阅读说明：本技术 一种镍电解液中2，6-吡啶二甲酸的高效液相色谱检测方法 (High performance liquid chromatography detection method for 2, 6-pyridinedicarboxylic acid in nickel electrolyte ) 是由 张峰瑞 李亦婧 郭勇 苏兰伍 卢建波 张四增 宛顺磊 卢晓锋 王帅 于 2021-05-31 设计创作，主要内容包括：本发明提供了一种镍电解液中2,6-吡啶二甲酸的高效液相色谱检测方法。首先采用氢氧化钠调节样品pH值使镍离子沉淀,然后再采用高效液相色谱-紫外检测器对2,6-吡啶二甲酸进行检测,高效液相色谱条件为：所用色谱柱为C18色谱柱；所用流动相A为甲醇,流动相B为乙酸溶液,最后根据2,6-吡啶二甲酸的标准曲线得到镍电解液样品中2,6-吡啶二甲酸的含量。本发明解决了2,6-吡啶二甲酸的双齿配体结构极易与电解液中镍离子生成配合物影响检测的问题,方法操作简单,分析时间短、灵敏度高、准确性高且稳定性高,为检测镍电解液中的2,6-吡啶二甲酸提供了新的技术手段。(The invention provides a high performance liquid chromatography detection method of 2, 6-pyridinedicarboxylic acid in a nickel electrolyte. Firstly, adjusting the pH value of a sample by using sodium hydroxide to precipitate nickel ions, and then detecting the 2, 6-pyridinedicarboxylic acid by using a high performance liquid chromatography-ultraviolet detector, wherein the conditions of the high performance liquid chromatography are as follows: the chromatographic column is C18 chromatographic column; and finally, obtaining the content of the 2, 6-pyridinedicarboxylic acid in the nickel electrolyte sample according to a standard curve of the 2, 6-pyridinedicarboxylic acid. The method solves the problem that the bidentate ligand structure of the 2, 6-pyridinedicarboxylic acid is easy to generate a complex with nickel ions in the electrolyte to influence the detection, has simple operation, short analysis time, high sensitivity, high accuracy and high stability, and provides a new technical means for detecting the 2, 6-pyridinedicarboxylic acid in the nickel electrolyte.)

1. A high performance liquid chromatography detection method of 2, 6-pyridinedicarboxylic acid in a nickel electrolyte comprises the following steps:

(1) desalination treatment of samples

Taking a sample to be detected containing 2, 6-pyridinedicarboxylic acid nickel electrolyte, adjusting the pH value of the sample to 12 by using a sodium hydroxide solution, converting nickel ions into nickel hydroxide precipitate, centrifuging to obtain supernatant, adjusting the pH value to 6.5-7.5 by using a hydrochloric acid solution, and performing constant volume by using deionized water to obtain a liquid to be detected;

(2) sample detection

Performing high performance liquid chromatography detection on the liquid to be detected to obtain the chromatographic peak area of the 2, 6-pyridinedicarboxylic acid; the chromatographic conditions are as follows: the chromatographic column is C18 chromatographic column; the mobile phase A is methanol, and the mobile phase B is acetic acid solution; an ultraviolet detector with a detection wavelength of 225-265 nm; the detection temperature is 20-40 ℃; the flow rate is 0.5-1.5 mL/min; the sample injection amount is 5-20 mu L;

(3) sample content calculation

According to a standard curve of the 2, 6-pyridinedicarboxylic acid, the content of the 2, 6-pyridinedicarboxylic acid in the nickel electrolyte is calculated by combining the chromatographic peak area of the 2, 6-pyridinedicarboxylic acid;

the linear equation of the standard curve of the 2, 6-pyridinedicarboxylic acid is as follows: y = 2.0722x-24.38, correlation coefficient R²= 0.993; wherein x is the mass concentration of 2, 6-pyridinedicarboxylic acid, unit: mg/L, y is the chromatographic peak area of 2, 6-pyridinedicarboxylic acid, unit: intens.

2. The high performance liquid chromatography detection method of 2, 6-pyridinedicarboxylic acid in a nickel electrolyte as claimed in claim 1, characterized in that: in the step (1), the concentration of the sodium hydroxide solution is 1 mol/L; the concentration of the hydrochloric acid solution was 0.5 mol/L.

3. The high performance liquid chromatography detection method of 2, 6-pyridinedicarboxylic acid in a nickel electrolyte as claimed in claim 1, characterized in that: in the step (2), the mass percent of the acetic acid solution is 1-5%.

4. The high performance liquid chromatography detection method of 2, 6-pyridinedicarboxylic acid in a nickel electrolyte as claimed in claim 1, characterized in that: in the step (2), the volume ratio of the mobile phase A to the mobile phase B is 5: 95-15: 85.

5. The high performance liquid chromatography detection method of 2, 6-pyridinedicarboxylic acid in a nickel electrolyte as claimed in claim 1, characterized in that: in the step (2), the chromatographic peak with the retention time of 8.682min is taken as the target chromatographic peak of the 2, 6-pyridinedicarboxylic acid.

