(WAT) - Get Report

said its first-quarter earnings and revenue guidance remains unchanged from the previous forecast offered in January, but the company's shares plunged 28% as investors apparently weren't reassured.

Shares of Waters, which makes laboratory and scientific equipment, dropped $12.50 to $32 in recent

New York Stock Exchange

trading, breaking through the 52-week low of $37.18. The stock has traded as low as $31.50.

For the first quarter ending this month, Waters expects earnings of 26 cents a share, with a possible variation of 1 cent to 2 cents. In the year-ago period, the company earned 23 cents a share. Nine analysts surveyed by

Thomson Financial/First Call

-- until recently First Call/Thomson Financial -- expect the Milford, Mass., company, to earn 26 cents.

Waters forecast first-quarter sales growth of 14% to 16% before the effects of foreign currency translation are factored in, or 10% to 12% after currency effects. In the same period a year ago, the company posted a top line of $180.6 million. First Call carries an estimate from only one analyst, who expects the company to post revenue of $203.6 million.