Carbomer Gelation Indicator for Acid–Base Titration of Colorless, Colored, and Opaque Juice Samples

IF 3 3区农林科学 Q2 FOOD SCIENCE & TECHNOLOGY

Food Analytical Methods Pub Date : 2025-06-18 DOI:10.1007/s12161-025-02828-5

K. P. Khadeeja Thanha, P. Ayisha Sana, C. G. Jincy, U. S. Jijith, K. Pramod

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Abstract

This study explores the feasibility of using carbomer (Carbopol 940) as a novel gelation indicator for acid–base titration, in particular, for colored and opaque samples where traditional visual indicators are ineffective, focusing on the determination of citric acid content in fruit juice. The pH-dependent gelation property of carbomer in alkaline solutions was exploited to visually detect the titration endpoint. The developed method using carbomer gelation as an indicator exhibited strong linearity with an R² value of 0.9983 and demonstrated accuracy with recovery rates near 100%. Precision was confirmed by low percent relative standard deviation (%RSD) values for repeatability and intermediate precision. The method’s detection limit (DL) was 5.83 mg and the quantitation limit (QL) was 17.67 mg. A key finding was the successful application of the carbomer gelation indicator in the analysis of colored citric acid solution and a marketed colored pomegranate juice. Comparison with the traditional phenolphthalein pH indicator method in a colorless lemon juice showed no statistically significant difference in the results (p-value > 0.05), indicating the efficiency of the carbomer method even for colorless matrices. The results suggest that carbomer gelation serves as a cost-effective and reliable visual indicator for acid–base titrations, offering a significant advantage for analyzing colored samples where the color change of conventional indicators is obscured.

Graphical Abstract

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卡波姆凝胶指示剂用于无色、有色和不透明果汁样品的酸碱滴定

本研究探讨了卡波姆（Carbopol 940）作为一种新型凝胶指示剂用于酸碱滴定的可行性，特别是对于传统目测指示剂无效的有色和不透明样品，重点研究了果汁中柠檬酸含量的测定。利用卡波姆在碱性溶液中的ph依赖性胶凝特性来直观地检测滴定终点。该方法以卡波姆胶凝为指标，线性关系良好，R2值为0.9983，准确度接近100%。精密度通过低百分比相对标准偏差（%RSD）值确认重复性和中间精密度。方法检出限（DL）为5.83 mg，定量限（QL）为17.67 mg。一个关键的发现是卡波姆凝胶指示剂在有色柠檬酸溶液和市售有色石榴汁分析中的成功应用。在无色柠檬汁中与传统的酚酞pH指示剂法比较，结果无统计学差异（p值>； 0.05），说明卡波姆法即使对无色基质也是有效的。结果表明，卡波姆凝胶是一种成本效益高、可靠的酸碱滴定视觉指示剂，在分析有色样品时具有显著的优势，而传统指示剂的颜色变化是模糊不清的。图形抽象

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来源期刊

Food Analytical Methods 农林科学-食品科技

CiteScore

6.00

自引率

3.40%

发文量

244

审稿时长

3.1 months

期刊介绍： Food Analytical Methods publishes original articles, review articles, and notes on novel and/or state-of-the-art analytical methods or issues to be solved, as well as significant improvements or interesting applications to existing methods. These include analytical technology and methodology for food microbial contaminants, food chemistry and toxicology, food quality, food authenticity and food traceability. The journal covers fundamental and specific aspects of the development, optimization, and practical implementation in routine laboratories, and validation of food analytical methods for the monitoring of food safety and quality.