DataTable dtChem = new DataTable();
ada.Fill(dtChem);  // Fills datatable with data from Excel
cmd.Parameters.Clear();
cmd.CommandText = "dbo.insertDataChem";
cmd.Parameters.AddWithValue("@chemResults", dtChem);
cmd.Parameters.AddWithValue("@eddName", strFileName);
cmd.ExecuteNonQuery();

create PROCEDURE [dbo].[insertDataChem]
    @chemResults as dbo.udtableDataChem READONLY
    , @eddName nvarchar(100) = null
AS

BEGIN
    INSERT INTO CEDEN_ChemResults
    SELECT cr.SampleDate, cr.*,  @eddName, CURRENT_TIMESTAMP FROM @chemResults cr
END

CREATE TYPE [dbo].[udtableDataChem] AS TABLE(

    ...

    [MDL] [decimal](30, 15) NULL,   // data type changed
    [RL] [decimal](30, 15) NULL,    // data type changed
    [DilutionFactor] [nvarchar](200) NULL,  // original data type
    [ExpectedValue] [nvarchar](200) NULL,  // original data type

    ...

)