|Year : 2014 | Volume
| Issue : 3 | Page : 316-324
Standardization of Shodhita Naga with special reference to thermogravimetry and infra-red spectroscopy
Dhirajsingh S Rajput1, Biswajyoti Patgiri2, Vinay J Shukla3
1 Department of Rasashastra and Bhaishajya Kalpana, Ashwin Rural Ayurved College, Ashwi BK, Sangamner, Maharashtra, India
2 Department of Rasashastra and Bhaishajya Kalpana, Institute for Post Graduate Teaching and Research in Ayurveda, Gujarat Ayurved University, Jamnagar, Gujarat, India
3 Pharmaceutical Chemistry Laboratory, Institute for Post Graduate Teaching and Research in Ayurveda, Gujarat Ayurved University, Jamnagar, Gujarat, India
|Date of Web Publication||20-Mar-2015|
Dhirajsingh S Rajput
Lecturer, Department of RS and BK, Ashwin Rural Ayurved College, Manchi Hill, Ashwi BK, Tal - Sangamner, Dist - Ahmedanagar, Maharashtra - 413 714
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: Standardization of Ayurvedic medicine is the need of hour to obtain desired quality of final product. Shodhana literally means purification, is the initial step to make drugs like metals, minerals and poisonous herbs suitable for further procedure. Shodhana of metals/minerals help to expose maximum surface area of drug for chemical reactions and also in impregnation of organic materials and their properties in the drug. Thermo-gravimetric analysis (TGA) facilitates in identifying the presence of organic matter and change in the melting point of metal whereas Fourier transform infra-red spectroscopy (FTIR) assists in identifying the presence of various functional groups. Aim: To standardize the process of Naga Shodhana and to study the change in chemical nature of Shodhita Naga in each media through TGA and FTIR. Material and Methods: Samanya and Vishesha Shodhana of Naga was carried out. Time taken for melting of Naga, physico-chemical changes in media used for Shodhana and weight changes after Shodhana were recorded. Samples of Naga were collected after Shodhana in each media for TGA and FTIR analysis. Results: Average loss occurred during Shodhana was 6.26%. Melting point of Ashuddha Naga was 327.46°C, and it was 328.42°C after Shodhana. Percentage purity of Naga (percentage of lead in Naga) decreased after Shodhana from 99.80% to 99.40%. FTIR analysis of Shodhita Naga in each sample showed stretching vibrations particularly between C-H and C-N bonds that are indicating the presence of various organic compounds. Conclusion: According to TGA and FTIR analysis, Shodhana process increases melting point of Naga and initiation of new physico-chemical properties which are indicated by detection of large number of functional groups and organo-metallic nature of Shodhita Naga.
Keywords: Fourier transform infra-red spectroscopy, Naga, Shodhana, standardization, thermo-gravimetric analysis
|How to cite this article:|
Rajput DS, Patgiri B, Shukla VJ. Standardization of Shodhita Naga with special reference to thermogravimetry and infra-red spectroscopy. AYU 2014;35:316-24
|How to cite this URL:|
Rajput DS, Patgiri B, Shukla VJ. Standardization of Shodhita Naga with special reference to thermogravimetry and infra-red spectroscopy. AYU [serial online] 2014 [cited 2022 Aug 11];35:316-24. Available from: https://www.ayujournal.org/text.asp?2014/35/3/316/153754
| Introduction|| |
Rasashastra consists of study of Mercury along with a number of metals, minerals, gems, many plants and animals products. In Rasashastra, thousands of medicinal formulations are mentioned, which contain incinerated metals/minerals as essential and major ingredients. As, metals/minerals contains toxic properties, they are to be subjected to specified classical procedure that remove some of the physical and chemical impurities. These processes also help to potentiate the therapeutic property of metal/mineral. Shodhana literally means "purification" or "to purify" is one such method in which metals/minerals are processed with specific liquid media and involves procedures like Swedana (boiling), Mardana (trituration) etc.  In other words Shodhana is the process of detoxification, which involves application of various unit operative procedures like mixing, grinding, heating etc., to minimize or remove the toxic properties and to impart desired qualities in the material.
