nitrogen parameters in wastewater (effluent) · covering the parameters as described in table 1....

Quality Documentation

February 2013

Proficiency test SPIL-4 (2011) Nitrogen parameters in wastewater (effluent)

Proficiency test SPIL-4 (2011) Quality documentation February 2013

Smedeskovvej 38 DK-8464 Galten Denmark Tel: +45 7022 4266 Fax: +45 7022 4255 e-mail: [email protected] Web: www.eurofins.dk

Client

Environmental laboratories

Client’s representative

Project

Proficiency test SPIL-4 (2011)

Project No

20404-14

Authors

Stine Ottsen

Date 2013-02-14

Approved by Ulla Lund

Quality Documentation 20130404

Revision Description By Approved Date

Key words Analytical quality, assigned value, precision, accuracy, homogeneity, stability, total nitrogen, ammonia, nitrite+nitrate, conductivity, pH, wastewater

Classification

Open

Internal

Proprietary

Distribution No of copies

DANAK Eurofins:

Stine Ottsen, Ulla Lund

2 File

CONTENTS

1 INTRODUCTION ......................................................................................................... 1-1

2 FEATURES OF THE PROFICIENCY TEST ................................................................ 2-1 2.1 Sample preparation ..................................................................................................... 2-1 2.2 Statistical analysis of participants’ data ....................................................................... 2-1 2.3 Assigned and spike value ............................................................................................ 2-1 2.3.1 Assigned and spike values .......................................................................................... 2-2 2.3.2 Test of spike values ..................................................................................................... 2-2 2.3.3 Test of assigned values ............................................................................................... 2-2

3 HOMOGENEITY AND STABILITY OF SAMPLES ...................................................... 3-1

4 CONCLUSION ............................................................................................................. 4-1

5 REFERENCES ............................................................................................................ 5-1 APPENDICES A List of participants ........................................................................................................ A-1 B Sample preparation ..................................................................................................... B-1 C Control of spike value ................................................................................................. C-1 D Control of recovery ..................................................................................................... D-1 E Concentration level ...................................................................................................... E-1 F Homogeneity and stability ............................................................................................ F-1

1-1

1 INTRODUCTION

A proficiency test on the analysis of nitrogenparameters in wastewater was conducted on 17 November 2011. The proficiency test was organised by Eurofins Miljø A/S.

The present report contains Eurofins’ documentation for the quality of the proficiency test. Results of the proficiency test including data from participating laboratories and statistical analysis of these data were issued in a report to all participants and DANAK /1/ on 19 December 2011.

2-1

2 FEATURES OF THE PROFICIENCY TEST

Participants in the proficiency test were a total of 75 laboratories from Denmark, Nor-way and Sweden. A list of participants is shown in Appendix A.

The closing date for submission of results was 5 December 2011. All participants ex-cept laboratory no. 10 and 40 had submitted their results before the dead-line.

2.1 Sample preparation

The parameters covered in the proficiency test are listed in Table 2 as are the abbrevi-ations used in this report.

Four samples were dispatched for the proficiency test. The samples were sample pairs covering the parameters as described in Table 1. The matrix of the samples represent-ed wastewater, in this case effluent. Sample preparation is described in Appendix B.

Table 1 Samples in the proficiency test Sample name Parameters A1/B1 TN, NH4, NO2+3, γ25 A2/B2 pH

2.2 Statistical analysis of participants’ data

A split-level design was used. The data analysis was performed in accordance with ISO 5725: “Accuracy (trueness and precision) of measurement methods and results” (1994) /2/ and as described in detail in Spliid (1992) /3/. A short introduction to the sta-tistics and a list of symbols and abbreviations used is given in Eurofins document “Schedule for a proficiency test”, which is available at Eurofins’ home page /4/.

The statistical model used is based on the assumption that the variances for the two samples in a sample pair are identical. The assumption was tested (F-test, 95% confi-dence level) and the result was that the two variances may be assumed to be identical for all parameters.

2.3 Assigned and spike value

An overview of the concentrations in the samples (the assigned values) and the differ-ence in concentration between the two samples of a sample pair (spike value) are shown in Table 2 compared to the range of concentrations normally encountered in effluent.

