Ixora Chinensis Flower Extract Natural Indicator
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Int. J. Chem. Sci.: 7(1), 2009, 219-224
USE OF IXORA CHINENSIS FLOWER EXTRACT AS A NATURAL INDICATOR IN ACID BASE TITRATION R. L. JADHAV∗, N. S. MAHAJAN, N. V. PIMPODKAR, S. B. GARJE and P. P. KARANDE Department of Pharmaceutical Chemistry, Satara College of Pharmacy, SATARA - 415 004 (M. S.) INDIA
ABSTRACT The Red Ixora is found in the wild and is cultivated in the gardens too. The flowers of this shrub are used in the worship of some deities and in folk medicine. The present work highlights the use of Ixora flower extract as acid base indicator in different types of acid base titrations. The equivalence points obtained by the flower extract are coincident with the equivalence points obtained by standard indicators. In case of weak acid and weak base titration, the results obtained by the flower extract matched with the results obtained by mixed indicator. This natural indicator is found to be very useful, economical, simple and accurate for said titration. Key words : Ixora chinensis, Acid base indicator, Natural indicator, Ixora flower.
INTRODUCTION Ixora is a genus from the family Rubiaceae, consisting of tropical evergreens and shrubs. Though native to tropical areas in Asia, especially India, Ixora now grows commonly in tropical climates in the USA, such as Florida. Ixora is also commonly known as West Indian Jasmine. Plants possess leathery leaves, ranging from 3 to 6 inches in length, and produce large clusters of tiny flowers in the summer1-4. There are about 400 species spread from Africa to India to Southern Asia. For red color, Ixora is popular in warm South Florida with blooms all year long, but maximum beauty is from late spring through the early winter months, peaking in the hot months5. The juice of the flower is useful in dysentery and also used on sores, chronic ulcers and scabies6. Ixora genus consists of flavone glycoside chrysin-5-o-xylopyranoside isolated from ∗
Author for correspondence; Email : [email protected]
220
R. L. Jadhav et al.: Use of Ixora Chinensis….
stems. Aerial parts afforded 6,7-dimethoxy coumarin whereas ceryl alcohol, β-sitosterol, cysteine, serine, glycine, proline and aspartic acid isolated from seeds7. Chinese Ixora flowers mainly consist of flavonoids and anthocyanins8. As flavonoids, anthocyanins are present in flowers of Ixora chinensis and are pH sensitive9. It has been hypothesized that the flower extract could be utilized as an indicator for different types of acid base titrations.
EXPERIMENTAL Material and methods Analytical grade reagents were made available by Satara College of Pharmacy, Satara. Reagents and volumetric solutions were prepared as per standard methods10, 11. The Ixora chinensis flowers were collected from plants growing in the hilly region of Satara and authenticated from Department of Botany, Yashwantrao Chavan College of Science, Satara. The selected flowers were collected. The fresh petals were cut into small pieces and were kept at –20°C. For the freeze-dried petals, those of the selected flowers were freeze-dried to minimize oxidative loss before grinding into fine powder with a mechanical blender12. The resulting powder was then extracted with methanolic hydrochloric acid, when the anthocyanins were converted into their corresponding soluble chlorides. From this solution, anthocyanins were isolated by using ether9. Finally extract was filtered and used as indicator. The anthocyanins isolated by this method were confirmed by using various characteristic tests13. The experiments were carried by using the same set of glasswares for all type of titrations. As the same aliquots were used for both titrations i.e. titration by using standard indicators and flower extract, the reagent were not calibrated. The equimolar titrations were performed using 10 mL of titrant with three drops of indicator. All the parameters for experiment are given in Table 1. A set of five experiments was carried out and mean and standard deviation were calculated from results.
