Relative Percent Difference

Check for Relative Percent Difference (RPD) values for field duplicate sample results that fall outside Quality Control (QC) limits.

Notes:

•It is important that RT_MATRIX.MEDIUM_CODE be populated for this check to work properly.

•DT_RESULT_QC is not used for this check.

Check

Check name is EarthSoft.DQM.RelativePercentDiffField = Field Duplicate RPD.

Parameters

This check uses three Global Parameters:

1.reportable_result – DT_RESULT.REPORTABLE_RESULT values to include in DQM datasets

2.result_type_code – DT_RESULT.RESULT_TYPE_CODE to include in DQM datasets

3.test_type_batch – AT_TEST_BATCH_ASSIGN.TEST_BATCH_TYPE to include in DQM dataset

Thirteen parameters are available for this check. None of these parameters allow for input of analyte-specific or method-specific PARAM_VALUEs. However, if matrix-specific AND analyte- or method-specific control limits are wanted, RT_DQM_CONTROL_LIMITS.FIELD_DUP_RPD_CL needs to be populated.

1.Medium_code_soil – RT_MATRIX.MEDIUM_CODE for DT_SAMPLE.MATRIX_CODE for soil samples. Defaults to "Soil".

2.Medium_code_water – RT_MATRIX.MEDIUM_CODE for DT_SAMPLE.MATRIX_CODE for water samples. Defaults to "Water".

3.Multiplier – Multiplier used with detection limit in the FIELD DUPLICATE check to test for results with concentrations > multiplier * detection limit. Defaults to 5.

4.MultiplierSoil – Multiplier used with detection limit in the FIELD DUPLICATE check to test soil samples for results with an absolute difference in concentrations > multiplierSoil * detection limit. Defaults to 2.

5.AD_multiplier_DL – Multiplier used with the detection limit to define non-detect results, AD_multiplier_DL * detection limit. Defaults to 1. 

6.result_type_code - Which RESULT_TYPE to use. Defaults to "TRG".

7.Rpd_control_limit_other – RPD control limit for other samples. Defaults to 25.

8.Rpd_control_limit_soil – RPD control limit for soil samples. Defaults to 35.

9.Rpd_control_limit_water – RPD control limit for water samples. Defaults to 20.

10.Sample_type_Field_Dup – Defaults to "FD".

11.Field_dup_detection_limit – Detection limit column to use in the Field RPD calculation (e.g. quantitation_limit or reporting_detection_limit). Defaults to first_non_null_value.

12.Compare_to_reported_field_dup – Y/N option to compare the calculated RPD to the reported RPD for Field Duplicate samples. Defaults to “N”.

13.Acceptable_variance_field_dup – acceptable variance when comparing the calculated RPD to the reported RPD for Field Duplicate samples. Defaults to 1.

Additional Notes for Parameters:

If compare_to_reported = "Y" then:

1.DQM will compare the calculated RPD to the laboratory reported value in the qc_rpd column of field duplicate result.

2.If the difference exceeds acceptable_variance, then DQM will create an error in the Errors tab.

Notes:

•Default parameter values listed above refer to the value provided in the DQM Starter QAPP.xlsx.

•The RT_DQM_CONTROL_LIMITS.METHOD_ANALYTE_GROUP_CODE for the FIELD_DUP_RPD_CL must be null or it must be a dataset selection on the Start Event Form.

Rules

•FIELD DUP RPD > CL - DT_RESULT.RESULT_NUMERIC >= multiplier * Detection Limit and the relative percent difference (RPD) between the results was higher than the control limit (RPD_CL)

•FIELD DUP ABS DIFF > DETECTION LIMIT - The absolute difference was greater than the AD_Multiplier * Detection Limit.

Exceptions

Review results with DT_SAMPLE.SAMPLE_TYPE_CODE = sample_type_Field_Dup.

•Parent Sample: Find the parent sample using DT_SAMPLE.PARENT_SAMPLE_CODE or DT_FIELDQC_BATCH_PARTNER.

•TEST #1: For both samples, is DT_RESULT.RESULT_NUMERIC >= multiplier * DT_RESULT.REPORTING_DETECTION_LIMIT?

oIf TRUE, then calculate rpd_dup. If rpd_dup > rpd_cl, then qualify the results.

·If the MEDIUM_CODE of DT_SAMPLE.MATRIX_CODE = medium_code_soil, then rpd_cl = rpd_control_limit_soil.

·If the MEDIUM_CODE of DT_SAMPLE.MATRIX_CODE = medium_code_water, then rpd_cl = rpd_control_limit_water,

·ELSE rpd_cl = rpd_control_limit_other.

oIf FALSE, then TEST #2.

•TEST #2: Is ABS_DIFF > AD_multiplier * Detection_Limit?

Definitions:

ABS_DIFF = Absolute difference in the parent and duplicate concentrations = ABS(Parent - Dup).
Where detect_flag = N for one of the two values in the field duplicate pair, the Detection Limit * AD_Multiplier_DL is used as the value for the concentration of the non-detect in the ABS_DIFF calculation.

AD_Multiplier: If the RT_MATRIX.MEDIUM_CODE of DT_SAMPLE.MATRIX_CODE = medium_code_soil,

•then AD_multiplier = multiplierSoil

•else AD_multiplier = 1.

Detection_Limit = RT_DQM_CHECK_PARAM.PARAM_CODE = field_dup_detection_limit OR the value in the first column that is not NULL:

•DT_RESULT.REPORTING_DETECTION_LIMIT

•DT_RESULT.QUANTITATION_LIMIT

•DT_RESULT.METHOD_DETECTION_LIMIT

oIf TRUE, then qualify the results.

Using control limits from RT_DQM_CONTROL_LIMITS is discussed in more detail here.

Errors

In the Errors tab of the DQM Event Review Form, these errors may be listed:

1."One of the required rules for this check is not present in the RT_DQM_RULE table."
If you receive this error, the QAPP can be updated following the How to Update Existing QAPPs documentation page.

2."The variance between the reported RPD ({0}) and the calculated RPD ({1}) exceeded the Acceptable Variance ({2}).
This is an error or warning.

3."Field Duplicate Detection Limit is Not Numeric."
If you receive this error, the check will be skipped.

4."Detect Flag = Y and Field Duplicate Result_Numeric is NULL."
If you receive this error, the check will be skipped.

5."Field Duplicate Parent Sample missing."
If you receive this error, the check is skipped on the field duplicate pair. There may be more than one field duplicate pair in the dataset and if both samples are present, the check will run on the other pair.

6."Detect Flag = Y and Field Duplicate Parent Sample Result_Numeric is NULL."
If you receive this error, the check will be skipped.