Rewrite the procedure in third person & in past tense:

Procedure

You will be provided with post-mitochondrial supernatantfractions from rat liver of control rats and phenobarbitone-treatedrats. Carry out the assay for drug metabolism as follows.

A

1. Take 4 ml incubation medium (containing substrate aminopyrine)into each test flask.
2. Take 4 ml incubation medium (containing no substrate into oneflask (reagent blank)).
3. Add 700 ml 0.25 M sucrose solution to all flasks.
4. Pre-incubate all flasks at 37 °C for five minutes.

B

1. Add 300 ml liver homogenate supernatant to all flasks.
2. Shake unstoppered at 37 °C for 30 minutes.

C

1. Add 2 ml ZnSO₄.7H₂O (8.9%) solution toall flasks. Mix.
2. Remove flask from bath and leave for five minutes.
3. Add 2 ml saturated Ba(OH), 8H₂O solution. Mixwell.
4. Transfer to 10 ml test tube and centrifuge at 200rpm for 10minutes.

D

1. Prepare formaldehyde standards. Pipette 2.5 ml portions of eachconcentration into a test tube (LPS).  Use 2.5 ml wateras a blank.
2. Add 1.5.ml Nash reagent to each tube and vortex.

E

1. Place 2.5 ml supernatant (from tubes treated under section C)into test tube.
2. Add 1.5 .ml Nash reagent. Vortex
3. Incubate all tubes (including standards) at 60 °C for 30minutes.
4. Leave to cool.  Read absorbency at 412 nm against ablank reagent.
5. Read formaldehyde standards against a reagent blank.
6. Express results as ~mmol formaldehyde formed/h/g/liver(homogenate).