Repo ort No. 95 Waters Proficiency Testin ng Roun nd No. 8 - Total Solids, Total Suspendedd Solids, Total Dissolved Solids - August 05 Acknowledgments PTA wishes to gratefully acknowledge the technical assistancee provided for this program by Dr M Buckley-Smith and Mrs R Ryan, Global Proficiency Ltd (New Zealand). Also our thanks go to Global Proficiency Ltd (New( Zealand) and to Global Proficiency Ptyy Ltd (Australia) for the supply and distribution of the t samples. Copyright Proficiency Testing Australia, 055 PO Box 7507 SILVERWATER NSW 8, Australia SD 9.7..09
CONTENTS. Foreword.... Program Features and Design.... Statistical Format... 4. PTA and Technical Advisers' Comments... 4 5. Outlier Results... 5 6. References... 5 APPENDIX A Results and Data Analysis Total Solids... A Total Suspended Solids... A7 Total Dissolved Solids... A APPENDIX B Sample Homogeneity and Stability Homogeneity and Stability Testing... B APPENDIX C Documentation Instructions to Participants... C Method Codes... C Results Sheet... C4
. Foreword This report summarises the results of a proficiency testing program on the determination of Total Solids, Total Suspended Solids and Total Dissolved Solids in waters. This is round 8 in a planned series of programs involving the analysis of chemical and physical parameters of waters. The exercise was conducted in June 05 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 Mrs D Mihaila and the Technical Advisers were Dr M Buckley-Smith and Mrs R Ryan, Global Proficiency Ltd (New Zealand). This report was authorised by Mrs F Watton, PTA Quality Business Development Manager.. Program Features and Design. 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. Please note that a number of laboratories reported more than one set of results and, therefore, their code numbers (with letter) could appear several times in the same data set.. 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.. Participants were provided with two plastic bottles (labelled PTA and PTA ) containing water samples for the analysis of Total Solids, Total Suspended Solids and Total Dissolved Solids..4 A total of 46 laboratories received samples, comprising: - 5 Australian participants; and - overseas participants, including: - Brunei Darussalam (), Indonesia (), Malaysia (), New Zealand (), Papua New Guinea (), Peru (), Russia (), Tanzania (), Thailand (). Of these 46 laboratories, one was unable to submit results by the due date..5 Results (as reported by participants) with corresponding summary statistics (i.e. number of results, median, normalised interquartile range, uncertainty of the median, robust coefficient of variation, minimum, maximum and range) are presented in Appendix A (for each sample and for each of the analyses performed)..6 A robust statistical approach, using z-scores, was utilised to assess laboratories testing performance (see Section ). Robust z-scores and ordered z-score charts relevant to each test are presented in Appendix A.
The document entitled Guide to Proficiency Testing Australia, 04 (reference []) defines the statistical terms and details the statistical procedures referred to in this report..7 A tabulated listing of laboratories (by code number) identified as having outlier results can be found on page 5..8 Prior to sample distribution, a number of randomly selected samples were analysed for homogeneity and stability. Based on the results of this testing (see Appendix B) it was considered that the samples utilised for this program were homogeneous and stable. As such, any results later identified as outliers could not be attributed to any notable sample variability.. 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.. 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 with an absolute value less than or equal to.0 is considered to be satisfactory, whereas, a z-score with an absolute value greater than or equal to.0 is considered to be an outlier and is marked by the symbol. Laboratories are also encouraged to review results which have an absolute z-score value between.0 and.0 (i.e..0 < z-score <.0). These results are considered to be questionable results. Each determination was examined for outliers with all methods pooled. The table on page 5 summarises the outlier results detected.. Results Tables and Summary Statistics The tables in Appendix A contain 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 results tables and consists of: - No. of Results: the total number of results for that test/sample; - Median: the middle value of the results; - Normalised IQR: the normalised interquartile range of the results; - Uncertainty of the Median: a robust estimate of the standard deviation of the Median; - Robust CV: the robust coefficient of variation expressed as a percentage, i.e. 00 x Normalised IQR / Median; - Minimum: the lowest laboratory result; - Maximum: the highest laboratory result; and - Range: the difference between the Maximum and 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 a correction 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: = number of results. Please see reference [] for further details on these robust summary statistics.. Ordered Z-score Charts The charts in Appendix A indicate each laboratory's robust z-score, in order of magnitude, marked with its laboratory code number. From these charts, each laboratory can readily compare its performance relative to the other laboratories. These charts contain solid lines at +.0 and -.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.
4 4. PTA and Technical Advisers Comments 4. 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 Global Proficiency Ltd s Standard Operating Procedures to ensure samples were fit-for-purpose, homogeneous and stable. Solutions were stable and homogeneous, and medians obtained from this proficiency round were in consistent agreement with the expected levels (dope concentration), as shown in Table. As the assigned value for each analyte in this program is the median of the results submitted by the participants, the uncertainty of the median for each analyte has been calculated and is presented in Table below. Table. Comparison of expected levels (dope concentration) and proficiency medians. The values of the calculated uncertainty of the median are also presented. Analyte Sample Dope Concentration (mg/l) Median (mg/l) Uncertainty of the Median (mg/l) Total Solids (TS) Total Suspended Solids (TSS) Total Dissolved Solids (TDS) PTA 550 54.0. PTA 50 58.0. PTA 50 45.50 0.8 PTA 00 97.60. PTA 500 498.0 4.6 PTA 50 60.0 4. Overall, the performance of participants in this round was good, with robust CVs below 0% for all analytes.
