Ion chromatographic method for simultaneously measuring trace amount of anions in high-purity phosphoric acid
A technology of high-purity phosphoric acid and ion chromatography, applied in the field of ion chromatography to determine trace anions in high-purity phosphoric acid, to meet the detection requirements, fast analysis and high accuracy
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Embodiment 1
[0032] Embodiment 1: Optimization of chromatographic conditions
[0033] Due to the high concentration of phosphate in high-purity phosphoric acid, when using conventional single sodium carbonate eluent, the chromatographic peak of phosphate is between nitrate and sulfate, which interferes with the qualitative determination of trace nitrate and sulfate. Thus affecting the accuracy of quantitative results. According to the characteristics of three valence states of phosphate radicals, it is possible to increase the pH value of leaching so that the phosphate radicals are mainly converted into trivalent PO 4 3- exists in the form such that PO 4 3- The retention time will be extended, in all the ion F to be detected - , Cl - , NO 3 - and SO 4 2-The chromatographic peaks behind the peak, so as not to affect the F - , Cl - , NO 3 - and SO 4 2- qualitative and quantitative. It is found through experiments that when the concentration of sodium hydroxide in the eluent...
Embodiment 2
[0034] Example 2: F - , Cl - , NO 3 - and SO 4 2- Analysis of Mixed Standard Solutions
[0035] (1) Repeatability
[0036] The standard mixed solution of the same concentration was injected continuously for 6 times to obtain F - , Cl - , NO 3 - and SO 4 2 The relative standard deviations of the peak areas were 1.87%, 2.06%, 1.60% and 1.65%, respectively.
[0037] (2) Linear relationship
[0038] For formulated F - , Cl - , NO 3 - and SO 4 2- The linear solution of , according to the injection sequence from low concentration to high concentration, the injection analysis is carried out, and the F at different concentrations is obtained - , Cl - , NO 3 - and SO 4 2- The peak area of the peak area, respectively with the concentration of the ion to be measured (mg / L) as the abscissa, with its peak area as the ordinate plotting, to obtain F - , Cl - , NO 3 - and SO 4 2- working curve, respectively attached figure 2 , image 3 , Figure 4 and ...
Embodiment 3
[0039] Embodiment 3: the pretreatment of high-purity phosphoric acid sample
[0040] (1) Selection of pH value of sample solution
[0041] Add 8, 10, and 12 mL of 12g / L NaOH solution to 0.1 g of phosphoric acid sample respectively, and after distilling to 100 mL with secondary deionized water, measure the pH values of 5.1, 7.5, and 11 respectively, and test the three Sample solutions with different pH values were injected and analyzed. It was found that the retention time of the ion to be measured in the sample solution with a pH value of 5.8 was delayed by 2 minutes compared with the retention time of the ion to be measured in the standard solution, and that in the sample solution with a pH value of 11 The retention time of ions is 1.5min earlier than the retention time of chloride ion and sulfate group in the standard solution, and the retention time of chloride ion and sulfate group in the sample solution with a pH value of 7.5 is very close to the retention time of chl...
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