Report No. 769 Waters Proficiency Testing Round 143...

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Report No. 769

Waters Proficiency Testing

Round 143 - Biochemical Oxygen Demand (BOD)

Chemical Oxygen Demand (COD) Total Organic Carbon (TOC) -

August 2012

Acknowledgments

PTA wishes to gratefully acknowledge the technical assistance provided for this program by Ms S Semczuk of the Australian Water Quality Centre. Also our thanks go to the Environmental Resource Associates (ERA) for the supply of samples and to Global Proficiency Pty Ltd (Melbourne, Australia) for distributing the samples.

© Copyright Proficiency Testing Australia, 2012

PO Box 7507 SILVERWATER NSW 2128, Australia

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CONTENTS

1. Foreword............................................................................................................................1

2. Program Features and Design...........................................................................................1

3. Statistical Format ...............................................................................................................2

4. PTA and Technical Advisor’s Comments ..........................................................................4

5. Outlier Results .................................................................................................................15

6. Reference ........................................................................................................................15

APPENDIX A – Results and Data Analysis

Biochemical Oxygen Demand (BOD).................................................................................... A1

Chemical Oxygen Demand (COD) ........................................................................................ A4

Total Organic Carbon (TOC) ................................................................................................. A7

APPENDIX B – Sample Homogeneity and Stability

Homogeneity and Stability Testing........................................................................................ B1

APPENDIX C – Documentation

Instructions to Participants ................................................................................................... C1

Method Codes ...................................................................................................................... C3

Results Sheet ....................................................................................................................... C4

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1. Foreword

This report summarises the results of a proficiency testing program on the determination of Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) in waters. This is round 143 in a planned series of programs involving the analysis of chemical and physical parameters of waters. The exercise was conducted in May 2012 by Proficiency Testing Australia (PTA). The main aim of the program was to assess laboratories’ abilities to competently perform the prescribed analyses. The Program Coordinator was Ms D Mihaila and the Technical Advisor was Ms S Semczuk of the Australian Water Quality Centre. This report was authorised by Mrs F Watton, PTA Quality – Business Development Manager.

2. Program Features and Design 2.1 Each laboratory was randomly allocated a unique code number for the program to

ensure confidentiality of results. Reference to each laboratory in this report is by code number only.

2.2 Laboratories were provided with the "Instructions to Participants" and "Results Sheet"

(see Appendix C). Laboratories were requested to perform the tests according to their routine methods.

2.3 Participants were provided with one sealed vial (labelled R143) for analysis of

biochemical oxygen demand, chemical oxygen demand and total organic carbon. 2.4 A total of 57 laboratories received samples, comprising:

- 38 Australian participants; and

- 19 overseas participants, including:

- Brunei Darussalam (1), China (1), Indonesia (2), Kenya (1), Malaysia (2), New Zealand (2), Papua New Guinea (4), Singapore (3), Thailand (3).

Of these 57 laboratories, 7 were unable to submit results by the due date. 2.5 Results (as reported by participants) with corresponding summary statistics (i.e.

number of results, median, uncertainty of the median, normalised interquartile range, robust coefficient of variation, minimum, maximum and range) are presented in Appendix A (for each sample and for each of the analyses performed).

2.6 A robust statistical approach, using z-scores, was utilised to assess laboratories’

testing performance (see Section 3). Robust z-scores and z-score charts relevant to each test are presented in Appendix A.

The document entitled Guide to Proficiency Testing Australia, 2012 (reference [1]) defines the statistical terms and details the statistical procedures referred to in this report.

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2.7 A tabulated listing of laboratories (by code number) identified as having outlier results can be found on page 15.

2.8 Prior to sample distribution, a number of randomly selected samples were analysed

for homogeneity. Based on the results of this testing (see Appendix B) it was considered that the samples utilised for this program were homogeneous. As such, any results later identified as outliers could not be attributed to any notable sample variability.

3. Statistical Format

For each test, where appropriate, the following information is given:

- a table of results and calculated z-scores;

- a list of summary statistics; and

- ordered z-score charts. 3.1 Outlier Results and Z-scores In order to assess laboratories’ testing performance, a robust statistical approach,

using z-scores, was utilised. Z-scores give a measure of how far a result is from the consensus value (i.e. the median), and gives a "score" to each result relative to the other results in the group.

