Validation of oxalate methods for the detection of oxalate in calcium gluconate by ion chromatography

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Validation of oxalate methods for the detection of oxalate in calcium gluconate by ion chromatography

Calcium gluconate is an important organic calcium supplement product, compared to calcium carbonate, which is an inorganic calcium, organic calcium is more easily absorbed by the human body and is more suitable for a wider range of people. One of the main factors affecting the body's calcium absorption is the anionic contaminants in the product, such as oxalate (c2o42-), which combines with calcium to form insoluble calcium oxalate. Therefore, the entry of oxalate into the human body not only affects the absorption of calcium, but also has the hidden danger of causing kidney stones for long-term accumulation. In the preparation process of calcium gluconate, there is usually oxalate formation, and the oxalate content has become one of the important indicators for evaluating the quality of calcium gluconate.

Ion chromatography (ic) is an important analytical testing technique for analyzing various anions and anions, which has the advantages of fast analysis speed, high accuracy, simplicity, and simultaneous separation and detection of multiple ions. Micro-source detection uses advanced ion chromatograph dionex ics5000+, the oxalate content in calcium gluconate is methodologically verified and detected, and the system applicability, exclusivity, detection limit, quantitative limit, linear range, repeatability, intermediate precision, accuracy, solution stability and durability are investigated.

Analytical Methods:

Instrument model: Thermo Fisher Scientific Dionex ics5000+

Anion exchange column: dionex ionpac as4a-sc 4mm*250mm

Eluent solution: na2co3-nahco3 solution

Detector: Reject conductivity detector

Column temperature: 30 °C

Flow rate: 2 ml/min

Injection volume: 50 μl

In the verification project 6, the rsd of oxalate peak area in the photoned solution was 0.27%, and the 7-needle rsd of each module plus the control 6 needles was 0.59%-1.44%. The detection limit and quantitative limit were: the oxalate signal-to-noise ratio in the lod solution was greater than 3, the detection limit was 0.0005%, the oxalate signal-to-noise ratio in the loq solution was greater than 10, the peak area rsd was 2.53, and the quantitative limit was 0.0015%. Oxalate has a good linear relationship in the range of 0.9069~4.5347 μg/ml, and the correlation coefficient r is 0.9960>0.99, which meets the accepted standards. The repeatability and accuracy results were: the recovery rate was 107.9%-109.2%, the rsd was 0.41%, and the recovery rate of oxalate in the accuracy solution ranged from 103.5%-109.0%.

The results of the oxalate residue detection method in calcium gluconate are verified to meet the requirements of the acceptable standards set in the protocol. This method has good linearity, good repeatability, exclusivity and accuracy, and is suitable for the detection of oxalate residues in calcium gluconate.

At the same time, micro-source detection used this method to test two batches of calcium gluconate produced by an enterprise, and the test results were as follows:

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Sample name

Sample lot number

Analyze the project

Analysis results, %

Quantitative limit, %

Calcium gluconate

202110003

Oxalate

0.0020%

0.0015%

202111006

&lt;0.0015%

Reference Method: Chinese Pharmacopoeia 2020 Part IV General Principles 9101 Guiding Principles for Verification of Analytical Methods

Chinese Pharmacopoeia 2020 Part IV General 0513 Ion Chromatography