2-2

Table 2 Assigned and spike value

Parameter Abbreviation Unit Typical Range Assigned value Spike valueTotal nitrogen TN mg/L N 2 --10 4.96 0.58 Ammonium NH4 mg/L N 0.1 – 2 0.805 0.114 Nitrite+nitrate NO2+3 mg/L N 1 – 5 2.75 0.30 Conductivity γ25 mS/m 50 – 300 58.4 0.28 pH pH - 6 – 9 7.78 0

2.3.1 Assigned and spike values In order to ensure optimal use of the data, the assigned value is calculated as the av-erage of the median for both samples in the sample pair after subtraction of the spike value. The spike values are calculated from sample preparation except for γ25 where the spike value is the difference between median values for the two samples in the sample pair.

The assigned value for TN is operationally defined and is a consensus value based upon the median for method no. 1 and 2 (TN). A list of method identification numbers is found in the report to participants /1/. Assigned values for NH4, NO2+3, conductivity and pH are consensus values for all laboratories based on the median.

2.3.2 Test of spike values A comparison was made (t-test, 95% confidence level) between the spike value and the difference in concentration between the two samples in the sample pair found from the laboratories’ results, see Appendix C. The test revealed a significant difference be-tween the two for NH4. However, the difference is numerically small and has insignifi-cant influence on the general quality of analyses estimated from the data as well as on the evaluation of accuracy of participating laboratories.

2.3.3 Test of assigned values The assigned value and the average of the results obtained from all laboratories were also compared (t-test, 95% confidence level), see Appendix D. The test revealed a sig-nificant difference between the two for pH. The average from all laboratories was 7.71, 0.07 pH-units below the assigned value. The difference could be attributed to influence from a few laboratories. The test was repeated after exclusion of the results from la-boratory no. 3, 24, and 52 and now showed no significant difference. The assigned value is therefore kept unchanged.

3-1

3 HOMOGENEITY OF SAMPLES

The homogeneity of samples was tested using the following parameters as indicators:

Ammonium Homogeneity test

Nitrite+nitrate Homogeneity test

pH Homogeneity test

The results of control measurements are shown in Appendix F. The appendix also gives the results of the statistical evaluation of the control data. The data are analysed by analysis of variance (ANOVA) giving:

1. the standard deviation/variance for replicates (the contribution from analytical vari-ability),

2. the between bottle standard deviation/variance (the contribution from heterogenei-ty)

Homogeneity is evaluated by comparing the between bottle variance to 0.15 * the max-imum tolerated deviation from the assigned value specified by the Danish EPA /5/ (“sigma” in the calculations is 0.5 times the maximum tolerated deviation). This test en-sures that heterogeneity will not have negative influence on the evaluation of partici-pant performance /6/.

The appendix also shows the standard deviation within and between laboratories from the proficiency test to allow comparison between tests performed and average quality from participating laboratories.

The tests for homogeneity show that the samples are homogeneous.

4-1

4 CONCLUSION

The quality control performed, including test of sample homogeneity as well as test of recovery of spike and assigned values, shows that the samples and their assigned val-ues are suitable for testing the proficiency of the participating laboratories for all pa-rameters. The results are also suitable for estimation of the general quality of analyses among all participating laboratories.

For NH4 the participants did not recover the assigned value. Eurofins’ scrutiny of the combined evidence gave the conclusion that the assigned value is correct. The as-signed value is therefore kept unchanged and it is recommended as the basis for eval-uation of participating laboratories.

5-1

5 REFERENCES

/1/ Eurofins Miljø A/S, Proficiency test SPIL-4 (2011), Report to participants, December 2011.

/2/ ISO 5725-2, Accuracy (trueness and precision) of measurement methods and re-

sults – Part 2: Basic method for the determination of repeatability and reproduci-bility of a standard measurement method, 1994.

/3/ Spliid, H., Procedure and analysis of data for proficiency tests and environmental

analyses, Report to Danish Environmental Protection Agency, 1994 (in Danish). /4/ Eurofins A/S, Schedule for a proficiency test, document may be downloaded from

www.eurofins.dk/proficiencytest. /5/ Ministry of Environment regulation no. 900 on quality criteria for environmental

measurements, 17 August 2011 (in Danish). /6/ ISO 13528, Statistical methods for use in proficiency testing by interlaboratory

comparison, 2005.

