How to separate a line into two strings?

Quote:

C#

string[] words = line.Split(delimiterChars);

split is wrong approach because there is more than 1 space in line.
I recommend to use RegEx because you will be able to describe a sequence that will match only once.
This will split at space only id followed by double quote:

(\t| )(?=")

Just a few interesting links to help building and debugging RegEx.
Here is a link to RegEx documentation:
perlre - perldoc.perl.org[^]
Here is links to tools to help build RegEx and debug them:
.NET Regex Tester - Regex Storm[^]
Expresso Regular Expression Tool[^]
RegExr: Learn, Build, & Test RegEx[^]
Online regex tester and debugger: PHP, PCRE, Python, Golang and JavaScript[^]
This one show you the RegEx as a nice graph which is really helpful to understand what is doing a RegEx: Debuggex: Online visual regex tester. JavaScript, Python, and PCRE.[^]
This site also show the Regex in a nice graph but can't test what match the RegEx: Regexper[^]

string input = "one two three";
input.Split(new[] { ' ' }) == { "one", "two", "three" }
input.Split(new[] { ' ' }, 2) == { "one", "two three" }

// Linq not used here

string line = @"CONNECTION.TEST ""the connections is confirmed""";

// find first whitespace char ndx
int ndx = Array.FindIndex(line.ToCharArray(), ch => char.IsWhiteSpace(ch));

string line1 = line.Substring(0, ndx);

// using Substring
string line2BySubString = line.Substring(ndx).TrimStart();

// using Remove
string line2ByRemove = line.Remove(0,ndx).TrimStart();

Some discussion here of various techniques for finding the first index of a specific character in a string: [^]