Here is a way to get the disk volume id

[vba]

Function DiskVolumeId(Drive As String) As String
Dim sTemp As String
Dim iPos As Long
iPos = InStr(1, Drive, ":")
Drive = IIf(iPos > 0, Left(Drive, iPos), Drive & ":")
sTemp = Hex(CreateObject("Scripting.FileSystemObject") _
.Drives.Item(CStr(Drive)).SerialNumber)
DiskVolumeId = Left(sTemp, 4) & "-" & Right(sTemp, 4)
End Function
[/vba]

which you can get with

diskvolumeid("C")