ISO_NWIPs-for-Ballot

ISO/NP

In the 1 H NMR spectra, the proton nuclei ( 1 H) within the same molecule but in different chemical 370 environments are observed as separate signals with different chemical shifts according to the 371 resonance frequencies. The signal intensity S i is given by Formula (3). 372 0 / / i i ) (cos 1 1 sin K 1i r i1 r M e e P VM mN S TT TT (3) 373 where 374 S i is the intensity (area) of a signal; 375 K is a constant; 376 N i is the number of protons; 377 V is the volume of the sample solution; 378 m is the mass of the sample; 379 M is the molar mass of the analyte; 380 P is the purity or content of the analyte; 381 is the excitation pulse angle (flip angle); 382 T 1i is the spin-lattice relaxation time of the nuclei ( 1 H) providing the signal; 383 T r is the repetition time; 384 M 0 is the equilibrium magnetization. 385 The subscript i here indicates each separate signal, and the relaxation times will differ according to the 386 environments of the 1 H nuclei. The signal-to-noise ratio (SNR) is improved by co-adding multiple 387 acquisitions of the spectrum. When this is done if the time between acquisitions uses a T r that is 388 sufficiently longer than the longest relaxation time T 1 in the analyte, the condition of 1 1 1 r / TT e will 389 be satisfied for all signals from the analyte, and the area of a signal will indicate the intensity 390 proportional to the number of resonating nuclei, and Formula (3) can be expressed as Formula (4) 391 below. 392 i k N S (4) 393 where 394 S is the signal area; 395 N i is the number of protons; 396 k is a constant related to the measurement of the sample solution being analysed. 397

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