Final Report Report No.: 1 Program No.: WAT-CH-0001 Program ...

Report No.: 1 

Final Report 

Program No.: WAT-CH-0001 

Program Name: Physicochemical parameters in underground water 

Date: December 1, 2012 

Acknowledgement 

PQP should acknowledge the technical assistance provided by East Azerbaijan Water & 

Wastewater Laboratory for this program which was included sample preparation, homogeneity 

and stability testing of samples and also technical advice in different stages of this program 

including design, execution and evaluation of participants results. 

PQP Proficiency testing 

Apt. 9- 3rd floor- No. 20- 6th St.- Ghaem Magham Farahani St., Tehran- Iran, Postal Code: 

1586844137 

Tel.: +98(21)88546426-7, Fax: +98(21)88546443, Email: info@qualitypioneers.ir


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Page 2 of 57


Table of Contents 

1. Introduction ....................................................................................................................... 5 

2- Test Materials ....................................................................................................................... 5 

2-1- Preparation of samples ................................................................................................. 5 

2-2- Samples homogeneity .................................................................................................. 5 

2-3- Samples Stability .......................................................................................................... 5 

2-4- Distribution .................................................................................................................... 5 

3- Statistical design of the program ....................................................................................... 5 

4- Features of the program ...................................................................................................... 6 

4-1- Number of Participants ................................................................................................. 6 

4-2- Supplied samples .......................................................................................................... 6 

4-3- Parameters .................................................................................................................... 6 

4-4- Participants instruction ................................................................................................ 6 

4-5- Confidentiality ............................................................................................................... 6 

4-6- Appeals .......................................................................................................................... 7 

5- Summary of results ............................................................................................................. 7 

6- Statistical evaluation of results .......................................................................................... 8 

6-1- General........................................................................................................................... 8 

6-2- Calculation of assigned value ...................................................................................... 8 

6-3- Standard deviation for proficiency assessment (SDPA) ............................................ 9 

6-4- Measurement uncertainty of the assigned value (u x ) ................................................. 9 

6-5- Purpose of performance scoring ................................................................................. 9 

6-6- z-scores ......................................................................................................................... 9 

7- PQP and technical advisor comments ..............................................................................10 

7-1- Metrological Traceability of Assigned Values ............................................................10 

7-2- Methodology summary ................................................................................................10 

7-3- Overall performance ....................................................................................................12 

8- References ..........................................................................................................................13 

Appendix A- Results and data analysis .................................................................................14 

Appendix B- Homogeneity and stability testing ...................................................................46 

B-1- Homogeneity testing ...................................................................................................46 

B-2- Stability testing ............................................................................................................54 

Page 3 of 57


Appendix C- Documents .....................................................................................................55 

C-1- Instructions to participants .........................................................................................55 

C-2- Results Sheet ...............................................................................................................57 

Page 4 of 57


1. Introduction 

This report is a summary of the results of participating laboratories in proficiency testing 

program Physicochemical parameters in underground water round no. 1. The aim of this 

program is to enable laboratories to monitor and improve the quality of their routine analytical 

measurements, for the benefit of their customers. It also enables laboratories to demonstrate to 

customers, regulators and accreditation bodies the validity of their analytical measurements. 

Participation in PQP proficiency testing provides independent evidence of laboratory 

performance for both laboratory management and customers. 

This proficiency testing was performed by Pasargad Quality Pioneers (PQP) in November, 

2012. The program coordinator was Ms. Bahar Hosseinzadeh. This report was authorized by 

Mr. Hamidreza Dehnad, PQP proficiency testing technical manager on December 1, 2012 

Signature: 

2- Test Materials 

2-1- Preparation of samples 

The test material was prepared by East Azerbaijan Water & Wastewater Laboratory. The 

samples were taken from one of the underground sources of drinking water in Tabriz. 

The samples were stored at 4 °C until dispatch. 

2-2- Samples homogeneity 

Ten randomly selected samples were analysed in duplicate for homogeneity by East 

Azerbaijan Water & Wastewater Laboratory. Based on the results of this testing, it was 

concluded that the samples were sufficiently homogeneous, therefore any results later identified 

as outliers could not be attributed to sample variability. The results of homogeneity testing have 

been summarized in Appendix B. 

2-3- Samples Stability 

Three randomly selected samples were analysed in duplicate for stability by East Azerbaijan 

Water & Wastewater Laboratory at a date later than homogeneity testing according to the 

results submission deadline defined for the participants. Based on the results of this testing, it 

was concluded that the samples were sufficiently stable during the period of program execution, 

therefore any results later identified as outliers could not be attributed to sample instability. The 

results of stability testing have been summarized in Appendix B. 

2-4- Distribution 

The dispatch date was November 4, 2012. Each laboratory received 2 x 1 L water samples 

together with a covering letter, participants instruction and a result sheet. 

3- Statistical design of the program 

Participating laboratories were each supplied 2 x 1 L water samples labeled “Sample 1 & 2 

(WAT-CH-0001)”. One result was reported for all tests. For each statistically analysed test, 

Page 5 of 57


robust statistical procedures were used to generate the z-scores and summary statistics for 

each test. 

The assigned value (X) and the standard deviation of proficiency assessment ( ) has been 

determined according to the criteria given in clause 6 of this report. 

4- Features of the program 

4-1- Number of Participants 

A total of 31 laboratories received samples. A total of 27 laboratories returned results for 

inclusion in this report. 

4-2- Supplied samples 

Participating laboratories were each supplied 2 x 1 L water samples sample labeled “Sample 1 

& 2 (WAT-CH-0001)”. 

