METHOD FOR QUANTITATIVE ANALYSIS

Abstract

The present invention provides a method for quantitative analysis of a compound in a sample characterized in that the quantitative analysis is performed by a method of using an external standard which obtains NMR spectra of a sample and a standard substance and then compares them, and it can be applied even to an insoluble sample.

Claims

1. A method for quantifying a compound in a sample comprising the steps of: 1) obtaining NMR spectrum of NMR active atom of a standard substance containing the NMR active atom contained in the compound, and NMR spectrum of the NMR active atom of the compound under the same condition; 2) obtaining FID (free induction decay) amplification values of characteristic peaks in the NMR spectrum of the standard substance and the NMR spectrum of the sample, respectively; and 3) comparing the respective HD amplification values to measure the concentration of the compound in the sample.

2. The method for quantifying a compound in a sample according to claim 1, wherein the NMR active atom is hydrogen, lithium, carbon, fluorine, silicon, phosphorus, lead, or tin.

3. The method for quantifying a compound in a sample according to claim 1, wherein the same condition is that, when performing NMR measurement, the number of scans, the delay time, the pulse width, the pulse power, the receiver gain, and the spinning rate are the same.

4. The method for quantifying a compound in a sample according to claim 1, wherein the characteristic peak in the NMR spectrum of the sample is a characteristic peak of a compound contained in the sample.

5. The method for quantifying a compound in a sample according to claim 1, wherein the concentration of a compound in the sample can be measured by comparing the HD amplification values as shown in Equation 1 below:
Concentration of compound in sample (wt %)=(A/B)×(C/D)×(E/F)×(G/H)  [Equation 1] in the Equation 1, A is the number of NMR active atoms in a molecule of a standard substance corresponding to the characteristic peak of the above standard substance, B is the number of NMR active atoms in a molecular of a compound corresponding to the characteristic peak of the sample, C is the molecular weight of the compound, is the molecular weight of the standard substance, E is the mass of the standard substance used to obtain the NMR spectrum of the standard substance, F is the mass of the sample used to obtain the NMR spectrum of the sample, G is the FID amplification value of the sample, and H is the FID amplification value of the standard substance.

6. The method for quantifying a compound in a sample according to claim 1, wherein the sample is an insoluble sample.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG. 1 shows the extraction result of the FID amplification value for HMB 50 sample in Example 1 of the present invention.

[0044] FIG. 2 shows a .sup.207Pb SSNMR spectrum for PbI.sub.2, a first sample, and a second sample in Example 2 of the present invention.

[0045] FIG. 3 shows a .sup.207Pb SSNMR spectrum of Pb(NO.sub.3).sub.2 in Example 2 of the present invention.

[0046] FIG. 4 shows the extraction result of FID amplification value for the characteristic peak of PbI.sub.2(DMSO).sub.2 in Example 2 of the present invention.

[0047] FIG. 5 shows the extraction result of the FID amplification value for the characteristic peak of PbI.sub.2(DMSO) in Example 2 of the present invention.

[0048] FIG. 6 shows TGA result of the second sample in Example 2 of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0049] Hereinafter, preferred examples will be presented to aid in understanding of the present invention. However, the following examples are provided for illustrative purposes only, and the content of the present invention is not limited by these Examples.

[0050] In the following Examples, unless stated otherwise, the NMR spectrum used Agilent DD2 600 MHz SSNMR (using a 1.6 mm SSNMR probe) and the FID amplification values were obtained using Agilent's Vnmrj 4.2 software.

Example 1: Quantification of HMB in a Sample

[0051] In order to verify the quantification method according to the present invention, experiments were conducted using HMB (hexamethylbenzene) and ADM (adamantane). Samples of HMB 50 (ADM:HMB=50:50 (wt %)) and HMB 30 (ADM:HMB=70:30 (wt %)) were prepared, respectively, using HMB (HMB 100 wt %) with the external standard. The external standard sampled in the NMR rotor was 19.48 mg, while HMB 50 and HMB 30 were 19.89 mg and 19.88 mg, respectively.

