Section NR 149.50 - Technology requirementsThe purpose of this section is to establish minimum requirements that can significantly affect data quality but are not always clearly or consistently addressed in all approved methods.
Note: The Department will take the applicability of these requirements into consideration when there are new approved methods or advancements in technology.
(1) OXYGEN DEMAND ASSAYS (BOD or CBOD). (a) The environmental conditions for the analysis of biochemical oxygen demand and carbonaceous biochemical oxygen demand shall be 17 to 23 °C.(b) When dissolved oxygen meters are calibrated using a water-saturated air or air-saturated water standard, the laboratory shall verify concentrations in mg/L of those standards by comparing those concentrations to the dissolved oxygen theoretical saturation point. The measured concentration shall be at or near the theoretical saturation point.(c) The laboratory shall use the theoretical saturation point, based on temperature and barometric pressure, on each day of analysis to assess supersaturation. Note: When barometric pressure and temperature measurement features are available on the DO meter, they should be taken from the DO meter
(d) The laboratory shall properly treat supersaturated samples before an initial dissolved oxygen measurement is performed.(e) When the laboratory uses pipets to deliver sample volumes, the tips shall be manufactured to be wide-bore.(f) When the laboratory analyzes multiple method blanks and glucose-glutamic acid standards in an analytical batch, each method blank and glucose-glutamic acid standard analyzed shall be assessed individually and associated to the entire analytical batch unless individual method blanks and individual glucose-glutamic acid standards are clearly documented to be traceable to specific groups of 20 samples.(g) The laboratory shall seed disinfected samples and nitrogenous demand inhibited samples.(h) The laboratory may not add nitrogenous demand inhibitor to the glucose-glutamic acid standard, to seed material, or method blanks.(i) The laboratory shall use sample volumes for dilutions that are sufficient to expect 2 mg/L depletion in at least one dilution.(j) When equipment with multiple dissolved oxygen probes is employed, the laboratory shall calibrate each probe. Sample records shall be traceable to the probe used.(k) The laboratory shall calibrate dissolved oxygen probes on each day of use. (l) The laboratory shall use local barometric pressure which has not been adjusted to sea level.(m) When determining residual chlorine, a minimum detection capability of 0.1 mg/L shall be met.(2) COLORIMETRIC OR TURBIDMETRIC. (a) Except for inverse chemistries, the laboratory shall use calibration blanks in the initial calibration of colorimetric or turbidimetric analyses, and those calibration blanks shall be assigned the measured response. Note: High range chemical oxygen demand and hexavalent chromium are two tests where inverse chemistries are utilized.
(b) When closed vials are digested using block digesters for total phosphorus, the laboratory shall perform the digestion at 150 ± 2 °C for a minimum of 30 minutes.(c) When the laboratory uses sulfide strips, the sulfide strips shall have a minimum detection capability of 10 mg/L.(d) The laboratory may not dilute samples after the color reagent has been added to the samples.(e) The laboratory shall process hexavalent chromium standards the same as samples.(3) ELECTROMETRIC ASSAYS (I.E. ION-SELECTIVE ELECTRODE). When the laboratory performs electrometric assays, the laboratory shall perform an initial calibration on each day of analysis.(4) GRAVIMETRIC ASSAYS - RESIDUE (SOLIDS). (a) The laboratory may not use Buchner funnels or Gooch crucibles for determination of total suspended solids or total dissolved solids.(b) When the laboratory uses pipets to deliver sample volumes for total solids and total suspended solids, the pipet tips shall be manufactured to be wide-bore.(5) GRAVIMETRIC ASSAYS - OIL & GREASE AS HEXANE EXTRACTABLE MATERIALS (HEM). (a) When using the solid phase extraction technique, the laboratory may not allow polar solvents to contact the sample. (b) The laboratory shall use activated silica gel for silica gel-treated determinations.(6) TITRIMETRIC OR POTENTIOMETRIC TITRATION ASSAYS. When standardization is required by method, the laboratory shall standardize all titrants monthly, unless all the following are met: (a) Unused titrant is never poured back into the original container.(b) Titrants shall always be protected from light.(c) LCS recovery control limits shall be set at 90 to 110%, or tighter, and recovery is achieved.(7) NONDISPERSIVE IR OR MICROCOULOMETRY. (a) For total organic carbon determinations, the laboratory shall perform an inorganic carbon removal check with each analysis batch.(b) For aqueous samples with results greater than or equal to the LOQ, the laboratory shall perform duplicate injections until the relative percent difference is 10% or less.(8) ION CHROMATOGRAPHY (IC). The width of the retention time window that the laboratory uses to make identifications shall be based upon measurements of actual retention time variations of standards over the course of a day unless analyst experience provides for another defensible procedure.(9) FLAME ATOMIC ABSORPTION SPECTROPHOTOMETRY (FLAA). (a) The laboratory shall perform at least two consecutive readings for all samples, standards, and quality control samples, and the laboratory shall use the average for calculating results.(b) When sample concentrations are greater than the LOQ, the laboratory shall use a control limit of 10% or less for the relative percent difference between replicate aspirations.(c) The laboratory shall include the same acid types and concentrations in calibration standards as those used in samples.(10) GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROPHO-TOMETRY (GFAA). (a) The laboratory shall use at least two firings for all samples, standards, and quality control samples.(b) 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.(c) 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.(d) The laboratory shall include the same acid types and concentrations in calibration standards as those used in samples.(11) 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.(12) INDUCTIVELY COUPLED PLASMA EMISSION SPECTROPHOTOMETRY (ICP). (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.(b) 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.(c) 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.(d) 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.(e) 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.(f) Adjusting background correction shall require re-evaluation of any interference corrections that are affected by the element to which the background correction was made.(13) INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY (ICP/MS). (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. (b) All quality control samples shall be performed on the isotope used for identification and quantitation.(14) GAS CHROMATOGRAPHY (GC). (a) 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.(b) 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: 1. For each compound reported, the process used to determine which peaks are used to identify and quantitate the compound.2. For each compound reported, the process used to determine how the laboratory quantitates the compounds when the compound exhibits weathering, degradation, or positive interferences.3. For aroclors, the process used to determine how the laboratory quantitates each aroclor when more than one aroclor is present in the sample.(15) GAS CHROMATOGRAPHY-MASS SPECTROMETRY (GC/MS). (a) The laboratory shall meet full scan tune requirements before selective ion monitoring analysis begins.(b) 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.(16) HAZARDOUS WASTE CHARACTERISTICS. (a) The laboratory shall stir samples during pH measurements for toxicity characteristic leaching procedure fluid type determinations.(b) The laboratory shall perform a flashpoint standard suitable for ignitability determinations for each batch of samples analyzed for flashpoint analysis.(17) PREPARATORY METHODS. (a) Unless otherwise required by the method, the laboratory shall fortify any quality control sample prior to the addition of the preparation reagents.(b) The laboratory shall perform microwave preparations with instruments that utilize temperature feedback control.Wis. Admin. Code Department of Natural Resources NR 149.50
Adopted by, 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, eff. 6/29/2021 Pursuant to s. 299.11(4) (c), Stats., this chapter is shown as amended eff. 6-29-21 by CR 17-046.