4-3- Parameters 

The following determinations were to be performed on the samples: 

 

 

 

 

 

 

 

 

 

 

 

Calcium 

Magnesium 

Total Hardness 

Alkalinity 

Sodium 

Potassium 

Chloride 

Sulphate 

Fluoride 

Conductivity 

Total Dissolved Solids (TDS) 

4-4- Participants instruction 

Laboratories were requested to perform the tests according to the “Instructions to Participants" 

and to record their results on the accompanying "Results Sheet”, all of which were distributed to 

participants with the samples (Appendix C). 

The methods used by each participant are summarized in Appendix A. 

4-5- Confidentiality 

Each laboratory was randomly allocated a unique code number for the program to enable 

confidentiality of results. Reference to each laboratory in this report is made by its code number. 

National Water and Wastewater Engineering Company as a regulatory authority has requested 

PQP to directly provide the proficiency testing results to them so the performance of the affected 

Page 6 of 57


participants i.e. laboratories of water and wastewater companies in this program has also been 

reported to National Water and Wastewater Engineering Company. 

4-6- Appeals 

The participants are able to appeal against the evaluation of their performance in this program 

through the program coordinator. In one week period after receiving the appeal, PQP sends a 

letter to the participant to acknowledge the receipt of the appeal and ensure the participant that 

their appeal will be handled in a timely manner. 

The participant will be notified of the results after the actions are confirmed with a response 

letter. 

5- Summary of results 

Results for this proficiency test are summarized as follows: 

Test 

Calcium 

(mgCa/L) 

Magnesium 

(mgMg/L) 


(mgCaCO3/L) 

Alkalinity 

(mgCaCO3/L) 

Sodium 

(mgNa/L) 

Potassium 

(mgK/L) 

Choride 

(mgCl/L) 

Sulphate 

(mgSO4/L) 

No. of 

Results 

Assigned 

Value 

SDPA 1 

( ) 

standard 

uncertainty 

of the 

assigned 

value (u x ) 

No. of 

satisfactory 

scores 

( ) 

Satisfactory 

(%) 

27 152.01 8.90 2.14 24 88.9 

27 29.73 4.64 1.12 25 92.6 

27 500.63 15.00 3.61 21 77.8 

26 334.10 10.04 2.46 17 65.4 

25 115.30 6.80 1.70 18 72.0 

24 6.65 0.77 0.21 21 87.5 

27 101.16 7.21 0.08 21 77.8 

27 268.50 19.48 4.69 20 74.1 

Fluoride (mgF/L) 25 0.43 0.23 0.058 --- --- 

Conductivity 

(µS/cm @ 25°C) 

Total Dissolved 

Solids (mg/L) 

27 1403.29 64.46 15.51 23 85.2 

26 880.22 109.78 26.91 25 96.2 

1 Standard Deviation of Proficiency Assessment 

Page 7 of 57


6- Statistical evaluation of results 

6-1- General 

The object of the statistical procedure employed is to obtain a simple and transparent result, 

which the participant and other interested parties can readily appreciate. The procedure follows 

that recommended in ISO 13528: 2005, Statistical methods for use in proficiency testing by 

interlaboratory comparisons. 

6-2- Calculation of assigned value 

The assigned value is the value selected as being the best estimate of the ‘true value’ for the 

parameter under test. The assigned value X for the test material used in this round of a 

proficiency testing scheme is the robust average of the results reported by all the participants in 

the round using the below algorithm: 

Denote the p items of data, sorted into increasing order, by: 

x 1 , x 2 , ..., x i , ..., x p 

Denote the robust average and robust standard deviation of these data by x* and s*. 

Calculate initial values for x* and s* as: 

x* = median of x i (i = 1, 2, ..., p) 

s* = 1,483 median of x i − x * (i = 1, 2, ..., p) 

Update the values of x* and s* as follows. Calculate: 

δ = 1,5s* 

For each x i (i = 1, 2, ..., p), calculate: 

δ 

δ 

δ 

δ 

Calculate the new values of x* and s* from: 

The robust estimates x* and s* has been derived by an iterative calculation, i.e. by updating the 

values of x* and s* several times using the modified data, until the process converges. 

Convergence is assumed when there is no change from one iteration to the next in the third 

Page 8 of 57


significant figure of the robust standard deviation and of the equivalent figure in the robust 

average. 

6-3- Standard deviation for proficiency assessment (SDPA) 

The standard deviation used to assess the proficiency of participants in this round of scheme 

is derived from the results reported by the participants in the round Two methods have been 

used for determination of SDPA as follows: 

Method 1: Robust standard deviation (s*) 

The standard deviation is the robust standard deviation of the results (s*) reported by all the 

participants, calculated using the algorithm in 6-2. 

Method 2: IQR 

The standard deviation is the interquartile range (IQR). IQR is a measure of the variability of the 

results. It is equal to the interquartile range (IQR) multiplied by a correction factor of 0.7413, 

which makes it comparable to a standard deviation. The interquartile range is the difference 

between the lower and upper quartiles. The lower quartile (Q1) is the value below which, as 

near as possible, a quarter of the results lie. Similarly the upper quartile (Q3) is the value above 

which a quarter of the results lie. The IQR = Q3 – Q1 and the normalised IQR = IQR × 0.7413. 

6-4- Measurement uncertainty of the assigned value (u x ) 

The standard uncertainty of the assigned value X is estimated as: 

Where p is the number of participants. 

6-5- Purpose of performance scoring 

Once the assigned value for the parameters under test has been established, participant 

laboratories are assessed on the difference between their result and the assigned value, with 

this difference being represented by a performance score, normally the z-score. The 

advantages of a z-score are: 

- Results can be expressed in a form that is relatively easy to interpret and understand 

- Results can be summarized in graphical or tabular form to depict overall performance 

- A performance score allows participants to directly compare their own result with others 

- If consistent statistical values are applied, a performance score enables participants to 

monitor and trend their own performance over time. 

