Allamanda blanchetii flower extract as an improvised indicator in acid base Titration
Swapna. A. S*, Vishnu M V, Irene V R, Meera T R, Farsana A, Melba Paulson, Joona E
Sanjo College of Pharmaceutical Studies, Chithali Post, Vellapara, Palakkad, Kerala- 678702.
*Corresponding Author E-mail: swapnasurendran88@gmail.com
ABSTRACT:
Nowadays synthetic indicators are the choice of acid - base titrations. But due to environmental pollution, cost and availability, the search for natural compounds as an acid - base indicator was started. The present study was designed to evaluate the juice extracted from flower petals of Allamanda blanchetii (Family: Apocyanaceae) as a titration indicator. A comparative study of Allamanda blanchetii flower juice, a natural indicator, with synthetic indicators like phenolphthalein, methyl orange and neutral red – methylene blue mixed indicators were carried out to evaluate the accuracy of the water extract of the flower as an acid base indicator. Promising results were obtained for Allamanda blanchetii flower extract when compared against standard synthetic indicators. Titration shows sharp colour change at the equivalence point. The equivalence points obtained by the flower extract coincide with the equivalence point obtained by standard indicators. This natural indicator is found to be very useful, economical, simple and accurate for acid base titrations. According to all the evidence obtained after titrimetric analysis, the water extract of the flower shows effective and accurate results as that of synthetic indicators in acid base titrations. The advantage of using natural indicators in titrations is that, they can be prepared freshly and they are economical and ecofriendly.
KEYWORDS: Allamanda blanchetii, Acid-base titration, Phenolphthalein, Methyl orange, Neutral red, Methylene blue.
INTRODUCTION:
Titrimetric analysis refers to quantitative chemical analysis carried out by determining the volume of solution of known concentration which is quantitatively react with the measured volume of analyte solution. Based on the reactions involved titrations are classified into acid-base titration, Complexometric titration precipitation titration and redox titration.
Acid base indicators are large organic molecules that behave as weak acids that can donate hydrogen ions to water molecules to form conjugate bases. The colour change of indicator is depends on the concentration of H+ ions, which is most conveniently expressed using the pH scale. A suitable pH indicator must be chosen in order to detect the endpoint of the titration.
Natural indicators are dues or pigments that can be isolated from a variety of sources, including plants, fungi and algae. Many of the flowers contain a class of organic pigments called anthocyanins that change colour with pH. The advantage of natural indicator is that they are biodegradable thus helps in minimizing the use of synthetic non degradable dyes.[1,2,3]
MATERIALS AND METHODS:
Collection of flower:
The flowers of Allamanda blanchetii were collected from local areas of Palakkad (Kerala) and petals were separated from the flower. Then petals were washed with water to remove dust.
Reagents:
Ammonia, Acetic acid, Hydrochloric acid, Sodium hydroxide, Methyl orange and Phenolphthalein. All reagents used were of analytical grade and were obtained from Nice Chemicals Private Limited, Kochi, Kerala.
Preparation of reagents[4]
Preparation of 0.1M Sodium hydroxide: Dissolve 4.2g of sodium hydroxide in sufficient carbon dioxide-free water to produce 1000ml.
Preparation of 0.1M Hydrochloric acid: Dilute 8.5ml of hydrochloric acid with water to produce 1000ml.
Preparation of 0.1M NH4OH: Dilute 7.5ml of ammonia with water to produce 1000ml.
Preparation of 0.1N CH3COOH: Dilute 5.7ml of concentrated acetic acid with water to produce 1000ml.
Preparation of juice from petals of Allamanda blanchetii:
30g of fresh petals of Allamanda blanchetii were cut into small pieces and macerated with 300ml of water for two hours. Filtered through filter paper and the filtrate is used as indicator.
Identification test for anthocyanin:
0.2g of extract added with 1ml of 2N NaOH and heat it for 5minutes, appearance of bluish green colour.
Confirmation Test for Anthocyanin
1. 1ml of flower extract is added with 2M HCl and heat it for 5minutes, appearance of purple or magenta colour.
2. 1ml extract is added with 2M NaOH, appearance of green colour.
Colour change interval of the indicator at different pH (1-10):
To locate the exact colour change interval of the indicator, buffer solutions of pH 1-10 were prepared. After preparing the solution two drops of the flower extract is added to each test tube having solutions with pH ranging from 1-10. Colour change was observed in each case and results are shown in Figure 2.[10]
Procedure for acid base titration using flower extract and standard indicator:
10ml of titrate with three drops of indicator (Allamanda blanchetii) was titrated against titrants and the colour changes for the indicator is listed in Table 1. 10ml of titrate with standard indicator was titrated against titrant and the results of screening are listed in Table 2.