Samanya (general) and Vishesha (special) Shodhana methods have been explained in classics. Samanya Shodhana is conducted by sequential quenching of heated metal/mineral in liquid medias like Tila Taila (sesame oil), Takra (butter milk), Kanji (fermented sour gruel), Gomutra (cow urine) and Kulattha Kwatha (decoction of seeds of Dolichos biflorus Linn);  while for Vishesha Shodhana different medias are preferred for different metals/minerals. But, the effect of Shodhana procedure on the chemical properties of metal is not clearly known. Naga (lead) was selected for present work and an attempt has been made to study the effect of each media on Naga through thermogravimetry and Fourier transform infra-red spectroscopy (FTIR).
| Materials and Methods|| |
Ashuddha Naga (raw lead), Tila Taila, Takra, Gomutra, Kanji, seeds of Kulattha, and Churnodaka (lime water) were used as raw materials. Ashuddha Naga was collected from Pharmacy, Gujarat Ayurved University, Jamnagar and authenticated as per the qualities mentioned in classical texts.  Tila Taila, Gomutra and Kulattha seeds were procured from the local market. Takra, Kanji, Kulattha Kwatha and Churnodaka were prepared by adopting the reference of Sushurata Samhita Parada Vigyaniya,  Sharangadhara Samhita and Rasatarangini respectively.
Ashuddha Naga (3 kg) was collected, divided into three equal batches and subjected for both Samanya and Vishesha Shodhana. Samanya Shodhana was carried out by quenching molten lead thrice in Tila Taila, Takra, Kanji, Gomutra and Kulattha Kwatha respectively.  Each time 2 l of fresh liquid was taken. Vishesha Shodhana was done by quenching molted Naga in Churnodaka for 7 times.  For thermo-gravimetric analysis (TGA) and FTIR, 30 g of sample was separated after completing Shodhana in each media. Analysis of all liquid medias was done immediately after the process.
For Samanya Shodhana of Naga 2 l of Tila Taila was taken in Pithara Yantra (a specially prepared iron vessel with a lid having a central hole of 2 cm in diameter). Ashuddha Naga was heated in an iron ladle and the molten metal was quenched in Tila Taila. After 5 min, Naga was collected. This process of quenching in Tila Taila for two more times using fresh Taila. Similar quenchings were continued in further liquids viz., Takra, Kanji, Gomutra and Kulattha Kwatha. Vishesha Shodhana of Naga (VSN) was done by 7 times quenching in Churnodaka. For each batch and for each quenching 2 l fresh Churnodaka was utilized. Caution was taken to prevent physical injury while quenching due to bumping of molten Naga.
Required equipments with specification
- Iron ladle - length: 89.5 cm, diameter of body: 15 cm, depth: 5 cm, capacity: 800 ml
- Pithara Yantra - body height: 30 cm, diameter: 17 cm; Lid - shape: Conical, diameter of the hole: 2 cm, capacity: 5800 ml
- Burner: 20 cm diameter
- Other - electric weighing machine; stainless steel vessels, measuring pot and spoon.
| Observations and Results|| |
Flame was caught in melted Naga during Samanya Shodhana from 2 nd quenching in Tila Taila. Pungent smell, hissing sounds and a rush of black fumes were observed after quenching and iron ladle turned to yellowish. Appearance of flame was continued up to first quenching in Takra, possibly due to the presence of Tila Taila. No significant change in taste and odor in liquid media was observed after quenching. Some part was converted into yellowish powder after each quenching. Melting time of Naga was gradually increased after Shodhana in each media. Shining of Naga was decreased after quenching in Kanji and Gomutra. Shining of Naga was significantly decreased, and blackish ashes were observed floating over melted Naga after Shodhana in Kulattha Kwatha. Average time taken for melting of Naga in Tila Taila, Takra, Kanji, Gomutra, and Kulattha Kwatha were 5.5, 6.17, 6.73, 7.09, and 851 min respectively [Table 1] [Table 2]. Total 18 l each liquid media was utilized for Samanya Shodhana for three batches of Naga. Slight changes were observed in the color, odor, pH, specific gravity (SG) and total solid content of all media. During VSN, hissing sound was observed during quenching. Slight shining was appeared after Shodhana in Churnodaka. Total 42 l of Churnodaka was utilized for complete Shodhana of Naga in three batches. Average time taken for melting of Naga in Churnodaka was 8.91 min. Slight changes in color, odor, pH, SG and total solid content of Churnodaka was observed [Table 3]. Average percent decrease in weight after Samanya and VSN were 8.77 and 6.84 respectively [Table 4] [Table 5] [Table 6].