Technical Field

The invention relates to a high performance liquid chromatography detection method of 2, 6-pyridinedicarboxylic acid in a nickel electrolyte, belonging to the technical field of analytical chemistry.

Background

The nickel-based plating layer has excellent wear resistance, corrosion resistance and oxidation resistance, is firmly combined with a matrix, and is widely applied to corrosion protection of steel materials. With the development of national economy and the improvement of the living standard of people, the coating is required to have both functionality and decoration. The brightener with a certain component is added into the nickel electrolyte, so that the glossiness of the plating layer can be effectively improved, and the decorative effect of the plating layer is improved. 2, 6-pyridine dicarboxylic acid is a nitrogen heterocyclic brightening agent and is used as a brightening agent in semi-bright nickel to prevent the formation of a passivation film; in the multi-layered nickel, the delamination between the plating layers can be reduced.

The brightener containing carboxyl is easy to react at the cathode, 2, 6-pyridinedicarboxylic acid is continuously consumed in the plating solution, and in order to ensure the stability of the plating solution, the content of the 2, 6-pyridinedicarboxylic acid in the plating solution needs to be detected, so that the brightener is added to the system in a planned way. At present, the detection of 2, 6-pyridinedicarboxylic acid in the nickel electrolyte is not reported.

Disclosure of Invention

The invention aims to provide a method for detecting 2, 6-pyridinedicarboxylic acid in a nickel electrolyte, which has the advantages of high sensitivity, high accuracy and high stability.

The invention relates to a method for detecting 2, 6-pyridinedicarboxylic acid in nickel electrolyte, which is characterized in that 2, 6-pyridinedicarboxylic acid is easy to generate complex with nickel ions in the electrolyte to affect detection due to the unique bidentate ligand structure of the 2, 6-pyridinedicarboxylic acid, and the sample needs to be subjected to nickel removal pretreatment first, so that the method comprises the desalting pretreatment method and liquid chromatography detection of the sample, and comprises the following specific steps:

(1) determination of chromatographic conditions

Preparing a standard solution with the 2, 6-pyridinedicarboxylic acid concentration of 200mg/L by using deionized water to fix the volume of a 2, 6-pyridinedicarboxylic acid standard substance, analyzing by using a liquid chromatograph, obtaining a corresponding retention time of 8.682min as shown in figure 1, and determining chromatographic conditions as follows:

the chromatographic column is C18 chromatographic column; the mobile phase A is methanol, and the mobile phase B is acetic acid solution; an ultraviolet detector with a detection wavelength of 225-265 nm; the detection temperature is 20-40 ℃; the flow rate is 0.5-1.5 mL/min; the sample injection amount is 5-20 mu L; the mass percentage of the acetic acid solution is 1% -5%; the volume ratio of the mobile phase A to the mobile phase B is 5: 95-15: 85.

(2) Preparation of Standard solutions

Preparing a standard solution with the concentration of 1mg/mL by using a nickel electrolyte without 2, 6-pyridinedicarboxylic acid as a 2, 6-pyridinedicarboxylic acid standard substance, and diluting to prepare a standard working solution with a concentration gradient, wherein the concentration gradient series of the 2, 6-pyridinedicarboxylic acid in the standard working solution are 50mg/L, 80mg/L, 100mg/L, 130mg/L, 150mg/L and 200 mg/L.

(3) Desalination treatment of standard working solutions

And (3) adjusting the pH value of the standard working solution to 12 by using 1mol/L sodium hydroxide solution to convert nickel ions into nickel hydroxide precipitate, centrifuging to obtain a supernatant, adjusting the pH value to 6.5-7.5 by using 0.5mol/L hydrochloric acid solution, and fixing the volume by using deionized water.

(4) Drawing a working curve

Performing liquid chromatography detection on the standard working solution subjected to desalting treatment under the chromatographic condition in the step (1), performing linear regression on the peak area of the 2, 6-pyridinedicarboxylic acid and the corresponding mass concentration of the peak area to obtain a linear regression equation, namely a standard curve of the 2, 6-pyridinedicarboxylic acid, wherein the linear equation and the detection limit are shown in a table 1:

the detection accuracy, precision and recovery rate were verified by the following methods: the standard solution of 1mg/mL is diluted continuously until the signal-to-noise ratio S/N is 3, the sample concentration is taken as the detection Limit (LOD), and the concentration corresponding to 10 times the signal-to-noise ratio is taken as the lower limit of quantification (LOQ). Taking a nickel electrolyte with the concentration of 80mg/L of 2, 6-pyridinedicarboxylic acid as an adding standard recovery experiment, adding 1mg/mL standard solution into the nickel electrolyte with the concentration of 80mg/L of 2, 6-pyridinedicarboxylic acid by calculating the accuracy of a recovery rate investigation method and investigating the precision of the recovery rate by Relative Standard Deviation (RSD), wherein the adding standard levels are respectively 20mg/L, 50mg/L and 70 mg/L, measuring for 6 times in parallel at each adding level, and calculating the adding standard recovery rate by using the following formula;

C₁is the sample concentration, C₂For adding the concentration of the sample, C₃Is an addition scalar quantity.

