Example Proposed MDL Calculations using 2009 Post-FACDQ Pilot Study Data 

Data generated during EPA’s 2009 post-FACDQ Pilot Study (EPA 821-R-11-005) were used to provide 

an example of how the proposed procedure would be used to calculate MDLs based on blank results and 

on spiked sample results. The 2009 study included an assessment of various detection limit (DL) 

procedures using blank and/or spiked sample data generated with EPA Methods 200.7 and 625. Because 

one of those DL procedures utilized the same calculation formula that is used in the proposed MDL, the 

2009 study contains data from which the proposed MDL procedure could be applied. 

The 2009 study included the evaluation of more than one limit: single-laboratory MDLs calculated using 

a t-statistic (DLT) and a tolerance limit k (DLK), single-lab LCMRLs, and an MRL determined using the 

individual laboratories’ LCMRLs. The multi-phase study included calculation of initial start-up limits, 

verification/adjustment of the initial limits using additional data, and use of a third set of blank and spiked 

sample data to independently evaluate the calculated limits based on pre-determined detection and 

quantitation MQOs. Due to the large number of analytes to be assessed using the two methods, the 

laboratories often analyzed extra spiked samples at some concentrations and analyzed additional 

concentrations that weren’t required for that analyte. As a result, the number of available results for which 

the proposed MDL procedure could be applied varied across laboratories and analytes.

Details regarding the specific set of 2009 Pilot Study data used in the calculation of the MDL based on 

blanks (MDLb) and spiked samples (MDLs) for each method and laboratory are as follows. 

•

•

•

MDLb (both methods): All pre-existing blank sample data submitted by the labs at the start of the 

2009 study, including those used in the calculation, lab evaluation, and independent statistical 

evaluation of the 2009 limits, were used in this calculation, with the exception of any results that were 

flagged as invalid by the laboratory or data reviewers. This yielded 78-131 available blank results for 

each lab/analyte for Method 200.7, and 30-32 blank results for each lab/analyte for Method 625. 

MDLs (Method 200.7): All spiked sample data at the spike level chosen as appropriate for a 

Quantitation Limit (QL) based on the laboratories’ DLT calculated during the 2009 study were used. 

These spiked samples included the initial evaluation of MQOs at that spike level, the ongoing 

evaluation of MQOs at that spike level, and any additional results from samples spiked at the same 

concentration that were not required but were reported. Any results that were flagged as invalid by the 

lab or data reviewers were excluded. This yielded between 14 and 28 available spiked sample results

for most labs/analytes (Laboratory 3 used slightly different spike levels during the QL verification 

analyses that did not exactly match the determined QLs for some analytes, so only seven spiked 

samples were available for some analytes). 

MDLs (Method 625): All spiked sample data at the spike level chosen as appropriate for a QL based 

on downspiking evaluations performed by the laboratories’ during Task 2 of the 2009 study were 

used. These spiked samples included the initial evaluation of MQOs at that spike level, the ongoing 

evaluation of MQOs at that spike level, and any additional results from samples spiked at the same 

concentration that were not required but were reported. Any results that were flagged as invalid by the 

laboratory or data reviewers were excluded. As a result, at least 7, and as many as 16, spiked samples 

were available for the calculation for most labs/analytes (in some cases a laboratory used slightly 

different spike levels during the QL verification analyses that did not exactly match the determined 

QLs for some analytes, so only seven spiked samples were available for those analytes).
Page 1 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Copper