A z-score close to zero indicates that the result agrees well with those from other

laboratories. Whereas, a z-score with an absolute value greater than or equal to 3.0 is considered to be an outlier and is marked by the symbol “§”.

Each determination was examined for outliers with all methods pooled. The table on

page 15 summarises the outlier results detected. 3.2 Results Tables and Summary Statistics Each of these tables contains the results returned by each laboratory, including the

code number for the method used, and the robust z-score calculated for each result. Results have been entered exactly as reported by participants. That is, laboratories

which did not report results to the precision (i.e. number of significant figures) requested on the Results Sheet have not been rounded to the requested precision before being included in the statistical analysis.

A list of summary statistics appears at the bottom of each of the tables of results and consists of:

- the number of results for that test/sample (No. of Results);

- the median of these results, i.e. the middle value (Median);

- the uncertainty of the median;

- the normalised interquartile range of the results (Normalised IQR);

- the robust coefficient of variation, expressed as a percentage (Robust CV) - i.e. 100 x Normalised IQR / Median;

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- the minimum and maximum laboratory results; and

- the range (Maximum - Minimum).

The median is a measure of the centre of the data. The normalised IQR is a measure of the spread of the results. It is calculated by multiplying the interquartile range (IQR) by 0.7413, a factor which converts the IQR to an estimate of the standard deviation. The IQR is the difference between the upper and lower quartiles (i.e. the values above and below which a quarter of the results lie, respectively). For normally distributed data, the uncertainty of the median is approximated by:

n

normIQR×2

π

Please see reference [1] for further details on these robust summary statistics.

3.3 Ordered Z-Score Charts On these charts each laboratory's robust z-score is shown, in order of magnitude, and

is marked with its code number. From these charts, each laboratory can readily compare its performance relative to the other laboratories.

These charts contain solid lines at +3.0 and -3.0, so that outliers are clearly

identifiable as those laboratories whose "bar" extends beyond these "cut-off" lines. The y-axis of these charts has been limited, so very large z-scores appear to extend beyond the chart boundary.

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4. PTA and Technical Advisor’s Comments 4.1. Metrological Traceability and Measurement Uncertainty of Assigned Values Consensus values (median) derived from participants’ results are used in this program. These values are not metrologically traceable to an external reference. Sample preparation was undertaken according to Environmental Resource Associates’ Standard Operating Procedures to ensure samples were fit-for-purpose, homogenous and stable. The sample R143 was expected to contain the following levels:

Analysis Biochemical Oxygen Demand

Chemical Oxygen Demand

Total Organic Carbon

Certified Value (mg/L) 111 179 70.8

The assigned value for this program is the median of the results submitted by the participants. The table below presents the median values and their calculated uncertainty, for the analyses performed. Analysis

Median (mg/L)

Uncertainty of the median (mg/L)

Biochemical Oxygen Demand 112.0 3.0

Chemical Oxygen Demand 173.0 2.8

Total Organic Carbon 71.20 0.88

The median values for all analyses are in good agreement with the expected values. Overall, the performance of participants in this round was good, with robust CVs comparable with those from previous programs and lower than 10% for Chemical Oxygen Demand and for Total Organic Carbon.

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4.2. Analysis of Round 143 Results 4.2.1. Biochemical Oxygen Demand (BOD) The following table compares the BOD median and robust CV from this round to those obtained in previous PTA rounds.

Round Sample Median (mg/L) Robust CV (%) Participan ts

This study R143 112.0 13.9 43

Report 722 R132 55.00 9.6 44

Report 654 1 68.40 19.7 56

The BOD testing was successfully carried out with satisfactory results (|z-score|≤2.0) ranging between 81 – 143 mg/L. Out of 43 participants, four questionable results (2.0<|z-score|<3.0) were reported (laboratories 263, 297, 442 and 529). Three outliers results (|z-score|≥3.0) were obtained, requiring follow-up action on behalf of participant laboratories 135, 239 and 460. Figure 1 exhibits the spread of results and the methods used for BOD testing in this round. The data set formed an approximately normal distribution and the vast majority of participants in this round used the APHA Part 5210 B method.