RESULTS AND DISCUSSION The flower extract was screened for its use as an acid base indicator in various acid base titrations, and the results of this screening was compared with the results obtained by standard indicators methyl red, phenolphthalein and mixed indicator (methyl orange :
221
Int. J. Chem. Sci.: 7(1), 2009
bromocresol green) (0.1 : 0.2)] for strong acid v/s strong base (HCl and NaOH), strong acid v/s weak base (HCl and NH4OH), weak acid v/s strong base (CH3COOH and NaOH), and weak acid v/s weak base (CH3COOH and NH4OH) titrations, respectively14. All these parameters are shown in Table 1. Table 1. Parameters used for analysis and the comparison of color change Titrand
Titrant
HCl
Indicator color change Standard (pH range)
Flowers extract (pH range)
NaOH
Red to Yellow (3.8 - 8.8)
Green to Colorless (4 - 8)
HCl
NH4OH
Colorless to Pink (3.5 - 8)
Green to Colorless (4 - 8)
CH3COOH
NaOH
Colorless to Pink (4.5 - 9)
Green to Colorless (5 - 9)
CH3COOH
NH4OH
Orange to Blue-green (4.5 - 7.8)
Green to Colorless (5 - 8)
HCl: - Hydrochloric acid, NaOH: - Sodium hydroxide, NH4OH: - Ammonium hydroxide.CH3COOH: - Acetic acid. For all titrations, the equivalence points obtained by the flower extract matched with the equivalence points obtained by the standard indicators. The results of screening are listed in Table 2. Table 2. Results of screening Sr. No.
Titration (Titrant v/s Titrand)
Strength in Moles
1
NaOH v/s HCl
0.1
0.5
1.0
Indicator
Mean ± S.D.
Methyl red
10.2 ± 0.13
Flower extract
10.1 ± 0.19
Methyl red
10.3 ± 0.13
Flower extract
10.2 ± 0.16
Methyl red
10.1 ± 0.15
Flower extract
10.0 ± 0.08 Cont…
222
R. L. Jadhav et al.: Use of Ixora Chinensis….
Sr. No.
Titration (Titrant v/s Titrand)
Strength in Moles
Indicator
Mean ± S.D.
2
HCl v/s NH4OH
0.1
Phenolphthalein
5.3 ± 0.16
Flower extract
5.1 ± 0.25
Phenolphthalein
5.2 ± 0.15
Flower extract
5.1 ± 0.17
Phenolphthalein
5.4 ± 0.08
Flower extract
5.3 ± 0.09
Methyl red
10.6 ± 0.05
Flower extract
10.7 ± 0.22
Methyl red
10.5 ± 0.13
Flower extract
10.6 ± 0.18
Methyl red
10.3 ± 0.12
Flower extract
10.2 ± 0.13
Mixed indicator
4.8 ± 0.23
Flower extract
4.9 ± 0.27
Mixed indicator
4.7 ± 0.20
Flower extract
4.9 ± 0.28
Mixed indicator
4.8 ± 0.12
Flower extract
4.8 ± 0.19
0.5
1.0
3
CH3COOH V/S NaOH
0.1
0.5
1.0
4
CH3COOH V/S NH4OH
0.1
0.5
1.0
HCl: - Hydrochloric acid, NaOH: - Sodium hydroxide, NH4OH: - Ammonium hydroxide.CH3COOH: - Acetic acid, S.D.: - Standard deviation.
CONCLUSION For all titrations, the equivalence points obtained by the flower extract are
223
Int. J. Chem. Sci.: 7(1), 2009
coincident with the equivalence point obtained by standard indicator, while in case of weak acid and weak base titration, the results obtained by the flower extract matched with the results obtained by standard indicator. But it was noted that if we decreased the strength of weak acid and weak base, the sharpness of color change was also deceased. The Ixora flower extract is beneficial for weak acid and weak base titration because it involves use of mixed indicator, while the flower extract can be used alone in such titrations. Other benefit of this titration is that it gives colorless end point at the equivalence point. If we add more amount of titrant (base), it gives greenish yellow colored solution. This natural indicator is found to be very useful, economical, simple and accurate for these titrations.
REFERENCES 1.
V. Swarup, Garden Flowers, National Book Trust, New Delhi (1997) p. 6-7.
2.