5 4. Analysis of Round 8 Results 4.. Total Solids (TS) Table compares the Total Solids medians and robust CVs from this round to those obtained in previous PTA rounds. The CVs for Total Solids were similar or better than seen in previous rounds. Table. Comparison of current round variability and proficiency medians of Total Solids testing with the results of the previous two rounds. Median Round Sample Robust CV (%) Participants (mg/l) PTA 54.0.6 This study PTA 58.0 4. Report 89 Report 80 PTA 75.0 6. 4 PTA 45.0 4.0 4 PTA 7.0 6. 49 PTA 66.0 8. 49 Bias / Accuracy The Total Solids testing was successfully performed, with satisfactory results ( zscore.0) ranging between 5 569 mg/l for sample PTA and 9 87 mg/l for sample PTA. Out of participants, three questionable results (.0 < z-score <.0) were reported for sample PTA (laboratories 86, 55 and 6) and two questionable results were reported for sample PTA (laboratories 55 and 64). Four outlier results ( z-score.0) were obtained for sample PTA, requiring followup action by laboratories 7, 464, 499 and 568. Five outlier results were obtained for sample PTA, requiring follow-up action by laboratories 7, 0, 464, 499 and 568. The most likely source of error, causing low bias when testing these proficiency samples, is incomplete transfer of the entire contents of the bottle into the volumetric flask, with rinsing as per the instructions to participants. It is important to rinse the sides of the bottle, the cap, the funnel and the stem of the funnel. Once the entire sample has been transferred, the vessel should be brought to volume and mixed thoroughly. Vigorous shaking for at least thirty seconds will mix the sample, but a magnetic stir bar for 5-0 min will ensure a more homogeneous sample. The Total Solids data set formed an approximately normal distribution with no substantial bias attributable to any one method (Figures and ). The method most frequently used for Total Solids analysis was APHA 540 B (Total Solids Dried at 0-05ºC - method code ), which was used by approximately 64% of participants.
6 Total Solids - Sample PTA 4 0 6 APHA 540 B US EPA 060. Calculation Other Not specified Frequency 8 4 0 50 75 400 45 450 475 500 55 550 575 600 65 650 675 Results (mg/l) Figure. Spread of results for Total Solids testing of sample PTA, with a median of 54.0 mg/l. Total Solids - Sample PTA 4 0 6 APHA 540 B US EPA 060. Calculation Other Not specified Frequency 8 4 0 60 90 0 50 80 0 40 70 400 40 460 490 50 550 Results (mg/l) Figure. Spread of results for Total Solids testing of sample PTA, with a median of 58.0 mg/l.
7 Measurement Uncertainty (MU) The MU reported by participants can be seen in Figures and 4. Out of participants, (70%) submitted MU information. A small number of the stated MUs did not accurately reflect the difference between the median and the participant s result for these proficiency samples. Total Solids ± MU - Sample PTA 4 APHA 540 B Calculation Other Not Specified Frequency 0 0 7.5 5.5 0 7.5 45 5.5 60 67.5 75 8.5 90 97.5 Measurement Uncertainty (mg/l) Figure. MU for Total Solids testing of sample PTA, as reported by participants, compared with 95% confidence interval for overall reproducibility, ± 9.5 mg/l in this round, shown as a dashed line. The range of MU for Total Solids was expected to be between 6. 4. mg/l (.% - 7.8%) for sample PTA and between 6.5 44.5 mg/l (.8% -.4%) for sample PTA, based on minimum / maximum uncertainty criteria (u min and u max ) described in ISO 58:05 []. Laboratories a, 8 and 55 may wish to re-examine their measurement uncertainty for Total Solids testing, as their MU was smaller than the uncertainty of the assigned value (95% CI) for one or more of the samples tested. It is possible that these laboratories have underestimated their MU, particularly in light of the variability expected in natural water samples. It should be noted, however, that the u min and u max are informative indicators only and can not be solely used to validate or invalidate the MUs reported. Of slightly less concern were the laboratories who reported MU that were larger than three times the normalised interquartile range, NIQR (U max ), however this can be explained by the unusually tight homogeneity of these artificial solids samples compared to a natural sample which would be expected to have more variability.
8 Total Solids ± MU - Sample PTA 6 5 APHA 540 B Calculation Other Not specified 4 Frequency 0 0 7.5 5.5 0 7.5 45 5.5 60 67.5 75 8.5 90 97.5 Measurement Uncertainty (mg/l) Figure 4. MU for Total Solids testing of sample PTA, as reported by participants, compared with 95% confidence interval for overall reproducibility, ± 5.8 mg/l in this round, shown as a dashed line. A t-test of all the results (outliers removed), indicated that the overall reproducibility for Total Solids testing was 54.0 ± 9.5 mg/l (5.5%) for sample PTA and 58.0 ± 5.8 mg/l (7.%) for sample PTA (95% CI). Over the last six PTA rounds (Reports 95, 89, 80, 767, 74, 698), where samples presented ranged between 6 mg/l 600 mg/l Total Solids, the average reproducibility was 5%. This is a good approximate MU and laboratories starting out calculating their MU can compare their values against this PTA estimation.