Biochemical Oxygen Demand (BOD) (mg/L) -R143

0

2

4

6

8

10

12

14

16

18

20

0 15 30 45 60 75 90 105 120 135 150 165 180 195

Results (mg/L)

Freq

uenc

y

APHA Part 5210 B

Other

Figure 1. Spread of results for BOD proficiency testing of sample R143, with a median of 112.0 mg/L. Participants’ investigations of BOD outlier results from previous programs revealed errors due to:

� Incorrect dilutions; � Failure to calibrate dissolved oxygen meters; � Transcription errors;

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� Contamination of dilution water; � Evaporation of water seals during incubation; � Seeding not used or seeds not properly activated when required; and � High dissolved oxygen in blank due to algae growth in plastic tubing.

Measurement Uncertainty Out of 43 participants, 33 (77%) submitted MU information. There is a large variety of MU values stated by participants, ranging from 0.387 to 30 mg/L. Several of the stated MUs did not accurately reflect the difference between the participant’s result and the median obtained for this proficiency sample. A t-test of results (outliers removed, 95% confidence interval) indicated the reproducibility for BOD in this round was 112.0 ± 35.1 mg/L. The MU stated by participants can be seen in Figure 2 below and gives an indication of the expected MU for these samples, based on the 95% confidence interval for overall reproducibility in this round.

Biochemical Oxygen Demand (BOD) MU (mg/L) - R14 3

0

1

2

3

4

5

6

7

8

9

0 3 6 9 12 15 18 21 24 27 30 33 36 39

MU (mg/L)

Fre

quen

cy APHA Part 5210 B

Figure 2. MU for BOD, as stated by participants, compared with 95% confidence interval for overall reproducibility (----) ( ±35.1 mg/L) in this round. Figure 3 below displays the BOD results and MU compared to the median. Also included are the reproducibility limits. Laboratories 124, 239, 297, 442, 444, 460, 529 and 549 may need to re-examine their MU calculations, as their result was further from the median than their stated uncertainty.

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Figure 3. Biochemical Oxygen Demand (BOD) - Results of Sample R143, including MU, compared to the median

Results of S

ample R

143, including MU

, compared to t

he median

Biochem

ical Oxygen D

emand (B

OD

) - Sam

ple R143

Biochemical Oxygen Demand (BOD) - Sample R143

10

30

50

70

90

110

130

150

170

190

210

230

112

126

129

131

141

157

181

214

227

231

239

297

301

315

316

319

356

400

407

416

419

421

426

442

444

460

488

499

509

517

529

542

549

Laboratory Code

Res

ult (

mg/

L)

Result ± MU Median Reproducibility Limits

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4.2.2 Chemical Oxygen Demand (COD) The following table compares the Chemical Oxygen Demand (COD) median and robust CV from this round to those obtained in previous PTA rounds.


This study R143 173.0 8.4 43

Report 722 R132 91.50 8.3 42

Report 654 1 110.0 9.4 53

The COD testing was successfully carried out with satisfactory results (|z-score|≤2.0) ranging between 144 – 202 mg/L. Out of 43 participants, three questionable results (2.0<|z-score|<3.0) were reported (laboratories 407, 435 and 441). Three outliers results (|z-score|≥3.0) were obtained, requiring follow-up action on behalf of participant laboratories 141, 478 and 488. Figure 4 exhibits the spread of results and the methods used for COD testing in this round. The data set formed an approximately normal distribution, with no significant bias attributable to any one method.

Chemical Oxygen Demand (COD) (mg/L) -R143

0

1

2

3

4

5

6

7

8

9

10

11

12

90 100 110 120 130 140 150 160 170 180 190 200 210 220

Results (mg/L)

Fre

quen

cy

APHA Part 5220 B

APHA Part 5220 C

APHA Part 5220 D

Other

Figure 4. Spread of results for COD proficiency testing of sample R143, with a median of 173.0 mg/L. Previous programs have revealed errors in COD testing due to:

� Contamination of deionised water (organic material from deioniser resin column); � Transcription errors; � Calculation errors; and � Contamination from glassware not properly cleaned.

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Measurement Uncertainty Out of 43 participants, 32 (74%) submitted MU information. There is a large variety of MU values stated by participants, ranging from 1 to 46 mg/L. Several of the stated MUs did not accurately reflect the difference between the participant’s result and the median obtained for this proficiency sample. A t-test of results (outliers removed, 95% confidence interval) indicated the reproducibility for COD in this round was 173.0 ± 29.8 mg/L. The MU stated by participants can be seen in Figure 5 below, broken down by the methods used, and gives an indication of the expected MU for these samples, based on the 95% confidence interval for overall reproducibility in this round.