RESULTS:
Colour change of the indicator at different pH (1-10):
In acidic PH extract of Allamanda blanchetii shows a pink colour and in basic pH shows green colour
Figure 1: Colour change of extract at pH 1-10
Titrations of acids and bases:
10 ml of titrant with two drops of indicator Allamanda blanchetii (A.B.) was titrated against titrates and the colour changes for the indicator is listed in Table 1.
Result of screening for strong acids and bases (HCL x NaOH), Weak acid x Strong base (CH3COOH x NaOH), Weak base x Strong acid (NH4OH x HCl) and Weak base x Strong acid (NH4OH x CH3COOH) are listed in Table 2.
Table 1. Colour change of the flower extract in acid-base titrations.
Titrate |
Indicator |
Colour at Initial point |
Titrant |
Colour at End Point |
|
HCL |
Allamanda blanchetii |
Pink |
NaOH |
Green |
|
CH3COOH |
Allamanda blanchetii |
Pink |
NaOH |
Green |
|
NH4OH |
Allamanda blanchetii |
Green |
HCL |
Pink |
|
NH4OH |
Allamanda blanchetii |
Green |
CH3COOH |
Pink |
Table 2. Titration of acids and bases
|
Sl. No |
Titrant |
Titrate |
Burette reading for Allamanda blanchetii extract |
Burette reading for Standard indicator |
|
1 |
HCl |
NaOH |
10.76 ±0.05 |
10.86 ±0.05 (phenolphthalein) |
|
2 |
CH3COOH |
NaOH |
9.76 ±0.057 |
9.8 ±0.1(phenolphthalein) |
|
3 |
NH4OH |
HCl |
11.83 ±0.057 |
11.76 ±0.115 (Methyl orange) |
|
4 |
NH4OH |
CH3COOH |
11.63 ±0.057 |
11.73 ±0.115 (Neutral red-Methylene blue) |
DISCUSSION:
Natural indicators are the results of ever increasing demand of mankind towards better alternatives, which not only reduces cost but also healthful to the user and on all results obtained by natural indicator is similar to that of available synthetic indicator. Juice obtained from the flowers of Allamanda blanchetii can be used as indicator in all types of acid base titrations. The results obtained in all types of acid base titrations lead us to conclude that the presence of anthocyanins in Allamanda blanchetii may be the reason for the sharp colour changes which had occurred at end point of titration.
CONFLICT OF INTEREST:
The authors declared no conflict of interest.
REFERENCE:
1. Sarita Kadam, Adhik Rao Yadav, Vijay Raje and Karishma Waghmare. Comparative study of natural and synthetic indicators. Der Pharma Chemica, 2013, 5(1):296-299.
2. Harshal Chavan, Prutha Shirodkar, A. S. Dhake, Dr. A.G. Jadhav. Natural indicators as alternative to synthetic acid base indicators. Indo American Journal of Pharmaceutical Sciences 2017; 4 (11): 4078-4082.
3. A.A. Napoleon, Pharmaceutical Analysis Theory and Practical, Kalaimani publishers and Distributors, Tamilnadu, 2012.
4. Indian Pharmacopoeia, 1996, Vol-II, 4th edition, Ministry of Health and Family Welfare, Govt. of India, Controller of Publication, New Delhi, Pages A-147, A-149, A-169 & A-192.
5. E. Vadivel, Shubham D. Chipkar. Eco-friendly natural acid-base indicator properties of four flowering plants from Western Ghats. International Journal of Pharmacy and Pharmaceutical Sciences 2016; 8(6): 250-252.
6. Shivaji H. Burungale and Ankush V. Mali. Natural indicator as a eco-friendly in acid base titration. Journal of Chemical and Pharmaceutical Research, 2014; 6(5):901-903.
7. Bahadori A and Maroufi N G. Volumetric Acid-Base Titration by using of Natural Indicators and Effects of Solvent and Temperature. Austin Chromatography 2016; 3(1): 1041.
8. Sarita Kadam, Adhikrao Yadav, Vijay Raje and Karishma Waghmare. Comparative study of natural and synthetic indicators. Der Pharma Chemica, 2013, 5(1):296-299.
9. Chinmoy Paul, Debarupa D. Chakraborty, Amitava Ghosh, Prithviraj Chakraborty. Natural Indicator as a substitute to Synthetic indicator-A Developmental Approach. Journal of Applied Pharmaceutical Science 2014; 4 (09): 120-122.