A. B. Rendle, The Classification of Flowering Plants, Vol II, 2nd Edition, Cambridge Univ. Press (1959) p. 560.
3.
Gymnosperms and Monocotyledons, Vikas Publishing House, pp. 337-339.
4.
P. Shulka and S. P. Misra, An Introduction to Taxonomy of Angiosperms, Vikas Publishing House, New Delhi (1994) p. 363.
5.
N. S. Subrahmanyam, Laboratory Manual of Plant Taxonomy, Vikas Publishing House, New Delhi (1996) p. 359, 409, 563, 609.
6.
http://en.wikipendia.org/wiki/plant
7.
http://mgonline.com/gardenia.htm
8.
R. P. Rastogi and B. N. Mehrotra, Compendium of Indian Medicinal Plants, Vol. IV, CDRI, Lucknow and NISC, New Delhi (2002) pp. 406-407.
9.
G. R. Chatwal, Organic Chemistry of Natural Products, Vol II, 4th Edition, Himalaya Publishing House (2007) p. 2.38-2.40.
10. G. H. Jaffrey, J. Bassett, R. C. Denny and J. Mendham, Vogel’s Textbook of Quantitative Chemical Analysis, 5th Edition, ELBS, Longman Group, England (1996) p. 262. 11. Government of India, Ministry of Health Family Welfare, Indian Pharmacopoeia, Vol II, Controller of Publications, Delhi (1996) p. A-208.
224
R. L. Jadhav et al.: Use of Ixora Chinensis….
12. J. Tinoi, N. Rakariyatham, R. L. Deming, Determination of Major Carotenoid Constituents in Petal Extracts of Eight Selected Flowering Plants in the North of Thailand, Chiang Mai J. Sci., 33(2), 327 – 334 (2006). 13. I. L. Finar, Organic Chemistry: Stereochemistry and the Chemistry of Natural Products, Vol II, 5th Edition, ELBS Publication (1975) pp. 769-771. 14. http://en.wikipedia.org/wiki/PH_indicator. Revised : 25.10.2008
Accepted : 01.11.2008
USE OF IXORA CHINENSIS FLOWER EXTRACT AS A NATURAL INDICATOR IN ACID BASE TITRATION R. L. JADHAV∗, N. S. MAHAJAN, N. V. PIMPODKAR, S. B. GARJE and P. P. KARANDE Department of Pharmaceutical Chemistry, Satara College of Pharmacy, SATARA - 415 004 (M. S.) INDIA
ABSTRACT The Red Ixora is found in the wild and is cultivated in the gardens too. The flowers of this shrub are used in the worship of some deities and in folk medicine. The present work highlights the use of Ixora flower extract as acid base indicator in different types of acid base titrations. The equivalence points obtained by the flower extract are coincident with the equivalence points obtained by standard indicators. In case of weak acid and weak base titration, the results obtained by the flower extract matched with the results obtained by mixed indicator. This natural indicator is found to be very useful, economical, simple and accurate for said titration. Key words : Ixora chinensis, Acid base indicator, Natural indicator, Ixora flower.
INTRODUCTION Ixora is a genus from the family Rubiaceae, consisting of tropical evergreens and shrubs. Though native to tropical areas in Asia, especially India, Ixora now grows commonly in tropical climates in the USA, such as Florida. Ixora is also commonly known as West Indian Jasmine. Plants possess leathery leaves, ranging from 3 to 6 inches in length, and produce large clusters of tiny flowers in the summer1-4. There are about 400 species spread from Africa to India to Southern Asia. For red color, Ixora is popular in warm South Florida with blooms all year long, but maximum beauty is from late spring through the early winter months, peaking in the hot months5. The juice of the flower is useful in dysentery and also used on sores, chronic ulcers and scabies6. Ixora genus consists of flavone glycoside chrysin-5-o-xylopyranoside isolated from ∗
Author for correspondence; Email : [email protected]
220
R. L. Jadhav et al.: Use of Ixora Chinensis….
stems. Aerial parts afforded 6,7-dimethoxy coumarin whereas ceryl alcohol, β-sitosterol, cysteine, serine, glycine, proline and aspartic acid isolated from seeds7. Chinese Ixora flowers mainly consist of flavonoids and anthocyanins8. As flavonoids, anthocyanins are present in flowers of Ixora chinensis and are pH sensitive9. It has been hypothesized that the flower extract could be utilized as an indicator for different types of acid base titrations.
