Comparison of three analytical methods for separation of mineral and chelated fraction from an adulterated Zn-EDTA fertilizer

Different analytical procedures are being employed in the world to quantify the chelated portion in a zn-edta fertilizer. agriculture department,government of the punjab is following shahid́s analytical method in this regard. this method is based on ion-chromatography (ic) that separates the mineral zinc (zn) from an adulterated zn-edta fertilizer sample i.e. mixture of mineral and chelated zn fractions. to find out its effectiveness and suitability,this comparative study was carried out by analyzing adulterated,non-adulterated zn-edta standard and zn-edta samples taken from market in thrice following three methods namely shahid́s (ic) analytical method,atomic absorption spectrophotometric (aas) method based on the principle of precipitating the mineral zn fraction at high ph value by using alkali solution of suitable concentration and analysis of filtrate containing only chelated fraction and association of official analytical chemists (aoac) method fm-841 respectively. adulterated zn-edta samples were prepared by mixing of known quantity of mineral zn with chelated zn-edta standard. the results showed that shahid́s analytical method and aas method,both successfully estimated the chelated fraction. the aoac fm-841 method was insensitive to put a ceiling on the mineral fraction hence did not furnish the reliable results. the shahid́s analytical method was selected being equally effective to produce reliable results both for solid and liquid zn-edta samples. the aas method was comparable in only liquid samples.