6-6- z-scores 

Z-score of the participants is calculated using the following formula: 

Page 9 of 57


In which: 

x: participant result 

µ: assigned value 

SDPA: Standard deviation for proficiency assessment 

For the purposes of performance assessment for a single round, z scores are interpreted as 

follows: 

Z-Score 

Interpretation 

Satisfactory Result 

Questionable result 

Unsatisfactory result 

7- PQP and technical advisor comments 

7-1- Metrological Traceability of Assigned Values 

Consensus values derived from the participants’ results are used in this program. These values 

are not metrologically traceable to any external reference. 

7-2- Methodology summary 

Participants’ methods are tabulated according to the information supplied by the participants. 

Calcium 

Method 

Number of 

results 

% of total Median Sat. (%) 

Atomic Absorption Spectroscopy 1 3.7% 163.90 100% 

Ion chromatography 1 3.7% 149.94 100% 

Photometry 3 11.1% 146.00 67% 

Titration 21 77.8% 151.75 90% 

Other 1 3.7% 156.40 100% 

Magnesium 

Method 

Number of % of 

results total 

Median Sat. (%) 


Calculation 15 55.6% 29.04 87% 

Ion Chromatography 1 3.7% 26.78 100% 

Photometry 4 14.8% 29.60 100% 

Titration 5 18.5% 29.00 100% 

Other 1 3.7% 28.8 100% 

Page 10 of 57


Total hardness 

Method 

Number of 

results 


Photometry 3 11.1% 490.00 33% 

Titration 24 88.9% 501.50 83% 

Alkalinity 

Method 

Number of 

results 


Photometry 2 7.7% 325.00 100% 

Titration 24 92.3% 335.95 63% 

Comments: since only two laboratories have used photometry method so the comparison of 

two methods based on the satisfactory results is not suitabl and titration method is an 

acceptable method for analysis of alkalinity. 

Sodium 

Method 

Number 

of results 



Calculation 1 4.0% 92.00 0% 

Flame Photometry 15 60.0% 117.50 67% 


Other 3 12.0% 103.50 67% 

Potassium 

Method 

Number 

of results 





Other 3 12.5% 5.00 67% 

Chloride 

Method 

Number of 

results 


Colorimetry 5 18.5% 96.00 60% 


titration 12 44.4% 104.75 83% 

other 3 11.1% 126.00 33% 

Page 11 of 57


Sulphate 

Method 

Number of 

results 



Turbidimetry 17 63.0% 266.40 65% 

other 4 14.8% 266.50 75% 

Fluoride 

Method 

Number of 

results 


Ion Chromatography 6 25.0% 0.24 --- 

Spectrophotometry 14 58.3% 0.48 --- 

other 4 16.7% 0.38 --- 

Comments: in case of using ion chromatography method, the analysis should be done by using 

a suitable effluent and removal of interferences. 

Conductivity 

Method 

Number of 

results 


Conductivity Meter 24 88.9% 1399.50 88% 

other 3 11.1% 1408.00 67% 

Total Dissolved Solids 

Method 

Number of 

results 


Drying @ 180°C 12 46.2% 945.50 100% 

Calculation 4 15.4% 903.50 100% 

other 10 38.5% 777.00 90% 

7-3- Overall performance 

Samples have been collected and prepared according to standard methods for the examination 

of water and wastewater. 

Assigned values for each parameter have been determined form the participants results in this 

program and statistical calculations. 

In case of fluoride, due to the variations in the results the evaluation of participants performance 

is not possible. Since the analysis of fluoride is a very sensitive procedure and diferrent 

parameters such as sample and standards temperature can affect the measurement process so 

it is expected to improve the test methods results by carefully take the above mentioned 

cautions into consideration. 

Page 12 of 57


8- References 

1- ISO/IEC 17025: 2005, general requirements for the competence of testing and 

calibration laboratories. 

2- ISO/IEC 17043: 2010, Conformity assessment — General requirements for proficiency 

testing 

3- ISO 13528: 2005, Statistical methods for use in proficiency testing by interlaboratory 

comparisons 

4- PR-14- rev. 00, PQP Performance evaluation Procedure 

5- PR-15- rev. 00, PQP Homogeneity and stability Procedure 

Page 13 of 57


Appendix A- Results and data analysis 

Calcium 

Lab. Code Method Result (mgCa/L) Z-score 

1 Titration 157.50 0.62 

2 AAS 163.90 1.34 

3 Titration 156.80 0.54 

4 Other 156.40 0.49 

5 Titration 153.00 0.11 

6 Titration 160.00 0.90 

7 Titration 144.29 -0.87 

8 Titration 140.60 -1.28 

9 Titration 143.23 -0.99 

10 Ion Chromatography 149.94 -0.23 

11 Photometry 168.00 1.80 

12 Titration 156.00 0.45 

13 Titration 163.60 1.30 

14 Titration 156.00 0.45 

15 Photometry 146.00 -0.67 

16 Titration 151.75 -0.03 

17 Titration 150.60 -0.16 

18 Titration 155.20 0.36 

23 Titration 143.50 -0.96 

24 Titration 149.90 -0.24 

25 Photometry 112.80 -4.40 

26 Titration 150.00 -0.23 

27 Titration 146.80 -0.58 

28 Titration 110.00 -4.72 

29 Titration 185.60 3.77 

30 Titration 157.17 0.58 

31 Titration 145.00 -0.79 

Page 14 of 57

Frequency 


Data Statistics 

Number of results 27 

Number of excluded 0 

results* 

Assigned value 152.01 

Uncertainty of assigned 2.14 

value 

SDPA** 8.90 

* The influence of outliers on summary statistics has been minimized by the use of robust 

statistical methods but obvious blunders, such as those with incorrect units, decimal point 

errors, and results for a different proficiency test item are removed from the data set and treated 

separately. These results are not the subject to outlier tests or robust statistical methods. 

