occurred that added to the UV signal used for monitoring the elution.

Die gaschromatografische Bestimmung nichtflüchtiger Carbonsäuren in Pflanzensubstanz

The estimation of non‐volatile carboxylic acids in plant material by gas‐liquidchromatography..A method for the estimation of non volatile carboxylic acids in plant material by GLC is described. The organic acids or salts are extracted by 1 N HC1, separated from the cations, the neutral constituents, and the stronger mineral acids by ion exchangers. After the elutriation the acids are dried, dissolved in tetrahydrofurane, and transferred into trimethylsilyl derivatives by bis (trimethylsilyl) acetamide (BSA).The retention time and the specific peak area of 19 carboxylic acids are given. The reliability of the data is tested in three ways by the estimation of the total variance, the calculation of the variances of the different analytical steps by the aid of the variance analysis, and the determination of the losses. Malonate, succinate, fumarate, malate, aconitate, citrate, shikimate, and quinate are quantitatively determinable. In addition it seems feasible to estimate tartrate, cis and trans aconitate, citrate and isocitrate if both isomeric compounds in the same plant sample are present by the use of several different columns and to estimate uronic acids by the application of another silylating reagent. Oxalate and glycerate are indeterminable with this method.The time needed for 1 analysis is less than 1 hour. As the extraction and the chromatographic seperation should be repeated it is practicable to analyse the average of 2 plant samples a day.