The most common and most likely answer to this crossword clue is the 8 letter word NITRITES
I've seen this crossword clue in The Guardian
N
I
T
R
I
T
E
S
More clues leading to the result NITRITES
Buddy explains!

The straight part
We know that "Salts" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case salts = nitrites.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does NITRITES mean?
NITRITES noun- Any salt or ester of nitrous acid
- The univalent radical -NO2, and the anion NO2-