A P P E N D I C E S

A P P E N D I X A

List of participants

A-1

Laboratory Town Country AquaDjurs - Fornæs Renseanlæg Grenaa Denmark

Bjergmarken R/A, Roskilde Forsyning Roskilde Denmark

CP Kelco ApS, Spildevandslaboratoriet Ll. Skensved Denmark

Eurofins Miljø A/S Vejen Denmark

Faxe Forsyning Faxe Denmark

Fredericia Spildevand A/S Fredericia Denmark

Greve Forsyning Greve Denmark

Hach Lange ApS Brønshøj Denmark

Halsnæs Kommunale Forsyning A/S Liseleje Denmark

Hedensted Spildevand A/S Daugård Denmark

Holstebro Centralrenseanlæg, Vestforsyning A/S Holstebro Denmark

Højmarklaboratoriet Lem St. Denmark

Højvang Miljølaboratorium Dianalund Denmark

Ikast-Brande Renseanlæg Ikast Denmark

Kerteminde Forsyning - Spildevand A/S Kerteminde Denmark

Kolding Spildevand A/S Bjert Denmark

Korsør Renseanlæg Korsør Denmark

Køge-Egnens Renseanlæg Køge Denmark

LabVest I/S Holstebro Denmark

Lynettefællesskabet I/S København K Denmark

Mølleåværkets Driftslaboratorium Lyngby Denmark

Måløv Renseanlæg Måløv Denmark

Nyborg Renseanlæg Nyborg Denmark

Næstved Centralrenseanlæg Næstved Denmark

Provas Haderslev Forsyningsservice Haderslev Denmark

Randers Spildevand A/S Randers NØ Denmark

Rensningsanlæg Øst, Esbjerg Esbjerg Denmark

Rensningsanlæg Øst, Esbjerg, Spildevandslaborato-riet Esbjerg Denmark

Ringkøbing-Skjern Forsyning A/S Skjern Denmark

Ringsted Renseanlæg Ringsted Denmark

Rønne Renseanlæg Rønne Denmark

Skælskør Renseanlæg Skælskør Denmark

Slagelse Renseanlæg Slagelse Denmark

Sun Chemicals, E30 Køge Denmark

Svendborg Centralrenseanlæg Skårup Fyn Denmark

A-2

Sønderborg Renseanlæg Sønderborg Denmark

Vandrens - Stigsnæs Industripark A/S Skælskør Denmark

Vejen Renseanlæg Vejen Denmark

Vejle Centralrenseanlæg, Laboratoriet Vejle Denmark

Ålborg Renseanlæg Vest Ålborg Denmark

Ålborg Renseanlæg Øst Ålborg Øst Denmark

Statoil ASA, Kollsnes processanlegg Rong Norway

Statoil Petroleum AS, Snøhvit Melkøya, drift Rypefjord Norway

Akzo Nobel Functional Chemicals AB Cellulosic Specialties, QHSE Örnsköldsvik Sweden

ALcontrol AB Karlstad Sweden

Arctic Paper Grycksbo AB Grycksbo Sweden

Arctic Paper Munkedals AB Munkedal Sweden

Ernemar Laboratoriet Oskarshamn Sweden

Eurofins Environment Sweden AB Lidköping Sweden

GRYAAB AB Göteborg Sweden

Holmen Paper Norrköping Sweden

Ineos Sweden AB Stenungsund Sweden

Kalmar Vatten AB, VA-lab, Avloppsreningsverket Kalmar Sweden

Kristianstad Kommun, C4 Teknik, Kommunteknik Kristianstad Sweden

Käppalaverket Lidingö Sweden

Laboratoriet vid Smedjeholms Arv Falkenberg Sweden

Mjölby Kommun Mjölby Sweden

Motala Kommun Motala Sweden

NSVA/Öresundsverket Helsingborg Sweden

Preem AB Göteborg Göteborg Sweden

Preemraff Lysekil Lysekil Sweden

Rottneros Bruk AB Rottneros Sweden

St1 Refinery AB Göteborg Sweden

Stora Enso Publication Paper Hyltebruk Sweden

Södra Cell AB Mönsterås Mönsterås Sweden

Trollhättan Energi AB, VA-lab Arvidstorp Trollhättan Sweden

Uddebo Laboratorium Luleå Sweden

Uppsala Vatten o. Avfall AB, Vattenlaboratoriet Uppsala Sweden

VIVAB Varberg Sweden

Västerviks Miljö & Energi AB, Vattenlaboratoriet Västervik Sweden

Yara AB Köping Sweden

A P P E N D I X B

Sample preparation

B-1

Stock solution Prepared from Concentration Stock TN 3.00 g Disodium edetate, 2H2O

