13th Proficiency testing scheme for chemical analysis of Water in - PowerPoint PPT Presentation

13th Proficiency testing scheme for chemical analysis of Water in Africa Frieda Nambahu NamWater Applied Scientific Services Windhoek Namibia 1

NAMWATER  The bulk water supplier for Namibia  Established in 1997 from MAWF  100% GRN owned  +/- 80 million m3 potable water per annum  28 000 customers  Asset base N$4 billion  670 employees  Supplies all towns except 5  Operating on cost recovery basis since establishment 2

OUTLINE  Background of the SADCMET PT scheme  Participation  Growth of the SADCMET PT Scheme  Overview of a PT round  Details of the PT process  Evaluation & Assessment  Performance scoring  Changes and Progress of Parameters  Summary of the Parameters  Overall Success  Challenges 2017  Conclusion – M Conradie 3

BACKGROUND OF THE SADMET PT SCHEME 2004 The first workshop was held in February in Windhoek, Namibia, with participants from 16 countries where the need for a PT scheme was identified. Training on basic issues of quality in analytical laboratories was also addressed at this workshop. 1 st PT round; Evaluation workshop in Pretoria, South Africa 2004 2 nd PT round; Evaluation workshop in Dar es Salaam, Tanzania 2005 Training session on measurement uncertainty 2006 3rd PT round; Evaluation workshop in Gaborone, Botswana Training session on method validation and control charts 2007 4th PT round; Evaluation workshop in Dar es Salaam, Tanzania Training session on validation and measurement uncertainty October: Poster presentation at the Eurachem workshop in Proficiency testing in analytical chemistry, microbiology and medicine in Rome, Italy 4

BACKGROUND OF THE SADCMET PT SCHEME cont.. 5 th PT round; Evaluation workshop in Kampala, Uganda 2008 Training session on the Management requirements of the ISO17025 6 th PT round; Evaluation workshop in Mahé, Seychelles 2009 Test & Measurement conference: Presentation of Chemical analyses of water in Africa, South Africa 7 th PT round; Evaluation workshop in Windhoek, Namibia 2010 Training session on estimation of measurement uncertainty using validation and quality control October: Poster presentation at the Eurachem Workshop in Proficiency testing in analytical chemistry, microbiology and laboratory medicine in Istanbul, Turkey 5

BACKGROUND OF THE SADCMET PT SCHEME cont.. 8 th PT round; Evaluation workshop in Port Louise, Mauritius 2011 Training session on ensuring the quality of analytical results – Trueness and Precision 10 th PT round; Evaluation workshop in Nairobi, Kenya 2013 Training session on control charts 11 th PT round; Evaluation workshop in Lusaka, Zambia 2014 Training session on measurement uncertainty October: Poster presentation at the Eurachem workshop in Proficiency testing in analytical chemistry, microbiology and laboratory medicine in Berlin, Germany 12 th PT round; Evaluation workshop in Gaborone, Botswana 2015 Training session on Inter-laboratory tests, basic statistics and control charts 6

% PARTICIPATION PER COUNTRY 7

# LABORATORIES PER COUNTRY 2006 2007 2008 2009 2010 2011 2013 2014 2015 2016 Angola 0 0 1 0 0 0 0 0 0 0 Botswana 2 4 2 3 3 3 3 3 3 3 Burundi 1 1 1 2 2 2 Congo 4 5 3 8 7 5 Eritrea 0 0 1 0 0 0 0 0 0 1 Ethiopia 1 0 0 0 0 1 1 2 1 2 Ghana 1 0 0 0 0 Kenya 5 3 3 7 9 7 12 13 8 10 Lesotho 1 1 1 1 1 1 1 1 1 1 Madagascar 2 2 3 3 2 2 2 3 3 3 Malawi 2 3 1 1 2 2 1 1 1 2 Mauritius 4 3 5 6 6 5 4 5 5 4 Mosambique 2 0 0 0 0 0 0 0 0 0 Namibia 3 3 3 3 3 3 3 3 3 4 Rwanda 1 1 1 1 0 0 Seychelles 2 1 1 1 1 1 1 3 3 3 South Africa 0 1 1 1 1 1 1 1 1 1 Swaziland 0 1 2 3 0 0 0 0 1 1 Tanzania 6 12 11 12 13 10 12 15 18 14 Uganda 5 5 5 5 4 5 4 2 3 5 Zambia 2 3 1 3 3 1 1 2 2 2 Zimbabwe 2 5 5 5 4 4 6 7 5 5 Expert labs 3 TOTAL 39 47 46 54 58 54 57 72 67 71 8