EXPERIMENTAL Material and methods Analytical grade reagents were made available by Satara College of Pharmacy, Satara. Reagents and volumetric solutions were prepared as per standard methods10, 11. The Ixora chinensis flowers were collected from plants growing in the hilly region of Satara and authenticated from Department of Botany, Yashwantrao Chavan College of Science, Satara. The selected flowers were collected. The fresh petals were cut into small pieces and were kept at –20°C. For the freeze-dried petals, those of the selected flowers were freeze-dried to minimize oxidative loss before grinding into fine powder with a mechanical blender12. The resulting powder was then extracted with methanolic hydrochloric acid, when the anthocyanins were converted into their corresponding soluble chlorides. From this solution, anthocyanins were isolated by using ether9. Finally extract was filtered and used as indicator. The anthocyanins isolated by this method were confirmed by using various characteristic tests13. The experiments were carried by using the same set of glasswares for all type of titrations. As the same aliquots were used for both titrations i.e. titration by using standard indicators and flower extract, the reagent were not calibrated. The equimolar titrations were performed using 10 mL of titrant with three drops of indicator. All the parameters for experiment are given in Table 1. A set of five experiments was carried out and mean and standard deviation were calculated from results.
RESULTS AND DISCUSSION The flower extract was screened for its use as an acid base indicator in various acid base titrations, and the results of this screening was compared with the results obtained by standard indicators methyl red, phenolphthalein and mixed indicator (methyl orange :
221
Int. J. Chem. Sci.: 7(1), 2009
bromocresol green) (0.1 : 0.2)] for strong acid v/s strong base (HCl and NaOH), strong acid v/s weak base (HCl and NH4OH), weak acid v/s strong base (CH3COOH and NaOH), and weak acid v/s weak base (CH3COOH and NH4OH) titrations, respectively14. All these parameters are shown in Table 1. Table 1. Parameters used for analysis and the comparison of color change Titrand
Titrant
HCl
Indicator color change Standard (pH range)
Flowers extract (pH range)
NaOH
Red to Yellow (3.8 - 8.8)
Green to Colorless (4 - 8)
HCl
NH4OH
Colorless to Pink (3.5 - 8)
Green to Colorless (4 - 8)
CH3COOH
NaOH
Colorless to Pink (4.5 - 9)
Green to Colorless (5 - 9)
CH3COOH
NH4OH
Orange to Blue-green (4.5 - 7.8)
Green to Colorless (5 - 8)
HCl: - Hydrochloric acid, NaOH: - Sodium hydroxide, NH4OH: - Ammonium hydroxide.CH3COOH: - Acetic acid. For all titrations, the equivalence points obtained by the flower extract matched with the equivalence points obtained by the standard indicators. The results of screening are listed in Table 2. Table 2. Results of screening Sr. No.
Titration (Titrant v/s Titrand)
Strength in Moles
1
NaOH v/s HCl
0.1
0.5
1.0
Indicator
Mean ± S.D.
Methyl red
10.2 ± 0.13
Flower extract
10.1 ± 0.19
Methyl red
10.3 ± 0.13
Flower extract
10.2 ± 0.16
Methyl red
10.1 ± 0.15
Flower extract
10.0 ± 0.08 Cont…
222
R. L. Jadhav et al.: Use of Ixora Chinensis….
Sr. No.
Titration (Titrant v/s Titrand)
Strength in Moles
Indicator
Mean ± S.D.