milli-Q water up to 1000 g TN: 226 mg/kg N

Stock NH4 1.000 g Ammonium chloride (NH4Cl) milli-Q water up to 1000 g

NH4: 262 mg/kg N

Stock NO3 2.50 g Potassium nitrate (KNO3) milli-Q water up to 1000 g

NO3: 346 mg/kg N

Sample Sample prepared from TN mg/L N

NH4 mg/L N

NO3 mg/L N

ConductivitymS/m

A1 200.00 g stock NH4 350.00 g stock NO3 250.00 g stock TN Filtered untreated water from Bram-ming Nord sewage treatment plant up to 65.00 kg

a+3.54 b+0.81 c+1.87 d

B1 14.99 g stock NH4 30.00 g stock NO3 25.00 g stock TN Sample A1 up to 34.00 kg

0.998· (a+3.54)

+ 0.587

0.998· (b+0.81)

+ 0.115

0.998· (c+1.87)

+ 0.306

e

Sample Sample prepared from pH

A2/B2 Filtered untreated water from Bramming Nord sewage treatment plant f

A P P E N D I X C

Control of spike value

C-1

Total nitrogen, mg/L N Control of differences within sample pairs

Laboratory Difference AB

1 0.080 2 0.180 3 -0.080 4 0.080 UG 5 0.130 6 -0.140 7 0.690 UC 8 0.030 9 -0.098

11A -0.040 11B 0.060

12 -0.010 13 -0.010 14 -0.020 15 -0.030 16 0.080 17 -0.030 18 1.840 UC 19 -0.070 20 - 21 -0.140 22 0.000 23 0.040 24 0.080 25 0.040 26 0.050 27 0.080 28 1.010 UC 29 - 30 -0.210 31 0.050 32 0.220 33 -0.110 34 - 35 -0.020 36 -0.200 37 -0.160 38 -0.100 39 -0.110 41 -0.075 42 -0.020 43 -0.020 44 -0.110 45 0.050 46 0.090 47 0.180 48 -0.032 49 0.000 50 -0.040 51 0.320 52 -0.120

53A -0.490 53B -

54 0.170 55 -0.090 56 0.030

57 0.010 58 -0.130 59 -0.055 60 0.040 61 - 62 -0.220 63 -0.110 64 0.000 65 -0.390 66 0.010 67 0.012 68 0.080 69 0.620 UC 70 0.200 71 0.120 72 0.320 73 0.070 74 -0.010 75 -0.390

No of labs., p 65 No of repl., n 2

d -0.016 s² 0.021 s 0.145

t = √p · (d/s) -0.9066 Sign. level, p(t) 0.3680 No test statistics were found to be signifi-cant UC denotes a Cochran outlier UG denotes a Grubbs outlier

C-2

Ammonium, mg/L N Control of differences within sample pairs


1 0.0065 2 -0.0210 3 -0.0100 4 -0.0060 5 0.0230 6 -0.0060 7 - 8 0.0160 9 0.0000

11A 0.0090 11B -

12 -0.0290 13 0.0240 14 0.0140 15 0.0130 16 0.0440 17 0.2170 UC 18 0.0170 19 0.0040 20 -0.0160 21 0.0030 22 -0.0040 23 -0.0030 24 0.0040 25 -0.0020 26 0.0180 27 -0.0020 28 -0.0030 29 - 30 0.0140 31 0.0100 32 -0.0010 33 -0.0030 34 0.0140 35 0.0070 36 0.0010 37 -0.0160 38 - 39 0.0740 UC 41 0.0145 42 -0.0020 43 -0.0090 44 0.0150 45 0.0340 46 0.0010 47 -0.0150 48 0.0200 UG 49 -0.0060 50 0.0340 UG 51 0.0200 52 -0.0360 UG

53A 0.0140 53B -

54 -0.0060 55 0.0140 56 0.0100

57 -0.0030 58 0.0060 59 - 60 -0.0260 61 0.0000 62 - 63 -0.0020 64 0.0040 65 -0.0010 66 0.0110 67 0.0240 68 - 69 - 70 -0.0060 71 0.0040 72 -0.0160 73 0.0080 74 0.0110 75 -0.0010


d 0.0036 s² 0.0002 s 0.0136

t = √p · (d/s) 2.0495 Sign. level, p(t) 0.0448 * * denotes that there is a significant differ-ence (t-test, 5%-level) ** denotes that there is a significant differ-ence (t-test, 1%-level) *** denotes that there is a significant differ-ence (t-test, 0.1%-level) UC denotes a Cochran outlier UG denotes a Grubbs outlier