10. Pokharna Gaura, Jain Naveen Kuma, Nalwaya Narendra, Chatap V. K. Bougainvillea glabra–A Natural Indicator. Pharmacognosy Journal 2010; 2(5): 25-28.
11. Stanley I. R. Okoduwa, Lovina O. Mbora, Matthew E. Adu, and Ameh A. Adeyi. Comparative Analysis of the Properties of Acid-Base Indicator of Rose (Rosa setigera), Allamanda (Allamanda cathartica), and Hibiscus (Hibiscus rosa-sinensis) Flowers. Biochemistry Research International 2015; 1-4.
12. Manoj A. Suva. Opuntia ficus indica (L.) Fruit Extract as Natural Indicator in Acid-Base Titration. Jouirnal of PharmaSciTech 2014; 3(2): 85-87.
13. Sudarshan Singh, S. B. Bothara and Sangeeta Singh. Acid-Base Indicator Properties of Dyes from Local Flowers: Cassia aungostifolia Linn., Thevetia peruviana (Pers.) K. Schum and Thevetia thvetiodes (Kunth) K. Schum. Pharmacognosy Journal 2011; 3(19): 35-39.
14. Tukiran and Andika Pramudya Wardana. Thunbergia erecta L. Flower as an alternative acid-base Natural Indicators. Rasayan Journal of Chemistry 2018; 11(2): 773-779.
15. Daniel A. Abugri, Ohene B. Apea and Gregory Pritchett. Investigation of a Simple and Cheap Source of a Natural Indicator for Acid-Base Titration: Effects of Synthesis and Conditions on Natural Indicators. Green and Sustainable Chemistry 2012; 2: 117-122.
16. Lavanya D, Guna shekhar G, Purushothom A and Pallavi A. Green Chemistry: A study on acid-base indicator property of various flower pigments. International Journal of Research and Development in Pharmacy and Life Sciences 2018; 6(6): 3155-3163.
17. Daniel A. Abugri, Ohene B. Apea, Gregory Pritchet. Investigation of a Simple and Cheap Source of a Natural Indicator for Acid-Base Titration Effects of System Conditions on Natural Indicators. Green and Sustainable Chemistry, 2012; 2: 117-122.
18. Yogini Bambardekar, Neena Anand, Chirag Gawali and Umesh Varade. Green alternative to Synthetic indicator in acid-base Titrations. Research Journal of Chemical and Environmental Sciences 2015; 3(6): 64-65.
19. P. V. Pavar, P. H. Sharma, P. R. Onkar and J. G. Avari. Beetroot (Beta vulgaris) herbal alternative to synthetic acid base indicator use in titrimetric analysis, Journal of Biochemistry & Pharmacology 2013; 2:4.
20. Garg S, Garg A, Shukla P, Mathew J, Viswakarma D, Sen S. Investigation of plant source of natural indicator of acid-base titration to reduce the use of harmful chemicals in some extent. International Journal of Biology, Pharmacy and allied sciences 2018; 7(1): 64-70.
21. Berhane Alexander, Ahmed Imran, Sahle Tewelde, Hiya Ahmedin, Asgedom Ghebray and Chand Roop. Studies of Eco- friendly natural acid-base pH indicators properties of two flowering plants from Adi-Nifas and Mai-Nefhi Eritrea. Journal of Pharmacognosy and Phytochemistry 2018; 7(5): 1817-1822.
22. Rohit M. Jamdar, Mayur N. Ghotkar, Rohit R. Mahajan, Ranjit S. Jadhav, Ganesh B. Vambhurkar and Pravin P. Honmane. Bauhinia racemosa as Natural pH Indicator. Asian Journal of Pharmaceutical Analysis 2019; 9(2); 89-92.
23. Pramod Kumar Jain, Pushpa Jain and Prajvi Jain Green chemistry: Petal sap of Delonix regia as a substitute for hazardous internal indicators in volumetric analysis, Bioscience Biotechnology Reasearch Communications 2019; 6(2): 186-189.
24. R. L. Jadhav, N. S. Mahajan, N. V. Pimpodkar and C. S. A. Magdum. Use of Eugenia jambolana fruit extract as a natural indicator in acid base titration. International Journal of Chemical Science 2008; 6(2): 637-642.
Received on 07.08.2020 Revised on 05.10.2020
Accepted on 27.11.2020 ©Asian Pharma Press All Right Reserved
Asian J. Pharm. Res. 2021; 11(1):6-8.
DOI: 10.5958/2231-5691.2021.00002.2