am I able to determine Ca in the protein sample with ICP-MS 7800 ( Include Helium collision and High Matrix)?

my sample is expected to contain  Calcium at the level of 20ppm.  we are trying to determine it with 7800 ICP-MS (includes Helium collision and High Matrix). 

my questions are following: 

1. can we reduce FP from 1550 W to 900W, so we can use cold plasma to test 40Ca? 

2. how do we define  "total dissolved solid" to the digested sample?

for example, sample weight 0.5g, after digested , then diluted to 50mL. is TDS 1%?

we need to evaporate digested liquid sample , then get some solid left, dilute to 50mL. Then  we calculate TDS by solid weight divided by 50. then TDS is much less than 1%. 

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