** Method 1 in clause 6-3 (robust standard deviation) has been used for determination of SDPA. 

12 

Histogram of participants Z-scores for Ca 

10 

8 

6 

4 

Frequency 

2 

0 

-5 -4 -3 -2 -1 0 1 2 3 4 5 More 

Z-scores 

Page 15 of 57

Z-score 


5.00 

4.00 

3.00 

2.00 

1.00 

0.00 

-1.00 

-2.00 

-3.00 

-4.00 

-5.00 

-6.00 

28 25 8 9 23 7 31 15 27 24 10 26 17 16 5 18 12 14 4 3 30 1 6 13 2 11 29 

Lab No. 

Methodology Summary 

Method 

Number of 

results 



Ion chromatography 1 3.7% 149.94 100% 

Photometry 3 11.1% 146.00 67% 

Titration 21 77.8% 151.75 90% 

Other 1 3.7% 156.40 100% 

Page 16 of 57


Magnesium 

Lab. Code Method Result (mgMg/L) Z-score 

1 Calculation 28.08 -0.36 

2 AAS 24.20 -1.19 

3 Calculation 33.60 0.83 


5 Titration 29.00 -0.16 

6 Titration 26.00 -0.81 





11 Photometry 33.30 0.77 


13 Photometry 29.20 -0.12 


15 Photometry 30.00 0.06 

16 Titration 28.56 -0.25 




24 Titration 37.90 1.76 

25 Photometry 22.46 -1.57 

26 Other 28.80 -0.20 



29 Titration 38.40 1.87 



Page 17 of 57

Frequency 





results* 



value 

SDPA** 4.64 






14 

Histogram of participants Z-scores for Mg 

12 

10 

8 

6 

4 

2 

0 

-3 -2 -1 0 1 2 3 More 

Z-scores 

Page 18 of 57

Z-score 


3.00 

2.00 

1.00 

0.00 

25 12 7 2 6 14 10 17 4 1 16 18 26 5 30 13 27 15 11 31 3 23 8 24 29 9 28 

-1.00 

-2.00 

-3.00 



Method 

Number of % of 

results total 

Median Sat. (%) 


