The phrase "a certain pair of" is correct and usable in written English.
It can be used when referring to a specific but unspecified pair of items or people, often to create intrigue or emphasize the uniqueness of the pair.
Example: "I found a certain pair of shoes that I just had to buy; they were unlike anything I had seen before."
Alternatives: "a specific pair of" or "one particular pair of".
Every now and then he'll notice, after making a big kick, that he was wearing a certain pair of socks.
His mother thought a certain pair of beds that the countess had gotten possession of, should rightly have been hers.
Us parents had enjoyed a good run, but our children had finally twigged that greater forces wanted them to conform to a certain pair of types.
He starts cataloguing Hannah's physical faults — a slight jiggle in her upper arms, a flattening of her butt in a certain pair of jeans.
If you remember when you were a child, and frightened, and everything seemed impossibly big and loud and sharp and hard except a certain pair of familiar arms, this will have to stop.
But Britain's rocky relationship with Eurovision could be rekindled this year by a boyband well past their sell-by date and a certain pair of Irish twins with gravity-defying hair.
This folding requires a certain pairing of the corresponding nucleotides in the strands that come to bind (Fig. 4a).
θ (v 1, v 2 ) is either 0 or 1, depending on whether a certain pairing of input volumes contributes to the objective function.
The observed frequency of codon pairs is the ratio of occurrence of a certain pair to occurrence of all 3721 codon pairs, calculating from full length ORFs excluding the first and stop codons, as mentioned above.
Just be careful to not to over- or underestimate the kind of prices a certain pair or a group of cattle will go at.
Salt pairs are known to serve as "water activity buffers": 12, 13, 54, 55 when both species of a certain pair are simultaneously present, the water activity of the system reaches the equilibrium value.
