PHP: Replace in file using regex pattern

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I have a CSV file of 1GB. in the same some of the cells having newline \n so while calling fgetcsv() it breaks.

So first of all I want to correct the file's data and want to replace every new line surrounded with "" using regex below is my regex pattern. \".[\n[:alnum:]?\ ?\-?\,?\:?\/\.?]+."

But I don't have the idea that how to process the whole file.