All results in ug/L

MDL Summary

Lab 1

Blanks Spikes

No. of results 78 15

Spike Conc. NA 4

Mean -0.005525609 NA

Std. Dev. 0.651297421 1.429282

t-statistic 2.375756994 2.624494

MDLb 1.541798795

MDLs 3.751142658

Spike/MDLs 1.066341743 OK

Max. MDL 3.751142658

Data source 

for Max MDL spikes

Lab 2

Blanks Spikes

No. of results 131 14

Spike Conc. NA 6

Mean 0.080381679 NA

Std. Dev. 1.559765961 0.745143

t-statistic 2.355374585 2.650309

MDLb 3.754214782

MDLs 1.974858542

Spike/MDLs 3.038192292 OK

Max. MDL 3.754214782

Data source 

for Max MDL blanks

Lab 3

Blanks Spikes

No. of results 93 14

Spike Conc. NA 20

Mean -0.0221251 NA

Std. Dev. 2.66471693 2.685339

t-statistic 2.36756577 2.650309

MDLb 6.286767494

MDLs 7.1169769

Spike/MDLs 2.810181947 OK

Max. MDL 7.1169769

Data source 

for Max MDL spikes

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Copper

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

0.110192198 3.904315291

-1.172794574 3.473491248

-0.410128994 3.833579032

0.184235903 4.037972079

0.135578175 4.109013187

0.22177357 3.069275774

0.60628568 4.507359741

-0.168719745 3.665449667

1.434762742 9.188680853

-0.329757351 4.698745904

0.546078285 4.760787246

-0.425599897 4.671931822

0.626738615 4.68827267

-0.390079261 4.74388168

0.139936755 5.763216588

0.016945955

0.046957889

-0.646932899

-0.343701375

Lab 2 MB Lab 2 Spike 

Result Result

-1 5.53

0.98 6.16

1.33 6.5941

0.94 5.48

1.31 6.25

0.14 5.3466

2.49 5.1603

-0.76 5.5009

-0.33 4.3021

-0.61 6.8877

-0.75 6.508

-1.96 5.8244

-2.56 6.766

-1.68 6.6588

-0.33

-1.21

-0.85

-1.84

-0.47

Lab 3 MB Lab 3 Spike 

Result Result

-4.591831376 20.2

-3.879824183 19.4

-0.872600748 23.2

-0.667889009 23.8

0.986243953 16.2

3.211006913 17.6

3.318523541 18.9

-3.596476278 23.4

-4.919131008 23.8

-5.836270553 22.6

-0.947259598 19.6

5.588759485 20.2

6.379432274 18.7

7.549726956 16.3

6.881223767

2.081867584

-1.233152897

2.253657908

-0.64847756
Page 2 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Copper

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

-0.3588574

-0.102554651

-0.828046993

0.433466795

0.064076761

0.39685425

0.375563998

-0.059071791

0.311081507

-0.828321407

0.392678633

0.097757272

-0.161907832

0.187397003

-0.507532146

-1.295727469

0.328143311

0.171099157

0.534106735

0.036357735

0.416425235

0.952534423

1.155377186

0.523802194

-0.354632341

-0.013640397

0.350564903

-0.143705215

1.1479094

0.246609916

0.212729772

-0.368725013

-1.157498786

-0.553013253

-0.880721356

-1.121877272

-0.459824289

0.187241916

0.150739308

-0.131231976

Lab 2 MB Lab 2 Spike 

Result Result

-0.66

-0.39

-1.94

0.05

-0.29

-1.54

-0.62

-0.98

1.08

0.72

1.52

2.43

3.48

0.05

0.77

-2.36

0.58

-0.89

-1.93

-0.19

0.88

-1.37

3

-1.65

1.07

-0.14

0.59

1.27

0.29

-0.58

1.11

1.84

1.02

0.44

2.37

0.65

3.49

0.85

0.43

-0.47

Lab 3 MB Lab 3 Spike 

Result Result

-6.123918829

2.327201914

0.429690413

0.379531136

-1.666120762

-0.335349391

-3.309510774

3.644419725

1.037008668

3.685436725

3.551120536

-1.905364228

0.390009411

0.668776259

0.007814075

-0.891098859

0.503700004

-1.337329948

-0.337700116

3.41617634

-0.060301119

1.145106548

0.127701491

3.183536644

3.10385928

0.823500842

0.378234309

-0.997287001

-1.494213866

-0.262263845

-0.679475493

-0.35853038

0.503621875

-0.620339762

0.852734187

1.389700349

-0.315385951

-2.251664879

-2.054771117

-2.431827731
Page 3 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Copper

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

0.760452094

0.408115203

0.021368439

-0.341096861

-0.720774585

-0.335755679

-1.289879145

0.767373303

-0.391282385

-0.752602741

-1.143802567

-0.650297186

-0.406086623

0.401588143

1.742103952

1.787142836

0.668550909

-0.673370395

0.189856294

Lab 2 MB Lab 2 Spike 

Result Result

-2.2

-1.76

-2.3

-2.45

-1.91

-2.49

-0.38

-0.23

1.21

2.57

2.15

-0.72

-2.98

-1.93

-1.4

0.14

-1.78

1.65

0.98

0

-0.33

0.24

0.71

2.59

1.21

2.73

2.53

2.35

-1.75

0.05

-0.14

0.7

-0.88

-1.3

-1.54

0.96

0.05

0.96

0.05

1.63

Lab 3 MB Lab 3 Spike 

Result Result

-2.456182528

-4.632705316

3.024572093

0.385143052

2.096686253

3.515015516

1.589134146

2.144785609

-1.970505942

-0.705776349

-0.863588199

-0.666133421

1.532329711

0.2856228

2.116116657

0.054010691

0.237685197

-3.746769119

0.148143566

-1.798935847

-3.00034412

-6.147546282

-1.200529664

-1.09135812

-1.588174933

-3.359588071

-2.961591992

0.27692216

-1.030095785

-0.16914572

1.594202589

-0.86589601

2.431306668

-0.408399091
Page 4 of 24

Lab 1 MB 

Result

Lab 1 Spike 

Result

Lab 3 MB 

Result

Lab 3 Spike 

