Here are some references for measuring EI:
Ciarrochi, J., Chan, A., Caputi, P., & Roberts, R. (2001). Measuring emotional intelligence. Emotional intelligence in everyday life: A scientific inquiry, 2, 25-24.
Tapia, M. (2001). Measuring emotional intelligence. Psychological Reports, 88(2), 353-364.
Mayer, J. D., Salovey, P., Caruso, D. R., & Sitarenios, G. (2003). Measuring emotional intelligence with the MSCEIT V2. 0. Emotion, 3(1), 97.
Brackett, M. A., & Salovey, P. (2006). Measuring emotional intelligence with the Mayer-Salovery-Caruso Emotional Intelligence Test (MSCEIT). Psicothema, 18(Suplemento), 34-41.
Dulewicz, V., Higgs, M., & Slaski, M. (2003). Measuring emotional intelligence: Content, construct and criterion-related validity. Journal of Managerial Psychology, 18(5), 405-420.
A very brief definition of emotional intelligence is an aspect of general intelligence described as the ability of an individual to evaluate, express, or manage emotions of self and others, which increases the adaptation to social situations. Management of emotions of self is based on one's self-efficacy (belief in their ability).
Two instruments for measurement are the MSCEIT or Bar-On Emotional Quotient Survey.
I would be very leery of "emotional intelligence." As far as I am concerned, there's no real evidence that it measures anything that is distinguishable from trait Big Five agreeableness. It's certainly NOT an element of general intelligence, which is completely uncorrelated with agreeableness.
So can we say,MSCEIT version 2 is the best method available to asses the EI.
In my opinion, the MSCEIT 2 is a very good testing instrument. The Bar-On, however, provides a deeper insight into an element of EI/EQ, which is self-efficacy. The validity of either can depend on the theories and criteria of the research as each instrument looks at different variables.
'Emotional Intelligence' is a subset of personality traits put together and 'marketed' differently. There is nothing of 'Intelligence' (the ability to respond effectively to unstructured and unpredictable situations) in Emotional Intelligence. Usually the factors which constitute so called emotional intelligence are - Emotional Stability, Empathy, Affiliation, Sensitivity, Self-confidence etc.