GROWTH OF THE SADCMET PT SCHEME 9

OVERVIEW OF A PT ROUND • The annual notification is send out by the end of February with the schedule of activities for the year. Phase 1 • Registration usually close by the end of April • Identification & calculation of target values • Ordering of Chemicals & Consumables Phase 2 • Download certificates of analyses (COA) • Preparation of the stock solutions and bulk samples • Packing and distribution of the parcels Phase 3 10

OVERVIEW OF A PT ROUND cont.. • Calculations of reference values and measurement uncertainties • Results submission by participants Phase 4 • Evaluation of the Results • Generation of reports Phase 5 • Deal with enquires • Preparation for evaluation workshop Phase 6 11

DETAILS OF THE PT PROCESS Preparation phase Sample bottles:  Wash all 480 bottles twice with deionized water  Bottles & caps were put in the oven @ 60 ° C overnight  Check dryness  Cap bottles to prevent them from dust  Prepare the exact amount of labels for the number of bottles (480 for 80 laboratories)  Stick labels on the bottles  Complete for all the sample bottles and store the bottles in numbered crates Balances:  Calibration of the balances is done by an external body (Namibian Standards Institution)  Calibration certificates are obtained for the 3 balances  Verification with certified internal mass pieces 12

DETAILS OF THE PT PROCESS cont.. Purity:  The certificates of all the salts and wires are obtained  The purity for all substances and wires is used to calculate the reference values Glassware:  Label the glassware appropriately  Arrange the glassware accordingly to create a systematic flow 13

DETAILS OF THE PT PROCESS cont.. Sample preparation phase Weighing of the stock solution  Weigh the different target masses for the 3 levels of each parameter in a beaker by difference on balance  Start with the wires since the wires needs to digest for the substance to dissolve completely  Continue with the salts Preparation of stock solutions  Weigh empty flask, transfer the substance into the volumetric flask  Fill up the flask and weigh the final mass  Dilutions, especially for the heavy metals, Weigh 100g of stock solution in a beaker by difference weighing  Follow the same procedure for all the 20 parameters(3 levels) 14

DETAILS OF THE PT PROCESS Washing of sample bottles Weighing of the stock solutions 15

DETAILS OF THE PT PROCESS Digestion of the wires Weighing of the stock solutions 16

DETAILS OF THE PT PROCESS cont.. Preparation of bulk samples  Initial weighing of the empty containers  Fill the containers with deionized  Calculate target weight from density  Rinse stock solutions into the 100L container  Fill to target weight  Stir combined solution for 20 minutes 17

DETAILS OF THE PT PROCESS cont.. Anions : SO 4 , Cl, NO 3 , F, PO 4, TDS, Conductivity 3 1 2 Cations : Na, K, Ca, Mg, Fe, Mn, Cd, Cu, Pb, Zn, Al, As, Cr, Co, Ni 4 5 6 18

DETAILS OF THE PT PROCESS cont.. Sample dispensing  After 20 minutes of stirring, 1 L is flushed out  The conductivity of the sample is checked before dispensing into the sample bottles and after every 20 samples  Tank is washed properly (4-5times) with deionized water between the batches  Before starting with the next batch, check the conductivity of the wash water until it reads the same as the deionized water  Pack the samples in the appropriate crates and pack the crates into the walk in fridge  Samples kept at 4 ⁰ C in the Fridge Preparation of the documentation  Prepare hard copy of results sheets and the method information  Prepare all the labels and documentation for transportation for all the countries and participants 19

DETAILS OF THE PT PROCESS Preparation of bulk samples Dispensing of samples 20

DETAILS OF THE PT PROCESS cont.. Packaging of the samples  Request quotes from the courier  Pack the samples ( one at a time) into the boxes  Add documentation and addresses of all the participants  Confirm the cost with the PTB to proceed 21

DETAILS OF THE PT PROCESS cont.. Pick up of the parcels Packing Parcels were pick up on the 07 July 2016 at NamWater Delays:   Some parcels were left behind by the courier and were picked up later 22

DETAILS OF THE PT PROCESS Left NamWater on 07 July 2016 23

DETAILS OF THE PT PROCESS cont.. Testing phase Calculation of reference values  Identity all sources of uncertainty in the analytical measurements and list them with the use of a fish bone diagram calibration 1 m K2SO4 m ss_t calibration 2 F SO4/K2SO4 buoyancy correction K  The identified sources were: • Purities of the substances used m total m total • Uncertainty of the three balances used precision 1 precision 2 • Uncertainty of molecular mass were neglected m tara m tara • Density of final samples • Buoyancy calibration 1 calibration 2      calibration 2 calibration 3 m F P m precision calibration  m tara m tara K SO SO / K SO ss lot c 2 4 4 2 4 lot   m m K precision 2 precision 3 temperature ss _ t lot m total m total table  lot calibration 2 calibration 3 Purity m ss m lot 24