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Water in the Clinical Laboratory

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Presentation on theme: "Water in the Clinical Laboratory"— Presentation transcript:

1 Water in the Clinical Laboratory
Role of water in Clinical Diagnostic Purification technologies basics Delivering water to the clinical analyzer Mikael Cleverstam WW Clinical Business Manager

2 Putting it all together
Diagnostic instruments Troubleshooting Your analyzer Assay development Patient results CLSI New standards Water quality as part of the quality process Water purification Diagnostic Instruments Quality system Quality Control Patient Results Water Quality Medical Technologist

3 Normal seen Problems Frequent Calibrations High CV%
Fluctuation in quality results over the day/week/month Interfered assays Calcium Interfered by rocks, leaves, geology ALP Interfered by biofilm, detergent, rocks CK Interfered by water treatment Amylase Interfered by citrus fruit, detergents, leaves LD Interfered by effluent, leaves, H2O2 Phosphorus Interfered by citrus fruit, leaves Iron Interfered by rocks, leaves, detergents Magnesium Interfered by citrus fruit Triglycerides Interfered by plastics, chemicals Urea Interfered by citrus fruit, water treatment Troponin I Interfered by biofilm

4 Water for Clinical Analysers
Cuvette washing Tubing and probe rinsing Reagent and buffer reconstitution Dilution Water Baths

5 Diagnostic Instruments
Clinical Analyzers Diagnostic Instruments Features and benefits of automation Precision optical systems for accuracy in testing Automatic sampling and dilutions modes Real time alerts to patient and QC failures Improved software alerts end user to mechanical failures Cost benefits Workflow efficiency and high speed through put Instrumentation targeted to reduce operating cost with more efficient technology Reduced operator interface

6 Diagnostic Instruments
Assay Development Diagnostic Instruments Measuring chemical changes in the body for diagnosis, therapy and prognosis has resulted in new assay development Multiple method testing on a single analyzer Current research methodologies for infectious disease and tumor marker’s are moving from research labs in universities to the clinical laboratory Complex methodologies are being fully automated for more routine use

7 Unique Challenges for Medical Technologist
Verification of final clinical results to be accurate and precise are determined by Medical Technologist Clinical decisions are not solely made on the test result, but in conjunction with the patient’s history and symptoms Software alerts, QC reviews, calibration must all be within stated limits before results are released Troubleshooting instrument problems result in production delays, are costly and non-productive activities that must be performed and documented ➙ Try to avoid diagnostic instrument service because it is expensive

8 Reviewing Patient Results
All analytical and pre-analytical factors must be reviewed and documented Medical Technologist must review all test results If results are flagged, troubleshooting the cause is necessary Diagnostic Instruments Quality Control Medical Technologist Patient Results

9 Troubleshooting procedures
Sample handling procedures confirmed Quality control must be reviewed Shifts and trends Peer group Previous data Assay Reagent issue Calibrator stability Mechanical Instrument malfunction Error codes If above solutions do not correct the erroneous result, further troubleshooting must identify cause before results can be released to physicians ➙ Delayed patient treatment. Diagnostic Instruments Quality Control Medical Technologist Patient Results

10 Diagnostic Instruments
Next Steps Diagnostic Instruments Water Quality Medical Technologist NO YES NO YES Outside Source YES WHY ?? Water Quality

11 Water Quality Water Quality Quality results are dependent upon reliable instrumentation and known water quality Analytical factors need to be controlled and optimized to reduce the number of test failures, failed calibrations, and high blanks that can contribute to erroneous patient results Maintenance of high purity water system is essential to reliable results

12 Understanding Water Quality and Methodology
Water should be considered a bulk reagent on any analyzer The high purity water system is a separate unit, not monitored by diagnostic software on the clinical analyzer The unique properties of water if not processed and monitored can produce subtle changes in assay methods These changes in water quality can lead to erratic and inconsistent results The quality of water required or its impact on the testing method is often not considered until the purchase is complete

13 Diagnostic Instruments
Diagnostic Dilemma Diagnostic Instruments Water Quality Smaller sample size and reaction vessel are subjected to harsher environment Inevitable build-up of biofilm in instruments, manifolds and tubing require more frequent decontaminations but Less and less time available for maintenance of the instruments Some sensitive assays can become contaminated with bacteria and ions Bacteria release enzymes and ions whose behavior is similar to the enzymes targeted in the assay method ➙ Increased need to monitor water quality as closely as any other instrument malfunction