9 Total Solids - Sample PTA Results of sample PTA, including MU, compared to the median 6 44 4 7 7 86 a 9b 8 98 40 40 499 59 54 545 55 56 568 588 6 64 660 700 650 600 550 500 450 400 50 00 Total Solids - Sample PTA Laboratory Code Result ± MU Median Uncertainty of the Median Figure 5. Total Solids - Results of sample PTA, including MU, compared to the median. Results (mg/l)
0 Total Solids - Sample PTA Results of sample PTA, including MU, compared to the median 6 44 4 7 7 86 a 9b 8 98 40 40 499 59 54 545 55 56 568 588 6 64 660 550 500 450 400 50 00 50 00 Total Solids - Sample PTA Laboratory Code Result ± MU Median Uncertainty of the Median Figure 6. Total Solids - Results of sample PTA, including MU, compared to the median. Results (mg/l)
4.. Total Suspended Solids (TSS) Table compares the Total Suspended Solids medians and robust CVs from this round to those obtained in previous PTA rounds. The variability of results in this round was similar to those seen in previous rounds. Table. Comparison of current round variability and proficiency median of Total Suspended Solids testing with the results of the previous two rounds. Median Round Sample Robust CV (%) Participants (mg/l) PTA 45.50 9.8 45 This study PTA 97.60 6. 45 Report 89 Report 80 PTA 66.00 6. 54 PTA 8.00 6. 55 PTA 70.00 9. 68 PTA 48.00 9. 68 Bias / Accuracy The Total Suspended Solids testing was successfully performed, with satisfactory results ( z-score.0) ranging between 6.7 54. mg/l for sample PTA and 85.8 09.4 mg/l for sample PTA. Out of 45 participants, two questionable results (.0 < z-score <.0) were reported for sample PTA (laboratories 688 and 699) and two questionable results were reported for sample PTA (laboratories 9b and 590). Six outlier results ( z-score.0) were obtained for sample PTA, requiring followup action by laboratories 9b, 40, 475, 545, 55 and 57. Two outlier results were obtained for sample PTA, requiring follow-up action by laboratories 475 and 64. For those laboratories having difficulties with their Total Suspended Solids testing, APHA [] recommends method blanks using the dilution water and duplicate analyses to be carried out. Duplicate determinations should agree within 5% of their average weight. If the technique used by laboratories involves pipetting a measured volume onto the seated glass-fibre filter, APHA [] recommends pipetting from the approximate midpoint of the container but not in the vortex created by the magnetic stirrer, to get a more homogeneous sample. Subsampling is a major source of error in this testing. Laboratories whose results biased low on the suspended solids test and high on the dissolved solids test may have used a filter with pores that were larger than those used by other laboratories, allowing a greater proportion of the finer solids particles to pass through the filter. Filter pore sizes used by laboratories ranged between 0.45.0 µm and the median was. µm. Nearly half of laboratories who stated their filter brand were using Whatman. Others included Advantec, Merck Millipore, MicroScience, Pall and Sartorius filters. The Total Suspended Solids data set formed an approximately normal distribution with no substantial bias attributable to any one method (Figures 7 and 8). The method
most frequently used for Total Suspended Solids analysis was APHA 540 D (Total Suspended Solids Dried at 0-05ºC - method code 5), which was used by approximately 80% of participants. Total Suspended Solids - Sample PTA 4 0 APHA 540 D US EPA 060. Other Not specified 6 Frequency 8 4 0 8 8 8 8 4 48 5 58 6 68 Results (mg/l) Figure 7. Spread of results for Total Suspended Solids testing of sample PTA, with a median of 45.50 mg/l. Total Suspended Solids - Sample PTA 4 0 APHA 540 D US EPA 060. Other Not specified 6 Frequency 8 4 0 40 47.5 55 6.5 70 77.5 85 9.5 00 07.5 5.5 0 7.5 Results (mg/l) Figure 8. Spread of results for Total Suspended Solids testing of sample PTA, with a median of 97.60 mg/l.
Measurement Uncertainty (MU) The MU reported by participants can be seen in Figures 9 and 0. Out of 45 participants, 4 (76%) submitted MU information. Half of participants stated MUs did not accurately reflect the difference between the median and the participant s result for these proficiency samples. Total Suspended Solids ± MU - Sample PTA 7 6 APHA 540 D Other Not specified 5 Frequency 4 0 0 4 5 6 7 8 9 0 Measurement Uncertainty (mg/l) Figure 9. MU for Total Suspended Solids testing of sample PTA, as reported by participants, compared with 95% confidence interval for overall reproducibility, ± 8.4 mg/l in this round, shown as a dashed line. The range of MU for Total Suspended Solids was expected to be between.7. mg/l (.6% - 9.%) for sample PTA and between. 7.8 mg/l (.% - 8.%) for sample PTA, based on minimum / maximum uncertainty criteria (u min and u max ) described in ISO 58:05 []. Laboratories 74, 8, 4, 498, 499, 59, 55 and 674 may wish to re-examine their measurement uncertainty for Total Suspended Solids testing, as their MU was smaller than the uncertainty of the assigned value (95% CI) for one or more of the samples tested. It is possible that these laboratories have underestimated their MU. An MU of less than.6% for sample PTA and less than.% for sample PTA is unlikely to be appropriate for natural waters samples and may have been calculated from repeatability standard deviations (SD r ) rather than reproducibility (SD R ). The SD R accounts for much more of the variability inherent in this test. It should be noted, however, that the u min and u max are informative indicators only and can not be solely used to validate or invalidate the MUs reported. Laboratory 0 reported an MU of ±70 mg/l, which was much greater than three times the normalised interquartile range, NIQR (the recommended U max ) and requires investigation by this laboratory, although it may have simply been a transcription error.
4 Total Suspended Solids ± MU - Sample PTA 9 8 7 APHA 540 D Other Not specified 6 Frequency 5 4 0 0 4 6 8 0 4 6 8 0 4 < 6 Measurement Uncertainty (mg/l) Figure 0. MU for Total Suspended Solids testing of sample PTA, as reported by participants, compared with 95% confidence interval for overall reproducibility, ±.8 mg/l in this round, shown as a dashed line. A t-test of all the results (outliers removed), indicated that the overall reproducibility for Total Suspended Solids testing was 45.50 ± 8.4 mg/l (8.5%) for sample PTA and 97.60 ±.8 mg/l (.%) for sample PTA (95% CI). Over the last six PTA rounds (Reports 95, 89, 80, 767, 698, 6), where samples presented ranged between 4 mg/l 5 mg/l Total Suspended Solids, the average reproducibility was %. This is a good approximate MU and laboratories starting out calculating their MU can compare their values against this PTA estimation.
