using System;

​

public class Example

{

   public static void Main()

   {

       var dateString = "06:24";

       var t = DateTime.TryParseExact(dateString, "HH", System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.None, out DateTime date);

       var t2 = DateTime.TryParseExact(dateString, "H:m", System.Globalization.CultureInfo.InvariantCulture, System.Globalization.DateTimeStyles.None, out DateTime date2);

       if(t) Console.WriteLine("HH succeeds");

       if(t2) Console.WriteLine("H:m succeeds");

       Console.WriteLine(date.ToUniversalTime());

       Console.WriteLine(date2.ToUniversalTime());

​

   }

}