private void PART_tbChemicalName_KeyDown(object sender, KeyEventArgs e)
        {
            this.tbChemicalNumber.Text = "";
            PART_tbChemicalName.IsDropDownOpen = true;

            if (e.Key.ToString() == "Return")
                this.btnMSDS_Click(sender, e);

            else if (PART_tbChemicalName.Text.Length > 2)
            {
                setItemsChemicalNames(
                    this.dTable,
                    this.PART_tbChemicalName,
                    Properties.Settings.Default.ConnectStringToExcel,
                    " WHERE [F4] LIKE '" + PART_tbChemicalName.Text + "%'");
            }
        }

this.textBox1.TextChanged += new System.Windows.Controls.TextChangedEventHandler(this.textBox1_KeyUp);