Federal mediators adjourned contract negotiations between striking nurses and the management of Group Health Association yesterday for the second time in the 19-day walkout, as resolution remained elusive.

"Chances for a settlement do not look good," said mediator Brian Flores.

Flores said he adjourned the talks after management representatives of GHA, the area's largest health maintenance organization, rejected the nurses' latest proposal, which was offered Sunday. GHA reiterated its Sunday offer, and the nurses promptly rejected it.

"We're running out of ways to be fair," said Martin Krall, a lawyer leading the GHA negotiation team. "There's a substantial amount of money on the table, yet all our proposals have been rejected."

The board of GHA met last night and according to Krall, "reaffirmed and approved" management's latest proposal.

Although the two sides are within a few hundred dollars of each other's proposals for 1982 annual salaries, Flores said, they diverge at the second and third years.

The 85 strikers, represented by the independent Registered Nurses and Physical Therapists Association, are seeking what they term parity with nurses working at similar organizations in the area.

Dr. Edward J. Hinman, executive director of GHA, insists that the wage demands are excessive and would have to be passed on to the organization's 112,000 member-patients.

In the offer rejected by the nurses yesterday, GHA offered an increase of 16.2 percent for the present year, retroactive to Jan. 1, and an 8 percent raise for next year. The starting salary for nurses is currently $14,627 and the average salary is $16,977.

For the following year, management proposed calculating the average salary paid to nurses at 42 health institutions in the area at the start of 1983 and again in 1984. If that average rose beyond the 8 percent level for 1983, GHA would pay the nurses the difference. If not, the nurses would still receive an 8 percent increment.

The nurses' latest proposal called for a starting salary of $17,200 for this year and $19,200 for 1983. The third year, under the nurses' proposal, would be subject to binding arbitration.

An additional issue is the nurses' demand for increased staffing, which GHA officials say has been resolved.