Reporting Limit Calculations

Method 26A:

Method M26A DL = Adjusted volume * (mL) x 0.05 ug/mL (lowest calibration standard). 

e.g. 4000 mL x 0.05 ug/mL = 200 ug 

 

= the adjusted volume is typically 4000 mL based on a starting impinger charge volume of 200 

mL (100 + 100 for impingers 1 & 2) of 0.1N H2SO4. The adjustment is necessary to "matrix 

match" the samples to the standards. If a higher Normality is used then a higher adjusted volume 

will be required. 

Method-033:

Method-033 DL = Adjusted volume (mL) if required x 0.1 ug/mL (lowest calibration 

standard). 

e.g. 200 mL x 0.1 ug/mL = 20 ug 

 

Here the samples are analyzed as received as long as they are 0.1N H2SO4. If a higher Normality 

is used then a higher adjusted volume will be required. 

Method 0031 VOST:

VOST results are reported at the MDL (Method Detection Limit). Method Detection Limits are 

calculated by using the standard deviation from a minimum of 8 replicate low level spikes. Each 

analytes standard deviation is multiplied by the appropriate Student T value to determine the 

statistically derived reporting limit.

Method 29:

For Method 29 the analyst takes the statistically determined MDL (Method Detection Limit) 

value and multiplies it by a “factor” in order to determine the RDL (Reporting Detection Limit). 

This process is similar to the one employed in Method 23 where the EDL is determined based on 

a constant factor of 2.5 times the signal to noise ratio. 

For the ICP/MS this “factor” can vary. The factor is determined by the analyst at the bench and 

takes into account all relevant factors such as, final volumes, interferences, matrix issues, etc. The 
RDL (Reporting Detection Limit) reported is the lowest concentration that the lab feels can be 

reported within the 99% confidence interval. For values below this RDL the uncertainty 

increases. Section 5.5.5.2.2.1 bullet H refers to the ICP/MS procedure. 

Method 23:

Reporting limits for Method 23 are calculated on a per sample basis. The EDL (Estimated 

Detection Limit) is determined based on a constant factor of 2.5 times the signal to noise ratio as 

defined in Method 23/8290. This EDL value is generally less than the RDL (Reporting Detection 

Limit), that is equivalent to the lowest calibration standard but in certain cases it may be higher 

due to “matrix” effects. The EDL may even be less than the statistically derived MDL (Method 

Detection Limit). 

Method M0010 PAH:

PAH results are reported at the MDL (Method Detection Limit) multiplied by the number of 

“splits”. Method Detection Limits are calculated by using the standard deviation from a minimum 

of 8 replicate low level spikes. Each analytes standard deviation is multiplied by the appropriate 

Student T value to determine the statistically derived reporting limit. 

Method M0011 Formaldehyde:

Formaldehyde results are reported at the RDL (Reporting Detection Limit) that is equivalent to 

the lowest calibration standard. 

Method 5 Particulates:

A single filter is weighed 10 times and RDL is determined as the weight difference. Ten 

individual vials are spiked with acetone containing 5 mg of material. Detection Limits are 

calculated by using the standard deviation from these 10 replicate low level spikes. The standard 

deviation is multiplied by the appropriate Student T value to determine the statistically derived 

reporting limit. 

Method OTM-028:

A portion of reagent water that has been spiked with a known amount of material is extracted 3 

times with Methylene Chloride. The solvent is evaporated to dryness. Detection Limits are 

calculated by using the standard deviation from these 10 replicate low level spikes. The standard 

deviation is multiplied by the appropriate Student T value to determine the statistically derived 

reporting limit. The non-extractable portion is determined by the weight difference on a series of 

10 vials. Detection Limits are calculated by using the standard deviation from these 10 replicates. 

The standard deviation is multiplied by the appropriate Student T value to determine the 

statistically derived reporting limit.