Determination of iron in blood.


The procedures to follow are as follows:

DETERMINATION OF IRON IN BLOOD

a) PREPARATION OF SAMPLE

1. Pipette 1 cm3 blood into a 100 cm3 volumetric flask, add 4 cm3 of the concentrated. Sulphuric acid provided (iron free) and whirl the flask to agitate the mixture for one minute. This detaches the iron from the Haemoglobin molecules.

2. Add 4 cm3 of saturated Ammonium persulphate solution, mix. Ammonium persulphate oxidises the iron to the ferric state.

3. Dilute to about 50 cm3 with distilled water, add 4 cm3 of 10% Sodium tungstate solution. Cool, dilute to volume and mix thoroughly-This precipitates the proteins.

4. Filter through a dry filter paper into a clean dry flask.

b) PREPARATION OF A STANDARD SOLUTION Dilute 20 cm3 of the standard Ferric ammonium sulphate solution (0.861g/L) provided to l00 cm3 in a volumetric flask.

c) TO PREPARE A STANDARD CURVE 1. Set up the following range of tubes:- See Table A 2. Stand for 5 minutes, the colour is stable for the next 30 minutes,

3. Read the absorbance of the solutions against the blank at 480nm.

4. Plot a graph of absorbance against the respective-Ferric iron concentrations.

Read off the ferric iron concentration of the blood filtrate. Account for dilation of the blood and. so find the concentration of iron in the original blood sample Determine the Haemoglobin concentration of the blood sample (Haemoglobin contains 0.335% iron). Discuss the result.

THE LAB REPORT

AIM OF THE PRACTICAL

The aim of the practical was to determine the concentration of iron in the blood. This was achieved by comparing the value obtained from the blood sample with that of standard iron solutions.

INTRODUCTION The determination of the iron present in blood provides a way for calculating the concentration of haemoglobin in blood. The latter is given as containing 0.335 % of iron (handout). The concentration of haemoglobin can thus be calculated from the concentration of iron by simple proportion. Haeme is an iron containing porphyrin called iron-protoporphyrin IX. Haemoglobin is the red pigment present in the red blood cell and has a molecular weight of 64 450. It is a globular molecule made up of 4 sub-units each of which contains a haeme moiety conjugated to a polypeptide. Haemoglobin has two important functions- it carries oxygen and carbon dioxide, and acts as a buffer in maintaining the blood reaction (Ghai, 1988). 1.0 g of haemoglobin, when fully saturated with oxygen, carries 1.34 ml of this gas.

METHOD As prescribed in the handout. The contents of each tube are shown in Table 1. below, along with the respective absorbance values.

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