The recovery and precision of the added standard are shown in Table 2:

(5) desalination treatment of samples

Taking a nickel electrolyte sample to be detected containing 2, 6-pyridinedicarboxylic acid, adjusting the pH value of the sample to 12 by using 1mol/L sodium hydroxide solution to convert nickel ions into nickel hydroxide precipitate, centrifuging to obtain supernatant, adjusting the pH value to 6.5-7.5 by using 0.5mol/L hydrochloric acid solution, and performing constant volume by using deionized water to obtain a liquid to be detected.

(6) Sample detection

And (3) carrying out high performance liquid chromatography detection on the liquid to be detected under the chromatographic condition of the step (1) to obtain the chromatographic peak area of the 2, 6-pyridinedicarboxylic acid. FIG. 2 is an HPLC chromatogram of a sample of nickel electrolyte containing 2, 6-pyridinedicarboxylic acid directly injected without desalting treatment; FIG. 3 is an HPLC chromatogram of a sample of nickel electrolyte containing 2, 6-pyridinedicarboxylic acid after a desalting pretreatment, showing that the problem of nickel ion influence on detection is effectively solved after the desalting treatment.

(7) Sample content calculation

And (4) according to the standard curve of the 2, 6-pyridinedicarboxylic acid in the step (4), combining the chromatographic peak area of the 2, 6-pyridinedicarboxylic acid in the step (6), and calculating to obtain the content of the 2, 6-pyridinedicarboxylic acid in the nickel electrolyte.

The invention has the beneficial effects that:

the invention adopts a pretreatment method for removing nickel by hydroxide precipitation, establishes a detection analysis method for measuring 2, 6-pyridinedicarboxylic acid in nickel electrolyte by HPLC, realizes the content detection of 2, 6-pyridinedicarboxylic acid in nickel electrolyte, and solves the problem that the bidentate ligand structure of 2, 6-pyridinedicarboxylic acid is easy to generate complex with nickel ions in the electrolyte to influence the detection. The method is simple to operate, short in analysis time, high in sensitivity, high in accuracy and high in stability, and provides a new technical means for detecting the 2, 6-pyridinedicarboxylic acid in the nickel electrolyte.

Drawings

FIG. 1 is a HPLC chromatogram of a standard solution of 2, 6-pyridinedicarboxylic acid;

FIG. 2 is an HPLC chromatogram of a sample of nickel electrolyte containing 2, 6-pyridinedicarboxylic acid directly injected without desalting treatment;

FIG. 3 is an HPLC chromatogram of a sample of nickel electrolyte containing 2, 6-pyridinedicarboxylic acid after desalting pretreatment.

Detailed Description

The technical means of the present invention will be described in detail below with reference to examples.

The instruments and reagents used in the invention are as follows:

high performance liquid chromatography (Agilent 1100, Agilent corporation, usa); ultraviolet detector (Agilent VWD, Agilent company, usa).

2, 6-pyridine dicarboxylic acid is used as an analytical reagent; acetic acid and methanol are chromatographic grade reagents.

Example 1

(1) Desalination treatment of samples

Taking a nickel electrolyte sample to be detected containing 2, 6-pyridinedicarboxylic acid, adjusting the pH value of the sample to 12 by using 1mol/L sodium hydroxide solution to convert nickel ions into nickel hydroxide precipitate, centrifuging to obtain supernatant, adjusting the pH value to 6.5-7.5 by using 0.5mol/L hydrochloric acid solution, and performing constant volume by using deionized water to obtain a liquid to be detected.

(2) Sample detection

And (3) carrying out high performance liquid chromatography detection on the liquid to be detected to obtain the chromatographic peak area of the 2, 6-pyridinedicarboxylic acid, wherein the chromatographic conditions are as follows:

a chromatographic column: c18(4.6 mm. times.300 mm,5 μm); column temperature: 25 ℃; sample introduction amount: 20 mu L of the solution; flow rate: 1.0m L/min; mobile phase: a is methanol, B is 3% acetic acid solution by mass, and A: B =10: 90; and an ultraviolet detector of 265 nm.

(3) Sample content calculation

According to the standard curve of the 2, 6-pyridinedicarboxylic acid, the content of the 2, 6-pyridinedicarboxylic acid in the nickel electrolyte is calculated by combining the chromatographic peak area y = 2.0722x-24.38 (x is the mass concentration of the 2, 6-pyridinedicarboxylic acid, and y is the chromatographic peak area of the 2, 6-pyridinedicarboxylic acid) of the 2, 6-pyridinedicarboxylic acid, and the content of the 2, 6-pyridinedicarboxylic acid in the sample is 90.68 mg/L.

Example 2

The procedure of example 1 was repeated except that the samples of the nickel electrolyte solution containing 2, 6-pyridinedicarboxylic acid to be tested were different, and the content of 2, 6-pyridinedicarboxylic acid in the samples was 110.25mg/L as determined and analyzed by HPLC.

Example 3

The procedure of example 1 was repeated except that the samples of the nickel electrolyte containing 2, 6-pyridinedicarboxylic acid to be tested were different, and the content of 2, 6-pyridinedicarboxylic acid in the samples was 58.33mg/L as determined by HPLC analysis.