C-3

Nitrite+nitrate, mg/L N Control of differences within sample pairs


1 0.020 2 0.030 3 0.050 4 0.100 5 0.579 UC 6 -0.080 7 -0.100 8 0.010 9 0.014

11A -0.010 11B -0.020

12 -0.010 13 - 14 - 15 -0.010 16 -0.100 17 - 18 0.050 19 0.000 20 -0.000 21 0.030 22 0.030 23 0.040 24 -0.070 25 -0.010 26 - 27 0.020 28 0.070 29 - 30 0.020 31 -0.020 32 0.030 33 0.020 34 - 35 0.090 36 0.050 37 -0.010 38 - 39 0.010 41 3.055 UC 42 0.020 43 0.030 44 -0.050 45 -0.050 46 0.040 47 0.150 48 0.004 49 0.000 50 0.030 51 - 52 -0.050

53A - 53B -

54 -0.010 55 -0.030 56 -0.040

57 0.000 58 -0.060 59 - 60 -0.010 61 -0.120 62 - 63 -0.010 64 - 65 0.010 66 -0.050 67 -0.027 68 - 69 - 70 0.010 71 0.040 72 0.020 73 - 74 0.010 75 0.010


d 0.002 s² 0.002 s 0.048

t = √p · (d/s) 0.3048 Sign. level, p(t) 0.7617 No test statistics were found to be signifi-cant UC denotes a Cochran outlier

C-4

Conductivity, mS/m Control of differences within sample pairs


1 -0.02 2 - 3 - 4 -0.02 5 -0.02 UG 6 -0.02 7 - 8 - 9 0.28

11A 0.00 11B -

12 - 13 - 14 -0.22 15 0.08 16 -0.72 17 0.18 18 - 19 0.28 UG 20 -0.02 21 - 22 - 23 - 24 - 25 -0.02 26 0.68 27 - 28 - 29 -3.52 UC 30 - 31 -0.02 32 - 33 - 34 - 35 0.88 UG 36 - 37 - 38 - 39 0.28 41 - 42 - 43 0.08 44 - 45 0.08 46 -0.12 47 -0.72 48 0.68 49 - 50 0.08 51 -0.42 52 -

53A - 53B -

54 - 55 -0.42 56 -

57 0.28 58 - 59 - 60 - 61 - 62 -0.12 63 - 64 -0.72 65 0.58 66 -0.02 67 - 68 - 69 - 70 0.28 71 -0.02 72 - 73 -0.02 74 0.08 75 0.58


d 0.02 s² 0.13 s 0.36

t = √p · (d/s) 0.2871 Sign. level, p(t) 0.7760 No test statistics were found to be signifi-cant UC denotes a Cochran outlier UG denotes a Grubbs outlier

C-5

pH, Control of differences within sample pairs


1 -0.040 2 0.080 3 0.030 4 0.010 5 0.000 6 0.000 7 - 8 0.030 9 0.010

11A -0.050 11B -

12 0.030 13 -0.020 14 0.070 15 0.150 16 0.000 17 0.010 18 0.040 19 -0.100 20 -0.010 21 -0.010 22 0.080 23 -0.100 24 -0.190 25 0.016 26 -0.060 27 -0.180 28 -0.710 UC 29 -0.060 30 -0.020 31 0.030 32 - 33 -0.040 34 - 35 0.000 36 0.100 37 0.050 38 0.000 39 -0.050 41 0.000 42 -0.430 UC 43 0.000 44 0.100 45 -0.070 46 -0.040 47 -0.050 48 0.470 UC 49 -0.020 50 -0.150 51 -0.060 52 0.030

53A 0.085 53B 0.087

54 0.010 55 -0.070 56 0.080

57 -0.090 58 0.010 59 0.080 60 -0.150 61 -0.340 UC 62 -0.450 UC 63 0.020 64 0.100 65 -0.110 66 -0.030 67 -0.060 68 -0.119 69 0.010 70 -0.060 71 -0.050 72 0.080 73 0.020 74 0.076 75 -0.110


d -0.010 s² 0.005 s 0.072

t = √p · (d/s) -1.0997 Sign. level, p(t) 0.2755 No test statistics were found to be signifi-cant UC denotes a Cochran outlier

