DQM Check for Lab Blank Contamination

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DQM Check for Lab Blank Contamination

The DQM Check for Lab Blank Contamination identifies detected concentrations of target analytes in laboratory blanks. If a detected analyte in a laboratory blank is also contained in an associated sample at a similar level as that in the blank, DQM will qualify the associated sample result.

 

Check

The check name is EarthSoft.DQM.LabBlankContamination.

 

Parameters

This check uses the following five parameters:

1.LabBlankSampleType - the sample_type_code used for laboratory blanks – defaults to LB.

2.MethodBlankSampleType - the sample_type_code used for laboratory method blanks – defaults to MB.

3.Multiplier – used by DQM to determine if a result can be qualified as non-detect - defaults to 1 if no value supplied.

4.Common_lab_multiplier – used by DQM to determine if a result identified as a common laboratory contaminant can be qualified as non-detect; depends on CAS_RN field being populated and defaults to 2 if no value is supplied.

5.Flag_blank – if TRUE, the laboratory blanks are also qualified – defaults to TRUE.

 

Using a value for multiplier from RT_DQM_CONTROL_LIMITS is discussed in more detail here.

 

Note:

The default value is used if there is no record in RT_DQM_CHECK_PARAM for an input parameter.

The default value is used if the PARAM_VALUE is NULL in RT_DQM_CHECK_PARAM.

 

Rules

There are three rules:

1.BLANK CONTAMINATION = Qualify the result in the blank sample if a concentration is detected and the FLAG_BLANK parameter = TRUE.

2.RESULT > BLANK * MULTIPLIER = Qualify an associated result if sample result > multiplier * concentration detected in the associated blank.

3.RESULT < BLANK * MULTIPLIER = Qualify an associated result if sample result < multiplier * concentration detected in the associated blank. Assuming the qualifier for this rule = “U”, then this will indicate the result is non-detect. When Completing an Event and saving qualifiers, there is also an option to set DETECTED_YN to "N" for all results with a "U" qualifier.

 

Associated results are found by:

1.Matching results (with detected concentrations only) by Method, Fraction, CAS_RN and TEST_BATCH_ID. If matching samples are found, the process stops.

2.If no matching results are found in Step 1, results (with detected concentrations only) are matched by Method, Fraction, CAS_RN and LAB_SDG.

 

Note: To use the TEST_BATCH_ID, it must be added to DT_TEST_BATCH and then the TEST_ID of the blank sample, and all of the associated TEST_IDs are added with their TEST_BATCH_ID and TEST_BATCH_TYPE to AT_TEST_BATCH_ASSIGN (usually done by EDP format).

 

Exceptions

For Lab Blanks

Review blanks if Flag_blank = TRUE

Review results with DT_SAMPLE.SAMPLE_TYPE_CODE = LabBlankSampleType and MethodBlankSampleType

Qualify a result in a lab blank if reportable_result = Y and detect_flag=Yes

 

The dqm_remark for this exception is:  Contamination detected in this Blank.

 

For Associated Samples

Review results with DT_SAMPLE.SAMPLE_TYPE_CODE = LabBlankSampleType and MethodBlankSampleType

Qualify a result in an associated sample if reportable_result = Y and detect_flag=Yes and if sample result > multiplier * concentration detected in the associated blank.

 

An example dqm_remark for this exception is:  [5 > 1 * 4] Sample result > multiplier * concentration detected in the associated blank (sample_id:3281206, test_id:3281223, cas_rn:129-00-0)

Qualify a result in an associated sample if reportable_result = Y and detect_flag=Yes and if sample result < multiplier * concentration detected in the associated blank.

 

An example dqm_remark for this exception is: [5 < 1 * 6] Sample result < multiplier * concentration detected in the associated blank (sample_id:3281211, test_id:3281224, cas_rn:7440-66-6)

 

Errors

1.Blank unit error

 

This check includes an internal unit conversion function, which allows blanks with units for liquids to be compared to results for soil samples. This internal function includes:

ug/L to mg/kg

ug/L to ug/kg

mg/L to mg/kg

mg/L to ug/kg

 

Any combination of units found in RT_UNIT_CONVERSION_FACTOR will also be used.

 

The following error occurs if the units differ and none of the above conversion factors apply:

 

Associated result (. . . .  has units (. . . .) that do not convert to units of blank result (. . . .).  

 

For this check to work, a record must be added to RT_UNIT_CONVERSION_FACTOR for that combination.

 

2.Result Numeric is null
 
If the RESULT_NUMERIC column is null in the blank or the associated sample for a result, the following error message will be created:

 

“The RESULT_NUMERIC column is NULL in blank or associated result.”