ISO_NWIPs-for-Ballot

ISO/NP

Since signals from impurities in a deuterated solvent for NMR measurements will have an effect on the 654 accuracy of the quantification, it is recommended to use solvents with high purity [see ref. 16 and 17]. 655 656 6.5 NMR tubes 657 NMR tubes should exhibit minimal distortion and good circular symmetry to ensure good sensitivity 658 and resolution, and have thin, uniform-thickness walls made from borosilicate glass. The caps of the 659 tubes should be made using materials that will not leach plasticizers, etc. by the deuterated solvent. 660 NMR tubes commonly have an outer diameter of 3 mm, 5 mm, 10 mm, etc. In any size of NMR tube, it is 661 recommended to use tubes particularly suitable for NMR measurements. 662 NOTE NMR tubes are also called NMR test tubes. For tubes with an outer diameter of 5 mm, it is recommended 663 that they satisfy the following specifications: 664 outer diameter: 4,965 ＋ 0,005 -0,014 mm; 665 camber: ≤ 5 m; 666 total length: 180 mm to 200 mm. 667 668 6.6 NMR apparatus optimization 669 For NMR measurement, the line shape is adjusted by adding a corrective magnetic field gradients to 670 compensate for spatial imhomogenuty in the static magnetic field in the sample space. This is done by 671 applying electric currents to several shim coils placed around the sample position. 672 The NMR spectrometer should be adjusted in advance to minimize the potential for systemic 673 interference in the measurements, in accordance for example with the recommendations in the 674 manufacture’s instruction manual. The spectrometer sensitivity should be demonstratedprior to any 675 qNMR measurement using a reference solution such as 0.1% ethylbenzene in deuterated chloroform. 676 The field homogeneity of the spectrometer should be demonstrated using a solution of chloroform in 677 deuterated acetone such that the Full Width at Half Maximum (FHWM) of the chloroform peak is within 678 the established minimum values. 679 NOTE Sealed tubes containing a solution of 0,1 % ethylbenzene in deuterated chloroform are available 680 commercially for use when adjusting the sensitivity; sealed tubes containing a solution of 1 % to 3 % chloroform 681 in deuterated acetone are available commercially for use when adjusting the resolution. 682 683 6.7 Weighing of sample and reference materials for qNMR 684 The following procedure should be employed. 685 a) Record the relevant environmental conditions surrounding the balance before weighing a sample. 686 Usually the temperature has the largest impact on the balance performance. 687 b) Visually confirm that the weighing pan of the balance is clean. 688

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