When creating artwork for printed materials, some blues on a computer screen shift toward purple when printed. I have to correct for this problem regularly. Here’s what to do about it.
First, screens don’t and can’t display exactly what’s printed. Many screen colors shift to the nearest printable color when printed. In particular, blue often becomes purple(ish). The solution is changing the exact color mix.
Commercial printing is usually done with four colors (CMYK, see below), so you need to work with software that edits CMYK files.
Here’s one example of a color that looks blue on screen but turns purple in print: 
The CMYK formula is:
Cyan (C): 100
Magenta (M): 97
Yellow (Y): 18
Black (K): 19
That second number, magenta, should be lower than 70% of the first number, cyan, or you risk a shift toward purple.
The solution: In this case, change the color to a new mix with magenta less than 70% of cyan to prevent the purple shift (C100, M49, Y0, K70).
These colors might look similar when separated with some white space, but the formulas for each are different. To the point, the second color doesn’t become purple when printed.