When sample concentrations are greater than the LOQ, the laboratory shall use a control limit of 10% or less for the relative standard deviation of replicate firings.
When elements are measured at wavelengths lower than 200 nm, the laboratory shall analyze the samples with an instrument equipped with Zeeman background correction or equivalent.
The laboratory shall include the same acid types and concentrations in calibration standards as those used in samples.
Cold vapor atomic absorption spectrophotometry (CVAA).
The laboratory shall ensure that potassium permanganate is present after the two-hour digestion for Hg, or the sample shall be redigested using a smaller sample amount until potassium permanganate remains. Instead, the laboratory could choose to add more potassium permanganate to the affected samples and method blank and digest for an additional two hours.
Inductively coupled plasma emission spectrophotometry (ICP). NR 149.50(12)(a)(a)
The laboratory shall perform a spectral interference identification study before performing any sample analysis using the following single element standards: Ag, Al, As, B, Ba, Be, Ca, Cd, Ce, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, SiO2
, Sn, Sr, Ti, Tl, V, and Zn. When other interferences have been identified, the laboratory shall perform appropriate spectral interference identification studies for those interferences. The laboratory shall analyze the interfering elements to identify potential interelement interferences for each mode and wavelength used. This requirement applies to each instrument used for analysis.
The concentration of single element standards used in the spectral interference identification study shall be at or greater than the maximum concentrations encountered in samples.
At the beginning of each analysis day, the laboratory shall verify that interference corrections and background corrections are working properly through the analysis of interference check standards. The interference check standards shall include all the identified interferences at the maximum concentrations encountered in samples.
Interference correction is only valid to the concentration tested in the spectral interference identification study. Samples with interferences present greater than the concentrations tested shall be reanalyzed at a dilution, or if the instrument is capable, the laboratory may analyze a single element standard at the level in the sample to demonstrate that the apparent concentration is less than the LOQ; if it is not less than the LOQ, the interelement correction factors may be updated, and all of the associated data can be reprocessed.
When reporting results to the LOD, the concentration of each non-spiked target element in the interference check standard shall be less than 10/3 their corresponding LOD.
Adjusting background correction shall require re-evaluation of any interference corrections that are affected by the element to which the background correction was made.
Inductively coupled plasma-mass spectrometry (ICP/MS). NR 149.50(13)(a)(a)
Only those masses listed in methods may be used for identification and quantitation unless the laboratory has supporting data that identifies the potential interfering species for the masses used, and the correction equations needed to resolve the interferences are employed.
All quality control samples shall be performed on the isotope used for identification and quantitation.
For non-aqueous volatiles analysis, the laboratory shall ensure that the calibration standards contain the same preservative type as the samples, such as methanol, sodium bisulfate, and reagent water.
When the laboratory analyzes multi-peak compounds, such as aroclors, toxaphene, and technical chlordane, the laboratory shall document in its standard operating procedures all the following:
For each compound reported, the process used to determine which peaks are used to identify and quantitate the compound.
For each compound reported, the process used to determine how the laboratory quantitates the compounds when the compound exhibits weathering, degradation, or positive interferences.
For aroclors, the process used to determine how the laboratory quantitates each aroclor when more than one aroclor is present in the sample.
The laboratory shall meet full scan tune requirements before selective ion monitoring analysis begins.
For non-aqueous samples, the laboratory shall ensure that the calibration standards shall contain the same preservative type as the samples, such as methanol, sodium bisulfate, and reagent water.
The laboratory shall stir samples during pH measurements for toxicity characteristic leaching procedure fluid type determinations.
The laboratory shall perform a flashpoint standard suitable for ignitability determinations for each batch of samples analyzed for flashpoint analysis.
Unless otherwise required by the method, the laboratory shall fortify any quality control sample prior to the addition of the preparation reagents.
The laboratory shall perform microwave preparations with instruments that utilize temperature feedback control.
NR 149.50 History
History: CR 17-046: cr. Register February 2021 No. 782, eff. 6-29-21; correction in numbering in (6) made under s. 13.92 (4) (b) 1., Stats., and correction in (3), (6) (c) made under s. 35.17, Stats., Register February 2021 No. 782.