10139
This shortcoming can be remedied , in large measure , by including data from a direct Ca ( 2 + ) titration in the presence of a high , fixed Mg ( 2 + ) concentration .
 Ca ( 2 + ), Mg ( 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 + ), Mg ( 2 + )