Calculation 15 55.6% 29.04 87% 


Photometry 4 14.8% 29.60 100% 

Titration 5 18.5% 29.00 100% 

Other 1 3.7% 28.8 100% 

Page 19 of 57


Total hardness 

Lab. Code Method Result (mgCaCO3/L) Z-score 

1 Titration 508.00 0.49 

2 Titration 500.00 -0.04 

3 Titration 532.00 2.09 

4 Titration 507.70 0.47 

5 Titration 503.00 0.16 

6 Titration 506.00 0.36 

7 Titration 458.00 -2.84 

8 Titration 503.00 0.16 

9 Titration 520.00 1.29 

10 Titration 480.00 -1.38 

11 Photometry 558.60 3.86 

12 Titration 487.50 -0.88 

13 Titration 504.00 0.22 

14 Titration 500.00 -0.04 

15 Photometry 490.00 -0.71 

16 Titration 498.38 -0.15 

17 Titration 486.60 -0.94 

18 Titration 508.00 0.49 

23 Titration 497.00 -0.24 

24 Titration 530.00 1.96 

25 Photometry 374.00 -8.44 

26 Titration 495.00 -0.38 

27 Titration 491.00 -0.64 

28 Titration 450.00 -3.38 

29 Titration 624.00 8.23 

30 Titration 511.94 0.75 

31 Titration 500.00 -0.04 

Page 20 of 57

Frequency 





results* 



value 

SDPA** 15.00 






12 

10 

8 

6 

4 

2 

0 

Histogram of participants Z-scores for Total 

Hardness 

Z-scores 

Page 21 of 57

Z-score 


10.00 

9.00 

8.00 

7.00 

6.00 

5.00 

4.00 

3.00 

2.00 

1.00 

0.00 

-1.00 

-2.00 

-3.00 

-4.00 

-5.00 

-6.00 

-7.00 

-8.00 

-9.00 

25 28 7 10 17 12 15 27 26 23 16 2 14 31 5 8 13 6 4 1 18 30 9 24 3 11 29 



Method 

Number of 

results 


Photometry 3 11.1% 490.00 33% 

Titration 24 88.9% 501.50 83% 

Page 22 of 57


Alkalinity 

Lab. Code Method Result (mgCaCO3/L) Z-score 

1 Titration 339.00 0.49 

2 Titration 360.00 2.58 

3 Titration 334.00 -0.01 

4 Titration 336.90 0.28 

5 Titration 82.00 -25.10 

6 Titration 334.00 -0.01 

7 Titration 315.00 -1.90 

8 Titration 332.00 -0.21 

9 Titration 355.60 2.14 

10 Titration 216.00 -11.76 

11 Titration 310.00 -2.40 

12 Titration 335.00 0.09 

14 Titration 330.00 -0.41 

15 Photometry 320.00 -1.40 

16 Titration 339.50 0.54 

17 Titration 356.90 2.27 

18 Titration 340.00 0.59 

23 Titration 340.00 0.59 

24 Titration 346.00 1.18 

25 Photometry 330.00 -0.41 

26 Titration 304.00 -3.00 

27 Titration 338.19 0.41 

28 Titration 240.00 -9.37 

29 Titration 332.00 -0.21 

30 Titration 337.30 0.32 

31 Titration 380.00 4.57 

Page 23 of 57

Frequency 





results* 



value 

SDPA** 10.04 






9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

Histogram of participants Z-scores for Alkalinity 

-26 -25 -12 -11 -10 -9 -3 -2 -1 0 1 2 3 4 5 More 

Z-scores 

Page 24 of 57

Z-score 


6.00 

5.00 

4.00 

3.00 

2.00 

1.00 

0.00 

-1.00 

-2.00 

-3.00 

-4.00 

-5.00 

-6.00 

-7.00 

-8.00 

-9.00 

-10.00 

-11.00 

-12.00 

-13.00 

-14.00 

5 10 28 26 11 7 15 14 25 8 29 3 6 12 4 30 27 1 16 18 23 24 9 17 2 31 



Method 

Number of 

results 


Photometry 2 7.7% 325.00 100% 

Titration 24 92.3% 335.95 63% 

Page 25 of 57


Sodium 

Lab. Code Method Result (mgNa/L) Z-score 

1 Ion Chromatography 125.00 1.43 


3 Flame Photometry 117.50 0.32 

4 other 117.00 0.25 



8 AAS 113.60 -0.25 

9 Flame Photometry 81.40 -4.99 


11 AAS 106.70 -1.27 


13 other 118.40 0.46 










28 other 90.00 -3.72 




Page 26 of 57

Frequency 





results* 



value 

SDPA** 6.80 






12 

Histogram of participants Z-scores for Sodium 

10 

8 

6 

4 

2 

0 

-5 -4 -3 -2 -1 0 1 2 3 4 More 

Z-scores 

Page 27 of 57

Z-score 


3.00 

2.00 

1.00 

0.00 

-1.00 

9 28 30 15 25 31 11 29 14 8 27 10 4 3 24 26 13 6 2 18 17 16 12 1 7 

-2.00 

-3.00 

-4.00 

-5.00 



Method 

Number 

of results 



Calculation 1 4.0% 92.00 0% 



Other 3 12.0% 103.50 67% 

Page 28 of 57


Potassium 

Lab. Code Method Result (mgK/L) Z-score 




4 other 6.40 -0.33 


8 AAS 16.80 13.25 



11 AAS 7.00 0.46 


13 other 6.20 -0.59 










28 other 5.00 -2.15 




Page 29 of 57

Frequency 





results* 



value 

SDPA** 0.77 






12 

Histogram of participants Z-scores for Potassium 

10 

8 

6 

4 

2 

0 

-3 -2 -1 0 1 2 3 13 14 More 

Z-scores 

Page 30 of 57

Z-score 


9.00 

8.00 

7.00 

6.00 

5.00 

4.00 

3.00 

2.00 

1.00 

0.00 

-1.00 

-2.00 

-3.00 

28 31 24 30 16 29 13 4 1 18 10 3 26 17 25 11 14 27 9 12 15 2 7 8 



Method 

Number 

of results 





Other 3 12.5% 5.00 67% 

Page 31 of 57


Chloride 

Lab. Code Method Result (mgCl/L) Z-score 



3 Other 103.00 0.26 

4 Other 126.00 3.45 

5 Titration 94.00 -0.99 

6 Titration 97.00 -0.58 



9 Titration 108.50 1.02 

10 Titration 116.20 2.09 

11 Colorimetry 84.70 -2.28 

12 Titration 99.40 -0.24 



15 Colorimetry 140.00 5.39 


17 Titration 107.60 0.89 

18 Titration 97.00 -0.58 

23 Titration 106.40 0.73 

24 Titration 103.50 0.32 

25 Other 140.00 5.39 

26 Titration 106.00 0.67 

27 Colorimetry 102.46 0.18 

28 Titration 126.00 3.45 



31 Titration 95.00 -0.85 

Page 32 of 57

Frequency 




Number of excluded results* 0 


Uncertainty of assigned 

0.08 

value 

SDPA** 7.21 






14 

Histogram of participants Z-scores for Chloride 

12 

10 

8 

6 

4 

2 

0 

-3 -2 -1 0 1 2 3 4 5 6 More 

Z-scores 

Page 33 of 57

Z-score 


9.00 

8.00 

7.00 

6.00 

5.00 

4.00 

3.00 

2.00 

1.00 

0.00 

-1.00 

-2.00 

-3.00 

11 1 5 29 30 31 14 13 6 18 16 2 8 12 7 27 3 24 26 23 17 9 10 4 28 15 25 



Method 

Number of 

results 


Colorimetry 5 18.5% 96.00 60% 


titration 12 44.4% 104.75 83% 

other 3 11.1% 126.00 33% 

Page 34 of 57


Sulphate 

Lab. Code Method Result (mgSO4/L) Z-score 



3 Other 293.00 1.26 

4 Other 290.00 1.10 

5 Turbidimetry 260.00 -0.44 



8 Turbidimetry 347.00 4.03 













25 Other 193.00 -3.88 



28 Other 243.00 -1.31 




Page 35 of 57

Frequency 





results* 



value 

SDPA** 19.48 





** Method 2 in clause 6-3 (inter quartile range) has been used for determination of SDPA. 

9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

Histogram of participants Z-scores for Sulphate 

-6 -5 -4 -2 -1 0 1 2 3 3 4 5 6 7 8 9 10 

Z-scores 

Page 36 of 57

Z-score 


7.00 

6.00 

5.00 

4.00 

3.00 

2.00 

1.00 

0.00 

-1.00 

-2.00 

-3.00 

-4.00 

-5.00 

9 15 25 10 31 28 26 5 6 14 23 7 1 12 13 24 30 11 2 18 4 3 27 16 29 8 17 



Method 

Number of 

results 



Turbidimetry 17 63.0% 266.40 65% 

other 4 14.8% 266.50 75% 

Page 37 of 57


Fluoride 

Lab. Code Method Result (mgF/L) 

