Flame lily as Natural pH Indicator

 

Rohit R. Todkar*, Pallavi B. Patil, Ganesh B. Vambhurkar, Asha M. Jagtap,

Akshata S. Gavade, Nisha M. Jagtap, Asma D. Ambekari, Ankita M. Thorat

Rajarambapu College of Pharmacy, Kasegaon, Dist – Sangli, Maharashtra, India – 415404.

 

ABSTRACT:

The substance which causes change in colour with respect to change in pH of solution is termed as acid-base indicator. At different pH range every indicator shows different range of colors. There are numbers of chemical or synthetic indicators which are used in acid-base titration but these are slight costlier and not available easily every time hence natural indicator i.e. obtained from plant source are come forth, because plants easily available everywhere extraction process is less expensive. We use Flame lily flower extract and phenolphthalein as indicators in titration s of strong acid-strong base (HCl and NaOH), strong acid–weak base (HCl and NH₃), and weak acid-strong base (CH₃COOH and NaOH) and weak acid-weak base (CH₃COOH and NH₃). The result obtained from titration of natural indicator (i.e. Flame lily) are near to the result obtained from titration of standard indicator (i.e. phenolphthalein).in this research work we successfully prove that natural indicator can also used in titration.

 

 

 

INTRODUCTION:

In 1664 by Sir Robert Boyle first time reported the use of natural dyes as acid-base indicator in his collection of essays Experimental History of Colors^[1]. Indicators are may be dyes or pigments, we can isolate them from a variety of sources, like plants, algae and fungi.  Any flower, like, red, pink, yellow, blue or purple in color contains a organic pigment called anthocyanin that change color with change in pH^[2]. Boyle give important contribution in classification of substances according to acid-base theory using acid base indicator but this idea is practiced by earlier medieval painters, to make water colorants they use the dye treated with vinegar and lime water^[3].

 

We see many examples of colour change around us like change in colour of ice tea after addition of lemon juice. In acid base chemistry nature of solution confirmed by change in colour of litmus for acidic blue paper turns in to red, for basic it change red to blue, while in neutral state paper show no colour change. The plant products like tea, red cabbage, grape or turmeric at molecular level react with acid and bases and causes change in colour at different pH levels^[4][5]. the principle of change in colour of solution is depend up on donating or accepting the protons between titrate and titrend (according to protonic theory acids are proton donors and vice versa). after reaction solution reach up to certain ph at that time indicator play important role by change in colour. Numbers of indicators gives only two colours after treating with acid or base, but some shows wide range of colours^[6]. Acid base titration having many applications like to determine the unknown concentration of acid or base by exactly neutralizing the known concentration of acid and base, in qualitative analysis, for quantitative analysis etc^[7]. Change in colour during acid base titration is used to signal the end of acid base titration. Natural indicators prepared from various plant parts like flowers, leaves or fruits are advantageous than synthetic one, because synthetic indicators are costlier than natural also they can causes chemical pollution during manufacturing process^[8][9]. We can use some common flower pigments in acid base titration as an indicator for example, Red rose, Hibiscus Rosa sinensis^[10], Copper leaf, Clitoria ternetea^[11].

 

Medicinal Uses of Gloriosa superba (Flame lily). Gloriosa superba (Flame lily) complete detail. Habit and habitat of Gloriosa superba (Flame lily). Flame lily is a perennial tuberous climbing herb. They prefer tropical forest. It is a beautiful ornamental plant. Flame lily is the National flower of Zimbabwe. The length of flame lily is between 3 to 6 meters, and trained at 1.5 meter above the ground level. The stem is leafy. The color of flower is ranging from red with yellow margins to very pale yellow forms with a mauve or purple stripe, pale white forms also occur.

 

Flowers are 6 to 10 cm long, and 1 to 2.5 cm wide. The pedicel be up to 20 cm long. Flower has 6 stamens, the length of stamens is between 3 to 4 cm, and each bears a large anther at the tip that drops large amounts of yellow pollen. The fruit is a large, oblong capsule, 6 to 12 cm long, and containing about 20 globose red colored seeds in each valve. Flame lily has many medicinal properties like colchicine, gloriosine, pungent, bitter, acrid, heating, anthelmintic, laxative, alexiteric, abortifacient etc. Flame lily also used as a tonic, anti-periodic, anti- helminthic, anthelmintic, and laxative. The tuber has commonly been used as a suicidal agent among women in rural areas and it has also been used for homicide. The flowers are used in religious ceremonies.

 

 

Fig. 1: Flame lily

 

MATERIAL AND METHOD:

Collection and authentification of flowers:

The flowering plant of Flame lily flower collected from the sangli district region, Maharashtra. And authenticated from Kusumtai Rajarambapu Patil College, Islampur.

 

 

 

Extraction of flowers:

Collected flowers of Flame lily flower washed with distilled water and cut in to small pieces by using Sharpe blade. Then pigments are extracted by the maceration process using ethanol as solvent, pieces of petals are soaked into the ethanol for overnight. Then solution of pigment is filtered to remove the remaining flower matter (petals) from solution and used as natural indicator.

