There are 2 experiments in UV-Vis spectrophotometry lab practice, determination of drug content in dosage forms and isosbestic point determination. In those 2 experiments there are more than just 2 experiments. I hope all students can get those all things from this lab practice. Here are the point:
Hope this is useful :)
- Quality Control
UV-Vis spectrophotometry is very useful in Quality Control. In a series of quality control there are at least three things, sample preparation, identification assay, determination of content.
Sample preparation
Sample have to be treated first therefore we could do the analysis. The simplest treatments are dissolving, dilution.
Qualitative Analysis (Identification Assay)
It is important to know whether the analyte is as the same as we expect. To know that, we can do confirmation using UV-Vis spectrophotometry method. After that, compare the parameter that we got from analyte to the reference (you can do the comparison by analyzing the reference using the same method or by comparing the analyte parameter to reference parameter from the literature). The parameters are, maximum wavelength, absorptivity, spectra.
Quantitative Analysis (Determination of content using one point and multiple point method)
Instrumental analysis, like UV-Vis spectrophotometry, is comparative analysis, therefore the reference is a must. It is different with titration method that absolute analysis, in absolute analysis we could know the concentration of sample without reference.
We compare the sample and reference responses. We can use two methods in comparing the responses, there are one point method and multiple point method. In one point method, we use one level of reference concentration, in multiple point method we use five or more levels of reference concentration (in other words, we use the calibration curve).
After we get the sample concentration we can track back the compound amount in our sample. For example, we already know the concentration of Vitamin C sample solution. Based on the dilution we did, the tablet mass, we can calculate the amount of vitamin C in a tablet. After that, we calculate the percentage of vitamin C against to the claimed amount in its label. (Please note, don't calculate the percentage directly just by comparing sample and reference sample. The reason is.. because that's not the right way.). From the calculation then make conclusion whether the vitamin C tablet fulfill the requirement or not (Use the compendial requirement in Farmkope Indonesia IV or the latest USP).
- Multiple-component analysis
In isosbestic point determination, actually that's also a multiple-component analysis. Therefore, use the multiple component analysis calculation in this experiment.
- pKa determination
Another output from isosbestic point determination is pKa determination of the sample.
Hope this is useful :)
0 comments:
Post a Comment
Please feel free to comment
and please click Subscribe by Email to be notified for upcoming comments.