A P P E N D I X D

Control of recovery

D-1

Total nitrogen, mg/L N Control of recovery, average of results

Laboratory Sample pair AB

1 4.960 2 5.160 3 4.930 4 3.860 UG 5 4.305 6 5.240 7 5.445 UC 8 4.795 9 4.935

11A 4.950 11B 5.010

12 4.915 13 5.115 14 5.110 15 5.025 16 4.760 17 4.335 18 5.660 UC 19 4.815 20 - 21 5.240 22 5.100 23 5.270 24 5.050 25 4.915 26 4.905 27 5.050 28 4.725 UC 29 - 30 5.235 31 4.945 32 5.020 33 4.765 34 - 35 5.000 36 4.860 37 4.790 38 4.920 39 5.015 41 4.453 42 4.910 43 4.830 44 5.125 45 4.785 46 4.995 47 4.810 48 5.540 49 5.160 50 4.810 51 4.760 52 5.000

53A 4.595 53B -

54 4.625 55 5.325 56 4.825

57 5.445 58 4.755 59 4.938 60 4.840 61 - 62 5.510 63 4.625 64 5.090 65 4.905 66 4.645 67 5.504 68 4.460 69 5.090 UC 70 4.820 71 4.820 72 4.690 73 5.105 74 4.985 75 4.905


m 4.939 s² 0.065 s 0.254

Assigned value, µ 4.96 Recovery, % 99.6 t = √p · (m-µ)/s -0.6689 Sign. level, p(t) 0.5060 No test statistics were found to be signifi-cant UC denotes a Cochran outlier UG denotes a Grubbs outlier

D-2

Ammonium, mg/L N Control of recovery, average of results


1 0.8088 2 0.8035 3 0.8380 4 0.8230 5 0.8385 6 0.8330 7 - 8 0.8520 9 0.7900

11A 0.7915 11B -

12 0.8605 13 0.7970 14 0.7930 15 0.8315 16 0.7880 17 0.7985 UC 18 0.8065 19 0.7930 20 0.8780 21 0.7905 22 0.7920 23 0.7935 24 0.7950 25 0.7880 26 0.7960 27 0.8170 28 0.8055 29 - 30 0.7830 31 0.8030 32 0.7885 33 0.7735 34 0.8830 35 0.7945 36 0.8095 37 0.8580 38 - 39 0.9630 UC 41 0.8023 42 0.8080 43 0.8075 44 0.7295 45 0.9030 46 0.7985 47 0.8325 48 0.6810 UG 49 0.8000 50 0.6030 UG 51 0.8280 52 0.9480 UG

53A 0.7930 53B -

54 0.8130 55 0.8070 56 0.8250

57 0.8065 58 0.7910 59 - 60 0.8030 61 0.7930 62 - 63 0.8010 64 0.7810 65 0.8495 66 0.8435 67 0.8530 68 - 69 - 70 0.8330 71 0.8180 72 0.7880 73 0.8060 74 0.8025 75 0.8495


m 0.8125 s² 0.0009 s 0.0293

Assigned value, µ 0.805 Recovery, % 100.9 t = √p · (m-µ)/s 1.9989 Sign. level, p(t) 0.0501 No test statistics were found to be signifi-cant UC denotes a Cochran outlier UG denotes a Grubbs outlier

D-3

Nitrite+nitrate, mg/L N Control of recovery, average of results


1 2.720 2 2.835 3 2.635 4 2.650 5 -0.010 UC 6 2.970 7 2.750 8 2.875 9 2.831

11A 2.805 11B 2.770

12 2.715 13 - 14 - 15 2.745 16 2.550 17 - 18 2.805 19 2.750 20 2.780 21 2.735 22 2.705 23 2.900 24 2.775 25 2.762 26 - 27 2.700 28 2.865 29 - 30 2.770 31 2.660 32 2.785 33 2.700 34 - 35 2.715 36 2.665 37 2.805 38 - 39 2.925 41 4.053 UC 42 2.740 43 2.735 44 2.815 45 2.765 46 2.780 47 2.665 48 2.684 49 2.810 50 2.515 51 - 52 2.795