5 Total Suspended Solids - Sample PTA Results of sample PTA, including MU, compared to the median 6 8 44 4 5 7 7 74 86 0 0 9 a 9b 75 8 98 40 4 40 475 498 499 59 54 545 55 56 568 588 6 64 660 674 80 70 60 50 40 0 0 0 Total Suspended Solids - Sample PTA Laboratory Code Result ± MU Median Uncertainty of the Median Figure. Total Suspended Solids - Results of sample PTA, including MU, compared to the median. Results (mg/l)
6 Total Suspended Solids - Sample PTA Results of sample PTA, including MU, compared to the median 6 8 44 4 5 7 7 74 86 0 0 9 a 9b 75 8 98 40 4 40 475 498 499 59 54 545 55 56 568 588 6 64 660 674 80 70 60 50 40 0 0 0 00 90 80 70 60 50 40 0 Total Suspended Solids - Sample PTA Laboratory Code Result ± MU Median Uncertainty of the Median Figure. Total Suspended Solids - Results of sample PTA, including MU, compared to the median. Results (mg/l)
7 4.. Total Dissolved Solids (TDS) Table 4 compares the Total Dissolved Solids medians and robust CVs from this round to those obtained in previous PTA rounds. The variability of results this round was comparable to those seen in previous rounds. Table 4. Comparison of current round variability and proficiency median of Total Dissolved Solids testing with the results of the previous two rounds. Median Round Sample Robust CV (%) Participants (mg/l) PTA 498.0 4.5 7 This study PTA 60.0 7.7 7 Report 89 Report 80 Bias / Accuracy PTA 08.0 6. 48 PTA 56.0 6. 48 PTA 04.0 7. 55 PTA 0.0 8.4 55 The Total Dissolved Solids testing was successfully performed, with satisfactory results ( z-score.0) ranging between 454 54 mg/l for sample PTA and 0 00 mg/l for sample PTA. Out of 7 participants, five questionable results (.0 < z-score <.0) were reported for sample PTA (laboratories 8, 464, 55, 568 and 57) and one questionable result was reported for sample PTA (laboratory 4). Two outlier results ( z-score.0) were obtained for sample PTA, requiring followup action by laboratories 7 and 499. Four outlier results ( z-score.0) were obtained for sample PTA, requiring follow-up action by laboratories 7, 464, 499 and 568. For laboratories having difficulties with their Total Dissolved Solids testing, it is important to recognise that the drying time required in the method is sensitive to the composition of the sample. Samples with a high mineral concentration can absorb moisture and will require an extended drying time, and must be weighed quickly to ensure that moisture from the air does not affect the result (i.e. storing in a desiccator until the sample reaches room temperature prior to weighing). Adding successive aliquots of the sample until a final yield of between.5 00mg of dried residue is achieved and repeating the cycle of drying, cooling, desiccating and weighing until a constant weight is obtained or until the weight change is less than 4% of the previous weight; will help to improve the accuracy and precision of test results. The Total Dissolved Solids data set formed an approximately normal distribution with no substantial bias attributable to any one method (Figures and 4). The method most frequently used for Total Dissolved Solids analysis was APHA 540 C (Total Dissolved Solids Dried at 80ºC - method code 8), which was used by approximately 7% of participants.
8 Total Dissolved Solids - Sample PTA 6 4 0 APHA 540 C US EPA 060. Calculation Conductivity Other Not specified Frequency 8 6 4 0 05 0 55 80 405 40 455 480 505 50 555 580 605 60 Results (mg/l) Figure. Spread of results for Total Dissolved Solids testing of sample PTA, with a median of 498.0 mg/l. Total Dissolved Solids - Sample PTA Frequency 0 6 8 APHA 540 C US EPA 060. Calculation Conductivity Other Not specified 4 0 75 00 5 50 75 00 5 50 75 00 5 50 75 400 Results (mg/l) Figure 4. Spread of results for Total Dissolved Solids testing of sample PTA, with a median of 60.0 mg/l.
9 Measurement Uncertainty (MU) The MU reported by participants can be seen in Figures 5 and 6. Out of 7 participants, 7 (7%) submitted MU information. Many of the stated MUs (48%) did not accurately reflect the difference between the median and the participant s result for these proficiency samples. Total Dissolved Solids ± MU - Sample PTA 5 4 APHA 540 C Calculation Conductivity Other Not specified Frequency 0 0 7.5 5.5 0 7.5 45 5.5 60 67.5 75 8.5 90 97.5 Measurement Uncertainty (mg/l) Figure 5. MU for Total Dissolved Solids testing of sample PTA, as reported by participants, compared with 95% confidence interval for overall reproducibility, ± 5.8 mg/l in this round, shown as a dashed line. The range of MU for Total Dissolved Solids was expected to be between 9. 66.7 mg/l (.8% -.4%) for sample PTA and between 8. 60.0 mg/l (.% -.%) for sample PTA, based on minimum / maximum uncertainty criteria (u min and u max ) described in ISO 58:05 []. Laboratories 7, 0, a, 8, 4, 59, 545 and 55 may wish to re-examine their measurement uncertainty for Total Dissolved Solids testing, as their MU was smaller than the uncertainty of the assigned value (95% CI) for one or more of the samples tested. It is possible that these laboratories have underestimated their MU, particularly in light of the variability expected in natural water samples. It should be noted, however, that the u min and u max are informative indicators only and can not be solely used to validate or invalidate the MUs reported. Of slightly less concern were the laboratories who reported MU larger than three times the normalised interquartile range, NIQR (U max ), (Laboratories 86, 98, 6, 660), however this can be explained by the unusually tight homogeneity of these artificial solids samples compared to a natural sample, which would be expected to have more variability. Only laboratory 660 reported an unusually high fixed MU (90.0 mg/l) and may wish to re-examine their measurement uncertainty calculations (Figure 6). Most laboratories used MU values proportional to their results.
