Determination of Guanidinoacetic Acid and Impurity Content in Feed Additives by Wanyi Ion Chromatography

This application note describes the use of the Wayeal ion chromatography system for the determination of guanidinoacetic acid and related impurities in feed additives. The primary function of feed additives is to enhance feed performance and increase livestock production efficiency by means of trace-level supplementation.

The composition of feed additives is subject to extremely strict control to ensure safety, efficacy, and regulatory compliance. They must be added in strict accordance with established standards, with precise proportions based on product instructions and animal nutritional requirements. Excessive addition may lead to toxicity, while insufficient addition renders them ineffective. The illegal addition of any substances is strictly prohibited.

According to the Regulations on the Administration of Feeds and Feed Additives, the direct addition of hormones, unapproved chemical substances, and veterinary drug raw materials is strictly prohibited. Quality control of feed is ensured through the testing of both raw materials and finished products. Accurate content determination provides technical data support for enterprises.

Keywords: Ion chromatography, UV detector, Feed additives.

1. Instrument and Reagents

1.1 Ion Chromatograph Configuration List

Table 1 Instrument Configuration List

1.2 Reagents and Standards

Table 2 Reagents and Standards List

1.3 Experiment Material and Auxiliary Equipment

Prefilled Syringe Filter, Hydrophilic, 0.45μm

Syringe (20mL)

2. Experiment Method

2.1 Sample Pretreatment

Accurately weigh 0.2g of the dried sample into a 250mL beaker. Add 100mL of ultrapure water and place the beaker in an ultrasonic bath for 30 minutes. Repeat this extraction procedure 3 to 4 times. Quantitatively transfer the combined extract into a 1000mL volumetric flask, dilute to the mark with ultrapure water, and mix thoroughly. The prepared sample solution is then used both without dilution and after a 10-fold dilution. An appropriate portion of each solution is filtered through a 0.22μm membrane filter before being injected into the instrument for analysis.

2.2 Experiment Condition

Table 3 Chromatographic Condition

3. Experiment Result

3.1 Standards Chromatogram

The aanalysis is completed within 60 minutes, demonstrating good linearity and excellent linear repeatability. The limits of detection (LOD) and quantification (LOQ) are excellent, and sample repeatability is satisfactory, meeting the testing requirements.

Fig1 Overlaid Chromatograms of Calibration Standards

3.2 Linear Range

Appropriate volumes of the standard solutions were taken and diluted to construct calibration curves. The deviation of the linearity test results from the known concentrations was within the maximum permissible deviation. The correlation coefficient (R) was above 0.999 for all analytes, indicating excellent linearity.

Table 4 Linear Ranges for Each Analyte

Fig 2 Linearity Results for Each Analyte

3.3 Linearity Repeatability Test

Fig 3 Overlaid Chromatograms of 8 Consecutive Injections of the Lowest Calibration Standard (S1) for Repeatability Test.

Fig 4 Overlaid Chromatograms of 8 Consecutive Injections of the Mid-Point Calibration Standard (S3) for Repeatability Test

Fig 5 Overlaid Chromatograms of 8 Consecutive Injections of the Highest Calibration Standard (S7) for Repeatability Test

Table 5 Calibration Curve Repeatability Test Data

3.4 Limit of Detection (LOD) Test

Fig 6 hromatogram of the Detection Limit Test for Guanidinoacetic Acid

Table 6 Test Data for the Limit of Detection (LOD) and Limit of Quantification (LOQ) of Guanidinoacetic Acid

3.5 LOD and LOQ Test for Impurities

Fig 7 LOD and LOQ Test for Impurities

Table 7 LOD and LOQ Test Data for Impurities