The phrase "a single instance in" is correct and usable in written English.
It can be used when referring to one specific occurrence within a larger context or situation.
Example: "In a single instance in the study, the results were significantly different from the others."
Alternatives: "one occurrence in" or "a solitary example in".
"There's not a single instance in which merit pay for individual teachers has been shown to improve the performance of a troubled school district," he said.
The N.R.A.'s chief lobbyist in Washington, James Jay Baker, could not recall a single instance in which Mr. Bush, as governor, had opposed the group.
Fix the Court reported that it "did not find a single instance in which a justice made the decision to recuse due to an amicus-based conflict".
A Western diplomat who monitors the issue said he did not know of a single instance in which someone has been found innocent.
We mentioned in our previous column that we hadn't found a single instance in which President Obama advocated higher gas prices.
Mr Leon protests that the government does not cite a single instance in which analysis of metadata "actually stopped an imminent attack".
Indeed Indiana conceded it was unable to identify a single instance of in-person voter impersonation fraud in all of its history.
I cannot think of a single instance where, in front of the top dog at any financial institution, I wasn't hearing myself reducing simple website functionality to paper flow charts while self-checking the word "colors" instead of "palette".
For classes with fewer than 100 instances, a single instance was present in the validation and the rest in the training set.
Not a single instance was observed in which introgressed alleles were underrepresented in both populations, indicating that "hybridity" was not universally disfavored across different genetic backgrounds.
Calling out a single instance of sexism in a professional space hit a nerve far deeper than I ever imagined.
