CMA PRACTICE EXAM QUESTIONS AND
DETAILED SOLUTIONS 2026
▶ What are QC samples (blanks, fortified blanks, duplicates) used for?
Answer: They add confidence in the analysis, measure bias, precision, and
accuracy
Analyze a blank for every 20 samples
▶ Total Solids (TS) Answer: The material residue left after the evaporation
of the sample.
TS includes VS
▶ Volatile Solids (VS) Answer: The amount of a TS sample that is lost after
the dried sample is ashed.
▶ Dissolved solids Answer: the portion of solids that passes through a 2.0
mm (micrometer) or smaller nominal pore size filter
▶ Total Suspended Solids (TSS) Answer: The amount of undissolved
sample retained on the filter after filtration
TSS = dissolved + suspended solids, fixed + volatile solids
▶ Volatile solids Answer: Solids lost during combustion
▶ Fixed solids Answer: Solids left after sample is combusted
Not volatile
▶ Volatile Suspended Solids Answer: The amount of TSS sample that is
lost after the dried sample is ashed.
VS are used as a representation of the organic portion of a sample.
Sand grit, carbonates, and other inorganic elements do not lose weight
during ashing.
, ▶ How is TS and VS reported? Answer: Reported in % (Percent Dry
weight)
▶ What temperature is the oven for TS determination? Answer: 103-105 C
until steady weight
▶ When is steady weight reached? Answer: When successive dryings do
not change the weight of the sample by:
4% or 50mg
▶ TS calculation Answer: % TS= (dry sample) / (wet sample) * 100
%TS =
(A-B)/(C-B)*100
A: weight of dried sample + weight of dish (mg)
B: weight of dish (mg)
C=weight of wet sample + weight of dish (mg)
▶ How many duplicates should be analyzed? Answer: 10% of samples
should be analyzed in duplicate.
Duplicate weights should agree within 5% of their average
▶ Why should wet and dry TS samples be weighed quickly? Answer: -Wet
samples lose moisture through evaporation
-Dry samples will gain moisture once removed from the desiccator
▶ What is the oven temp for VS determination? Answer: 500C +/- 50 until
steady weight
▶ VS can only be done on a sample after Answer: TS determination
▶ VS Calculation Answer: %VS = (dry+dish - ashed+dish)*100 / (dried
sample)
%VS=
(A-D)*100/(A-B)
A:weight of dried sample + dish(mg)
B=weight of dish (mg)
DETAILED SOLUTIONS 2026
▶ What are QC samples (blanks, fortified blanks, duplicates) used for?
Answer: They add confidence in the analysis, measure bias, precision, and
accuracy
Analyze a blank for every 20 samples
▶ Total Solids (TS) Answer: The material residue left after the evaporation
of the sample.
TS includes VS
▶ Volatile Solids (VS) Answer: The amount of a TS sample that is lost after
the dried sample is ashed.
▶ Dissolved solids Answer: the portion of solids that passes through a 2.0
mm (micrometer) or smaller nominal pore size filter
▶ Total Suspended Solids (TSS) Answer: The amount of undissolved
sample retained on the filter after filtration
TSS = dissolved + suspended solids, fixed + volatile solids
▶ Volatile solids Answer: Solids lost during combustion
▶ Fixed solids Answer: Solids left after sample is combusted
Not volatile
▶ Volatile Suspended Solids Answer: The amount of TSS sample that is
lost after the dried sample is ashed.
VS are used as a representation of the organic portion of a sample.
Sand grit, carbonates, and other inorganic elements do not lose weight
during ashing.
, ▶ How is TS and VS reported? Answer: Reported in % (Percent Dry
weight)
▶ What temperature is the oven for TS determination? Answer: 103-105 C
until steady weight
▶ When is steady weight reached? Answer: When successive dryings do
not change the weight of the sample by:
4% or 50mg
▶ TS calculation Answer: % TS= (dry sample) / (wet sample) * 100
%TS =
(A-B)/(C-B)*100
A: weight of dried sample + weight of dish (mg)
B: weight of dish (mg)
C=weight of wet sample + weight of dish (mg)
▶ How many duplicates should be analyzed? Answer: 10% of samples
should be analyzed in duplicate.
Duplicate weights should agree within 5% of their average
▶ Why should wet and dry TS samples be weighed quickly? Answer: -Wet
samples lose moisture through evaporation
-Dry samples will gain moisture once removed from the desiccator
▶ What is the oven temp for VS determination? Answer: 500C +/- 50 until
steady weight
▶ VS can only be done on a sample after Answer: TS determination
▶ VS Calculation Answer: %VS = (dry+dish - ashed+dish)*100 / (dried
sample)
%VS=
(A-D)*100/(A-B)
A:weight of dried sample + dish(mg)
B=weight of dish (mg)