0 Total Dissolved Solids ± MU - Sample PTA 0 9 8 7 APHA 540 C Calculation Conductivity Other Not specified Frequency 6 5 4 0 0 7.5 5.5 0 7.5 45 5.5 60 67.5 75 8.5 90 97.5 Measurement Uncertainty (mg/l) Figure 6. MU for Total Dissolved Solids testing of sample PTA, as reported by participants, compared with 95% confidence interval for overall reproducibility, ± 4. mg/l in this round, shown as a dashed line. A t-test of all the results (outliers removed), indicated that the overall reproducibility for Total Dissolved Solids testing was 498.0 ± 5.8 mg/l (0.8%) for sample PTA and 60.0 ± 4. mg/l (.%) for sample PTA (95% CI). Over the last six PTA rounds (Reports 95, 89, 80, 767, 74, 698), where samples presented ranged between 99 mg/l 498 mg/l Total Dissolved Solids, the average reproducibility was 9%. This is a good approximate MU and laboratories starting out calculating their MU can compare their values against this PTA estimation.
Total Dissolved Solids - Sample PTA Results of sample PTA, including MU, compared to the median 6 8 44 4 7 7 74 86 0 a 9b 75 8 98 40 4 40 499 59 54 545 55 56 568 588 6 660 650 600 550 500 450 400 50 00 Total Dissolved Solids - Sample PTA Laboratory Code Result ± MU Median Uncertainty of the Median Figure 7. Total Dissolved Solids - Results of sample PTA, including MU, compared to the median. Results (mg/l)
Total Dissolved Solids - Sample PTA Results of sample PTA, including MU, compared to the median 6 8 44 4 7 7 74 86 0 a 9b 75 8 98 40 4 40 499 59 54 545 55 56 568 588 6 660 400 50 00 50 00 50 00 Total Dissolved Solids - Sample PTA Laboratory Code Result ± MU Median Uncertainty of the Median Figure 8. Total Dissolved Solids - Results of sample PTA, including MU, compared to the median. Results (mg/l)
4. Analysis of Results by Method Groups Further analysis of results by method groups was undertaken to provide specific information on individual method performance. In order for methods to be grouped for analysis, PTA requires at least sets of results from the same method group. For methods other than those presented below, there were less than results submitted for each method, therefore reliable conclusions cannot be drawn from analysing them separately on this occasion. 4... Total Solids The method APHA 540 B (Total Solids Dried at 0-05ºC - method code ) was most frequently employed for Total Solids analysis, with out of participants indicating the use of this method. Table 5 below presents the median, uncertainty of the medians and robust CVs for Total Solids results obtained by this method in round 8. Table 5. Variability and proficiency medians of Total Solids results obtained by method APHA 540 B. Median ± Robust Analyte Sample Participants Uncertainty of the Median CV (%) (mg/l) Total Solids PTA 54.0 ±.4. PTA 56.0 ±.4.5 The robust CVs obtained using this method were smaller, for both PTA and PTA samples, than those the general population of methods was able to achieve (CV PTA =.6%, CV PTA = 4.%). 4... Total Suspended Solids The method APHA 540 D (Total Suspended Solids Dried at 0-05ºC - method code 5) was most frequently employed for Total Suspended Solids analysis, with 6. out of 45 participants indicating the use of this method. Table 6 below presents the median, uncertainty of the median and robust CV for Total Suspended Solids results obtained by this method in round 8. Table 6. Variability and proficiency medians of Total Suspended Solids results obtained by method APHA 540 D. Median ± Robust Analyte Sample Participants Uncertainty of the Median CV (%) (mg/l) Total PTA 6 46.5 ±.00 0. Suspended Solids PTA 6 97.80 ±.9 6. The robust CVs obtained using this method were slightly larger, for both PTA and PTA samples, than those the general population of methods was able to achieve
4 (CV PTA = 9.8%, CV PTA = 6.%), however, these CVs were better than those published in APHA (4 mg/l, CV=0%; and 5 mg/l, CV=%). 4... Total Dissolved Solids The method APHA 540 C (Total Dissolved Solids Dried at 80ºC - method code 8) was most frequently employed for Total Dissolved Solids analysis, with 7 out of 7 participants indicating the use of this method. Table 7 below presents the median, uncertainty of the median and robust CV for Total Suspended Solids results obtained by this method in round 8. The robust CVs obtained using this method were equal to or better than those the general population of methods was able to achieve (CV PTA = 4.5%, CV PTA = 7.7%). Table 7. Variability and proficiency medians of Total Dissolved Solids results obtained by method APHA 540 C. Median ± Robust Analyte Sample Participants Uncertainty of the Median CV (%) (mg/l) Total PTA 7 489.0 ± 5. 4.5 Suspended Solids PTA 7 60.0 ± 4.0 6.4
5 5. Outlier Results Laboratories reporting results that have been identified as outliers are listed in Table 8 below. Table 8. Laboratory results identified as outliers for each analysis performed. Lab Code Total Solids Analysis Total Suspended Solids Total Dissolved Solids PTA PTA PTA PTA PTA PTA 7 0 9b 40 464 475 499 545 55 568 57 64 Note:. A indicates the occurrence of a z-score outlier result (i.e. those results for which z-score.0). 6. References [] Guide to Proficiency Testing Australia, 04 (This document can be found on the PTA website, www.pta.asn.au). [] ISO 58:05 Statistical methods for use in proficiency testing by interlaboratory comparisons. [] Standard Methods For the Examination of Water and Wastewater, 0. Published by APHA, AWWA, WEF ( nd Edition).
