INTRODUCTION:

Titrations are the essential chemistry laboratory method used for regular solutions with established concentration for quantitative study with substances of uncertain concentrations Substances which change color when the solution acidity changes are known as acid-base indicators. Indicator is a chemical agent used to measure a substance's acidity and alkalinity. They reveal pH of substance Switching color. These are popular acid dependent indicators that involve blue bromothymol, red methyl, orange methyl, phenolphthalein, and mixed indicators. Indicators are used in the measurement of the end point of titration at a small concentration. The apparent shift in the predictor is typically a shift of color, in certain instances a development or absence of turbidity ^[1]. We use litmus paper in the study of acid base chemistry to determine that a solution is acidic, normal or neutral depending on variations in colour. Both pH markers, such as litmus document, alter colors, based on how protons are contributed or admitted. The pH markers are either acids or bases themselves.^{2, 3}

Natural Indicators are dyes or pigments that can be derived from a broad variety of materials, including plants, fungi and algae. Sir Robert Boyle first mentioned the usage of natural dyes as acid-base markers in his essay collection Experimental History of Colors in 1664 Nevertheless; by utilizing measures for the laboratory analysis of such compounds, Boyle provided a major contribution to the early understanding of acids and bases. Synthetic indicators have some drawbacks such as high expense, scarcity and chemical emissions, and it would be more beneficial to produce natural indicators from different plant parts.⁴

Many plants or portions of the plants produce chemicals from the compound class of naturally colored anthocynins. They are red in acidic water, and essentially brown. Anthocynin can be derived from plant parts, including seeds, fruits, fruit, and roots, using water or other solvents. Through cutting the respective plant parts into tiny sections, usually through driving them, the indicator solutions are prepared through the mixer. Some other organic markers are used to identify the end point of measurement in titration, but these chemical markers are considered to be quite costly and are often inaccessible ^[5,6] and we tried to prepare markers from natural sources like pieces of plates Leaves, and nuts, and bulbs. As these plants are very widespread and readily available, they are considered to be economical as well as the indicator obtained from them. Therefore, the findings reported are the same as for normal indicators.^1,7

MATERIAL AND METHODS:

Glassware’s: Beakers, Petriplates, Conical flask, Burettes, Pipettes, etc.

Chemicals: ammonium hydroxide, Conc. HCL, ammonia, sodium hydroxide, acetic acid, mixed indicator, methyl red indicator, phenolphthalein. All analytical grade chemical reagents were made available by Satara College of Pharmacy, Satara.

Method: Fresh species of dragon fruit have been collected. Collected fruit by slicing blender washed with water, and pulp cut into very small pieces. The juice is also rubbed off with water and ethanol from the resulting most extracts^.[8] More pure pigment of color derived from water. Solution is eventually filtered to exclude peel matter and used as a natural indicator.^4,9]

Experimental work:

Figure No. 1: Procedure for Natural pH Indicator

RESULT AND DISCUSSION:

Table No. 1 Experimental screening of Hylocereus Undatus Pulp extract titration

Titration	Strength	Indicator	*Hylocereus undatus*
Titration	Strength	Indicator	Mean ± SD (n=3)
HCl Vs NaOH	0.1 N	Methyl red	16.46 ± 0.24
	0.1 N	Pulp solution	16.56 ± 0.26
	0.5 N	Methyl red	07.8 ± 0.35
	0.5 N	Pulp solution	08.4 ± 0.13
	1 N	Methyl red	07.6 ± 0.10
	1 N	Pulp solution	07.13 ± 0.25
	5 N	Methyl red	07.83 ± 0.35
	5 N	Pulp solution	07.46 ± 0.46
Hcl Vs NH₄OH	0.1 N	Phenolphthalein	40.36 ± 0.11
	0.1 N	Pulp solution	43.13 ± 0.14
	0.5 N	Phenolphthalein	34.9 ± 0.43
	0.5 N	Pulp solution	33.83 ± 0.37
	1 N	Phenolphthalein	20.7 ± 0.39
	1 N	Pulp solution	21.83 ± 0.48
	5N	Phenolphthalein	17.06 ± 0.35
	5N	Pulp solution	17.53 ± 0.39
CH₃OOH VS Na₄OH	0.1 N	Methyl red	03.8 ± 0.34
	0.1 N	Pulp solution	04.0 ± 0.38
	0.5 N	Methyl red	02.3 ± 0.01
	0.5 N	Pulp solution	02.0 ± 0.02
	1 N	Methyl red	02.9 ± 0.07
	1 N	Peel solution	02.2 ± 0.25
	5 N	Methyl red	02.4 ± 0.02
	5 N	Pulp solution	02.5 ± 0.03
CH3OOH VS NH₄OH	0.1 N	Methyl red	13.9 ± 0.09
	0.1 N	Pulp solution	13.6 ± 0.07
	0.5 N	Methyl red	15.8 ± 0.21
	0.5 N	Pulp solution	15.8 ± 0.21
	1 N	Methyl red	08.4 ± 0.12
	1 N	Pulp solution	08.2 ± 0.10
	0.5 N	Methyl red	14.2 ± 0.22
	0.5 N	Peel soution	14.5 ± 0.26

The dragon fruit Pulp extract was screened for use as an acid base indicator in acid base titration and the results of this screening were compared with the results obtained by standard indicators such as methyl red, phenolphthalein and mixed indicator for a strong acid- (HCl and NaOH), strong acid- base (HCl and NH4OH) And weak acid dependent titrations (CH₃COOH and NaOH) and weak acid-poor base titrations (CH₃COOH and NH₄OH). The equivalence point obtained by the respective natural indicator matched the equivalence points obtained by the regular indicator for all the titrations.

CONCLUSION:

The extract of the Hylocereus undatus pulp is useful for weak acid and weak base titration since it requires the use of mixed indicator, whereas these extracts can be used in these titrations alone. The natural indicators for these titrations are found to be extremely useful, economical, simple and precise. The dragon fruit is a good indicator, but it is not a very appropriate indicator for laboratory experiments as it should be prepared at the time of experiment. It is also impossible to keep the prepared predictor for a long time, as it is a biological sample.

Future Prospects:

The availability and the easy extraction technique with excellent performance and reliable results will make these natural flower and fruit peel indicators an effective replacement for synthetic indicators used in many laboratories and research institutes. In short, the industries, research laboratories, schools and chemical companies that use indicators for the determination of acidity, alkalinity, humidity, degree of reaction and so on would find the preliminary result of this study valuable in the production of efficient indicators from flowers and fruit peel substitutes or the possible replacement of standard indicators.

ACKNOWLEDGEMENT:

Authors thanks to Satara College of Pharmacy, Degaon, Satara and Principal, Dr. Nagesh Aloorkar for providing laboratory and chemicals for this work.

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Received on 06.04.2025 Revised on 10.05.2025

Accepted on 09.06.2025 Published on 12.07.2025

Available online from July 21, 2025

Asian Journal of Pharmaceutical Analysis. 2025; 15(3):203-205.

DOI: 10.52711/2231-5675.2025.00032

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