Not the question you asked but: Given that the time lost when you are broken off what you are doing, it often becomes a problem of never making progress. e.g. if it takes you 20 minutes to get back to where you were, if you get an interruption every 15 minutes ...
Solution is to one of the following:
1) Close your door until you are ready for all the interruptions.
2) If no door, put up a sign.
3) Ask people to email the issue and you will get back to them
4) I have taken to showing up early, when there is no one to interrupt me. aka 4 AM, interruptions seem to start around 9, which gives me 5 hours of real work.
When I do need to track time I use a spreadsheet. Easy math, easy record.