CWEA - LAB ANALYST III QUESTIONS
AND ANSWERS WITH SOLUTIONS 2024
What does COLOR measure? - ANSWER Amount of color units (CU) in a sample. Color caused by natural
metallic ions (Fe & Mg) & industrial wastes.
What is the test summary for COLOR? - ANSWER Sample -> Tubes -> Compare to color standards over
light source
Which of the following techniques is used to isolate anionic surfactants (as MBAS) from the sample
matrix? - ANSWER Extraction
In the cyanide determination, which one of the following is not an interference? - ANSWER Halogenated
aromatics
Which of the following is not a major interference in phenol determination? - ANSWER Hydroxy
derivatives of benzene
A freshly prepared sodium hydroxide (NaOH) solution is standardized against primary standard
potassium acid phthalate (KHC8H4O4). 0.8000 grams of potassium acid phthalate was dissolved into 50
mL CO2-free water. 2-3 drops of phenolphthalein were added. The sample was titrated to a faint pink
endpoint with 22 mLs sodium hydroxide. What is the normality of the sodium hydroxide? - ANSWER
0.178 N
What does an ICP source consist of? - ANSWER A flowing stream of argon gas ionized by an applied radio
frequency
In gas chromatography, electron capture detectors (ECD) are used to detect which of the following
compounds? - ANSWER Chlorinated hydrocarbon pesticides
Why is methlyene chloride replaced by hexane in sample preparation for analyses detected by GC
electron capture detection (ECD)? - ANSWER Chlorine compounds are detected by ECD
Which of the following methods is used to determine pesticides? - ANSWER EPA Method 608
, What analysis uses the purge and trap technique? - ANSWER Volatile organic compound analysis
The test for inhibitory residues on glassware and plastic ware determines the toxic or stimulatory effects
of dishwashing detergents used for bacterial analysis. Which bacterial genera is used for this test? -
ANSWER Enterobacter
The Water Suitability Test (Test for Bacteriological Quality of Reagent Water) determines the toxic or
stimulatory effects of the distilled or deionized water system. Which bacteria genera is used for this test?
- ANSWER Enterobacter
Short-term toxicity tests are inappropriate for: - ANSWER determining chronic toxicity.
Basic requirements for toxicity tests do not include: - ANSWER documented re-use of control test
organisms.
A test in which solutions and test organisms are placed in test chambers and kept there for the duration
of the test is called a: - ANSWER static test.
A test in which solution is replaced continuously in test chambers through the test duration is called a: -
ANSWER flow through test.
A preliminary test designed to establish approximate toxicity of a solution is called a: - ANSWER range
finding test.
A toxicity test designed to establish concentration at which a particular end point occurs is called a: -
ANSWER definitive test.
Which of the following types of control samples may be used to determine accuracy? - ANSWER Certified
reference material
Which of the following types of control samples may be used to determine precision? - ANSWER
Duplicate
AND ANSWERS WITH SOLUTIONS 2024
What does COLOR measure? - ANSWER Amount of color units (CU) in a sample. Color caused by natural
metallic ions (Fe & Mg) & industrial wastes.
What is the test summary for COLOR? - ANSWER Sample -> Tubes -> Compare to color standards over
light source
Which of the following techniques is used to isolate anionic surfactants (as MBAS) from the sample
matrix? - ANSWER Extraction
In the cyanide determination, which one of the following is not an interference? - ANSWER Halogenated
aromatics
Which of the following is not a major interference in phenol determination? - ANSWER Hydroxy
derivatives of benzene
A freshly prepared sodium hydroxide (NaOH) solution is standardized against primary standard
potassium acid phthalate (KHC8H4O4). 0.8000 grams of potassium acid phthalate was dissolved into 50
mL CO2-free water. 2-3 drops of phenolphthalein were added. The sample was titrated to a faint pink
endpoint with 22 mLs sodium hydroxide. What is the normality of the sodium hydroxide? - ANSWER
0.178 N
What does an ICP source consist of? - ANSWER A flowing stream of argon gas ionized by an applied radio
frequency
In gas chromatography, electron capture detectors (ECD) are used to detect which of the following
compounds? - ANSWER Chlorinated hydrocarbon pesticides
Why is methlyene chloride replaced by hexane in sample preparation for analyses detected by GC
electron capture detection (ECD)? - ANSWER Chlorine compounds are detected by ECD
Which of the following methods is used to determine pesticides? - ANSWER EPA Method 608
, What analysis uses the purge and trap technique? - ANSWER Volatile organic compound analysis
The test for inhibitory residues on glassware and plastic ware determines the toxic or stimulatory effects
of dishwashing detergents used for bacterial analysis. Which bacterial genera is used for this test? -
ANSWER Enterobacter
The Water Suitability Test (Test for Bacteriological Quality of Reagent Water) determines the toxic or
stimulatory effects of the distilled or deionized water system. Which bacteria genera is used for this test?
- ANSWER Enterobacter
Short-term toxicity tests are inappropriate for: - ANSWER determining chronic toxicity.
Basic requirements for toxicity tests do not include: - ANSWER documented re-use of control test
organisms.
A test in which solutions and test organisms are placed in test chambers and kept there for the duration
of the test is called a: - ANSWER static test.
A test in which solution is replaced continuously in test chambers through the test duration is called a: -
ANSWER flow through test.
A preliminary test designed to establish approximate toxicity of a solution is called a: - ANSWER range
finding test.
A toxicity test designed to establish concentration at which a particular end point occurs is called a: -
ANSWER definitive test.
Which of the following types of control samples may be used to determine accuracy? - ANSWER Certified
reference material
Which of the following types of control samples may be used to determine precision? - ANSWER
Duplicate