Result

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Copper

All results in ug/L

MDL Data

Lab 2 MB Lab 2 Spike 

Result Result

2.48

1.54

2.11

2.67

-0.68

-0.24

0.54

-0.68

-0.24

0.54

0.13

0.13

-0.22

0

3.76

-0.11

0.18

0.8

0.67

-1.26

-1.22

-2.6

-1.34

-3.67

-3.8

0.98

-0.65

-0.72

1.53

2.92

1.69

1.48
Page 5 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Silver

All results in ug/L

MDL Summary

Lab 1

Blanks Spikes

No. of results 78 15

Spike Conc. NA 4

Mean 0.07703704 NA

Std. Dev. 0.250260716 0.769163

t-statistic 2.375756994 2.624494

MDLb 0.671595688

MDLs 2.018664855

Spike/MDLs 1.981507722 OK

Max. MDL 2.018664855

Data source 

for Max MDL spikes

Lab 2

Blanks Spikes

No. of results 131 14

Spike Conc. NA 15

Mean -0.49374046 NA

Std. Dev. 2.338797303 1.61556

t-statistic 2.355374585 2.650309

MDLb 5.015003269

MDLs 4.281733304

Spike/MDLs 3.503254158 OK

Max. MDL 5.015003269

Data source 

for Max MDL blanks

Lab 3

Blanks Spikes

No. of results 100 14

Spike Conc. NA 6

Mean 0.025338134 NA

Std. Dev. 0.70945164 0.458584

t-statistic 2.364605862 2.650309

MDLb 1.702911641

MDLs 1.215389706

Spike/MDLs 4.936688182 OK

Max. MDL 1.702911641

Data source 

for Max MDL blanks

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Silver

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

0.009797505 3.702886257

1.044387899 3.363311619

0.078363692 3.400041844

0.326414874 3.322684964

-0.138432618 3.374602593

-0.132879628 3.403947192

0.035874404 3.028962158

0.009409216 3.419865493

0.136225658 6.364382097

0.042956834 3.939958896

0.206638231 3.685154805

0.091295681 3.988008742

0.352511018 3.759445222

-0.059856745 3.728240463

-0.046618457 3.685483405

-0.242465187

0.019637518

-0.32641973

-0.217056903

Lab 2 MB Lab 2 Spike 

Result Result

2.89 11.16

3.16 14.08

2.92 14.4946

2.49 13.86

1.43 13.86

-0.38 12.0578

1.74 13.5971

-1.81 15.4911

-0.98 13.4923

0.53 16.5105

-3.06 16.0789

-1.94 16.2632

-2.92 13.7577

-1.34 16.2615

-1.34

-2.77

-0.92

-1.54

0.39

Lab 3 MB Lab 3 Spike 

Result Result

0.370310279 6.83

0.003748583 6.42

2.142445021 5.36

-0.155697473 5.78

0.059735263 6.85

0.050421867 6.76

-0.477142907 6.49

-2.137285509 6.4

-1.435526378 7.12

-1.567383004 6.56

-1.158318585 6.58

0.020029751 6.8

0.671563372 6.28

-0.036067628 6.76

-0.024960758

0.044847021

-0.289745193

0.343485421

0.229751575
Page 6 of 24

Lab 1 MB Lab 1 Spike 

Result Result

-0.054387721

0.172753877

-0.063035217

0.031704528

0.469200175

0.310700459

0.213488197

0.101577445

0.08865954

-0.27513639

-0.205149301

-0.421075724

0.302345334

-0.037481913

0.028310651

-0.243765409

0.16704158

0.19516165

-0.274230827

0.267822014

-0.314993321

-0.394076364

0.312740889

-0.030790471

0.012583753

0.254795797

0.016413244

0.34159559

0.228616754

0.57980794

-0.13896459

-0.111172988

0.110551477

0.101702178

0.374889831

-0.047342733

0.160526657

0.114460323

-0.06542586

-0.117710454

Lab 2 MB Lab 2 Spike 

Result Result

1.62

-1.04

-0.65

0.07

-0.4

-0.09

-2.34

-2.85

2.08

0.43

3.24

3.82

6.56

-1.63

-1.55

-3.27

-1.09

-2.69

-3.34

-2.25

-0.4

-3.78

-2.49

-3.42

-0.16

-2.07

-2.04

-0.17

-0.33

-3.39

-1.61

0.97

-0.56

-0.65

1.41

2.19

3.14

-1.77

1.1

1.19

Lab 3 MB Lab 3 Spike 

Result Result

-0.202983787

0.405372471

0.196055758

-0.143462681

0.559464344

-0.133825535

-0.287863647

-0.702189306

-0.200629867

0.010732786

0.022558387

0.028061631

0.087223783

-0.505353109

0.357322988

-0.702167451

-0.272161172

-0.726957461

0.015662706

0.391527909

-0.43127135

0.191945511

-0.077860364

-0.698838576

0.052248205

0.814793787

0.158620062

-0.324208227

0.544542538

-0.271840976

-0.330026719

-0.4541795

-0.354093858

-0.500156688

-0.424019242

-0.438924252

-0.039927028

0.079008976

-0.348089451

-0.091171165

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Silver

All results in ug/L

MDL Data
Page 7 of 24

Lab 1 MB Lab 1 Spike 

Result Result

0.109410402

-0.087319938

0.307342944

-0.133214481

0.129406555

0.182589501

0.277991919

0.5704949

0.031544285

-0.010716933

0.042909546

-0.307620728

-0.132356153

0.202781638

0.165695684

0.034744986

0.267729916

0.616930193

0.388051057

Lab 2 MB Lab 2 Spike 

Result Result

-6

-5.74

-4.56

-4.73

-3.21

-6.17

-1.38

-0.08

2.21

4.74

1.74

2.43

-1.09

-1.01

1.34

4.1

1.76

-1.02

2.29

0

-0.99

-1.99

1.16

1.73

1.47

3.54

2.68

0.43

-3.17

-2.13

-2.48

0.43

-2.82

-2.56

-2.31

0.34

0.35

0.34

0.35

1.75

Lab 3 MB Lab 3 Spike 

Result Result

-0.037220206

-0.042882522

0.110044999

0.215118562

0.257063251

0.003569978

0.207336273

0.305278244

0.439466786

-0.657680402

0.405884935

0.392036424

