Determination of Cardanol- An Agricultural By-Product by Simple and Sensitive Spectrophotometric Method

Abstract

Cardanol, a phenolic compound is found in cashew nut shell liquid (CNSL.) a by-product of cashew industry. It holds considerable promise because of its large availability in tropical areas, low cost, biodegradability and structural characteristics. Simple, sensitive, selective, rapid and reliable spectrophotometric method for the determination of cardanol, an agriculture by-product has been developed. The method describes the reaction of cardanol with iron (III) and subsequent reaction with ferricyanide to yield a Prussian Blue product with a maximum absorption at 730 nm. The method obeys Beer's law. As many as ten independent anions and cations did not interfere with the determination.

Introduction: Cardanol (3-pentadecenyl phenol) is a phenolic compound with C₁₅ aliphatic chains in the meta position. It is a mixture of saturated and unsaturated (mono-, di- and tri-) compounds [commonly found in cashew nut shell liquid (CNSL), an alkyl phenolic oil which constitutes 25% of the total weight of cashew nut (Anacardium occidentale) a well-known species of the Anacardiaceae family. CNSL is obtained as a by-product of cashew industry, and is an important source of unsaturated hydrocarbon phenol.

Objectives: The work described in this paper forms part of a systematic investigation to develop new spectrophotometric methods for agri products - a field of paramount importance due to easy biodegradability and use of agricultural waste and by-products, in place of toxic chemicals - an area of current interest in environmental management.

Methods: Aliquots of standard solutions of cardanol and 2.0 ml each of iron (III) chloride and potassium ferricyanide were taken in 25-ml calibrated flask. The contents were mixed well and kept aside for 20 min at room temperature. It was then diluted to 25-ml mark with distilled water and the absorbance was measured at 730 nm against the corresponding reagent blank and calibration graph was constructed.

Results: The method is based on the reaction of cardanol with iron (III) salts in the presence of potassium ferricyanide in neutral medium to form a Prussian Blue (PB) product.

Conclusions: One of the recent frontiers of sustainable development has been the utilization of agricultural by-products. Effective utilization of any product is based on its quality, which, in turn, depends on the analytical data.

The procedure described in this paper is the spectrophotometric method which meets most of the demands of analytical chemists namely; selectivity, sensitivity, simplicity, rapidity, reliability and cost of analysis. In this method, it is necessary to use iron (III) as the oxidizing agent; the use of such simple reagents makes the procedure cost-effective. One of the important facts is that this study will open up a new area of research Further value-addition to this method can be achieved, if the procedure is combined with on-line or at-line system and this is currently under investigation.