Synthetic acid-base indicators, though widely used, present challenges such as toxicity, environmental hazards, and high cost. This study explores the preparation of eco-friendly pH indicator strips using natural sources including turmeric (Curcuma longa), rose (Rosa indica), beetroot (Beta vulgaris), and red cabbage (Brassica oleracea). Extracts were prepared by aqueous extraction and applied to paper strips to develop natural indicators. The prepared strips were tested on 59 household chemicals and 14 standard pH solutions (pH 1–14). The results demonstrated distinct color variations for acidic, neutral, and basic media. Red cabbage showed a wide color range comparable to universal pH paper, while turmeric, rose, and beetroot exhibited clear differentiation between acids and bases. The study confirms that natural indicators are cost-effective, biodegradable, non-toxic, and suitable alternatives to synthetic indicators for educational and analytical applications.
Bhardwaj et al. (Wed,) studied this question.