0.149543779

0.812413497

0.630166587

-0.027663274

-0.655725259

-0.650703187

-0.343881669

0.355994103

0.052477333

-0.589910821

2.387938611

-1.876231688

0.651168524

1.376003189

1.782828969

0.972235129

0.765953592

0.004253357

1.267816407

0.217527647

-0.2441594

0.014174874

-0.046912526

-0.511572061

-0.860185941

0.52025353

-0.067076142

0.959059331

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Silver

All results in ug/L

MDL Data
Page 8 of 24

Lab 1 MB 

Result

Lab 1 Spike 

Result

Lab 3 MB 

Result

Lab 3 Spike 

Result

1.982859409

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Silver

All results in ug/L

MDL Data

Lab 2 MB Lab 2 Spike 

Result Result

3.25

1.5

1.67

0.71

-2.83

-2.51

-0.24

-2.83

-2.51

-0.24

0.14

-0.36

0.72

-0.64

3.38

-2.16

-1.25

-1.62

0.51

-1.11

-3.03

-3.16

-1.89

-1.89

-4.75

2.26

-2.63

-4.12

-0.72

1.81

-0.07

-0.15
Page 9 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Potassium

All results in ug/L

MDL Summary

Lab 1

Blanks Spikes

No. of results 78 14

Spike Conc. NA 2000

Mean 198.7266104 NA

Std. Dev. 528.5911551 127.1687

t-statistic 2.375756994 2.650309

MDLb 1454.530744

MDLs 337.0362707

Spike/MDLs 5.934079427 OK

Max. MDL 1454.530744

Data source 

for Max MDL blanks

Lab 2

Blanks Spikes

No. of results 131 28

Spike Conc. NA 300

Mean -0.20717557 NA

Std. Dev. 52.00354179 16.12467

t-statistic 2.355374585 2.47266

MDLb 122.2806451

MDLs 39.87081607

Spike/MDLs 7.524300468 OK

Max. MDL 122.2806451

Data source 

for Max MDL blanks

Lab 3

Blanks Spikes

No. of results 95 21

Spike Conc. NA 1800

Mean 73.51775379 NA

Std. Dev. 290.5936506 283.8647

t-statistic 2.366674361 2.527977

MDLb 761.2582962

MDLs 717.603534

Spike/MDLs 2.508348851 OK

Max. MDL 761.2582962

Data source 

for Max MDL blanks

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Potassium

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

153.5441665 1969.219406

361.5118446 1990.862782

38.76742755 1798.061089

48.07283271 1972.452254

106.7234948 2055.727622

19.81261286 1912.960465

0.909211466 1912.289557

61.0455934 1958.383366

62.48872311 1910.276379

58.13170403 1897.510389

142.4393888 1861.136013

86.2978145 1851.173622

251.9017681 1679.223782

289.0659868 1575.220055

572.4680848

82.16176787

171.0982955

218.9532263

166.8923286

Lab 2 MB Lab 2 Spike 

Result Result

0 276.347

-33.14 292.902

-19.22 287.144

-0.64 292.901

-8.27 290.741

2.54 265.554

-2.55 266.994

1.28 287.088

4.49 273.977

32.69 296.06

3.81 269.835

12.06 256.722

10.15 291.228

33.63 308.483

21.57 295.42

-10.15 290.438

23.37 251.996

7.58 251.995

0.63 275.488

Lab 3 MB Lab 3 Spike 

Result Result

126.3033319 1420

-26.78716695 1360

-211.6862651 1330

-128.9135447 1330

-19.52748924 1330

-81.05942982 1130

171.6546612 1290

338.263206 1630

531.599417 1320

155.962646 1720

911.1728204 1860

-100.5229058 1460

187.0836177 1700

210.0579937 1620

-291.3230065 1130

-157.9649219 941

-234.1425776 1060

-93.65549832 1980

84.09563527 1760
Page 10 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Potassium

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

72.93611538

28.36882459

112.0623529

134.5576667

-48.23320623

155.8903944

-108.933274

252.5675393

1.214680164

213.4874181

-158.002266

-181.9862722

93.28303269

-246.1674985

-84.31565478

84.90830281

19.01310612

-145.0030105

-248.2746899

-102.2709378

-173.9781196

-146.7327156

-174.758202

-124.9487393

33.25802864

129.9873229

130.4768636

175.1769682

4479.513501

479.4832186

72.69011653

63.53852414

295.6684696

212.9293114

318.0144852

321.5147792

245.0584679

224.8612263

249.6272341

317.2926056

Lab 2 MB Lab 2 Spike 

Result Result

51.78 265.526

-85.47 277.627

-134.85 281.418

-66.48 296.816

-44.32 251.313

-55.17 280.009

-54.45 254.113

-28.66 279.312

14.33 258.31

-11.47

-6.3

0

5.04

17.6

31.2

12.32

51.52

28.82

-9.63

-45.91

-38.8

-59.49

13.42

-9.14

15.78

-27.41

-78.84

-65.88

-62.85

-18.57

-24.33

-31.38

-23.06

-20.49

-5.52

25.17

-18.21

-13.96

-14.16

8.01

Lab 3 MB Lab 3 Spike 

Result Result

-264.5595625 1500

222.1398379 1850

81.33553815

408.4785567

-5.841011147

-166.3709312

115.446366

351.1169385

239.096944

-87.04116169

-504.8530763

444.0816064

307.4220166

347.5674832

220.4657369

-480.2216703

807.2152463

773.3170995

-109.672253

-75.47753188

-207.9060183

-54.88481857

-196.9939038

136.9111424

260.5558568

51.6151023

60.74552727

104.3139823

181.4399576

221.1779418

96.68036868

44.50546335

162.4306251

128.0224961

-77.40426397

42.15066833

42.61556196

-128.9252091

91.29660848

-47.9637055
Page 11 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Potassium