Chemical Oxygen Demand (COD) MU (mg/L) - R143

0

1

2

3

4

5

6

7

8

9

10

11

0 4 8 12 16 20 24 28 32 36 40 44 48 52

MU (mg/L)

Fre

quen

cy

APHA Part 5220 B

APHA Part 5220 C

APHA Part 5220 D

Other

Figure 5. MU for COD, as stated by participants, compared with 95% confidence interval for overall reproducibility (----) ( ±29.8 mg/L) in this round. Figure 6 below displays the COD results and MU compared to the median. Also included are the reproducibility limits. Laboratories 141, 181, 227, 231, 239, 315, 316, 334, 356, 488, 499 and 549 may need to re-examine their MU calculations, as their result was further from the median than their stated uncertainty.

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Figure 6. Chemical Oxygen Demand (COD) - Results of Sample R143, including MU, compared to the median

Results of S

ample R

143, including MU

, compared to t

he median

Chem

ical Oxygen D

emand (C

OD

) - Sam

ple R143

Chemical Oxygen Demand (COD) - Sample R143

90

110

130

150

170

190

210

230

250

270

112

126

129

131

141

157

181

214

227

231

239

297

301

315

316

319

334

356

400

407

419

421

426

442

444

459

460

488

499

509

517

549

Laboratory Code

Res

ult (

mg/

L)


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4.2.3 Total Organic Carbon (TOC) The following table compares the Total Organic Carbon (TOC) median and robust CV from this round to those obtained in previous PTA rounds.


This study R143 71.20 5.2 28

Report 722 R132 36.45 4.3 24

Report 654 1 43.85 5.2 28

The TOC testing was successfully carried out with satisfactory results (|z-score|≤2.0) ranging between 63.8 – 78.6 mg/L. Out of 28 participants, three questionable results (2.0<|z-score|<3.0) were reported (laboratories 231, 419 and 460). Three outliers results (|z-score|≥3.0) were obtained, requiring follow-up action on behalf of participant laboratories 239, 421 and 486. Figure 7 exhibits the spread of results and the methods used for TOC testing in this round. The data set formed an approximately normal distribution, with no significant bias attributable to any one method. The majority of participants in this round used the APHA Part 5310 B method.

Total Organic Carbon (TOC) (mg/L) -R143

0

1

2

3

4

5

6

7

8

9

10

11

55 58 61 64 67 70 73 76 79 82 85 88 91 94

Results (mg/L)

Fre

quen

cy

APHA Part 5310 B

APHA Part 5310 C

APHA Part 5310 D

Other

>88

Figure 7. Spread of results for TOC proficiency testing of sample R143, with a median of 71.20 mg/L. Previous programs on TOC have revealed errors due to:

� Calibration standards; � Incorrect dilutions; � Transcription errors; and � Instrument malfunctions.

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Measurement Uncertainty Out of 28 participants, 19 (68%) submitted MU information. There is a large variety of MU values stated by participants, ranging from 1 to 17.8 mg/L. Several of the stated MUs did not accurately reflect the difference between the participant’s result and the median obtained for this proficiency sample. A t-test of results (outliers removed, 95% confidence interval) indicated the reproducibility for TOC in this round was 71.20 ± 8.95 mg/L. The MU stated by participants can be seen in Figure 8 below, broken down by the methods used and gives an indication of the expected MU for these samples, based on the 95% confidence interval for overall reproducibility in this round.

Total Organic Carbon (TOC) MU (mg/L) - R143

0

1

2

3

4

5

6

0 1.5 3 4.5 6 7.5 9 10.5 12 13.5 15 16.5 18 19.5

MU (mg/L)

Freq

uenc

y

APHA Part 5310 B

APHA Part 5310 C

APHA Part 5310 D

Other

Figure 8. MU for TOC, as stated by participants, compared with 95% confidence interval for overall reproducibility (----) ( ±8.95 mg/L) in this round. Figure 9 below displays the TOC results and MU compared to the median. Also included are the reproducibility limits. Laboratories 239, 315, 419, 421, 460 and 529 may need to re-examine their MU calculations, as their result was further from the median than their stated uncertainty.

