Determination of Choline Chloride in Choline Chloride·1-Naphthaleneacetic Acid Wettable Powder by NovaChroma IC Column

The choline chloride content is a core indicator of choline chloride wettable powder, directly determining the product's application value and safety. When the content meets the specified standard, it ensures that, as a plant growth regulator, choline chloride effectively promotes the transport of photosynthetic products in crops, enhances stress resistance, optimizes growth morphology, and achieves the expected effects of increasing yield and improving quality. Insufficient content not only fails to achieve the desired effects of growth promotion and lodging resistance but may also lead farmers to blindly increase application rates in pursuit of better results, thereby raising pesticide costs and increasing environmental burden. Conversely, excessive content may cause phytotoxicity to crops, resulting in issues such as leaf burn and growth stagnation. Furthermore, accurate content labeling also reflects product compliance, provides a reliable dosage reference for agricultural production, ensures that farmers apply the product scientifically, and avoids production risks caused by ambiguous ingredient information. Therefore, accurate determination of choline chloride is of great importance.

In this study, the choline chloride wettable powder was tested using a NovaChrom methanesulfonic acid-based cation chromatography column( MS-5C-P1, 4.6 × 250 mm). The testing procedure was straightforward, the results were stable, and the method met the analytical requirements, providing a reference for the determination of choline chloride using ion chromatography.

Keywords: Ion chromatography column; pesticide; choline chloride and 1-naphthaleneacetic acid wettable powder; cation chromatography column; choline chloride.

1. Experiment

1.1 Main Instrument and Reagents

Ion chromatograph: Wayeal ion chromatograph equipped with a conductivity detector and a cation suppressor.

Cation chromatography column: MS-5C-P1, 4.6×250mm;

Cation guard column: MS-5CG, 4×30mm;

Choline chloride standard: known choline chloride mass fraction of 98%;

Disposable syringe (5mL);

Aqueous syringe filter (0.45μm).

1.2 Sample Pretreatment

1.2.1 Preparation of Standard Solution

Weigh 0.0500g of choline chloride standard into a 50mL volumetric flask, add 40mL of ultrapure water, and dissolve by ultrasonic oscillation for 5 minutes. Remove the flask, allow it to cool to room temperature, dilute to the mark with ultrapure water, and mix well. Accurately transfer 5mL of the above solution using a pipette into a 50mL volumetric flask, dilute to the mark with ultrapure water, mix well, and set aside for later use.

1.2.2 Preparation of Test Solution

Weigh 0.3003g of Sample-1 and 0.3000g of Sample-2 into two separate 50mL volumetric flasks. Add 40mL of ultrapure water to each flask, and dissolve by ultrasonic oscillation for 5 minutes. Remove the flasks, allow them to cool to room temperature, dilute to the mark with ultrapure water, and mix well. Accurately transfer 5mL of the above solution using a pipette into a 50mL volumetric flask, dilute to the mark with ultrapure water, mix well, filter, and set aside for later use.

1.3 Instrument Working Condition

Column temperature: 40 °C;
Conductivity cell temperature: 45 °C;
Eluent: 12 mM MSA;
Flow rate: 1.0mL/min;
Injection volume: 10μL.

2. Result and Discussion

2.1 Test of Choline Chloride Standard Solution

Fig 1 Chromatograms of Two Consecutive Injections of Choline Chloride Standard Solution

Table 1 Test Data

2.2 Sample Test

Fig2. Test Chromatogram of Sample-1

Table 2 Test Data of Sample-1

Fig 3 Test Chromatogram of Sample-2

Table 3 Test Data of Sample-2

2.3 Calculation Formula

The peak areas of choline chloride obtained from the two injections of the test solution and from the two injections of the standard solution (one before and one after the test solution) were averaged separately.

ω1: The mass fraction of choline chloride in the test sample, expressed as a percentage (%).

A2: The average peak area of choline chloride in the test solution.

m1: The mass of the choline chloride standard, expressed in grams (g).

ωb1: The mass fraction of choline chloride in the standard, expressed as a percentage (%).

A1: The average peak area of choline chloride in the standard solution.

m2: The mass of the test sample, expressed in grams (g).

2.4 Calculation Result

3. Conclusion

In this study, the choline chloride·1-naphthaleneacetic acid wettable powder was tested using a NovaChrom methanesulfonic acid-based cation chromatography column (MS-5C-P1, 4.6×250 mm), and a Wayeal ion chromatograph. The tailing factor of choline chloride ranged from 1.386 to 1.416, and the retention time was 11.8 minutes. The test results were accurate, with good resolution and high sensitivity, meeting the analytical requirements.