SOP For sampling of raw material is described in this post which you can follow in the section of the Quality Assurance Department.

OBECTIVE
This procedure is laid down to take a homogeneous and representative sample of raw material (active ingredients & excipients) for analysis.
SCOPE 
This procedure is applicable to Warehouse and QA Department 
RESPONSIBILITY
Warehouse Officer
QA Officer
ACCOUNTABILITY
Manager Quality Assurance 
PROCEDURE 
Upon receiving Raw Material, Warehouse Incharge will generate GRN and raise the request for sampling to QA Department.
In the Warehouse, QA Officer checks that the material is properly placed in quarantine area.
Ensure that Physical Inspection Report is generated at the time of sampling and inspection.
Before sampling make sure that the area where sampling is to be carried out is properly cleaned, and will not adversely affect the quality of the material 
Check that RH and temperature conditions are up to the required standards.
Check the labels on container from the supplier which includes the material name, Batch No.  no. of containers, Mfg., Exp. Date, etc. against GRN.
Raw materials which are prone to moisture must be sampled under the controlled condition of RH.
If any container does not bear the manufacturer identification label, it should be rejected.
Use gloves & mask and ensure that clean sampling tools likes S.S. Scoop, Spatula are used to draw the sample.
Identify the no. of containers to be sampled according to sampling rule n+1.However, if the no. of containers in a lot are NMT 3 sample all the containers. Maximum no. of sampled to be drawn from a single lot is 11 even if total no. of containers is more than 100. (n= no of the containers) Note: In case of API, sampling of all the containers should be carried out.
Take out sample in a suitable clean and dry container (polythene bag, glass bottle etc.), sealed and identified by labelling with item name, GRN no. sample no. (S1, S2, S3 and so on)   
To ensure that withdrawn sample is representative of the entire quantity of the container, mix   thoroughly before samples.
In case of liquids, draw samples with the help of sucking pump. 
After sampling affix, the “Sampled” label, duly filled in, on containers from which sample is drawn.
After sampling the container should be sealed effectively to avoid any contamination.
Bring samples into the Q.C. laboratory along with documents i.e. physical inspection of incoming consignments (Raw Material) and certificate of analysis (if any) and then hand over to the QC for testing.