MKS Instruments Inc.‘s first-quarter sales plummeted 60 percent compared with the same period last year, landing at $76.7 million versus $193.4 million for the first quarter of 2008.

That’s a 39 percent decline from the $125.2 million the Andover-based process control products maker posted during the fourth quarter last year, and it fueled a deeper plunge into the red. MKS logged a net loss of $16.5 million during the quarter, compared with net income of $20.4 million during the first quarter of 2009.

President and CEO Leo Berlinghieri chalked the dismal results up to global economic recession, which led to slumping demand for the company’s semi-conductor products.

In response to the decline, MKS laid off 630 workers during the quarter, 24 percent of its total workforce, in a move aimed at saving about $40 million a year.

Berlinghieri said the company expects second-quarter sales in the $55 million to $75 million range and another net loss for the quarter.