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

503.141199

572.342068

118.2082291

50.43457085

225.8285203

295.402048

186.8943287

261.2031968

718.6896406

211.239011

237.577879

86.78275129

269.4539994

329.2981428

649.808391

322.5924649

167.4277477

146.4096638

281.8795196

Lab 2 MB Lab 2 Spike 

Result Result

1.2

-7.78

12.56

5.38

4.78

-5.39

-15.86

-17.69

-17.38

-11.17

-11.17

15.71

-25.13

-47.12

-10.05

-1.26

-25.13

-10.79

-3

-20.99

-12.91

-22.76

-41.82

-37.67

-11.02

-34.43

-55.24

-35.73

-16.26

10.04

-1.89

9.41

-31.38

-3.77

-13.18

26.64

53.27

26.64

53.27

29.4

Lab 3 MB Lab 3 Spike 

Result Result

-24.653982

47.64982897

-47.2494881

97.22695285

-29.96755426

-55.26157139

202.6678408

141.9904871

-47.99762911

624.3390425

465.785158

-9.291738868

-385.5434929

142.0124277

655.3401427

373.3956547

1366.572985

26.31389793

-137.2029207

14.76850179

75.02435449

1.311240121

45.70967162

-22.88442993

-159.857568

29.00855051

-44.19259202

-43.87674144

45.68359401

-169.8328224

-95.69571903

-146.82273

-26.21455002

-229.3366186

-111.2840695

-488.0875804
Page 12 of 24

Lab 1 MB 

Result

Lab 1 Spike 

Result

Lab 3 MB 

Result

Lab 3 Spike 

Result

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Potassium

All results in ug/L

MDL Data

Lab 2 MB Lab 2 Spike 

Result Result

37.98

7.97

22.05

8.58

16.48

21.53

29.78

16.48

21.53

29.78

326.44

302.06

69.24

120.68

50.77

10.9

17.8

52.14

1.9

-15.26

-13.99

-26.68

-39.05

-27.99

-86.57

-37.89

-31.67

-19.27

34.17

47.84

41.57

-16.79
Page 13 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Calcium

All results in ug/L

MDL Summary

Lab 1

Blanks Spikes

No. of results 78 14

Spike Conc. NA 250

Mean 27.49377235 NA

Std. Dev. 34.82303817 45.19941

t-statistic 2.375756994 2.650309

MDLb 110.2248488

MDLs 119.7924039

Spike/MDLs 2.086943678 OK

Max. MDL 119.7924039

Data source 

for Max MDL spikes

Lab 2

Blanks Spikes

No. of results 131 28

Spike Conc. NA 300

Mean 31.9110687 NA

Std. Dev. 105.7077811 14.98377

t-statistic 2.355374585 2.47266

MDLb 280.8924898

MDLs 37.04977941

Spike/MDLs 8.097214202 OK

Max. MDL 280.8924898

Data source 

for Max MDL blanks

Lab 3

Blanks Spikes

No. of results 99 14

Spike Conc. NA 150

Mean 7.41557008 NA

Std. Dev. 22.50332782 10.81437

t-statistic 2.36500241 2.650309

MDLb 60.63599463

MDLs 28.66141438

Spike/MDLs 5.233517021 OK

Max. MDL 60.63599463

Data source 

for Max MDL blanks

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Calcium

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

8.913142194 267.8350768

41.80811894 268.9355953

29.40816248 263.7230263

10.27613846 290.8747667

29.6154687 266.6347153

8.306378544 255.6012775

11.63235774 415.3567715

75.91422161 243.955909

7.621454791 239.3540887

18.19284447 247.9937423

289.4407611 239.1199719

39.53694632 244.4710158

54.26445595 249.5400299

37.39104407 242.7548859

28.42708863

20.62375633

12.36559774

64.9723499

23.91174729

Lab 2 MB Lab 2 Spike 

Result Result

22.07 313.16

16.08 310.379

0.2 335.71

18.16 321.256

-3.9 337.675

4.39 319.594

-1.49 333.278

34.29 341.154

37.1 317.843

14.8 314.813

2.82 313.164

6.59 318.147

-3.6 334.949

16.79 327.453

17.66 316.685

25.43 334.543

42.14 308.041

16.03 308.449

5.44 348.367

Lab 3 MB Lab 3 Spike 

Result Result

20.5338322 161

8.218626397 161

-14.319041 162

-48.44428121 156

6.671077364 157

11.32476353 147

14.75476233 157

5.063183633 161

6.67419835 152

9.005259978 153

6.486946168 167

6.333796544 170

9.711455931 181

8.426476602 186

8.838786697

12.13515428

33.44102443

13.09764017

