does making a wpf app (vs2012) a single instance app violate the MVVM pattern?

I'm still trying to sort out issues with Singleton Pattern, single instance app, and MVVM pattern.    From what I understand -- singleton pattern means some primary class is static but can't implement an interface.  I created a single instance WPF app that uses

private static Semaphore singleInstanceWatcher;

...

which works well for creating single instance app, but it also references/uses [DllImport("user32.dll")].  Does this violate MVVM pattern as far as being not so decoupled with the OS?

Rich P