53A - 53B -

54 2.705 55 2.715 56 2.770

57 2.660 58 2.750 59 - 60 2.735 61 2.800 62 - 63 2.695 64 - 65 2.965 66 2.865 67 2.931 68 - 69 - 70 2.615 71 2.770 72 2.680 73 - 74 2.745 75 2.965


m 2.760 s² 0.009 s 0.094

Assigned value, µ 2.75 Recovery, % 100.4 t = √p · (m-µ)/s 0.8043 Sign. level, p(t) 0.4246 No test statistics were found to be signifi-cant UC denotes a Cochran outlier

D-4

Conductivity, mS/m Control of recovery, average of results


1 56.81 2 - 3 - 4 58.81 5 54.61 UG 6 57.61 7 - 8 - 9 58.56

11A 58.42 11B -

12 - 13 - 14 58.91 15 58.66 16 58.36 17 58.21 18 - 19 53.06 UG 20 58.81 21 - 22 - 23 - 24 - 25 58.21 26 58.46 27 - 28 - 29 56.36 UC 30 - 31 58.41 32 - 33 - 34 - 35 51.76 UG 36 - 37 - 38 - 39 57.66 41 - 42 - 43 58.46 44 - 45 57.86 46 58.56 47 60.36 48 56.16 49 - 50 57.96 51 58.61 52 -

53A - 53B -

54 - 55 57.61 56 -

57 59.36 58 - 59 - 60 - 61 - 62 59.46 63 - 64 59.36 65 59.71 66 58.71 67 - 68 - 69 - 70 59.86 71 58.51 72 - 73 58.31 74 59.46 75 59.71


m 58.56 s² 0.76 s 0.87

Assigned value, µ 58.4 Recovery, % 100.3 t = √p · (m-µ)/s 1.0425 Sign. level, p(t) 0.3052 No test statistics were found to be signifi-cant UC denotes a Cochran outlier UG denotes a Grubbs outlier

D-5

pH, Control of recovery, average of results


1 7.820 2 7.850 3 7.405 4 7.765 5 7.800 6 7.820 7 - 8 7.845 9 7.835

11A 7.765 11B -

12 7.265 13 7.500 14 7.735 15 7.885 16 7.900 17 7.665 18 7.010 19 7.230 20 7.795 21 7.725 22 7.890 23 7.570 24 7.455 25 7.857 26 7.810 27 7.160 28 7.195 UC 29 7.890 30 7.540 31 7.925 32 - 33 7.500 34 - 35 7.760 36 7.810 37 7.755 38 7.800 39 7.845 41 7.580 42 7.495 UC 43 7.720 44 7.850 45 7.685 46 7.780 47 7.845 48 7.565 UC 49 7.730 50 7.515 51 7.880 52 7.475

53A 7.908 53B 7.918

54 7.725 55 7.793 56 7.760

57 7.195 58 7.145 59 7.820 60 7.975 61 7.220 UC 62 8.055 UC 63 7.960 64 7.650 65 7.725 66 7.775 67 7.900 68 7.813 69 7.805 70 7.910 71 7.855 72 7.990 73 7.850 74 7.693 75 7.725


m 7.714 s² 0.048 s 0.218

Assigned value, µ 7.78 Recovery, % 99.2 t = √p · (m-µ)/s -2.4527 Sign. level, p(t) 0.0169 * * denotes that there is a significant differ-ence (t-test, 5%-level) ** denotes that there is a significant differ-ence (t-test, 1%-level) *** denotes that there is a significant differ-ence (t-test, 0.1%-level) UC denotes a Cochran outlier

A P P E N D I X E

Concentration level

Concentration level SPIL-4 (2011)

Parameter Unit Sample Bottle no. I II Bottle Sample Assigned Spike Average Average value Measured Assigned