APPENDIX A Results and Data Analysis Total Solids... A Total Suspended Solids... A7 Total Dissolved Solids... A
Total Solids Results Samples PTA and PTA
A Total Solids Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 7 550 # 0.64 6 58 ± 47-0. 44 550 ± 0.64 96 56 #.49 4 54 ± 8. -. 7 59 ± 5 -.56 4 7 75 ± 9 -.79 74 59 # -0.85 86 5 ± 76.8 -.06 0 54.0 # 0.4 4 a 546 ± 6.7 0.5 # 9b 50 ± 64-0.78 6 5 # -0.7 8 5 ± -0.64 98 5 ± 78. -.5 40 54 ± 50 0.00 40 58 ± -0. 4 464 48 # -4.6 475 547 # 0.4 499 64 ± 45 7.4 59 540 ± 7.69-0.07 54 567 ± 54.85 545 54 ± 6 0.00 55 57 ± %.0 56 547 ± 0 0.4 568 594 ± 7.76 588 546 ± 55 0.5 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A Total Solids - cont. Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 590 549 # 0.57 6 5 ± 76.8 -.06 64 544 ± 40 0. 660 550 ± 70.0 0.64 688 540 # -0.07 699 55 # -0.4 4 No of Results: Median: 54.0 Normalised IQR: Uncertainty of the Median: 4.. Robust CV:.6% Minimum: 75 Maximum: 64 Range: 68 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A Total Solids - Sample PTA 688 Ordered Robust Z-Score Charts Total Solids - Sample PTA - Robust Z-Scores lab code Robust Z-Scores 7 464 86 6 7 98 4 74 9b 6 8 699 6 40 59 5 4 0 - - - -4-5 5 4 0 - - - -4-5 lab code z-score z-score
A4 Total Solids Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 7 70 # 0.8 6 56 ± -0. 44 68 ± 5 0.67 96 8 #.55 4 57 ±. -0.07 7 4 ± 5 -.0 4 7 5 ± -7. 74 6 # 0.0 86 47 ± 5. -0.74 0 45.0 # 6.7 4 a 6 ± 4.08 0.0 # 9b 49 ± 4-0.6 6 65 # 0.47 8 5 ± -0.4 98 40 ± 5.0 -. 40 46 ± 0-0.8 40 54 ± -0.7 4 464 76 # -.8 475 56 # -0. 499 50 ± 5 9.78 59 6 ± 7.897 0.4 54 60 ± 4 0. 545 57 ± 6-0.07 55 90 ± %.6 56 6 ± 0 0.0 568 46 ± 5 4.59 588 58 ± 6 0.00 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A5 Total Solids - cont. Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 590 69 # 0.74 6 49 ± 5.4-0.6 64 8 ± 40 -.0 660 54 ± 70.0-0.7 688 7 # 0.88 699 70 # 0.8 4 No of Results: Median: 58.0 Normalised IQR: Uncertainty of the Median: 4.8. Robust CV: 4.% Minimum: 76 Maximum: 50 Range: 7 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A6 Total Solids - Sample PTA 545 Ordered Robust Z-Score Charts Total Solids - Sample PTA - Robust Z-Scores lab code Robust Z-Scores 464 7 64 98 7 40 86 9b 6 8 40 660 6 475 4 5 4 0 - - - -4-5 5 4 0 - - - -4-5 lab code z-score z-score
Total Suspended Solids Results Samples PTA and PTA
A7 Total Suspended Solids Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 7 50 #.0 5 6 4.8 ± 6-0.6 5 8 47 ± 4.70 0.4 5 44 44. ±.9-0.7 5 96 4 # -0.56 6 4 4.5 ±.4-0.45 5 5 48. ± 4 0.6 5 4 48 # 0.56 # 7 4.6 ± 4.4-0.88 7 7 5. ±.6 5 74 46.5 ±.54 0. 5 86 50.0 ± 7.50.0 5 0 4. ±.00-0.7 5 0 49.5 ±.9 0.90 5 9 49.0 ± 8. 0.79 7 a 4.5 ±.4-0.45 # 9b 5 ± -4.6 5 6 5.0 #.46 5 75 4.5 ±. -0.45 5 8 47.8 ± 0.5 5 98 4. ± 6.50-0.49 5 40 60 ± 0.6 5 4 7 ± 5.0% -.9 5 40 45 ± 8-0. 7 464 47 # 0.4 5 474 44.7 # -0.8 7 475 6.5 ± 8.0-4.7 5 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A8 Total Suspended Solids - cont. Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 498 44 ± 4-0.4 # 499 8.5 ±. -.57 5 57 50. #.08 5 59 49.7 ±.4 0.94 5 54 5. ± 4.9.8 5 545 9.5 ±.4 -.60 5 55.0 ± % -7.76 5 56 49 ± 5 0.79 5 568 44.0 ± 7-0.4 5 57.8 # -.08 5 588 45 ± 8-0. 5 590 46.0 # 0. 5 6 47.0 ± 7.05 0.4 5 64 48.0 ± 0 0.56 5 660 45.5 ±.00 0.00 5 674 47.0 ±.5 0.4 5 688 4.0 # -.59 5 699 55 #.4 7 No of Results: 45 Median: 45.50 Normalised IQR: Uncertainty of the Median: 4.45 0.8 Robust CV: 9.8% Minimum:.0 Maximum: 60 Range: 49.0 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A9 Total Suspended Solids - Sample PTA 588 40 Ordered Robust Z-Score Charts Total Suspended Solids - Sample PTA - Robust Z-Scores lab code Robust Z-Scores 55 9b 475 545 57 688 4 499 7 0 6 96 98 4 a 75 498 568 474 44 5 4 0 - - - -4-5 5 4 0 - - - -4-5 lab code z-score z-score
