When you're trying to assess whether an article could be classed as primary research, the key aspect to consider is whether the researchers gathered their own data (primary) or made use of existing information (secondary).
To do this, check to see what kind of structure your article has. Primary research is often laid out in sections similar to the science experiments you did at school - Introduction, Methodology (or Methods), Results, Discussion, Conclusion. If your article doesn't have those kind of sections, and is arranged by themed subheadings as a more general commentary instead, it is unlikely to be considered primary research.
The 
abstract of the article is a way to quickly see if your article has the right type of structure.
For example, this article has sub-headings in the Abstract - Background, Methods, Results, Discussion and conclusions - which means it could be primary research.
It is important to read the article carefully to confirm that a) it is primary research and b) what type of methodology has been used. When doing this, look at the Methodology and Results sections in particular.
In the Methodology section, see if you can identify how the researchers gathered their information. Primary research methods could include questionnaires, surveys, interviews and focus groups, whereas secondary research may have trawled academic databases to retrieve articles on a topic. Literature reviews and systematic reviews are considered to be secondary research and may not be accepted by your tutors, although they can still provide useful background information and clues as to primary papers that may be of interest to you.
Quantitative research uses numbers and statistics to find patterns and reach conclusions whereas qualitative research relates more to peoples' thoughts, opinions and emotions. Mixed methods research uses a combination of the two approaches. As well as reading the Methodology section, the Results section can be a good indication of the approach used. If the results are mainly numerical, statistical or include tables, charts and graphs that would be quantitative. If the results present direct quotations from the study participants, that would be qualitative.
For further advice on identifying primary research, have a look at this study guide.
Further information on how to read and understand a journal article can be found in print and online resources, especially in the fields of health and medicine. Try looking on the LibrarySearch catalogue for study skills books about reading a paper/how to critique articles and websites such as the BMJ's collection of links based on Trisha Greenhalgh's book 'How to read a paper' (if you are prompted to login, choose the 'login via your institution' option) and Understanding Health Research, developed by the University of Glasgow.