1 Ion Chromatography 0.270 

2 Ion Chromatography 0.237 

3 Other





results* 


Uncertainty of assigned --- 

value 

SDPA --- 






Method 

Number of 

results 


Ion Chromatography 6 25.0% 0.24 --- 

Spectrophotometry 14 58.3% 0.48 --- 

other 4 16.7% 0.38 --- 

Page 39 of 57


Conductivity 

Lab. Code 

Method 

Result (µS/cm @ 

25°C) 

Z-score 

1 Other 1634.127 3.58 

2 Conductivity Meter 1440.000 0.57 

3 Conductivity Meter 1390.000 -0.21 

4 Other 1351.000 -0.81 




8 Other 1408.000 0.07 




















Page 40 of 57

Frequency 





results* 



value 

SDPA** 64.46 






12 

10 

8 

6 

4 

2 

0 

Histogram of participants Z-scores for 

Conductivity 

-3 -2 -1 0 1 2 3 4 More 

Z-scores 

Page 41 of 57

Z-score 


4.00 

3.00 

2.00 

1.00 

0.00 

-1.00 

5 11 28 24 4 18 7 10 9 3 26 16 30 6 31 8 13 23 12 2 17 25 29 14 15 27 1 

-2.00 

-3.00 

-4.00 



Method 

Number of 

results 


Conductivity Meter 24 88.9% 1399.50 88% 

other 3 11.1% 1408.00 67% 

Page 42 of 57


Total Dissolved Solids 

Lab. Code Method Result (mg/L) Z-score 

2 Drying @ 180°C 960.00 0.73 

3 Drying @ 180°C 995.00 1.05 


5 Drying @ 180°C 1001.00 1.10 

6 Other 756.00 -1.13 

7 Other 750.00 -1.19 

8 Drying @ 180°C 986.00 0.96 

9 Drying @ 180°C 693.28 -1.70 

10 Other 605.00 -2.51 

11 Drying @ 180°C 873.60 -0.06 

12 Drying @ 180°C 930.00 0.45 

13 Other 989.00 0.99 

14 Drying @ 180°C 894.00 0.13 


16 Drying @ 180°C 920.00 0.36 


18 Drying @ 180°C 1027.00 1.34 

23 Other 904.00 0.22 

24 Other 722.00 -1.44 

25 Other 876.80 -0.03 

26 Drying @ 180°C 931.00 0.46 

27 Other 696.00 -1.68 

28 Other 812.00 -0.62 

29 Other 798.00 -0.75 

30 Drying @ 180°C 970.00 0.82 


Page 43 of 57

Frequency 





results* 



value 

SDPA** 109.78 






14 

Histogram of participants Z-scores for TDS 

12 

10 

8 

6 

4 

2 

0 

-3 -2 -1 0 1 2 3 More 

Z-scores 

Page 44 of 57

Z-score 


4.00 

3.00 

2.00 

1.00 

0.00 

-1.00 

10 9 27 24 7 6 29 28 4 11 25 14 15 23 31 16 17 12 26 2 30 8 13 3 5 18 

-2.00 

-3.00 

-4.00 



Method 

Number of 

results 


Drying @ 180°C 12 46.2% 945.50 100% 

Calculation 4 15.4% 903.50 100% 

other 10 38.5% 777.00 90% 

Page 45 of 57


Appendix B- Homogeneity and stability testing 

B-1- Homogeneity testing 

Samples for this program were obtained from a natural water source by East Azerbaijan water 

and wastewater laboratory. A random selection of 10 samples was chosen prior to sample 

dispatch. Each of the selected test samples have been divided into two test portions using 

techniques appropriate to the test material to minimize between-test-portion differences. 

The results of the homogeneity testing has been analysed by PQP, in order to determine 

whether the samples are sufficiently homogeneous. 

The selected samples were analysed by East Azerbaijan water and wastewater laboratory for 

homogeneity. The homogeneity of the samples has been checked by applying ANOVA- Single 

Factor technique to compare between-samples and within-samples variations. If there is no 

significance difference between these two sources of variations then it can be concluded that 

the samples are homogeneous. 

The results of the homogeneity testing are as follows: 

Page 46 of 57



Sample 

Portion 1 Result Portion 2 Result 

(mgCaCO3/L) (mgCaCO3/L) 

A 487.5 485.0 

B 487.5 487.5 

C 490.0 487.5 

D 487.5 487.5 

E 490.0 490.0 

F 485 487.5 

G 487.5 485.0 

H 485.0 487.5 

I 487.5 485.0 

J 487.5 487.5 

The results of ANOVA- single factor analysis are as follows: 

Anova: Single Factor 

SUMMARY 

Groups Count Sum Average Variance 

A 2 972.5 486.25 3.125 

B 2 975 487.5 0 

C 2 977.5 488.75 3.125 

D 2 975 487.5 0 

E 2 980 490 0 

F 2 972.5 486.25 3.125 

G 2 972.5 486.25 3.125 

H 2 972.5 486.25 3.125 

I 2 972.5 486.25 3.125 

J 2 975 487.5 0 

ANOVA 

Source of 

Variation SS df MS F P-value F crit 

Between 

3.33333333 1.77777777 0.19144420 

Groups 30 9 

3 

8 

3 

Within Groups 18.75 10 1.875 

Total 48.75 19 

3.02038294 

7 

Considering the results of ANOVA analysis, it can be concluded that the samples are 

homogenous for this parameter. 

