1580
We found that the strong irritant compounds tested at 20 - 40 mM induced an intracellular Ca ( 2 + ) increase measurable by spectrofluorimetry in an automated test .
 Ca ( 2 + )
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Chemical 
Text: {0} 
Answer:
 Ca ( 2 + )