 

Chemicals:

Conc. HCl, Sodium hydroxide, ammonia, acetic acid, phenolphthalein indicator. All reagents of analytical grade were available by Rajarambapu College of Pharmacy, Kasegaon.

 

Glassware’s:

pH meter, conical flask (100 ml), burettes (50 ml), pipettes (10 ml), test tube etc.

 

Method:

Method for screening of Flame lily flower:

Screening of Flame lily flower was done by carry out various titrations between strong acid-strong base (HCl Vs NaOH), strong acid–weak base (HCl Vs NH₃), and weak acid-strong base (CH₃COOH Vs NaOH) and weak acid-weak base (CH₃COOH Vs NH₃) each having strength 1M, and using both flower extract and phenolphthalein as indicator. At the end of titration change in color with respect to change in pH is determined.

 

Method for experimental screening of Flame lily flower:

Experimental screening of flame lily flower was done by carry out various titrations between strong acid-strong base (HCl Vs NaOH), strong acid–weak base (HCl Vs NH₃), and weak acid-strong base (CH₃COOH Vs NaOH) and weak acid-weak base (CH₃COOH Vs NH₃) each having strength 0.1N, 0.5 N, 1N and 1.5N. In each titration 10ml of acid is diluted with 20ml of distilled water in volumetric flask and 2-3 drops of flower extract and phenolphthalein is taken as indicator in respective titration then volume required for color change (i.e. end point) was taken.

 

Table 1- Screening of Flame lily flower

Titrant	Titrand	Indicator colour change (pH range)
		Standard	Flower extract
HCl	NaOH	Green to Pink (4.2-6.0)	Pink to Greenish (2.9-6.4)
HCl	NH3	Pink to Colourless (6.3-7.5)	Pink to Greenish (3.9-7.4)
CH3COOH	NaOH	Green to Pink (4.4-6.2)	Pink to Greenish (4.7-5.5)
CH3COOH	NH3	Pink to Colourless (4.2-6.0)	Pink to Greenish (4.5-5.7)

 

 

 

Table-2: Experimental screening of Flame lily flower

Titration	Strength	Indicator	Flame lily
			Mean ±SD(n=5)
HCl Vs NaOH	0.1	Phenolphthalein	8.04±0.15
		Flower extract	8.01±0.10
	0.5	Phenolphthalein	7.70±0.28
		Flower extract	7.18±0.72
	1.0	Phenolphthalein	6.98±0.12
		Flower extract	6.14±0.34
	1.5	Phenolphthalein	6.96±0.21
		Flower extract	6.64±0.33
HCl Vs NH3	0.1	Phenolphthalein	12.98±0.21
		Flower extract	12.04±0.16
	0.5	Phenolphthalein	25.83±0.20
		Flower extract	24.44±0.40
	1.0	Phenolphthalein	26.31±0.24
		Flower extract	25.10±0.30
	1.5	Phenolphthalein	26.11±0.10
		Flower extract	25.20±0.30
CH3COOH Vs NaOH	0.1	Phenolphthalein	7.60±0.31
		Flower extract	8.30±0.20
	0.5	Phenolphthalein	7.91±0.30
		Flower extract	6.80±0.20
	1.0	Phenolphthalein	7.90±0.14
		Flower extract	6.60±0.21
	1.5	Phenolphthalein	7.80±0.01
		Flower extract	6.60±0.34
CH3COOH Vs NH3	0.1	Phenolphthalein	25.12±0.20
		Flower extract	25.50±0.90
	0.5	Phenolphthalein	26.01±0.20
		Flower extract	24.32±0.21
	1.0	Phenolphthalein	24.10±0.20
		Flower extract	24.60±0.20
	1.5	Phenolphthalein	23.30±0.20
		Flower extract	23.00±0.12

 

RESULT AND DISCUSSION:

The screening of flame lily flower extract is done for use as natural indicator in acid base titration and these obtained result from screening was compared with result obtained from standard indicator such as phenolphthalein for strong acid-strong base (HCl and NaOH), strong acid–weak base (HCl and NH₃), and weak acid-strong base (CH₃COOH and NaOH) and weak acid-weak base (CH₃COOH and NH₃) titrations. The result obtained from titration of natural indicator (i.e. Flame lily flower extract) are near to the result obtained from titration of standard indicator (i.e. phenolphthalein).

 

CONCLUSION:

The natural indicator (i.e. extract Flame lily flower) is beneficial because this natural indicator gives end point upon slight change in pH as earlier as compare to standard indicator (i.e. phenolphthalein), we can use these natural indicator alone in such acid-base titration. Hence this natural indicator economical and very useful as compare to synthetic one.

 

ACKNOWLEDGEMENT:

Authors are highly Acknowledge the help of laboratory staff of Rajarambapu College of Pharmacy, Kasegaon. For providing necessary equipment required for research work. Also we are highly Acknowledge the help and guidance of Dr. M. A. Bhutkar.

 

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Received on 28.11.2018       Accepted on 21.01.2019     

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Asian J. Pharm. Ana. 2019; 9(1):05-07.