Improving the accuracy of model-based quantitative nuclear magnetic resonance

Low spectral resolution and extensive peak overlap are the common challenges that preclude quantitative analysis of nuclear magnetic resonance (NMR) data with the established peak integration method. While numerous model-based approaches overcome these obstacles and enable quantification, they intrinsically rely on rigid assumptions about functional forms for peaks, which are often insufficient to account for all unforeseen imperfections in experimental data. Indeed, even in spectra with well-separated peaks whose integration is possible, model-based methods often achieve suboptimal results, which in turn raises the question of their validity for more challenging datasets. We address this problem with a simple model adjustment procedure, which draws its inspiration directly from the peak integration approach that is almost invariant to lineshape deviations. Specifically, we assume that the number of mixture components along with their ideal spectral responses are known; we then aim to recover all useful signals left in the residual after model fitting and use it to adjust the intensity estimates of modelled peaks. We propose an alternative objective function, which we found particularly effective for correcting imperfect phasing of the data – a critical step in the processing pipeline. Application of our method to the analysis of experimental data shows the accuracy improvement of 20 %–40 % compared to the simple least-squares model fitting.

ABUNDANCE OF YELLOW ALKALOID ‘BERBERINE’ IN THE MEDICINAL PLANT OF TALI KUNING (Tinospora dissitiflora Diels.) COLLECTED FROM MANOKWARI – WEST PAPUA

This research was conducting to quantify the berberine concentration. Rapid method using 1H-NMR was used to determine berberine quantitative and qualitatively from the crude extract. Tali kuning was collected from Manokwari Papua Barat and powdered with hammer mill. Sonication was employed to extract using methanol at room temperature. 500 µg authentic berberine chloride were dissolved in 5.4 mL methanol-d4 (containing 84.4 µg anthracene). 1H-NMR spectra were recorded in methanol-d4 (99,9%) using JEOL JNM-ECX 500. Each sample was scanned for 100 using the following parameter 0.18 Hz/point, spectral width 14400 Hz, pulse with 4.0 US, relaxation delay 2 sc. Peak areas were used for qualitative analysis and integration of each peach were employed for quantitative analysis. The results demonstrated that 1H-NMR signal pattern of H-13 and H-8 recorded from Tali Kuning, and Amur corktree were well recorded, and in accordance to the berberine chloride standard. Using peak integration of H-13 and H-8, the berberine quantity in Tali kuning is 18.06 mg/g of dried powder, and 22.78 mg//gr for Amur corktree. Berberine percentage based on the weight of oven-dried-extracts was 8.34% (MC 7.54%) and 12.04% (11,54%) for Amur corktree and Tali kuning.

LaueG software for displaying and processing neutron Laue images

An overview is presented of an integrated software package for the processing of Laue data from reactor and other continuous neutron sources. LaueG appears to the user as a graphical user interface with interactive graphic modes that depend on the task being performed: simple image display, cell indexing and refinement, peak integration, wavelength normalization and intensity corrections, or identification of statistical outliers. Other capabilities under development, though still usable, include satellite spots and modulated structures, twinned crystal analysis, and ab initio indexing of unit cells. The emphasis is on accurate intensities for structure refinement using an integrated graphical approach.

Estimating Chlorophyll-a Absorption with the Total Algae Peak Integration Retrieval TAPIR Considering Chlorophyll-a Fluorescence from Hyperspectral Top of the Atmosphere Signals in Optically Complex Waters

The Total Algae Peak Integration Retrieval TAPIR relates the chlorophyll-a absorption coefficient at 440 nm (a440) to the reflectance peak near 683 nm induced by chlorophyll-a properties. The two-step retrieval provides both the hyperspectral quantification of the phytoplankton fluorescence and scattering and the estimation of a440 from reflectance signals. Integrating the peak, the Total Algae Peak (TAP) accounts for the variance in the peak's magnitude, shape, and central peak wavelength. TAPIR is a solely optical approach estimating a440 and supports the application of retrieval-independent individual regional bio-optical models afterwards to retrieve the chlorophyll-a concentration. Simulations reveal the major sensitivity on the considered model chlorophyll-a absorption spectrum and its single scattering albedo. Additional water and atmosphere constituents have a low impact. An uncertainty assessment reveals uncertainties of less than 30% for TAPIR a440 greater than 0.8 m-1 and less than 38% for lower a440. In optically complex waters, first validation efforts promise the applicability of TAPIR for high chlorophyll-a concentration estimations in the presence of additional water constituents. The technique is generic and considers external conditions (sun zenith angle, number of measurement bands, surface or satellite measurements, and radiometric quantity). TAPIR applies to all kind of waters including optically complex waters, arctic to tropical regions, and inland, coastal, and open ocean waters. Among other hyperspectral satellite sensors, the Environmental Mapping and Analysis Program (EnMAP) provides sufficient sampling bands for the application of TAPIR.