INTER-LABORATORY COMPARISON OF SELENIUM IN MINE DRAINAGE Louis McDonald 1, Donglin (Lynn) Huang 1, Ben Faulkner 2, Ron Lilly 3, and Jason Unrine 4 1 West Virginia University, Division of Plant & Soil Science, Morgantown, WV 2 Bratton Farm, Princeton, WV, 3 Mallard Environmental Services, Shady Sp. WV 4 University of Kentucky, Department of Plant and Soil Sciences, Lexington, KY

Collection Procedure Don powder free nitrile gloves at each sample location. Label each tube with sample ID and indicate lab destination. Reglove. Uncap 5 borosilicate tubes and place caps on clean (dedicated plastic wrap). Immerse all 5 bottles into standing pool or in flowing stream and fill completely. Cap with no head space. Place tube in 100 ml zip lock bag and prepare for shipment. Bubble wrap and ship in iced durable cooler overnight or 2 day express or hand deliver. COC sticker on container. Tubes contain no preservative, sample is not filtered. 250 ml certified, unpreserved and finally, pre-acidified poly sample bottles will then be filled and transported (also without filtering). * Duplicate – one blind duplicate per location designated X-001 Blind Field Blank (DI water supplied by RE  ) - accomplished at exact field location at time of sample collection. Designated “B” Certified Reference Material also submitted as blind sample – designated by “J”

Certified Reference Material ($352/250 ml = $5,330/gallon)

Samples  Eight (8) Total  Five (5) field samples  One (1) field blank  One (1) certified reference  One (1) duplicate field sample  Split five (5) ways for five (5) labs  All labs determined total Se  Se speciation at two (2) labs  Se determined three (3) times on three (3) different days

Samples – expected results  01 Pond (5-10 µg/L)  02 Pond (0-10 µg/L)  05 Pond (0-10 µg/L)  14 Sediment Channel inlet (5-10 µg/L)  X5 Blind DUPLICATE of 05 Pond  B Blind BLANK (DI Water) (nd)  J Standard Reference Material (11.97 µg/L)

Instrumentation 1. G raphite F urnace - A tomic A bsorption ( GF-AA ) 2. A tomic A bsorption Z eeman -C orrected (AAZ) 3. H ydride G eneration – A tomic F luorescence (HG-AF) 4. H ydride- G eneration – I nductively C oupled P lasma (HG-ICP) 5. I on C hromatography- ICP - D ynamic R eaction C ell- M ass S pectroscopy (IC-ICP-DRC-MS)

Sample Handling  Certified borosilicate glass bottles, 40 mL, unpreserved  Polyethylene plastic bottles, 250 mL  Preserved (2 mL HNO 3 ) or Unpreserved  Filtered or unfiltered

Interpreting Results  Repeatability – If you send the same sample twice, do you get the same result for both?  Precision – If the same sample is run several times, how close are they to each other?  Accuracy – How close is the result to the ‘true’ value? Image Credit: R. Allen Chem222. UVa Accurate Not Precise Not Accurate Precise Accurate Precise

Total Se - Repeatability  One duplicate sample (05) - Are they different?  NO  No significant differences in duplicate sample for any lab.  Conclusion  Same sample submitted twice, you’ll get the same result.

Total Se – Precision CV (%) L4.4 A6.7 R10 S9.3 W13* CV = coefficient of variation = 100*standard deviation/mean Table 1. CV for CRM * = only two reps

Total Se - Precision Table 2. Mean and range CV for other samples Labmeanminmax L A R S W Conclusion – reasonably good precision for all labs.

Total Se - Accuracy Figure 1. Accuracy in determination of Certified Reference Standard.

Total Se - Accuracy  Assume IC-ICP-DRC-MS method = true Lab SampleLRSW % Table 3. Percent error in determinations of field samples.

Results - Speciation  IC – ICP – DRC – MS

Results - Speciation HG - ICP Fully Reduced to Se (IV) Aliquot 2 Se (IV) + Se(IV) Aliquot 1 Se (IV) Selenium Sample Se (IV) acidified with HCl Aliquot 3 Se (0) +Se (IV) +Se (VI) Se fully oxidized Reduced to Se (IV)

Results - Speciation  Organic Se (selenocyanate, methylseleninic acid  IC-ICP-DRC-MS = not detected  HG-ICP = not measured  Selenite  IC-ICP-DRC-MS = not detected  HG-ICP = not detected

Results - Speciation  Selenate SampleIC-ICP-DRC-MSHG-ICP μ g L Table 4. Selenate concentrations in four samples by two instrumental methods

Summary – Total Se  That most labs accurately determined the Certified Standard is promising

Summary – Total Se  That most labs accurately determined the Certified Standard is promising.  That most CVs were small is encouraging  Little variation for different days

Summary – Total Se  The variability in some labs indicates the need for  Certified Standard(s) for mine drainages

Summary – Total Se  The variability in some labs indicates the need for  Certified Standard(s) for mine drainages  Broader use of standard addition method to account for matrix effects.

Summary – Total Se  The variability in some labs indicates the need for  Certified Standard(s) for mine drainages  Broader use of standard addition method to account for matrix effects  Further research into the causes of variability

Summary – Total Se  The variability in some labs indicates the need for  Certified Standard(s) for mine drainages  Broader use of standard addition method to account for matrix effects  Further research into the causes of variability  Continued program of Inter-laboratory Proficiency Testing High CVs in our results Replaced parts, now getting significantly better data

Summary – Total Se  The variability in some labs indicates the need for  Certified Standard(s) for mine drainages  Broader use of standard addition method to account for matrix effects  Further research into the causes of variability  Continued program of Inter-laboratory Proficiency Testing The high CVs in our results Replaced parts, now getting significantly better results  Work toward developing a SOP for sample handling

Summary – Se Speciation  Selenium speciation is difficult, expensive  Some techniques are limited in their ability  But – speciation defines toxicity and treatment

Recommendations for Users  Insist on a QA/QC plan that convinces you of data quality  Consider spiking samples with and checking recovery in-house  Move toward speciation to guide treatment decisions