34.75989421
Page 14 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Calcium

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

24.48508725

25.19133925

11.08306372

28.99811075

21.90470669

19.7446982

26.55246466

17.72517506

27.89258055

16.39258824

15.04434212

51.05002125

15.21591395

20.02405267

23.8692069

53.57314802

45.57639819

14.98814351

18.58349649

41.27535995

28.69730425

18.13008953

61.93229633

34.43297974

17.11431166

15.37759284

81.1820023

10.21123331

17.05850903

33.39540955

34.47712061

19.29418565

14.36840874

12.14495135

-10.5168588

-14.16260231

-16.1774911

27.45565075

23.85681897

35.29783554

Lab 2 MB Lab 2 Spike 

Result Result

9.92 368.856

33.66 326.972

13.88 318.305

-3.7 323.132

-2.34 314.316

10.28 318.957

16.14 322.925

3.23 324.414

5.5 360.396

2.38

15.89

4.68

5.24

11.26

20.81

136.81

166.17

127.91

-0.13

-3.61

11.79

-2.19

364.02

7.87

121.83

-6.71

-6.87

20.44

1.44

7.68

7.86

15.76

8.54

0.95

14.7

13.89

13.68

14.25

-6.93

1.34

Lab 3 MB Lab 3 Spike 

Result Result

15.77100097

13.59143752

39.73524978

23.61807531

-1.67363297

14.9442262

-2.068797368

-0.664686617

29.01147732

-13.94078994

-30.01336099

32.16409025

19.20749472

-71.30266166

19.85615409

17.15794487

25.77726059

4.205912261

12.0480773

12.14073181

9.58671388

12.27271679

7.175008875

10.24436224

18.33283828

27.26688639

18.51051388

16.56076594

-0.523139105

8.572334376

12.82961547

18.84218348

8.684011672

10.18217272

2.462600559

6.442615425

7.173828945

6.674856611

10.84960634

8.32790055
Page 15 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Calcium

All results in ug/L

MDL Data

Lab 1 MB Lab 1 Spike 

Result Result

13.81335341

12.03330775

22.89086559

19.46839316

29.91832208

15.44028746

12.00521671

14.66326967

13.03371031

43.95358652

13.9338787

6.147445834

4.050128647

10.16934582

50.73693579

29.01294052

6.750605507

14.64279939

36.48816957

Lab 2 MB Lab 2 Spike 

Result Result

18.92

23.93

9.21

11.39

7.01

8.15

13.62

0.03

17.49

4.33

5.99

6.3

-2.5

1.41

29.08

2.63

-10.14

7.04

39.28

-4.75

10.51

-1.7

-3.42

23.88

68.41

-4.61

73.79

5.97

-4.36

4.87

3.58

0.94

-9.71

1.68

-7.73

12.17

9.39

12.17

9.39

28.47

Lab 3 MB Lab 3 Spike 

Result Result

11.14364811

34.69268841

20.62108321

4.181814697

11.70315135

13.05949312

7.702409302

9.027679095

27.5405228

-93.54798682

-75.62916982

-76.52538025

5.349697248

9.993973563

7.290918245

9.623527556

7.257183426

36.76606233

21.82859029

-0.163404341

2.140220528

23.23631054

1.233069858

-1.863066383

-2.843308588

7.033667634

-4.222525496

5.949150223

17.61840384

3.310065839

1.858570627

4.500041364

41.13049693

24.72913088

3.951067967

4.70263025

9.146684111

59.18512295

4.367238812

4.314811207
Page 16 of 24

Lab 1 MB 

Result

Lab 1 Spike 

Result

Lab 3 MB 

Result

Lab 3 Spike 

Result

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Calcium

All results in ug/L

MDL Data

Lab 2 MB Lab 2 Spike 

Result Result

7.85

11.21

5.21

25.77

10.66

85.28

15.5

10.66

85.28

15.5

28.88

-0.51

9.39

8.36

788.61

138.05

11.53

101.66

806.56

1.4

-3.7

-1.47

-0.47

-8.6

-27.2

-8.61

7

2.22

8.96

10.54

164.19

0.21
Page 17 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Pyrene

All results in ug/L

MDL Summary

Lab 4

Blanks Spikes

No. of results 30 14

No. of numeric 

results 16 14

Spike Conc. NA 0.5

Mean 0.019159977 NA

Std. Dev. 0.042880952 0.044464

Maximum 0.22893 0.42

99th percentile NA NA

t-statistic 2.46202136 2.650309

MDLb 0.22893

MDLs 0.117842905

Spike/MDLs 4.24293681 OK

Max. MDL 0.22893

