'Quite separately' is a correct and usable phrase in written English.
You can use it when you want to emphasize that two particular things are completely unrelated or independent of one another. For example, you could say: The company's financial situation is not in good shape, quite separately from the fact that they're facing legal action.
Quite separately, the Government has uncovered the mis-labelling of millions of battery-farm eggs as free-range.
Quite separately, it is a place where local Spanish motorists happily fill up with cheap petrol and forget to tell the customs men on their way back home.
Quite separately from Congress's wrangling over premiums and relief, America's setter of accounting standards, the Financial Accounting Standards Board (FASB), is revamping its rules for valuing pension plans.
Quite separately, Dr. Brian J. Druker, an oncologist interested in protein kinases, decided that a possible treatment for C.M.L. might be to inhibit the abnormal abl protein formed in the Philadelphia chromosome rearrangement.
Quite separately, attraction between you and a 'Water baby' (Cancer, Scorpio or Pisces) could be irresistible.
The cells are working quite separately from each other".
She had not anticipated, when they moved to Saint-Maure-de-Vercelles, that they would live quite so separately from the village.
The two would have quite happily existed separately from each other, but they're now beginning to sniff around each other's rears.
Due to the variety of constraints, these networks have some specificities, and evolved separately for quite a long time.
The movement of the COM and COP separately were quite different between OW and TW, but when describing the COM motion relative to the COP, the COM motions became similar qualitatively with similar butterfly patterns.
Reviewing and revising or updating any of the individual aspects separately is quite feasible, but mixed up on each of most pages of a document, the distinction between the aspects blurs, and the task of review and revision is so daunting that no one attempts it.