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Figure 9. Total Organic Carbon (TOC) - Results of Sample R143, including MU, compared to the median

Results of S

ample R

143, including MU

, compared to t

he median

Total O

rganic Carbon (T

OC

) - Sam

ple R143

Total Organic Carbon (TOC) - Sample R143

40

50

60

70

80

90

100

129

131

239

263

301

315

316

319

385

400

419

421

442

444

460

499

509

517

529

Laboratory Code

Res

ult (

mg/

L)


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4.3. Analysis of Results by Method Groups Further analysis of results by method groups is undertaken to provide specific information on individual method performance. In order for methods to be grouped for analysis, PTA requires more than ten sets of results from the same method group. For methods other than those presented below, there were less than ten results submitted, therefore reliable conclusions cannot be drawn from analysing them separately and these results have not been analysed by grouped methods. 4.3.1. Biochemical Oxygen Demand (BOD) The method APHA Part 5210B - method code 1 was most frequently employed for BOD analysis, with 41 laboratories indicating the use of this method and only two laboratories indicating other methods. The table below presents the median and normalised IQR of BOD results obtained by method 1.

Sample Method code Participants Median (mg/L) Robus t CV (%)

Potable 1 1 41 112.0 13.2

4.3.2. Chemical Oxygen Demand (COD) For COD analysis, the majority of participants (38 out of 43) used various APHA protocols. The method APHA Part 5220D - method code 6 was most frequently employed, with 19 laboratories indicating the use of this method. The table below presents the median and normalised IQR of COD results obtained by method 6.


Potable 1 6 19 178.0 11.0

4.3.3. Total Organic Carbon (TOC) For TOC analysis, the majority of participants (24 out of 28) used various APHA protocols. The method APHA Part 5310B - method code 12 was most frequently employed, with 18 laboratories indicating the use of this method. The table below presents the median and normalised IQR of TOC results obtained by method 12.


Potable 1 12 18 70.80 4.4

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5. Outlier Results

Laboratories reporting outlier results are listed in the following table:

Analysis Lab

Code Biochemical Oxygen Demand

Chemical Oxygen Demand

Total Organic Carbon

135 §

141 §

239 § §

421 §

460 §

478 §

486 §

488 §

1 A “§” indicates the occurrence of a z-score outlier result (i.e. those results for which

|z-score|≥3.0). 6. Reference

[1] Guide to Proficiency Testing Australia, 2012 (This document can be found on the PTA website, www.pta.asn.au)

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APPENDIX A

Results and Data Analysis Biochemical Oxygen Demand (BOD).................................................................................... A1

Chemical Oxygen Demand (COD) ........................................................................................ A4

Total Organic Carbon (TOC) ................................................................................................. A7

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Biochemical Oxygen Demand (BOD) Results

Sample R143

A1

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Biochemical Oxygen Demand (BOD)

Results by Laboratory Code

Sample R143

Lab Code

Result ± MU1 (mg/L)

Robust z-score2

Method Code3

112 118 ± 20 0.39 1

126 124 ± 11.4328 0.77 1

129 112 ± 18 0.00 1

131 112 ± 22 0.00 1

135 20.0 # -5.92 § 1

141 122 ± 11 0.64 1

147 84 # -1.80 3

157 114 ± 15 0.13 1

181 120 ± 15 0.52 1

203 102 # -0.64 1

214 97.1 ± 18.1 -0.96 1

227 99.0 ± 25 -0.84 1

231 108.8 ± 9.5 -0.21 1

239 39 ± 1 -4.70 § 1

242 121 # 0.58 3

263 67.4 # -2.87 1

297 68 ± 11 -2.83 1

301 117 ± 15 0.32 1

315 116 ± 11.7 0.26 1

316 125 ± 18 0.84 1

319 100 ± 17.4 -0.77 1

356 114 ± 6 0.13 1

398 90 # -1.42 1

400 125 ± 25 0.84 1

407 122 ± 29.8 0.64 1

416 102 ± 14.7 -0.64 1

417 114 # 0.13 1

419 117 ± 12 0.32 1

421 111 ± 17 -0.06 1 1 Where reported, results are shown with their corresponding

measurement uncertainty (MU). 2 "§"s denote outliers (i.e. those results for which |z-score| ≥ 3.0). Robust

z-scores are calculated as: z = (A - median) ÷ normalised IQR, where A is the participant laboratory's result.

3 Please refer to Appendix C (page C3) for method code descriptions.

A2

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Biochemical Oxygen Demand (BOD)-cont.


