Question

The company only has at its disposal the spectrometers we have in our lab (UV-Vis, IR, ICP-OES and Fluorescence; same vender and model) and you are supplied with the samples for analysis. Develop the method for the Zinc content of Cold-Eeze Tablets and perform analysis. At the completion of the analysis, present an overview of the instrument used (theory and operation) as well as a summary of the procedure and results.

Answer 1

Here We are using ICP-OES for Zinc Analysis.

Theory and Operation of ICP-OES-Inductively coupled plasma - optical emission spectroscopy is a technique in which the composition of elements in (mostly water-dissolved) samples can be determined using plasma and a spectrometer.ICP-OES is a trace-level, elemental analysis technique that uses the emission spectra of a sample to identify, and quantify the elements present. Samples are introduced into the plasma in a process that desolvates, ionises, and excites them,it become unstable and comes back in ground state to become stable ,at this time it release some energy for particular element it is calculated as concentration form. For Zinc Analysis use wavelength 213.857.

Procedure-By Microwave Digestion

1)Weigh homogenized samples, 0.5 ± 0.010 g for tablet into a clean microwave vessel liner. Teflon or polypropylene stirring rods may be used to manipulate samples.

2)Add 5 mL of concentrated HNO3, Ultra-pure grade, to each vessel.

a) Assemble the vessel according to the manufacturer’s instructions.

b) Place assembled vessels into the microwave according to the manufacturer’s instructions.

Program oven with parameters demonstrated to safely and effectively digest samples. Recommended parameters are listed below. It may be necessary to adjust these parameters to accommodate,

Power	1600 Watts
Ramp Time	12 Minute
Final Temperature	180 Degree Celcius
Temperature Hold Time	10 minutes
Cool Down Time	10 minutes

3) Allow vessels to cool, then transfer to a fume hood and allow vessels to equilibrate to room temperature.Slowly open the vent fittings and vent to atmospheric pressure, then disassemble vessels.

4)And finally makeup by DI water.

Analysis Procedure-Now we have solution ready for analysis by ICP-OES.For this we make some prepration to ready the instrument i.e ICP-OES . A calibration blank followed by at least 3 calibration standards covering the range of interest. Using linear regression analysis, plot relative response (response relative to ISTD response) vs. concentration in µg/L and determine slope (m), intercept (b), and correlation coefficient (r) of the calibration curve. This can be more than 0.995.

Now analyses the sample as we have prepared in solution by digestion procedure,and receive a concentration of Zinc in ppb by instrument.

Result-We can calculate the result by given formula

Zinc (ppb) = C x V / W

Where C = Analyte concentration in final extract, in µg/L

V= Final sample extract volume in milliliters

. W = Sample Weight(Tablet) in grams.