Application Of Ion-exchange Spectrophotometric Determination Of Trace Heavy Metals In Collagen

Lead and cadmium are hazardous because the poisons are cumulative and their toxic effects are severe. Chromium (III) may be considered as an essential trace element for the proper functioning of living organisms, on the other hand, chromium (VI) can be carcinogenic and toxic. Trace metals in collagen can be accumulated and absorbed by human being through food chain, thus produce harmful effect .Therefore, it is greatly significant for the determination of heavy metals in collagen.Spectrophotometry is most convenient for use due to its simplicity, low cost, sensitivity, rapidity and is easy to operate.In this paper, highly sensitive and selective spectrophotometric methods for the determination of trace lead (â…¡), chromium (â…¢) and cadmium in collagen have been developed based on the literature.This presentation includes the following parts:Part one: ReviewThe achievements on the application of spectrophotometric determination of lead, chromium(III) and cadmium are reviewed particularly.Part two:Trace lead (II) was separated from the matrix and adsorbed by 717-strong basic chloric type anion-exchange resin, while plenty of calcium and magnesium cations co-existed in sample were not adsorbed by the resin. Lead (â…¡) eluted from the resin react with XO to form 1:1 complex in pH 5.0-6.2 buffer solution. The apparent molar absorptivity is found to be 2.38x10⁴ L ? mol^-1 ? cm^-1 at 550 nm. Beer's law is obeyed in the concentration range of 0.04 4 μg ? mL^-1 with the detection limit 0.032 μg ? mL^-1. This method has been shown to be sensitive, simple and rapid.Part three:Color reaction of chromium (III) with CAS in the presence of CTMAB and ethanol was studied. Co-existed interferences were separated by 717-strong basic chloric type anion-exchange resin, and in the meantime NaF was used as mark reagent. The effect of increasing and stabilizing absorbance in the presence of CTMAB and ethanol was observed. The molar absorption coeffecient is 1.46x10 L-mol^-cm" at 626 nm. Beer's Law is obeyed in the range of 0⁰.15 fig ? mL"1, R.S.D. is less than 1.67 %. The sensitivity of this method is satisfied for the determination of trace chromium (III) in collagen.Part four:Kinetic-catalytic method has been widely applied in many analytical fields owing to its high sensitivity and sufficient accuracy without expensive and special equipment. A simple, rapid spectrophotometric method for the determination of cadmium has been developed. This method is based on the inhibitory effect of cadmium (II) on the catalytic action of CTMAB in discoloration reaction of crystal violet in ammonia medium. Beer's law is obeyed in the range of 0⁰.08 fig ? mL"1. The molar absorptivity e59o is 1.29xlO5 L ? mol"1 ? cm'1, limit of detection 1.01 ng-mL"1 and R.S.D. is 1.9 % (n=6). Trace cadmium could be effectively preconcentrated on the Cr-form of the resin and determined by inhibition-catalysis discoloring spectrophotometry. This method has been satisfactorily applied to the determination of trace cadmium in collagen.