Although the Carter administration insists that the economic recession is over, top corporate officers are not so sure.

According to a survey by the National Association of Accountants, only 9 percent of the top financial officers at the nation's biggest companies think the recession has ended, and most think the economic downturn will not end until at least the second quarter of next year.

Purchasing agents at big industrial companies reported better conditions in October, but evinced growing concern and uncertainty about the months ahead.

According to the monthly survey of purchasing agents at 225 big industrial corporations, attitudes among the buyers "are changing to such an extent that the comments showing concern and uncertainty about the months ahead now outnumber the optimistic ones."

"The uncertainties center around the presidential election, the success of the new model cars, the mercurial performance of interest rates and the money supply, the Iran-Iraq situation, the false recovery experienced by some businesses and the failure of the recession to significantly reduce inflation," according to the survey.

Both the purchasing agents and the top financial officers say that inflation is their central problem, and some financial officers think rapidly rising prices will throw the economy back into recession.

E. T. Grory of Superior Oil Co. told the National Association of Accountants that the economic recovery of the past few months will be upset by continuing inflation. The Federal Reserve Board will be forced to tighten monetary policy further, and "will precipitate another recession in the second quarter of 1981.

George Slocum, the chief financial officer at Transco Cos., said that while he thinks the recession will end in the second quarter of next year, the "sharp but relatively brief recession will be insufficient to control inflationary pressures for any more than a one-year retreat from the 1981 high."

The purchasing agents say that inflation, which eased last summer, is already on the upswing again. In September, 39 percent of the agents said that prices were higher than the month before. Last month 50 percent reported higher prices. "To add to the problem, the number reporting lower prices dropped to 2 percent from 4 percent last month," the survey said. "While the rate of rise (in those reporting higher prices) is increasing sharply, the total number reporting higher prices is much less than was seen throughout 1979 and the first few months of this year. But the trend is in the wrong direction."

Still, although the purchasing agents say they are concerned about the future, most of the results they reported in October are better than those in September. Production and new orders increased and with orders rising faster than production, output should increase in November, too.

But businesses are reducing their inventories, in part because of the activity but also because of the sharp rise in interest rates in August, September and October. Nearly half of the 225 purchasing agents surveyed said they cut back on their stocks because of the high rates (which make it more expensive to finance inventories) and half of those cutting back made large reductions.

The rise in rates also caused companies to be more cautious about capital investment. Except for a brief upsurge in September, captial spending at major industrial companies has been declining since last spring, according to the survey by the National Association of Purchasing Management.