|Table 1: Average time taken for quenching of Naga during Samanya Shodhana (min) |
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|Table 2: Average time taken for quenching of Naga during Samanya and Vishesha Shodhana (min) |
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Percent purity of Naga was decreased from 99.80 to 99.40 [Table 7] TGA study showed a slight increase in melting point of Naga and presence of some organic matter. FTIR spectra of all samples were taken in the region of 670-3400 cm−1 . General overview of all the samples indicate the presence of a large number of functional groups. Different peaks of stretching vibrations between various bonds specially C-H and C-N was observed in the samples of Naga.
| Discussion|| |
Shodhana concept was in existence since the time of Charaka Samhita as while enumerating the fundamentals necessary of Gunantaradhana.  The concept has further developed after the development of Rasashastra in the field of Ayurvedic medicine. In Rasashastra, generally metals/minerals and certain poisonous herbal drugs are processed through Shodhana to reduce their toxic nature. Repeated heating followed by quenching in various liquid medias is the basic method for Shodhana of metals. Repetition of heating and cooling disrupt the equilibrium between molecules and thus increases brittleness, reduces hardness and particle size of metal.
The media Tila Taila, Takra, Kanji, Gomutra, Kulattha Kwatha and Churnodaka are slight acidic, acidic, acidic, slight basic, basic and strong basic in order. The order of quenching is changed by various Acharyas, so the exact reason behind the particular sequence is not explainable. For Naga Shodhana, it was mentioned that 1 l of liquid is sufficient for immersion of 1 kg melted Naga but brittleness increases with an increase in the quantity of liquid media. Kulkarni DA advised to take liquid media 8 times to that of metal.  In pilot study, it is observed that double quantity of liquid media (i.e. 2 l) is sufficient for complete immersion as well as to get enough brittleness, therefore in present work double quantity of liquid media was taken for Naga Shodhana. Naga acquired silver luster after each quenching. This may be because impurities of Naga may get attracted towards the chemical components present in the media forming a bond with them and thus they may get separated. So each time new liquid media was taken. Intense heating and sudden dipping may create changes in physical as well as chemical properties of Naga making it suitable for Bhasma formation. Gradual increase in melting time is seen while quenching in various liquid medias. This may be due to conversion of some part of Naga into powder form (PbO). This powdered Naga absorbs liquids during quenching. The liquid media forms a layer around the metallic Naga. When this Naga is heated again, liquid media evaporates first, which may be the cause for longer melting time. According to Ayurvedic point of view, after repeated quenching, the heat stability of Naga may increases, causing an increase in time for melting. Some scholars opine that there is an increase in melting point of Naga,  but the analytical study proves that there is no significant increase in the melting point. pH, SG and total solid content of each liquid media was slightly increased after quenching of Naga, this may be due to slight alkaline nature of Naga and dissolution of some part or impurities from melted Naga. Detail analytical study is needed to know the exact reason.
Increasing pattern of temperature at the rate of 10°C/min was adopted for TGA analysis, maximum temperature given was 710°C.Raw Naga has a melting point 327.46°C. A regular increase and decrease is observed in the melting point of Naga after Shodhana in each media. TGA showed melting point of Tila Taila Shodhita Naga (TTSN), Takra Shodhita Naga (TKSN), Samanya Shodhita Naga (SSN) and VSN as 328.05 [Graph 1], 329.43 [Graph 2], 326.74 [Graph 3] and 328.42°C [Graph 4] respectively. Melting point was decreased in Kanji Shodhita Naga (KSN) and Gomutra Shodhita Naga (GSN), which are 326.90 [Graph 5] and 325.34°C [Graph 6] respectively. The endothermic peaks obtained in KSN, GSN and SSN at 307.05, 302.97 and 295.23 are due to formation of different gases. The delta-Y calculation was used to determine the percentages of the organic component. Oxidation of organic compounds present in the Shodhita Naga samples is indicated by increased value of delta-Y as well as the decline occurred in the weight of Naga on heating. As in the observation the corresponding value of delta-Y in TTSN and TKSN is negligible, but in KSN it is slightly increased and in GSN and SSN significant change is observed [Graphs 7-12]. Repeated heating and sudden cooling in various organic media leads to impart some organic matter and thus resulted in decreasing the purity of Naga from 99.40% to 99.80%. TGA also showed the presence of nonvolatile organic compounds in the material due to repeated quenching of Naga in different media.