Sample R143

Lab Code


Robust z-score2

Method Code3

426 134 ± 25 1.42 1

435 81 # -2.00 1

441 106 # -0.39 1

442 150 ± 22 2.45 1

444 81.0 ± 14.6 -2.00 1

447 119 # 0.45 1

460 182 ± 30 4.51 § 1

488 119 ± 23.8 0.45 1

499 111.720 ± 0.387 -0.02 1

509 109 ± 28 -0.19 1

517 105 ± 18.0 -0.45 1

529 78.5 ± 9.7 -2.16 1

542 116 ± 23 0.26 1

549 96 ± 12 -1.03 1

No of Results: 43

Median: 112.0

Uncertainty of the Median:

3.0

Normalised IQR:

15.5

Robust CV: 13.9%

Minimum: 20.0

Maximum: 182

Range: 162.0

1 Where reported, results are shown with their corresponding

measurement uncertainty (MU). 2 "§"s denote outliers (i.e. those results for which |z-score| ≥ 3.0).

Robust z-scores are calculated as: z = (A - median) ÷ normalised IQR, where A is the participant laboratory's result.


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Biochemical Oxygen Demand (BOD) - Sample R143 - Rob ust Z-Scores

Robust Z-Scores

Ordered R

obust Z-S

core Charts

A3

Biochem

ical Oxygen D

emand (B

OD

) - Sam

ple R143

297 52

9

435

444

147 39

8 227

319

416

517

441

231

509

421

214

549 20

3

263

239

135

129

499

-5

-4

-3

-2

-1

0

1

2

3

4

5

lab code

z-sc

ore

417

315

542

301

419

112

181

242

407

126

316

400 42

6

442

460

131

157

356 14

1

447

488

-5

-4

-3

-2

-1

0

1

2

3

4

5

lab code

z-sc

ore

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Chemical Oxygen Demand (COD) Results

Sample R143

A4

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Chemical Oxygen Demand (COD)


Sample R143

Lab Code


Robust z-score2

Method Code3

112 177 ± 5 0.27 6

126 170 ± 15.572 -0.21 4

129 191 ± 23 1.23 6

131 163 ± 16 -0.68 5

141 122 ± 5 -3.49 § 6

147 166 # -0.48 11

157 187 ± 15 0.96 4

181 200 ± 10 1.85 11

203 171 # -0.14 4

214 176 ± 15.1 0.21 5

227 193 ± 16 1.37 6

231 150 ± 16 -1.57 6

239 192 ± 1 1.30 6

242 177 # 0.27 11

258 166 # -0.48 11

263 181 # 0.55 6

297 170 ± 28 -0.21 5

301 178 ± 22 0.34 6

315 159 ± 11.5 -0.96 6

316 152 ± 19 -1.44 6

319 171 ± 25.7 -0.14 4

334 158 ± 3 -1.03 6

356 155 ± 3 -1.23 6

398 175 # 0.14 4

400 192 ± 29 1.30 5

407 209 ± 38.8 2.46 6

417 162 # -0.75 5

419 170 ± 25.5 -0.21 5

421 173 ± 1.7 0.00 6 1 Where reported, results are shown with their corresponding

measurement uncertainty (MU). 2 "§"s denote outliers (i.e. those results for which |z-score| ≥ 3.0). Robust

z-scores are calculated as: z = (A - median) ÷ normalised IQR, where A is the participant laboratory's result.


A5

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Chemical Oxygen Demand (COD)-cont.


Sample R143

Lab Code


Robust z-score2

Method Code3

426 182 ± 15 0.62 11

435 143 # -2.05 4

441 205 # 2.19 4

442 182 ± 22 0.62 6

444 158 ± 15.8 -1.03 4

447 180 # 0.48 6

459 170 ± 17.6 -0.21 5

460 173 ± 10 0.00 6

478 90.3 # -5.66 § 4

488 129 ± 25.8 -3.01 § 5

499 182.412 ± 2.295 0.64 5

509 184 ± 46 0.75 6

517 180 ± 14.0 0.48 4

549 186 ± 12.9 0.89 6

No of Results: 43

Median: 173.0


2.8

Normalised IQR:

14.6

Robust CV: 8.4%

Minimum: 90.3

Maximum: 209

Range: 118.7

1 Where reported, results are shown with their corresponding




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Chemical Oxygen Demand (COD) - Sample R143 - Robust Z-Scores