Total nitrogen mg/L N A1 78 4,75 5,50 5,13 5,13 4,96 0,31 0,58

B1 81 5,81 5,06 5,44 5,44 5,54

Ammonium mg/L N A1 78 0,805 0,814 0,810 0,810 0,805 0,113 0,114

B1 81 0,923 0,922 0,923 0,923 0,919

Nitrite+nitrate mg/L N A1 78 2,882 2,862 2,872 2,87 2,75 0,24 0,30

B1 81 3,172 3,041 3,107 3,11 3,05

pH A2 86 8,09 8,09 8,09 8,09 7,78 -0,11 0

B2 83 7,96 7,99 7,98 7,98 7,78

E-1

A P P E N D I X F

Homogeneity and stability

F-1

PT: SPIL-4 (2011) Parameter: Ammonium

Unit: mg/L N Sigma: 0,0919 10% Responsible for tests: AGK

10% level or 2*ST max

Homogeneity test Date: 2011-11-01

Sample x(a) x(b) average sd sd^2 A1-1 0,913 0,913 0,913 0,0000 0,00000 A1-15 0,915 0,915 0,915 0,0000 0,00000 A1-29 0,921 0,920 0,921 0,0007 0,00000 A1-43 0,924 0,926 0,925 0,0014 0,00000 A1-56 0,930 0,933 0,932 0,0021 0,00000 A1-70 0,924 0,928 0,926 0,0028 0,00001 A1-79 0,888 0,910 0,899 0,0156 0,00024 A1-83 0,916 0,917 0,917 0,0007 0,00000 A1-89 0,910 0,922 0,916 0,0085 0,00007 A1-95 0,929 0,923 0,926 0,0042 0,00002 Conclusions

ss = 0,008 0.3*sigma= 0,03 For homogeneity

General average (x) 0,919 Analytical Is sw < 0,15*sigma Sample average sd (sx) 0,0092 quality YES Within-sample sd (sw): 0,0059 Between-samples sd (ss): 0,0082 Homogeneity: Is ss < 0.3*sigma? SL in the Proficiency Test: 0,0283 YES SR in the Proficiency Test: 0,0299

F-2

PT: SPIL-4 (2011)

Parameter: Nitrite+nitrate Unit: mg/L N Sigma: 0,3085 10% Responsible for tests: AGK



Sample x(a) x(b) average sd sd^2 A1-1 3,094 3,085 3,09 0,0064 0,0000 A1-15 3,063 3,073 3,07 0,0071 0,0001 A1-29 3,094 3,094 3,09 0,0000 0,0000 A1-43 3,093 3,084 3,09 0,0064 0,0000 A1-56 3,125 3,104 3,11 0,0148 0,0002 A1-70 3,064 3,077 3,07 0,0092 0,0001 A1-79 3,080 3,093 3,09 0,0092 0,0001 A1-83 3,072 3,043 3,06 0,0205 0,0004 A1-89 3,089 3,102 3,10 0,0092 0,0001 A1-95 3,064 3,113 3,09 0,0346 0,0012 Conclusions

ss = 0,012 0.3*sigma= 0,093 For homogeneity

General average (x) 3,09 Analytical Is sw < 0,15*sigma Sample average sd (sx) 0,016 quality YES Within-sample sd (sw): 0,015 Between-samples sd (ss): 0,012 Homogeneity: Is ss < 0.3*sigma? SL in the Proficiency Test: 0,088 YES SR in the Proficiency Test: 0,094

F-3

PT: SPIL-4 (2011) Parameter: pH

Unit:

Sigma: 0,7708 2*sT max (grv.) Responsible for tests: AGK



Sample x(a) x(b) average sd sd^2 A-1 7,66 7,66 7,66 0,000 0,0000 A-10 7,66 7,71 7,69 0,035 0,0012 A-19 7,68 7,76 7,72 0,057 0,0032 A-28 7,66 7,78 7,72 0,085 0,0072 A-37 7,65 7,76 7,71 0,078 0,0060 A-46 7,67 7,70 7,69 0,021 0,0005 A-54 7,66 7,76 7,71 0,071 0,0050 A-63 7,67 7,77 7,72 0,071 0,0050 A-72 7,68 7,77 7,73 0,064 0,0040 A-81 7,68 7,78 7,73 0,069 0,0048 A-90 7,69 7,78 7,74 0,064 0,0040 A-99 7,69 7,72 7,71 0,021 0,0004 Conclusions

ss = 0 0.3*sigma= 0,23 For homogenei-ty

General average (x) 7,708 Analytical Is sw < 0,15*sigma Sample average sd (sx) 0,0219 quality YES Within-sample sd (sw): 0,0588 Between-samples sd (ss): 0 Homogeneity: Is ss < 0.3*sigma? SL in the Proficiency Test: 0,211 YES SR in the Proficiency Test: 0,217

nitrogen parameters in wastewater (effluent) · covering the parameters as described in table 1....

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