ISO_NWIPs-for-Ballot

ISO/NP

If the purity of an analyte is measured accurately, when the measurement is repeated, it should be 870 confirmed that the relative standard deviation of the ratio between the area of each signal used for 871 quantification of the analyte and the area of the signal for the qNMR standard reference material is at a 872 level that allows the desired quantification accuracy to be obtained. For example, if the target accuracy 873 is within 1 %, it is desirable to achieve a relative standard deviation of ≤0,5 % (for 6 or more repeated 874 measurements). 875 876 9.3.3 System performance for system suitability test 877 With regard to the sample solution, when measurements are performed under 1 H qNMR measurement 878 conditions, confirm that it is possible to observe complete separation of the signals for the reference 879 material and those of the analyte being quantified, and that there is no obvious overlap of signals from 880 impurities near either of these signals. 881 882 9.3.4 Test for required detectability for system suitability test 883 Verify that the signals for the tested target species and for the reference material for qNMR have 884 adequate SNR. For example, if the target accuracy is within 1 %, it is desirable to achieve SNRs of ≥100 885 for the signals used for quantification. 886 887 9.4 Ensuring traceability 888 Regularly calibrate the balance that is used for sample preparation [see ref. 9]. For the calibration, use 889 balance weights that have an assured SI traceability, in conformance with OIML R111-1:2004. 890 Reference materials for quantitative analysis that ensure SI traceability and have a clear traceability 891 source are available as CRMs from reference material producers who have been accredited in 892 accordance with ISO 17034:2016 requirements. The measurement uncertainty of the assigned purity of 893 the CRM and a statement of the basis of the traceability of the assigned value to the SI should be clearly 894 documented 895 NOTE Calibration is an operation that, under specified conditions, in a first step, establishes a relation between 896 the quantity values with measurement uncertainties provided by measurement standards and corresponding 897 indications with associated measurement uncertainties and, in a second step, uses this information to establish a 898 relation for obtaining a measurement result from an indication [see ref. 8]. 899 9.5 Ensuring the reliability of analysis values 900 To ensure the reliability of the analysis values, in addition to using qNMR reference materials with 901 guaranteed SI traceability, the samples shall be prepared using an balance that has been calibrated 902 using weights with certified SI traceability, The NMR measurements and data analysis shall be 903 undertaken under appropriate conditions using a procedure that as a minimum has been validated in 904 accordance with the requirements of ISO 17025:2017. This makes it possible to determine the 905 measurement uncertainty associated with the individual analysis values. 906 Even in cases where is difficult to evaluate all the factors affecting the uncertainty of the analysis values, 907 it is essential to verify that there are no abnormal values, e.g. by recording the deviation of the 908 measured values between the signals used for quantification (if the measurement values are obtained 909 from multiple signals) and the deviation of the measured values between sample preparations, and 910 comparing the repeatability of the measurements. 911

© ISO 2017 – All rights reserved

29