title: Validate System.DateTime is in a UTC format
body: <p>I have a requirement to store all of the dates recorded in database must be recorded as UTC. So far I can achieve this using Noda library with following method:</p>
  
  <pre><code>    public static DateTime NowUtc(string timeZoneId)
      {
          var timeZone = GetTimeZone(timeZoneId);
          var instant = SystemClock.Instance.Now;
          return instant.InZone(timeZone).ToDateTimeUtc();
      }
  </code></pre>
  
  <p>I'm going to validate every date that passed into data access layer must be in UTC format.</p>
  
  <p>How do I achieve that?</p>
  
  <p>Thanks</p>
  
  <p>Note: I have created a custom class library that used Noda as the core engine and the output is converted back to System.DateTime.</p>