FREE WW Laboratory Analysis Procedures and Quality Control Questions and Answers

Question 1

What is the standard incubation temperature and duration for the BOD5 test?

Accepted Answer

20°C for 5 days

Answer

35°C for 24 hours

Answer

25°C for 3 days

Answer

4°C for 7 days

Question 2

When is a 'grab sample' more appropriate than a 'composite sample'?

Accepted Answer

When measuring pH and chlorine residual

Answer

When measuring average daily BOD loading

Answer

When determining total weekly phosphorus discharge

Answer

When complying with a 24-hour average TSS limit

Question 3

In laboratory quality control, what is the purpose of analyzing a 'blank'?

Accepted Answer

To check for contamination of reagents or equipment

Answer

To calibrate the instrument

Answer

To determine the precision of the analyst

Answer

To verify the concentration of a known standard

Question 4

The procedure for Total Suspended Solids (TSS) requires filtering a sample through what?

Accepted Answer

A pre-weighed glass-fiber filter

Answer

A standard coffee filter

Answer

A piece of cheesecloth

Answer

A calibrated sedimentation cone (Imhoff cone)

Question 5

How often should a pH meter be calibrated?

Accepted Answer

Daily, before use

Answer

Once per month

Answer

Once per week

Answer

Only when it provides a reading that seems incorrect

Question 6

What is the holding time and preservation method for a sample that will be tested for fecal coliform?

Accepted Answer

Cool to <10°C, analyze within 8 hours

Answer

Add sulfuric acid to pH <2, analyze within 28 days

Answer

Freeze at -20°C, analyze within 7 days

Answer

No preservation needed, analyze within 48 hours

Question 7

A 'split sample' is sent to an external lab as part of a quality assurance program. What is the purpose of this?

Accepted Answer

To verify the accuracy of the in-house laboratory's results

Answer

To reduce the workload of the in-house lab

Answer

To get the results faster

Answer

To have a backup sample in case of a spill