Robust Z-Scores

Ordered R

obust Z-S

core Charts

A6

Chem

ical Oxygen D

emand (C

OD

) - Sam

ple R143

435 23

1

316

356

334

444 13

1

147

126

297

419

459

203

319

417

315 25

8

488

141

478

460

421

-5

-4

-3

-2

-1

0

1

2

3

4

5

lab code

z-sc

ore

242

301

447

517

263

426

509

549 12

9

239

400

227 18

1 441

407

398

214

112 15

7

442

499

-5

-4

-3

-2

-1

0

1

2

3

4

5

lab code

z-sc

ore

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Total Organic Carbon (TOC) Results

Sample R143

A7

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Total Organic Carbon (TOC)


Sample R143

Lab Code


Robust z-score2

Method Code3

126 70.8 # -0.11 12 129 68.9 ± 6.9 -0.62 12 131 73.1 ± 7.3 0.51 14 154 65.3 # -1.58 12 203 69.5 # -0.46 17 231 79.2 # 2.15 17 239 91 ± 1 5.32 § 13 263 72.6 ± 3.898 0.38 12 301 71.9 ± 9.0 0.19 13 315 67.9 ± 1.30 -0.89 12 316 71.8 ± 4.8 0.16 12 319 66.1 ± 7.21 -1.37 12 385 67.1 ± 12 -1.10 12 400 71.2 ± 10.7 0.00 12 417 71.5 # 0.08 12 419 80.6 ± 7 2.52 12 421 58.3 ± 9.9 -3.46 § 12 435 65.0 # -1.66 13 442 68 ± 10 -0.86 12 444 74.7 ± 5.98 0.94 13 447 74 # 0.75 12 460 61 ± 5 -2.74 13 478 71.2 # 0.00 12 486 490.30 # 112.51 § 17 499 72.410 ± 1.422 0.32 17 509 71.4 ± 17.8 0.05 12 517 70.8 ± 1.2 -0.11 12 529 65.3 ± 1 -1.58 12

No of Results: 28

Median: 71.20


0.88

Normalised IQR:

3.73

Robust CV: 5.2%

Minimum: 58.3

Maximum: 490.30

Range: 432.00 1 Where reported, results are shown with their corresponding




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Total Organic Carbon (TOC) - Sample R143 - Robust Z -Scores

Ordered R

obust Z-S

core Charts

A8

Total O

rganic Carbon (T

OC

) - Sam

ple R143

154

529

319

385

315

442 12

6

517

478

509

417

316

301

499 44

7

444

231 41

9

239

486

203

129

400

435

460

421

131

263

-5

-4

-3

-2

-1

0

1

2

3

4

5

lab code

z-sc

ore

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APPENDIX B

Sample Homogeneity and Stability

B1

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Homogeneity and Stability Testing Samples for this program were obtained from the Environmental Resource Associates (ERA). As such, all samples are subjected to rigorous stability and homogeneity testing. On the basis of this testing, the ampoules utilised for this program were considered to be homogeneous and stable.

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APPENDIX C

Documentation

Instructions to Participants ................................................................................................... C1

Method Codes ...................................................................................................................... C3

Results Sheet ....................................................................................................................... C4

C1

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PROFICIENCY TESTING AUSTRALIA

WATERS PROFICIENCY TESTING PROGRAM

CHEMICAL ANALYSIS ROUND 143 May, 2012 Biochemical Oxygen Demand (BOD) Chemical Oxygen Demand (COD) Total Organic Carbon (TOC)

INSTRUCTIONS TO PARTICIPANTS

**Please record (on the Results Sheet) the approximate temperat ure of the samples upon receipt**

Please note the following before commencing the analysis of the samples. 1. Samples

i) One sealed vial supplied by Environmental Resource Associates (ERA). The vial contains BOD, COD, TOC concentrates.

ii) The sample must be thoroughly mixed prior to analysis.

iii) The vial will require 200-fold dilution in reagent grade water.

Please Note: Where possible, proficiency testing samples should be treated as a routine

laboratory sample. 2. Sample Preparation Caution: Analysis must begin immediately after vial is opened.

i) Adjust vial temperature to 20º C. ii) Add approximately 100 - 200 millilitres (mL) deionised water to a one-litre volumetric

flask. iii) Shake the vial prior to opening. iv) Using a volumetric pipette, volumetrically transfer 5.0 mL of the concentrate into the

1000 mL volumetric flask. v) Dilute the flask to final volume with deionised water. vi) Cap the flask and mix contents well. vii) Immediately analyse the diluted sample by your normal procedures. viii) Report your result as mg/L for the diluted sample .