FTIR was performed to detect the presence of functional groups or organic legends in all samples of Naga collected after Shodhana in each media. General overview of FTIR spectra of all the samples indicates the presence of a large number of functional groups. The broad peak at 3435.57 cm−1 observed in TTSN is ordinary due to various O-H and N-H stretching vibrations indicating bond type similar to alcohol or phenol group. The medium to strong absorption peak around 2850-2925 cm−1 in all samples are assigned to C-H stretching vibration in alkyl compounds that may be characterized by the presence of high content of methylene in the complex mixture of these metallic compounds. The presence of peaks around 1730-1740 cm−1 in TKSN and SSN was assigned as carboxylic acid group. It was further assigned as C = O stretching vibration indicates presence of esters and lactones compounds. The carbonyl stretching vibration is characterized by absorption through the double bond region between 1950 and 1550 cm−1 . Ketones, aldehydes, acids, amides and carbonates all have absorption peaks around 1700 cm−1 . Esters, chlorides and acid aldehydes tend to absorb at slightly higher wavelengths; that is 1770-1725 cm−1 . Conjugation tends to lower the absorption peaks by about 20 cm−1 . It is frequently impossible to determine the type of carbonyl that is present solely on the basis of absorption in this region; however, examination of additional spectral region may provide evidence needed for clear-cut identification.
The peak region between 1500 and 700 cm−1 is known as fingerprint region. A small difference in the structure and constitution of a molecule result in significant changes in the distribution peaks in this region of the spectrum. Most single bonds give rise to absorption bands at these frequencies. The presence of peaks at 1407.03 cm−1 in TTSN was assigned to aromatic bond and arises due to C-C stretching vibration. The weak peaks between 1398 and 1400 cm−1 observed in TKSN, KSN, GSN, SSN and VSN are assigned to C-H stretching vibration indicative of the presence of alkyl compounds specifically methyl bond. Symmetric stretching was observed in TKSN and SSN at 1040.67 and 1044.39 cm−1 are indicating presence of primary alcohol group. A small peak in VSN at 1019.78 cm−1 is due to stretching vibration between C-N and assigned to aliphatic amines. Medium C-H stretching vibration peaks of vinyl compounds are appeared in SSN and VSN at 838.26 and 872.39 respectively are indicative of trisubstituted alkenes. Similar C-H stretching vibration peaks of vinyl compounds are observed in the region 670-700 cm−1 in all samples except TTSN but indicating cis-disubstituted alkenes. Thus, the FTIR study explores that Shodhana help in the impregnation of organic materials and their properties in the drug, making an organo-metallic forms compound. In addition to above, some minerals are also added to Shodhita materials that from the chemical point of view may be considered as impurities but from the therapeutic point of view may prove useful in potentiating their therapeutic effects. Observed functional groups in FTIR analysis support presence of minerals but more advanced analytical studies are needed to find out exact nature of those minerals. Shodhana process also helps to convert metal/mineral for further pharmaceutical process like Jarana and Marana. In presence study as per adopted reference of Sharangadhara Samhita, 3 times quenching of Naga was done for Shodhana, which leads to impregnation of some organic materials and conversion of Ashuddha Naga into organo-metallic form. From these results, it can be assumed that Shodhita Naga will be more organo-metallic if Shodhana carried out by adopting the reference in which 7 times quenching is preferred (Graphs 13-18).
| Conclusion|| |
TGA and FTIR are useful technologies to recognize the effect of Ayurvedic method of Shodhana of metals. About 2 l each liquid media is sufficient for proper Shodhana of 1 kg Naga. Melting point of Naga insignificantly increases after Shodhana. About 10-15% Naga is converted into yellowish powder form. TGA and FTIR analysis revealed the presence of organic compounds in Shodhita Naga and thus elaborate the initiation of new physico-chemical properties after Shodhana.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]