ช่วยด้วย!!!!เอาคอลัมน์นึงจากdtagridview มาใส่comboboxคือขอโค้ด ขอโค้ดตัดค่าซ้ำในcombo หน่อยค่ะ

   Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        For i As Integer = 0 To DataGridView1.Rows.Count
            If Check(DataGridView1.Rows(i).Cells(0).Value.ToString()) = True Then
                ComboBox1.Items.Add(DataGridView1.Rows(i).Cells(0).Value.ToString())
            End If
        Next
    End Sub
    Public Function Check(ByVal item As String)
        Dim ck As Boolean = True
        For j As Integer = 0 To ComboBox1.Items.Count
            If item = ComboBox1.Items(j).ToString() Then
                ck = False
                j = ComboBox1.Items.Count
            End If
        Next
        Return ck
    End Function