Page 47 of 57


Alkalinity 

Sample 


(mgCaCO3/L) (mgCaCO3/L) 

A 335.0 335.0 

B 337.5 335.0 

C 335.0 335.0 

D 337.5 335.0 

E 335.0 335.0 

F 337.5 335.0 

G 337.5 335.0 

H 337.5 335.0 

I 335.0 335.0 

J 335.0 337.5 


Anova: Single 

Factor 

SUMMARY 


A 2 670 335 0 

B 2 672.5 336.25 3.125 

C 2 670 335 0 

D 2 672.5 336.25 3.125 

E 2 670 335 0 

F 2 672.5 336.25 3.125 

G 2 672.5 336.25 3.125 

H 2 672.5 336.25 3.125 

I 2 670 335 0 

J 2 672.5 336.25 3.125 

ANOVA 

Source of 


0.83333333 0.44444444 0.88107921 

Between Groups 7.5 9 

3 

4 

1 


Total 26.25 19 

3.02038294 

7 



Page 48 of 57


Potassium 

Sample 


(mgK/L) 

(mgK/L) 

A 7.20 7.20 

B 7.20 7.20 

C 7.20 7.250 

D 7.20 7.30 

E 7.20 7.20 

F 7.20 7.25 

G 7.20 7.20 

H 7.30 7.20 

I 7.20 7.25 

J 7.25 7.30 


Anova: Single 

Factor 

SUMMARY 


A 2 14.4 7.2 0 

B 2 14.4 7.2 0 

C 2 14.45 7.225 0.00125 

D 2 14.5 7.25 0.005 

E 2 14.4 7.2 0 

F 2 14.45 7.225 0.00125 

G 2 14.4 7.2 0 

H 2 14.5 7.25 0.005 

I 2 14.45 7.225 0.00125 

J 2 14.55 7.275 0.00125 

ANOVA 

Source of 


Between Groups 0.0125 9 0.001388889 0.925925926 0.541304 3.020382947 


Total 0.0275 19 



Page 49 of 57


Sulphate 

Sample Portion 1 Result 

(mgSO4/L) 

Portion 2 Result 

(mgSO4/L) 

A 266.4 265.5 

B 257.4 258.2 

C 260.8 267.3 

D 257.0 263.1 

E 259.9 262.5 

F 267.8 266.5 

G 262.1 259.5 

H 266.4 257.5 

I 259.2 264.6 

J 266.1 266.5 


Anova: Single 

Factor 

SUMMARY 


A 2 531.9 265.95 0.405 

B 2 515.6 257.8 0.32 

C 2 528.1 264.05 21.125 

D 2 520.1 260.05 18.605 

E 2 522.4 261.2 3.38 

F 2 534.3 267.15 0.845 

G 2 521.6 260.8 3.38 

H 2 523.9 261.95 39.605 

I 2 523.8 261.9 14.58 

J 2 532.6 266.3 0.08 

ANOVA 

Source of 


Between 166.480 

18.4978333 1.80775307 0.18475495 

Groups 

5 9 

3 

4 

8 

Within Groups 102.325 10 10.2325 

Total 

268.805 

5 19 

3.02038294 

7 



Page 50 of 57


Fluoride 

Sample 


(mgF/L) 

(mgF/L) 

A 0.457 0.451 

B 0.456 0.455 

C 0.458 0.453 

D 0.455 0.451 

E 0.457 0.454 

F 0.456 0.453 

G 0.457 0.452 

H 0.456 0.455 

I 0.457 0.453 

J 0.454 0.457 


Anova: Single Factor 

SUMMARY 


A 2 0.908 0.454 0.000018 

B 2 0.911 0.4555 5E-07 

C 2 0.911 0.4555 0.0000125 

D 2 0.906 0.453 8E-06 

E 2 0.911 0.4555 4.5E-06 

F 2 0.909 0.4545 4.5E-06 

G 2 0.909 0.4545 0.0000125 

H 2 0.911 0.4555 5E-07 

I 2 0.91 0.455 8E-06 

J 2 0.911 0.4555 4.5E-06 

ANOVA 

Source of 


Between 0.0000130 

0.19727891 0.98869786 

Groups 

5 9 1.45E-06 

2 

2 

Within Groups 7.35E-05 10 7.35E-06 

Total 8.655E-05 19 

3.02038294 

7 



Page 51 of 57


Chloride 

Sample 


(mgCl/L) 

(mgCl/L) 

A 99.4 97.6 

B 99.4 97.6 

C 97.6 97.6 

D 99.4 97.6 

E 99.4 99.4 

F 97.6 99.4 

G 97.6 97.6 

H 99.4 99.4 

I 99.4 97.6 

J 99.4 99.4 


Anova: Single 

Factor 

SUMMARY 


A 2 197 98.5 1.62 

B 2 197 98.5 1.62 

C 2 195.2 97.6 0 

D 2 197 98.5 1.62 

E 2 198.8 99.4 0 

F 2 197 98.5 1.62 

G 2 195.2 97.6 0 

H 2 198.8 99.4 0 

I 2 197 98.5 1.62 

J 2 198.8 99.4 0 

ANOVA 

Source of 


Between Groups 7.938 9 0.882 1.088888889 0.444612742 3.020382947 


Total 16.038 19 



Page 52 of 57


Conductivity 

Sample Portion 1 Result 

(µS/cm@25°C) 

Portion 2 Result 

(µS/cm@25°C) 