C2

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Tests Requested For the sample prepared from the vial:

i) Biochemical Oxygen Demand (BOD) ii) Chemical Oxygen Demand (COD) iii) Total Organic Carbon (TOC) If unable to perform the above please note this on your Results Sheet. Reminder: It is recommended that a reagent water blank is analysed by the same method used to analyse the samples- please check your method procedure.

4. Safety i) Samples are for laboratory use only. ii) Participants should have sufficient experience and training to take the necessary

precautions when handling the samples and reagent chemicals and during disposal. iii) Use of safety glasses, gloves, and fume hoods, where appropriate during the

determinations, is recommended. 5. Reporting

i) Report results using three significant figures.

ii) Report results in milligrams per litre (mg/L). iii) Do not correct results for recovery. iv) In addition to reporting the results, record the method of analysis using the attached

codes.

v) Laboratories are also requested to calculate and report an estimate of measurement uncertainty (MU) for each reported measurement result. All estimates of MU must be given as a 95% confidence interval (coverage factor k ≈ 2) and reported in mg/L.

6. Testing should commence as soon as possible after receiving the sample and results

reported NO LATER THAN 15 June 2012 to:

Delfina Mihaila Proficiency Testing Australia PO Box 7507 SILVERWATER NSW 2128 AUSTRALIA Phone: +612 9736 8397 Fax: +612 9743 6664 Email: [email protected]

7. For this program your laboratory has been allocated the code number shown on the attached Results Sheet. All reference to your laboratory in reports associated with the program will be through this code number, thus ensuring the confidentiality of your results.

8. As a guide, ranges for the samples can be expected to be (in mg/L):

Analysis Range BOD 15-250 COD 30-250 TOC 6-100

C3

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Method Codes to be used for the Results Sheet

ANALYSIS METHOD DESCRIPTION

METHOD REFERENCE CODE

APHA APHA Part 5210 B 1

US EPA US EPA 0405.1 2


Other Other (please specify) 3

APHA Part 5220 B 4

APHA Part 5220 C 5

APHA

APHA Part 5220 D 6

US EPA 0410.1 7

US EPA 0410.2 8

US EPA 0410.3 9

US EPA

US EPA 0410.4 10


Other

Other (please specify)

11

APHA Part 5310 B 12

APHA Part 5310 C 13

APHA

APHA Part 5310 D 14

US EPA 0415.1 15 US EPA

US EPA 0415.2 16


Other Other (please specify) 17

Method Reference Key

i) APHA APHA “Standard Methods for the Examination of Water and Wastewater” 19th Edition (1995), 20th Edition (1998), 21st Edition (2005).

ii) USEPA USEPA 600/4 – 79 – 020.

C4

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PROFICIENCY TESTING AUSTRALIA

WATERS PROFICIENCY TESTING PROGRAM

CHEMICAL ANALYSIS ROUND 143

BIOCHEMICAL OXYGEN DEMAND (BOD) CHEMICAL OXYGEN DEMAND (COD) TOTAL ORGANIC CARBON (TOC) MAY 2012

RESULTS SHEET (mg/L)

Laboratory Code *Approximate temperature of samples upon receipt:

ANALYSIS Result (mg/L) ±MU* (mg/L) METHOD CODE




Please Note: Where possible, proficiency testing samples should be treated as a routine laboratory sample.

i) For each prepared sample only a single result is requested.

ii) Report results using three significant figures.

iii) Report results in milligrams per litre (mg/L).

iv) Do not correct results for recovery.

v) MU* Laboratories Measurement Uncertainty (MU) if known for the result. Please report in mg/L. ______________________ ________________________________ DATE SIGNATURE

Return results NO LATER THAN 15 June 2012 to: Delfina Mihaila Proficiency Testing Australia PO Box 7507 Phone: +61 2 9736 8397 SILVERWATER NSW 2128 Fax: +61 2 9743 6664 AUSTRALIA Email: [email protected]

INSTRUCT WATERS PROF TEST PROG 143

SD 9.17.05

- End of Report -

Report No. 769 Waters Proficiency Testing Round 143...

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