A0 Total Suspended Solids Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 7 05 #.5 5 6 95.5 ± 9-0.5 5 8 00 ± 0.0 0.40 5 44 97.6 ± 4. 0.00 5 96 9 # -0.78 6 4 94.0 ± 5. -0.6 5 5 96.5 ± 7-0.9 5 4 98 # 0.07 # 7 95.5 ± 4.4-0.5 7 7 05 ± 5.5 5 74 0 ±. 0.57 5 86 0 ± 5.5 0.9 5 0 9. ± -.06 5 0 05 ± 70.5 5 9 04 ± 7..08 7 a 9.4 ± 4.60-0.88 # 9b 80 ± 9 -.97 5 6 98.0 # 0.07 5 75 0 ± 5. 0.74 5 8 99.5 ± 0. 5 98 9.7 ±.9-0.8 5 40 04 ± 0.08 5 4 95 ± 5.0% -0.44 5 40 95 ± 7-0.44 7 464 98 # 0.07 5 474 00 # 0.40 7 475 4.0 ± 8.0-9.8 5 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A Total Suspended Solids - cont. Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 498 99 ± 0.4 # 499 9 ± -. 5 57 94.9 # -0.46 5 59 0 ±.0 0.74 5 54 07 ± 0.59 5 545 86.5 ±.4 -.87 5 55 9.0 ± % -0.78 5 56 0 ± 5 0.57 5 568 98.0 ± 5 0.07 5 57 94. # -0.57 5 588 96 ± 7-0.7 5 590 0 #.09 5 6 9.0 ±.6 -. 5 64 7. ± 0-4. 5 660 00 ± 0.0 0.40 5 674 0 ± 0.57 5 688 87.0 # -.79 5 699 95 # -0.44 7 No of Results: 45 Median: 97.60 Normalised IQR: Uncertainty of the Median: 5.9. Robust CV: 6.% Minimum: 4.0 Maximum: 0 Range: 68.0 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A Total Suspended Solids - Sample PTA 5 588 Ordered Robust Z-Score Charts Total Suspended Solids - Sample PTA - Robust Z-Scores lab code Robust Z-Scores 475 64 9b 545 688 499 6 0 a 98 96 55 4 57 57 4 40 699 7 6 5 4 0 - - - -4-5 5 4 0 - - - -4-5 lab code z-score z-score
Total Dissolved Solids Results Samples PTA and PTA
A Total Dissolved Solids Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 7 480 # -0.8 8 6 485 ± 56-0.58 8 8 550 ± 55.0.4 8 44 50 ± 0 0.54 8 96 50 # 0.99 9 4 47 ± 6.5 -.7 8 4 490 # -0.6 # 7 48 ± 5-0.76 7 4 ± 6-7.8 8 74 48 ± 8. -0.7 8 86 47 ± 70.8 -.7 8 0 500 ± 8.9 0.09 8 a 506 ±.5 0.6 # 9b 50 ± 50 0. 8 6 479 # -0.85 8 75 54 ± 6.7 8 475 ± -.0 8 98 48 ± 7.4-0.67 8 40 498 ± 50 0.00 8 4 509 ± 8.8% 0.49 8 40 500 ± 50 0.09 464 450 # -.6 8 475 49 # -0. 8 499 604 ± 4 4.77 59 489 ± 7.898-0.40 8 54 56 ± 55 0.8 0 545 489 ± 6-0.40 8 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A4 Total Dissolved Solids - cont. Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 55 56 ± %.8 8 56 5 ± 5 0.58 8 568 550 ± 66.4 8 57 440 # -.6 8 588 467 ± 47 -.9 590 504 # 0.7 8 6 460 ± 69.0 -.7 8 660 50 ± 90.0 0.54 8 688 50 # 0.8 8 699 50 # 0.99 No of Results: 7 Median: 498.0 Normalised IQR: Uncertainty of the Median:. 4.6 Robust CV: 4.5% Minimum: 4 Maximum: 604 Range: 80 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A5 Total Dissolved Solids - Sample PTA 475 4 Ordered Robust Z-Score Charts Total Dissolved Solids - Sample PTA - Robust Z-Scores Robust Z-Scores 7 57 464 6 588 4 86 8 6 7 7 74 98 6 59 545 5 4 0 - - - -4-5 5 4 0 - - - -4-5 lab code lab code z-score z-score
A6 Total Dissolved Solids Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 7 60 # 0.00 8 6 54 ± -0.0 8 8 95 ± 0.0.75 8 44 80 ±.00 8 96 6 # 0.0 9 4 4 ± 8.5-0.90 8 4 60 # 0.00 # 7 49 ± 5-0.55 7 46 ± 7-5.70 8 74 60 ± 9.90 0.00 8 86 46 ± 6.9-0.70 8 0 55 ± 5.7-0.5 8 a 79 ± 6.7 0.95 # 9b 67 ± 7 0.5 8 6 67 # 0.5 8 75 8 ± 4.05 8 48 ± -0.60 8 98 60 ± 9.0 0.00 8 40 50 ± 0-0.50 8 4 5 ± 8.8%.75 8 40 65 ± 7 0.5 464 78 # -9.09 8 475 55 # -0.5 8 499 ±.05 59 59 ± 9.66-0.05 8 54 5 ± 6-0.40 0 545 88 ± 6.40 8 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A7 Total Dissolved Solids - cont. Results by Laboratory Code Lab Code Result ± MU (mg/l) Sample PTA Robust z-score Method Code 55 97 ± %.85 8 56 50 ± 5-0.50 8 568 8 ± 9.40 8 57 56 # -0.0 8 588 4 ± 4-0.85 590 6 # 0.0 8 6 5 ± 8.0-0.5 8 660 80 ± 90.0.00 8 688 68 # 0.40 8 699 65 # 0.5 No of Results: 7 Median: 60.0 Normalised IQR: Uncertainty of the Median: 0.0 4. Robust CV: 7.7% Minimum: 78 Maximum: 8 Range: 50 Where reported, results are shown with their corresponding measurement uncertainty (MU). " " denotes an outlier (i.e. those results for which z-score.0). Robust z-scores are calculated as: z = (A - median) normalised IQR, where A is the participant laboratory's result. Please refer to Appendix C (page C) for method code descriptions.
