Estimation of Sodium Benzoate in Ayurvedic Formulation: Kashaya (Water Decoction)

Sodium benzoate, the food grade preservative, is the most commonly used preservative 

in kashaya-the water decoction of ayurvedic formulation. No standard procedure was known 

for the estimation of sodium benzoate in kashaya. The titrimetric estimation of benzoic acid 

using NaOH can be used asa standard method for its estimation. The amount of 

sodium benzoate observed in the commercial samples of nayopayam kashaya were many 

fold than that of maximum level allowed for food samples.

Ayurveda and other traditional medicines are gaining popularity,

particularly for the treatment of a variety of chronic diseases1. The ayurvedic

formulations asava and arista are resistant to deterioration because of the

removal of starch materials by fermentation and large proportion of alcohol

in them. The low growth rate of microbes in oil enhances the shelf life

period of oil preparations like ghrita and taila. The low water activity

resists the growth of microbes in formulations like vati, gutika, churna,

etc. However they cannot be stored for many years. The water preparations

like kashaya (water decoction) are least resistant to microbial attack and it

is the most common formulation in Kerala/South India. Traditionally

kashaya has to be consumed before cooling down to normal temperature

(35-40°C)2. Similarly the kudineer, the water decoction of siddha system

of medicine has to be consumed with in 3 h of preparation3.

The kashaya is easily prone to microbial attack and thus can be

marketed only by the addition of suitable preservatives. Large number of

natural preservatives like organic acids, terpenes and phenolic acids were

suggested especially of herbs origin4. The studies of these natural preservatives

are in primitive level5,6 and commercialization requires elaborate

studies in different branches of science. Law does not allow the addition of

non-herbal substances in herbal formulations. The Drugs and cosmetics

rules, 1945 is amended to prevent the addition of allopathic drugs to the

herbal products7. The addition of preservatives to Ayurvedic drugs are

supported by the draft national policy on ISM 2001, under section 7, states,

industry would be encouraged to adopt modern dosage form and follow

reasonable shelf life periods8.

Each producer had their own combinations of preservatives and kept

them as their secrets know how. Even then, the most common preservative

used in ayurvedic formulations is sodium benzoate, the food grade preservative

and generally recognized as safe (GRAS). There is no standard

method for the estimation of sodium benzoate (or similar compounds) in

kashaya. Number of methods using sophisticated instruments was available

for its estimation in food9-11. The volumetric method is adopted in

food chemistry12 since most of the Ayurvedic drug manufacturers are smallscale

industrialists and cannot afford costly instruments. More over with

the suggested laboratory equipments for GMP certification13 only volumetric

method is possible.

Standardization of procedure for the estimation of sodium benzoate is

conducted in two common kashaya’s containing least number of components.

Nayopayam kashaya containing dried roots of sida (Sida retusa L.

sanskrit – bala [In north India Sida cordifolia is usually used as bala but in

south India sida retusa is used], malayalam- kuruthotti), dry ginger (Zingiber

officinale Rose., sanskrit – sringa veram, malayalam – chukku) and cumin

(Cuminum cyminum Lin., sanskrit – geera, malayalam-geerakam) and

amrithotharam (amrithadi) kashaya containing stem of heart leaved moonseed

(Tinospora cordifolia Miers., sanskrit-guluchi/madhuparni,

malayalam-chittamrith), dry ginger and seed coat of chebulic mirobalan

(Terminalia chebula Retz., sanskrit – harithiki/abhaya/rohini, malayalam –

kaddukka). The kashaya’s were prepared as per the standard text14 with the

help of a registered medical ayurvedic practitioner.

Kashaya’s containing requisite concentration of sodium benzoate were

prepared by the addition of calculated amount of A.R. sodium benzoate

(Glaxo) in 100 mL samples of freshly prepared kashaya. The benzoate was

dissolved completely by stirring and kept for 1 d for attaining stabilization.

The amount of sodium benzoate was estimated by titrimetric method by

the estimation of benzoic acid using standard sodium hydroxide solution.

Pipette 50 mL spiked kashaya in to 250 mL standard flask. Add 8 g

powdered sodium chloride and dissolve with constant stirring. Using

satu rated sodium chloride solution diluted to 150 mL and made alkaline

to litmus with 10 % NaOH solution. The solution is made up to the mark

3422 Balachandran et al. Asian J. Chem.

with saturated sodium chloride solution. The solution is kept for 2 h with

occasional shaking (preferably overnight). 100 mL of the solution is transferred

in to 500 mL separating funnel. Add dil. HCl (1:3) drop by drop till

the solution is slightly acidic. Add 2 mL HCl in excess. The solution is

kept for 0.5 h for the complete conversion of benzoate to benzoic acid. The

solution is washed with 50, 40 and 30 mL of chloroform successively and

the washings are collected together in an R.B. flask. The formation of emulsion

is occasionally observed. If emulsion is formed, dilute with more water

and centrifuged if necessary. The complete brake down of emulsion is

required. It is observed that 90 % benzoic acid is found with the formed

emulsion. If a colour or opaqueness is developed in chloroform fraction,

washed with water till a clear solution is obtained. Excess washings were

avoided to reduce the removal of benzoic acid with water. The chloroform

was distilled off keeping the R.B. flask in a water bath. If there is a possibility

of simple organic acids like acetic acid in kashaya sample then the

complete evaporation of chloroform is required. The residue is dissolved

in minimum amount of ethyl alcohol or acetone and diluted to 20 mL with

water and titrated against standard 0.05 N NaOH solution taken in a

burette using phenolphthalein as indicator.

The amount of sodium benzoate in percentage = 

(Titre × Normality of NaOH × 144 × Volume The amount of sodium made up × 100 ) / ( Volume taken for estimation × Volume of kashaya pipetted × 1000 )

If the above procedure is followed using the same volumes of the solutions

as discussed then the equation is simplified to,

% sodium benzoate = 0.72 × Titre × Normality of NaOH

(To estimate as benzoic acid use 122 in place of 144 in the above equation)

S. BALACHANDRAN* and R. SUDHA DEVI

Department of Chemistry, P.R.N.S.S. College, Mattanur-670 702, India

E-mail: sbcnair@sify.com