Looking for a way to identify and store different strings

I have a sheet which can be of any number of rows, Column Y contains a text string. On one sheet it may be the same string on every row, on another it may have any number of different strings (not necessarily in ordered blocks).
so what I am trying to achieve is to scan down the list, locate a string that has not been used before, store it in a variable and move on with other code, then return to the list and repeat.
Something like:
for x = 2 to endoflist
'find unique string
'store string in variable
call rest_of_code
next

I hope I have explained this OK, unfortunately it is difficult for me to post a sample as this is part of a large project

any help or pointers in the right direction would be most appreciated.

'Unique' is a relative property: you can only determine it's uniqueness comparing it to something else. When will you consider a string 'unique'. You have to specify it first.
Besides you can always post a sample workbook that only takes your question into account. 'Being a part of a larger project' can't be a reason not to provide potential helpers essential information.

to get the unique items in column Y into column Z
to put them into array sn
to clear column Z

sub snb
  columns(25).advancedfilter xlfiltercopy,,cells(1,26),true
  sn=columns(26).specialcells(2)
  columns(26).clearcontents
end sub