How to find the minimum and maximum value of timestamp (hh:mm)?

I have a matrix called time_stamps which contain several time stamps for twitter data (when the tweet was posted). time_stamps is a 1645x5 char array right now. It contains 5 columns (12:44 is a time stamp with 5 characters). With this, I am trying to find the minimum time stamp and the maximum one. Which time is the least and which time is the most? I'm having trouble writing the code to do it though. Any help you can give would be much appreciated.

tunedData = readtable('parsed_tweets_small.csv');

time_stamps = table2array(tunedData(:,4)); %the 4th column indicates time stamps 

time_stamps = cell2mat(time_stamps);

%now i need to find the minimum and maximum of these time stamps

Answer 1

[Walter Roberson]

time_stamps = datetime(tunedData{:,4}, 'InputFormat', 'HH:mm');
min(time_stamps)
max(time_stamps)

[Peter Perkins]

Also, beginning in R2018a, you can convert "pure time" text timestamps to duration, so

time_stamps = duration(tunedData{:,4}, 'InputFormat', 'HH:mm');
min(time_stamps)
max(time_stamps)

[Walter Roberson]

Looks like it needs to be 'hh:mm' instead of 'HH:mm'. Which is inconsistent with datetime()

>> duration('13:48', 'InputFormat', 'hh:mm')
ans = 
  duration
   13:48:00
>> duration('13:48', 'InputFormat', 'HH:mm')
Error using duration (line 286)
Unsupported format 'HH:mm'. See the documentation of 'InputFormat' for valid formats. 
>> datetime('13:48', 'InputFormat', 'HH:mm')
ans = 
  datetime
   13-Apr-2018 13:48:00
>> datetime('13:48', 'InputFormat', 'hh:mm')
Error using datetime (line 616)
Unable to parse '13:48' as a date/time using the format 'hh:mm'.

datetime() needs HH for hours beyond 12 and treats hour '12' as 00 when 'hh' is used, but duration() rejects 'HH' as being invalid. :(