A8 Total Dissolved Solids - Sample PTA 4 7 Ordered Robust Z-Score Charts Total Dissolved Solids - Sample PTA - Robust Z-Scores Robust Z-Scores 464 7 4 588 86 8 7 40 56 54 6 6 0 475 57 59 5 4 0 - - - -4-5 5 4 0 - - - -4-5 lab code lab code z-score z-score
APPENDIX B Sample Homogeneity and Stability Homogeneity and Stability Testing... B
B Homogeneity and Stability Testing Samples for this program were obtained from Global Proficiency Ltd, New Zealand. As such, all samples are subjected to rigorous quality control and homogeneity / stability testing. Samples were manufactured from two solutions which formed a precipitate in the bottle. These were dispensed with an accuracy of 0.75% for PTA and 0.70% for PTA (99% CI). A random selection of ten samples was chosen from samples PTA for homogeneity and stability testing. Seven of these were stored chilled and the remaining three were subjected to 5ºC for three days for an accelerated ageing stability trial. The samples were then analysed by Hill Laboratories, New Zealand. The testing of Total Suspended Solids was performed using: filtration through Whatman 94 AH, Advantec GC-50 or equivalent filters (nominal pore size. -.5µm) and gravimetric determination (APHA 540 D nd ed. 0). The testing of Total Dissolved Solids was performed using filtration through GF/C filters (. µm) and gravimetric determination (APHA 540 C nd ed. 0 modified: drying temperature of 0-05 C was used rather than80 ± C). The Total Solids content was determined by calculation from the Total Suspended Solids and Total Dissolved Solids measurements. All stability samples showed no increased variability when compared to the chilled samples. Samples PTA were also tested to confirm the levels were within the expected range. Homogeneity and stability samples were treated in the same manner as for the PTA samples. Based on identical manufacturing procedure and sample handling, homogeneity and stability characteristics were assumed to be similar to samples PTA. From statistical analyses based on the results of this testing and rigorous quality control, it was considered that all samples were sufficiently homogeneous and stable, so that any results later identified as outliers should not be attributed to any notable sample variability. The results of homogeneity and stability testing are presented in Table B below. Please note that the mean results for these tests are not intended to be used as reference values. Table B. Homogeneity and stability testing of Round 8 samples. Round Samples PTA (g/m ) Samples PTA (g/m ) PTA 8 TSS TDS TS TSS TDS TS H 9.9 59.9 6.8 97.9 7. 69. H 7. 578. 65. 95.6 68.8 64.4 H 8.4 575. 6.5 H4 7.6 575.5 6. H5 40. 56.5 60.8 H6 40. 566. 606.4 H7 40. 566.5 606.8 S 4.5 568.0 60.5 99. 67.5 66.6 S 4.9 55. 594. S 4.7 568.8 6.4 RSD 5.4%.9%.6%.8% 0.7% 0.6%
APPENDIX C Documentation Instructions to Participants... C Method Codes... C Results Sheet... C4
C PROFICIENC CY TESTING AUSTRALIA WATERS PROFICIENCY TESTING PROGRAM CHEMICAL ANALYSIS ROUND 8 JUNE, 05 Total Solids (TS), Total Suspended Solids s (TSS), Total Dissolvedd Solids (TDS) INSTRUCTIOI ONS TO PARTICIPANTSS **Please record (on the Results Sheet) the approximate temperature of the samples upon receipt** Please note the following before commencingg the analysis of the samples.. Samples i) ii) iii) Two plastic bottles labelled PTA and PTA, suppliedd by Global Proficiency Ltd. The bottles contain 0 ml of artificial waste water concentratess for analysis of total solids, total suspendedd solids and total t dissolved solids. Each bottle will require dilution in reagent grade water. Please follow thee Sample Preparation section below. The bottles must be thoroughly mixed prior to analysis Please Note: Where possible, proficiency testing samples should s be treated as a routine laboratory sample.. Sample Preparation Note: The Residue sample colour is white. Caution: Analysis must begin immediately after bottle is opened. i) ii) iii) iv) v) vi) vii) A separatee sample must be prepared from each bottle. Adjust bottle temperature to 0ºC. Add approximately 8000 ml of reagent grade water to a one-litre volumetric flask. Record bottle ID number and mix thoroughly. Quantitatively transfer the t entire contents from the bottle into the flask, rinse the sides of the bottle with reagent grade water andd include this in the flask. Bring to volume with reagent grade water. Close the flask with a stopper and mix by inversion. viii) Repeat steps ii) vii) for second sample. Please report results for the diluted sample. SD 9.7..09
C. Tests Requested For the samples prepared from the two bottles PTA and PTA : i) Total Solids (TS). ii) Total Suspended Solids (TSS). iii) Total Dissolved Solids (TDS). (It is recommended that a reagent water blank is analysed by the same method used to analyse the samples.) If unable to perform the above please note this on your Results Sheet. 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) Select the appropriate method code for each test from the Method Code Table and record it on the Results Sheet. v) Calculate the measurement uncertainty (MU) for each reported result. All estimates of MU must be given as a 95% confidence interval (coverage factor k ) and reported in mg/l. Report MU using the same number of decimal places as for the result. 6. Testing should commence as soon as possible after receiving the samples and results reported NO LATER THAN 0 JULY 05 to: Delfina Mihaila Proficiency Testing Australia PO Box 7507 SILVERWATER NSW 8 AUSTRALIA Phone: +6 976 897 Fax: +6 974 6664 Email: dmihaila@pta.asn.au 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): Analyte Total Solids Total Suspended Solids Total Dissolved Solids Range 00 600 mg/l 0 50 mg/l 00 600 mg/l