A 1421 1421 

B 1421 1423 

C 1423 1421 

D 1423 1420 

E 1422 1418 

F 1421 1422 

G 1419 1421 

H 1422 1423 

I 1418 1420 

J 1419 1420 


Anova: Single 

Factor 

SUMMARY 


A 2 2842 1421 0 

B 2 2844 1422 2 

C 2 2844 1422 2 

D 2 2843 1421.5 4.5 

E 2 2840 1420 8 

F 2 2843 1421.5 0.5 

G 2 2840 1420 2 

H 2 2845 1422.5 0.5 

I 2 2838 1419 2 

J 2 2839 1419.5 0.5 

ANOVA 

Source of 


Between 

2.86666666 1.30303030 0.34138613 

Groups 25.8 9 

7 

3 

9 

Within Groups 22 10 2.2 

Total 47.8 19 

3.02038294 

7 



Page 53 of 57


B-2- Stability testing 

Samples for this program were obtained from a natural water source by East Azerbaijan water 

and wastewater laboratory. A random selection of 3 samples was chosen 30 days after the 

sample dispatch. Each of the selected test samples have been divided into two test portions 

using techniques appropriate to the test material to minimize between-test-portion differences. 

The results of the stability testing has been analysed by PQP, in order to determine whether the 

samples are sufficiently stable. The selected samples were analysed by East Azerbaijan water 

and wastewater laboratory for stability. The general average of the measurements obtained in 

the homogeneity check is compared with the general average of the results obtained in the 

stability check. The samples are considered to be adequately stable if: 

The results of the stability testing are as follows: 

Parameter 

Total 

hardness 

(mgCaCO3/L) 

Alkalinity 

(mgCaCO3/L) 

Potassium 

(mgK/L) 

Chloride 

(mgCl/L) 

Sulphate 

(mgSO4/L) 

Sample 

SDPA 

A’ B’ C’ 

? 

485.0 487.5 487.5 487.5 487.5 485.0 15 Yes 

335.0 335.0 337.5 335.0 337.5 335.0 10.04 Yes 

7.25 7.20 7.20 7.25 7.25 7.25 0.77 Yes 

99.4 99.4 99.4 97.6 99.4 97.6 7.21 Yes 

262.1 263.1 265.2 263.3 261.5 259.9 24.40 Yes 

Fluoride 

(mgF/L) 

Conductivity 

(µS/cm@25°C 

) 

0.451 0.456 0.457 0.455 0.452 0.454 0.23 Yes 

1420 1421 1422 1421 1423 1422 0.6 64.46 Yes 

Considering the results of stability analysis, it can be concluded that the samples are stable for the program’s 

parameters. 

Page 54 of 57


Appendix C- Documents 

C-1- Instructions to participants 

Sample WAT-CH-0001 Preparation Instruction 

Materials Supplied: 

- 2 x 1L samples in PE bottles labeled as Sample 

1 & 2 (WAT-CH-0001) 

WAT-CH-0001 

Sample 1 & 2 (WAT-CH-0001) 

- 

Preparation: 

Parameter 

Bottle for 

Analysis 

Instruction 

Calcium 

Magnesium 

Total 

Hardness 

Alkalinity 

Sodium 

Potassium 

Chloride 

Sulphate 

Fluoride 

Conductivity 

Total 

Dissolved 

Solids (TDS) 

Remarks: 

Sample 1 & 2 

(WAT-CH-0001) 

Sample 1 & 2 


Sample 1 & 2 


Sample 1 & 2 


Sample 1 & 2 


Sample 1 & 2 


Sample 1 & 2 


Sample 1 & 2 


Sample 1 & 2 


Sample 1 & 2 


Sample 1 & 2 


Analyze as 

supplied 

Analyze as 

supplied 

Analyze as 

supplied 

Analyze as 

supplied 

Analyze as 

supplied 

Analyze as 

supplied 

Analyze as 

supplied 

Analyze as 

supplied 

Analyze as 

supplied 

Analyze as 

supplied 

Analyze as 

supplied 

Sample 1 & 2 

(WAT-CH- 

0001) 

Sample 1 & 2 



Sample 1 & 2 



Sample 1 & 2 



Sample 1 & 2 



Sample 1 & 2 



Sample 1 & 2 



Sample 1 & 2 



Sample 1 & 2 



Sample 1 & 2 



Sample 1 & 2 



Calcium 

Magnesium 

Total 

Hardness 

Alkalinity 

Sodium 

Potassium 

Chloride 

Sulphate 

Fluoride 

Conductivity 

Total 

Dissolved 

Solids (TDS) 

Page 55 of 57


Sample WAT-CH-0001 Preparation Instruction 

1- For all the above mentioned parameters the 

results should be reported in the results sheet 

form and the test method should be specified. 

2- The laboratory should calculate and report the 

expanded measurement uncertainty with 95% 

confidence interval (coverage factor k=2). It 

should be noted that the reported value of 

uncertainty won’t be used for performance 

evaluation of your laboratory. 


k=2 

Page 56 of 57


C-2- Results Sheet 

Physicochemical parameters in underground water proficiency testing program- Round 1 


(Program No.) 

(Laboratory Code) 

Parameter Result Unit 

(±MU) 

Method 

Calcium 

mgCa/L 

Magnesium 

mgMg/L 


mgCaCO3/L 

Alkalinity 

mgCaCO3/L 

Sodium 

mgNa/L 

Potassium 

mgK/L 

Chloride 

mgCl/L 

Sulphate 

mgSO4/L 

Fluoride 

Conductivity 

Total Dissolved 

Solids (TDS) 

mgF/L 

µS/cm (20°C) 

µS/cm (25°C) 

mg/L 

:(Signature) 

تاريخ :(Date) 

امضا 

Page 57 of 57

Final Report Report No.: 1 Program No.: WAT-CH-0001 Program ...

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