[0052] For each of them, NMR spectra were obtained under the following conditions, and FID amplification values were respectively extracted for characteristic peaks corresponding to a methyl group of HMB. At this time, the delay time was changed to 1 sec, 5 sec and 30 sec, respectively, and experiments were conducted. [0053] pulse width=90 degree pulse [0054] number of scans=16 [0055] receiver gain=24 [0056] spinning rate=10 kHz

[0057] An example of the extraction result of FID amplification value for HMB 50 is shown in FIG. 1, and the extraction result of FID amplification value for the remaining samples and their quantitative results are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Delay time = 1 sec Delay time = 5 sec Delay time = 30 sec FID FID FID amplification Quantitative amplification Quantitative amplification Quantitative value value(wt %) value value(wt %) value value(wt %) External 14.0 — 19.1 — 18.5 — standard HMB 50 6.5 45.5 8.2 42.0 9.6 50.6 HMB 30 4.9 34.6 6.8 34.9 5.9 31.2

[0058] In Table 1 above, the quantitative value was calculated using Equation 1 described above. For example, in the case of HMB 50 at a delay time=30 sec, when substituted into Equation 1 described above, the quantitative value is as follows.

Quantitative value (wt %)=(A/B)×(C/D)×(E/F)×(G/H)

[0059] A (the number of methyl group in HMB molecule)=6

[0060] B (the number of methyl group in HMB molecule)=6

[0061] C (HMB molecular weight)=162.28 g/mol

[0062] D (HMB molecular weight)=162.28 g/mol

[0063] E (mass of sampled external standard in NMR rotor)=19.48 mg

[0064] F (mass of sampled HMB 50 in NMR rotor)=19.89 mg

[0065] G (FID amplification value of external standard)=18.5

[0066] H (FID amplification value of HMB 50)=9.6

[0067] As described above, it could be confirmed that the quantitativeness was improved with sufficient delay time, and an error was not large.

Example 2: Quantification of PbI.SUB.2.(DMSO).SUB.2 .in a Sample

[0068] 1) Preparation of Sample

[0069] An example of using a DMSO adduct (PbI.sub.2(DMSO).sub.2) as a perovskite precursor in order to produce perovskite used as a light absorber of a solar cell has been reported (Science 2015, Vol. 348, no. 6240, pp. 1234-1237). According to this literature, PbI.sub.2 was dissolved in DMSO to produce an intermediate, which was then heated to produce PbI.sub.2(DMSO). However, the intermediates mentioned above was mixed in (PbI.sub.2(DMSO).sub.2) and PbI.sub.2(DMSO), and the range of each content varies depending on the production conditions. In order to produce PbI.sub.2(DMSO) with high purity, it is necessary to confirm the concentration of PbI.sub.2(DMSO).sub.2 in the intermediate.

[0070] Thus, according to the above document, PbI.sub.2 (50 g) was dissolved in 150 mL of DMSO at 60° C., and then 350 mL of toluene was added dropwise. Subsequently, the precipitate was filtered and dried for 3 hours, and a portion thereof was taken as a ‘first sample’. The remaining samples except for the first sample were placed in a vacuum oven at 60° C. for 24 hours to prepare PbI.sub.2(DMSO), and a portion thereof was taken as a ‘second sample’.

[0071] 2) Selection of Characteristic Peaks

[0072] In order to select the characteristic peaks of PbI.sub.2(DMSO).sub.2 and PbI.sub.2(DMSO) in the first sample and the second sample, .sup.207Pb SSNMR spectrum was obtained for PbI.sub.2, a first sample and a second sample used in the above preparation under the following conditions using a 3.2 mm SSNMR probe at Agilent DO 2600 MHz, and the results are shown in FIG. 2. [0073] pulse power (tpwr)=55 [0074] pulse width (pw)=5.00 usec [0075] ax90=3500 [0076] delay time=5 sec [0077] number of scans=50000 [0078] receiver gain=60 [0079] spinning rate=25 kHz

[0080] As shown in FIG. 2, PbI.sub.2(DMSO).sub.2 and PbI.sub.2(DMSO) were present in the first sample, and the peak of PbI.sub.2(DMSO).sub.2 was taken as a characteristic peak. Also, PbI.sub.2(DMSO).sub.2 and PbI.sub.2(DMSO) were present in the second sample, and the peak of PbI.sub.2(DMSO) was taken as a characteristic peak.