2
HCl v/s NH4OH
0.1
Phenolphthalein
5.3 ± 0.16
Flower extract
5.1 ± 0.25
Phenolphthalein
5.2 ± 0.15
Flower extract
5.1 ± 0.17
Phenolphthalein
5.4 ± 0.08
Flower extract
5.3 ± 0.09
Methyl red
10.6 ± 0.05
Flower extract
10.7 ± 0.22
Methyl red
10.5 ± 0.13
Flower extract
10.6 ± 0.18
Methyl red
10.3 ± 0.12
Flower extract
10.2 ± 0.13
Mixed indicator
4.8 ± 0.23
Flower extract
4.9 ± 0.27
Mixed indicator
4.7 ± 0.20
Flower extract
4.9 ± 0.28
Mixed indicator
4.8 ± 0.12
Flower extract
4.8 ± 0.19
0.5
1.0
3
CH3COOH V/S NaOH
0.1
0.5
1.0
4
CH3COOH V/S NH4OH
0.1
0.5
1.0
HCl: - Hydrochloric acid, NaOH: - Sodium hydroxide, NH4OH: - Ammonium hydroxide.CH3COOH: - Acetic acid, S.D.: - Standard deviation.
CONCLUSION For all titrations, the equivalence points obtained by the flower extract are
223
Int. J. Chem. Sci.: 7(1), 2009
coincident with the equivalence point obtained by standard indicator, while in case of weak acid and weak base titration, the results obtained by the flower extract matched with the results obtained by standard indicator. But it was noted that if we decreased the strength of weak acid and weak base, the sharpness of color change was also deceased. The Ixora flower extract is beneficial for weak acid and weak base titration because it involves use of mixed indicator, while the flower extract can be used alone in such titrations. Other benefit of this titration is that it gives colorless end point at the equivalence point. If we add more amount of titrant (base), it gives greenish yellow colored solution. This natural indicator is found to be very useful, economical, simple and accurate for these titrations.
REFERENCES 1.
V. Swarup, Garden Flowers, National Book Trust, New Delhi (1997) p. 6-7.
2.
A. B. Rendle, The Classification of Flowering Plants, Vol II, 2nd Edition, Cambridge Univ. Press (1959) p. 560.
3.
Gymnosperms and Monocotyledons, Vikas Publishing House, pp. 337-339.
4.
P. Shulka and S. P. Misra, An Introduction to Taxonomy of Angiosperms, Vikas Publishing House, New Delhi (1994) p. 363.
5.
N. S. Subrahmanyam, Laboratory Manual of Plant Taxonomy, Vikas Publishing House, New Delhi (1996) p. 359, 409, 563, 609.
6.
http://en.wikipendia.org/wiki/plant
7.
http://mgonline.com/gardenia.htm
8.
R. P. Rastogi and B. N. Mehrotra, Compendium of Indian Medicinal Plants, Vol. IV, CDRI, Lucknow and NISC, New Delhi (2002) pp. 406-407.
9.
G. R. Chatwal, Organic Chemistry of Natural Products, Vol II, 4th Edition, Himalaya Publishing House (2007) p. 2.38-2.40.
10. G. H. Jaffrey, J. Bassett, R. C. Denny and J. Mendham, Vogel’s Textbook of Quantitative Chemical Analysis, 5th Edition, ELBS, Longman Group, England (1996) p. 262. 11. Government of India, Ministry of Health Family Welfare, Indian Pharmacopoeia, Vol II, Controller of Publications, Delhi (1996) p. A-208.
224
R. L. Jadhav et al.: Use of Ixora Chinensis….
12. J. Tinoi, N. Rakariyatham, R. L. Deming, Determination of Major Carotenoid Constituents in Petal Extracts of Eight Selected Flowering Plants in the North of Thailand, Chiang Mai J. Sci., 33(2), 327 – 334 (2006). 13. I. L. Finar, Organic Chemistry: Stereochemistry and the Chemistry of Natural Products, Vol II, 5th Edition, ELBS Publication (1975) pp. 769-771. 14. http://en.wikipedia.org/wiki/PH_indicator. Revised : 25.10.2008
Accepted : 01.11.2008
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