how to show all chacters of a string before the @ character

Question

Hi ive got the following qustion.

 

I have a an asp.net gridview. and one colum contains the user. However all the users have a

certain const value at the end like @blabla wich i dont want to show in the gridview colum

so user was pietje@blabla and i want to show just pietje.

 

I have got the following itemtemplate to show the hole user, but how can i remove the chachagters after the '@' ??

 

This is what i got already.

 

<asp:TemplateField HeaderText="Gebruiker" HeaderStyle-Width="30%" SortExpression="UserId">
    <ItemTemplate>
        <asp:Label ID="userLabel" runat="server" Text='<%#Eval("UserId").ToString()%>'></asp:Label>
    </ItemTemplate>
</asp:TemplateField>