Du Pont Co. Chairman Irving Shapiro warned today that his company and many others may be forced to withdraw their support of President Carter's wage and price guidelines unless the inflation rate eases soon.

Shapiro told the annual meeting of E.I. du Pont de Nemours & Co. shareholders here that the nation's largest chemical firm is still trying to honor the voluntary program.

"But," he added, "and this is a big but, it is a fact of life that unless the rate of increase in the cost of basic materilas moderates quickly or the guidelines are adjusted to recognize this condition, it will become very difficult for many industries to comply with the federal guidelines, no matter how strong their commitment to the president's voluntary program way be."

Shapiro has frequently been a leading spokesman for the nation's business community. His remarks today reflect a growing consensus in corporate suites that the president's anti-inflation campaign is close to being trampled under an oncoming rush of post-Teamster labor settlements and persistent advances in the prices of food and oil.

Something of the same sense of doom apparently has taken hold among Carter's key advisers, some of whom reportedly are pushing the president to impose stronger control measures in order to rein in an inflation rate that lately has been scoring in double digits.

Apart from creating a climate of concern and uncertainty, inflation has created a delicate public relations problem for companies flush with profits. The White House, for one, gave the business community a tongue-lashing last month over a 25 percent increase in fouth-quarter corporate profits compared with the same period in 1977.

In the wake of this criticism, Du Pont today reported record first-quarter earnings - up 48 percent over a years ago to $248 million ($5.11 a share) from $168 million ($3.45). Sales climbed 19 percent to $3 billion.

Such gains normally would be a cause for bragging by a corporate chief. But Shapiro took pains to assure shareholders and the public that inflation had little to do with Du Pont's robust first quarter.

"It is not a result of high selling price increases in the United States," he said. "In fact, our U.S. selling prices in the first quarter averaged only about z4 percent higher than in the same period of 1978." Worldwide, Du Pont's prices were up 5 percent, Shapiro added.

"There was no 'excess profitability' in our first-quarter results," Shapiro also said. "Far from it. The fact of the matter is that we are still recovering from the depressed earnings levels of the past several years. The company's net profit margin in the first quarter was 8.4 percent - well below the levels of the mid-1960s when margins exceeded 11 percent."

Shapiro attributed Du Pont's recent gains to a surge in sales abroad, sparked in part by the devaluation of the dollar. The company's foreign sales jumped 31 percent in the last three months over the same period a year ago.

Some of this increase, Shapiro said, was due to stockpiling by foreign firms, particularly those in Europe, that expect higher prices still to come.

Buoyed by these developments, Du Pont's directors today approved an increase in monthly pension benefits for retired employes - up 10 percent or $30, whichever is greater.

At the same time, Du Pont's 200,000 plus shareholders approved a 3-for-1 stock split, the first split for Du Pont in 30 years. It becomes effective on May 30.

Perhaps because of all the good news, the meeting went smoothly and was the shortest meeting in several years. Corporate gadflys Lewis Gilbert of New York and Evelyn Y. Davis of Washington both complimented Shapiro for what they said was the best annual meeting he has ever run. CAPTION: Picture, Du Pont Chairman Irving Shapiro answers question at annual meeting yesterday. AP