Data source for 

Max MDL blanks

Lab 5

Blanks Spikes

No. of results 30 16

No. of numeric 

results 0 16

Spike Conc. NA 3

Mean 0 NA

Std. Dev. 0 0.25691

Maximum 0 3.1627

99th percentile NA NA

t-statistic 2.46202136 2.60248

MDLb NA

MDLs 0.668604509

Spike/MDLs 4.486957478 OK

Max. MDL 0.668604509

Data source for 

Max MDL spikes

Lab 6

Blanks Spikes

No. of results 32 14

No. of numeric 

results 13 14

Spike Conc. NA 5

Mean 0.04625 NA

Std. Dev. 0.128734536 0.933141

Maximum 0.7 6.148

99th percentile NA NA

t-statistic 2.452824193 2.650309

MDLb 0.7

MDLs 2.473111317

Spike/MDLs 2.021744822 OK

Max. MDL 2.473111317

Data source for 

Max MDL spikes

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Pyrene

All results in ug/L

MDL Data

Lab 4 MB Lab 4 Spike 

Result Result

0 0.331

0.012821 0.317

0.0094173 0.322

0 0.328

0 0.325

0 0.309

0 0.261

0.017668 0.324

0 0.323

0 0.342

0 0.42

Lab 5 MB Lab 5 Spike 

Result Result

0 2.64

0 2.5341

0 2.5245

0 2.318

0 2.2889

0 2.8363

0 2.7627

0 2.5053

0 2.4808

0 2.2325

0 2.6486

Lab 6 MB Lab 6 Spike 

Result Result

0 4.132

0 3.931

0 4.252

0 5.222

0 5.585

0 5.546

0 6.148

0 2.967

0.01 3.205

0.01 3.985

0 4.787
Page 18 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Pyrene

All results in ug/L

MDL Data

Lab 4 MB Lab 4 Spike 

Result Result

0.014878 0.388

0 0.415

0 0.389

0.010825

0.015674

0.073021

0.044789

0.0338

0

0.22893

0.014736

0

0.015995

0.014865

0.028986

0.015488

0

0

0.022906

Lab 5 MB Lab 5 Spike 

Result Result

0 2.6518

0 2.9103

0 2.8412

0 3.1627

0 2.9375

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Lab 6 MB Lab 6 Spike 

Result Result

0.01 4.906

0 5.107

0 5.337

0.03

0

0.19

0.7

0

0

0

0.02

0.15

0.02

0

0.04

0

0.1

0.1

0.1

0

0
Page 19 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Diethyl Phthalate

All results in ug/L

MDL Summary

Lab 4

Blanks Spikes

No. of results 30 14

No. of numeric 

results 26 14

Spike Conc. NA 5

Mean 0.0369351 NA

Std. Dev. 0.0214302 0.561984

Maximum 0.086134 3.71

99th percentile NA NA

t-statistic 2.46202136 2.650309

MDLb 0.086134

MDLs 1.489432005

Spike/MDLs 3.356984397 OK

Max. MDL 1.489432005

Data source for 

Max MDL spikes

Lab 5

Blanks Spikes

No. of results 30 16

No. of numeric 

results 30 16

Spike Conc. NA 3

Mean 0.161691583 NA

Std. Dev. 0.139731288 0.748013

Maximum 0.553688 5.2446

99th percentile NA NA

t-statistic 2.46202136 2.60248

MDLb 0.505712998

MDLs 1.946688909

Spike/MDLs 1.541078282 OK

Max. MDL 1.946688909

Data source for 

Max MDL spikes

Lab 6

Blanks Spikes

No. of results 32 14

No. of numeric 

results 24 14

Spike Conc. NA 5

Mean 0.068125 NA

Std. Dev. 0.06502791 0.723742

Maximum 0.2 5.198

99th percentile NA NA

t-statistic 2.452824193 2.650309

MDLb 0.2

MDLs 1.918138986

Spike/MDLs 2.606693278 OK

Max. MDL 1.918138986

Data source for 

Max MDL spikes

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Diethyl Phthalate

All results in ug/L

MDL Data

Lab 4 MB Lab 4 Spike 

Result Result

0.025296 2.28

0.030486 2.42

0.018012 2.63

0 2.11

0.074166 3.33

0 3.71

0.027538 3.5

0.025252 2.08

0.032436 1.87

0.029906 2.49

0.031746 2.57

Lab 5 MB Lab 5 Spike 

Result Result

0.160398 5.2446

0.122293 3.4178

0.198404 2.4641

0.208915 2.325

0.301039 2.2989

0.098144 3.2585

0.471467 3.2292

0.127886 2.5672

0.0970539 2.5383

0.0712565 2.1807

0.0931468 2.4748

Lab 6 MB Lab 6 Spike 

Result Result

0 4.2

0.07 4.676

0.03 3.409

0 4.421

0 4.952

0 5.198

0.09 5.169

0.07 3.191

0.04 3.066

0.02 4.717

0.05 4.319
Page 20 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Diethyl Phthalate