[0081] 3) Extraction of FID Amplification Value of Standard Substance

[0082] Then, Pb(NO.sub.3).sub.2, (Pb(NO.sub.3).sub.2 100 wt %, 32 mg) were used as .sup.207Pb standard (external standard). .sup.207Pb SSNMR spectrum was obtained under the following conditions using Agilent DD2 600 MHz SSNMR (using a 1.6 mm SSNMR probe). The FID amplification value of the characteristic peak of Pb was extracted from the NMR spectrum of Pb(NO.sub.3).sub.2, and the result is shown in FIG. 3. [0083] pulse power(tpwr)=60 [0084] pulse width(pw)=90 degree pulse (2.25 usec) [0085] ax90=3500 [0086] delay time=5 sec [0087] number of scans=5000 [0088] receiver gain=60 [0089] spinning rate=35 kHz

[0090] 4) Quantification of PbI.sub.2(DMSO).sub.2 in a First Sample

[0091] .sup.207Pb SSNMR spectrum was obtained under the same condition as in 3) above using 21.98 mg of the first sample. In the above spectrum, the HD amplification value of the characteristic peak of PbI.sub.2(DMSO).sub.2 confirmed previously was extracted and the result is shown in FIG. 4.

[0092] Using the above results, PbI.sub.2(DMSO).sub.2 in the first sample was quantified as shown in Table 2 below.

TABLE-US-00002 TABLE 2 (C) Molecular weight of PbI.sub.2(DMSO).sub.2 617.27582 (g/mol) (D) Molecular weight of Pb(NO.sub.3).sub.2 331.21 (g/mol) (E) Mass of Pb(NO.sub.3).sub.2 32 mg (F) Mass of the first sample 21.98 mg (G) FIF Amplification value of the first sample 328.521 (H) FID amplification value of Pb(NO.sub.3).sub.2 1250.63  Concentration of PbI.sub.2(DMSO).sub.2 in the first sample ((C/D) × (E/F) × (G/H)) = 71.2(wt %)

[0093] 5) Quantification of PbI.sub.2(DMSO).sub.2 in a Second Sample

[0094] .sup.207Pb SSNMR spectrum was obtained under the same condition as in 3) above using 21.36 mg of the second sample. In the above spectrum, the FID amplification value of the characteristic peak of PbI.sub.2(DMSO) confirmed previously was extracted and the result is shown in FIG. 5.

[0095] Using the above results. PbI.sub.2(DMSO) in the second sample was quantified as shown in Table 3 below.

TABLE-US-00003 TABLE 3 (C) Molecular weight of PbI.sub.2(DMSO) 539.14238 (g/mol) (D) Molecular weight of Pb(NO.sub.3).sub.2 331.21 (g/mol) (E) Mass of Pb(NO.sub.3).sub.2 32 mg (F) Mass of the second sample 21.36 mg (G) FID amplification value of the second sample 495.414 (H) FID Amplification value of Pb(NO.sub.3).sub.2 1250.63  Concentration of PbI.sub.2(DMSO) in the second sample ((C/D) × (E/F) × (G/H)) = 96.6(wt %)

[0096] 6) Verification of Quantitative Analysis

[0097] In order to verify the results of the above quantitative analysis, the concentration was analyzed by the TGA method described in Science 2015, Vol. 348, no. 6240, pp. 1234-1237.

[0098] The TGA method is a method of quantifying the amount of DMSO, and when PbI.sub.2(DMSO) and PbI.sub.2 were present as in the second sample, quantitative analysis is possible, but when PbI.sub.2(DMSO) and PbI.sub.2(DMSO).sub.2 were present as in the first sample, it could not be confirmed by which structure the detected DMSO was caused. Therefore, only the second sample was quantified by TGA method, and the result is shown in FIG. 6.

[0099] The results of TGA of the second sample are shown in FIG. 6. Since PbI.sub.2 is decomposed above 600° C., the weight reduction up to 300° C. can be assumed to be due to DMSO. The starting mass of TGA was 7.401 mg and the weight reduction up to 300° C. was 1.038 mg. Therefore, the mass of DMSO in the second sample is 1.038 mg, which is 0.000013286 moles when converted to the number of moles (molecular weight of DMSO: 78.13). Since the DMSO in the second sample is present in PbI.sub.2(DMSO), the above number of moles is the same as that of PbI.sub.2(DMSO), thus yielding 7.163 mg when converting to mass, and the PbI.sub.2(DMSO) in the second sample is 96.78 wt % (7.163 mg/7.401 mg).

[0100] It could be confirmed that the above quantitative results are very similar to the concentration, 96.6 wt %, of PbI.sub.2(DMSO) in the second sample, which was analyzed by the quantification method according to the present invention.