All results in ug/L

MDL Data

Lab 4 MB Lab 4 Spike 

Result Result

0.058708 2.3

0 2.09

0 2.52

0.047148

0.030289

0.034525

0.070956

0.048454

0.03305

0.05196

0.043045

0.035834

0.032243

0.041832

0.062209

0.046217

0.038617

0.086134

0.051994

Lab 5 MB Lab 5 Spike 

Result Result

0.171461 2.526

0.33681 2.725

0.101924 2.8085

0.489194 3.3927

0.0481936 3.2934

0.0659635

0.03912

0.0436056

0.0343616

0.0590028

0.241974

0.0656188

0.070244

0.087202

0.110891

0.098961

0.0590694

0.553688

0.22346

Lab 6 MB Lab 6 Spike 

Result Result

0.07 4.142

0.09 4.9

0.05 5.117

0.12

0.05

0

0

0.2

0.03

0.06

0.04

0.15

0.03

0.12

0.1

0.1

0.2

0

0.2

0

0.2
Page 21 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Isophorone

All results in ug/L

MDL Summary

Lab 4

Blanks Spikes

No. of results 30 14

No. of numeric 

results 0 14

Spike Conc. NA 5

Mean 0 NA

Std. Dev. 0 0.306488

Maximum 0 4.71

99th percentile NA NA

t-statistic 2.46202136 2.650309

MDLb NA

MDLs 0.81228665

Spike/MDLs 6.155462485 OK

Max. MDL 0.81228665

Data source for 

Max MDL spikes

Lab 5

Blanks Spikes

No. of results 30 16

No. of numeric 

results 0 16

Spike Conc. NA 3

Mean 0 NA

Std. Dev. 0 0.23941

Maximum 0 2.9075

99th percentile NA NA

t-statistic 2.46202136 2.60248

MDLb NA

MDLs 0.623060596

Spike/MDLs 4.814940986 OK

Max. MDL 0.623060596

Data source for 

Max MDL spikes

Lab 6

Blanks Spikes

No. of results 32 14

No. of numeric 

results 1 14

Spike Conc. NA 5

Mean 0.003125 NA

Std. Dev. 0.01767767 0.631533

Maximum 0.1 5.013

99th percentile NA NA

t-statistic 2.452824193 2.650309

MDLb 0.1

MDLs 1.673756255

Spike/MDLs 2.987292795 OK

Max. MDL 1.673756255

Data source for 

Max MDL spikes

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Isophorone

All results in ug/L

MDL Data

Lab 4 MB Lab 4 Spike 

Result Result

0 3.5

0 3.57

0 3.73

0 3.67

0 4.71

0 3.95

0 4.15

0 4.03

0 4.13

0 4.03

0 4.05

Lab 5 MB Lab 5 Spike 

Result Result

0 2.4807

0 2.4643

0 2.6111

0 2.3982

0 2.3692

0 2.7877

0 2.6608

0 2.3932

0 2.3027

0 1.9861

0 2.183

Lab 6 MB 

Result

Lab 6 Spike 

Result

0 3.706

0 3.809

0 3.725

0 4.481

0 4.989

0 5.013

0 4.98

0 3.1

0 3.393

0 3.892

0 4.295
Page 22 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = Isophorone

All results in ug/L

MDL Data

Lab 4 MB Lab 4 Spike 

Result Result

0 4.04

0 3.79

0 4.16

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Lab 5 MB Lab 5 Spike 

Result Result

0 2.3252

0 2.5669

0 2.5902

0 2.9075

0 2.7958

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Lab 6 MB Lab 6 Spike 

Result Result

0 4.739

0 4.645

0 4.601

0

0

0

0

0

0

0

0

0

1

0

0

0

0

0

0

0

0

0.
Page 23 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = 2-Nitrophenol

All results in ug/L

MDL Summary

Lab 4

Blanks Spikes

No. of results 30 14

No. of numeric 

results 0 14

Spike Conc. NA 5

Mean 0 NA

Std. Dev. 0 0.398486

Maximum 0 4.16

99th percentile NA NA

t-statistic 2.46202136 2.650309

MDLb NA

MDLs 1.056111355

Spike/MDLs 4.734349247 OK

Max. MDL 1.056111355

Data source for 

Max MDL spikes

Lab 5

Blanks Spikes

No. of results 30 16

No. of numeric 

results 0 16

Spike Conc. NA 3

Mean 0 NA

Std. Dev. 0 0.237567

Maximum 0 2.9452

99th percentile NA NA

t-statistic 2.46202136 2.60248

MDLb NA

MDLs 0.61826255

Spike/MDLs 4.852307489 OK

Max. MDL 0.61826255

Data source for 

Max MDL spikes

Lab 6

Blanks Spikes

No. of results 32 14

No. of numeric 

results 0 14

Spike Conc. NA 5

Mean 0 NA

Std. Dev. 0 0.688035

Maximum 0 5.003

99th percentile NA NA

t-statistic 2.452824193 2.650309

MDLb NA

MDLs 1.823506539

Spike/MDLs 2.741969876 OK

Max. MDL 1.823506539

Data source for 

Max MDL spikes

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = 2-Nitrophenol

All results in ug/L

MDL Data

Lab 4 MB Lab 4 Spike 

Result Result

0 3.01

0 3.07

0 3.02

0 3.04

0 4.16

0 3.54

0 3.67

0 2.8

0 3.26

0 3.45

0 3.23

Lab 5 MB Lab 5 Spike 

Result Result

0 2.1296

0 2.1702

0 2.2667

0 2.0943

0 2.0304

0 2.3275

0 2.3552

0 2.1765

0 2.2279

0 2.0016

0 2.1995

Lab 6 MB 

Result

Lab 6 Spike 

Result

0 3.059

0 3.881

0 3.529

0 4.495

0 4.578

0 4.163

0 4.786

0 3.121

0 2.97

0 4.077

0 4.946
Page 24 of 24

NELAC MDL Calculations from Post-FACDQ Pilot Study Dataset

Analyte = 2-Nitrophenol

All results in ug/L

MDL Data

Lab 4 MB Lab 4 Spike 

Result Result

0 3.31

0 3.75

0 3.97

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Lab 5 MB Lab 5 Spike 

Result Result

0 2.262

0 2.4377

0 2.5325

0 2.9452

0 2.5661

0

0

0

0

0

0

0

0

0

0

0

0

0

0

Lab 6 MB Lab 6 Spike 

Result Result

0 4.355

0 3.951

0 5.003

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0