14 Diagnostic Instruments
Biofilm Formation Diagnostic Instruments Water Quality Organic Particles Surface Bacteria A biofilm is an agglomeration of particulates, organic substances and bacteria on the inner surface of the reservoir. As indicated earlier, bacteria do not “like” to grow alone, in the middle of water . They rather tend to stick to a support . This is what happens ususally inside reservoirs : some partciulates and organic substances bind to the surface; bacteria attach themselves to the same point, and a biofilm grows and becomes thicker with time, releasing from time to time bacteria in the stored water. NB : just to give an order of magnitude about what represents 1 cfu/ml. For a simple calculation, let’s consider that a bacteria occupies 0.1 um 3 (it usually occupies a smaller volume : Pseudomonas Diminuta volume is about 0.01 um3- this is just to make the demonstration easier).A 0.1 um3 volume corresponds to 0.1 x (10*-6m)3 = 10*-19 m3. Therefore, the volume occupied by 1 billion bacteria would be 10*-19 x 10*9 = 10*-10 m3 = 10*-7L = 10*-4 ml= ml . This means that 1ppb (1 part per billion ) bacteria corresponds to 1 bacteria per ml , or 10,000 bacteria per ml. Time Biofilm may shed bacteria, pyrogens etc

15 Demonstration of ALP release from bacteria
Diagnostic Instruments Water Quality Correlation between bacteria concentrations and levels of ALP in water Bacteria Strain (identification by 16S rDNA sequencing) Bacteria level (x 106 cfu/mL) ALP concentration (mUnit/mL) Sphingomonas paucimobilis Caulobacter crescentus Ralstonia pickettii 29.2 9.7 29.5 6.22 9.95 8.29

16 Diagnostic Instruments
Detection methods Diagnostic Instruments Water Quality Substrate-Phosphate ALP + Pi UV-Visible pNPP Fluorescence Attophos Starbright MUP ELF Chemiluminescence CDP-Star (dioxetane) CSPD (dioxetane) Lumigen PPD AMPPD

17 CLSI Water Quality Standards
Quality Control Water Quality New Standards released July 2006 (C3-A4 Vol. 26 No. 22) Nomenclature Type I,II,III has been replaced with purity types that provide more meaningful parameters CLRW (Clinical Laboratory reagent Water) replaces Type I,II for most applications IFW (Instrument Feed Water) allows instrument manufacturers to clarify specifications for their particular methods SRW ( Special Reagent Water) may be specified for specific applications when additional parameter are needed to insure water quality Autoclave and wash water will meet the requirements of previously classified Type III Complete review of the document should be done when considering new applications to insure the contaminants found in the source water do not become an issue

18 Water Contaminants Water: H2O …. and some other things
Presence of contaminants Particles Gases Microorganisms Ions Organics Purification technologies

19 Protecting the Water Purification Unit: Pretreatment cartridge
Due to the difference in water quality around the world, additional pretreatment cartridges are required. The cartridges provide protection and insure good performance of the reverse osmosis membrane The pretreatment packs include 0. 5 micron filter (1) to remove particles and activated carbon (2) to remove chlorine The activated carbon is impregnated with a small level of silver to prevent bacterial growth. Example of a pretreatment cartridge

20 What is reverse osmosis ?
P P Feed Water Permeate Reject

21 Technology Insight: Electro-Deionization
EDI module - Ion selective membranes - Ion exchange resins - Continuous current A - Anionic Membrane C - Cationic Membrane A C Cathode Na+ H+ OH- Cl- Product + Reverse Osmosis Water mS/cm - Anode Reject Resistivity: > 10 TOC: < 30 ppb No need for regeneration

22 Filters – Bacteria Removal
Screen 0.2 µm filters Designed for the removal of particles and microorganisms from liquids and gases. Use of PVDF membranes, provide high flow rates and throughputs, low extractables, broad chemical compatibility and the lowest protein binding of any membrane available.

23 Ultrafiltration Cut-off: 5 KDa to 20 KDa
Removes bacterial by-products such as most proteins and macromolecules (e.g. endotoxins) Utilized for immunochemistry assays Immunoenzyme assays based on reporter enzymes (alkaline phosphatase, ALP) are sensitive to ALP released by bacteria Also filters bacteria

24 Storage CLRW water with a resistivity >10 megohm-cm cannot be stored because ionic and organic contamination will leach from the atmosphere and container materials in which it is stored. CLRW water should be used as it is produced Stored water is never as pure as when it is made Storage of water enhances bacterial contamination Containers need to be cleaned thoroughly between refilling. Carboys, tanks, bottles Notorious source of contamination since we often refill them without thoroughly cleaning them when they are emptied Some plastic materials out-gas polymers and plasticizers, and these end up in the water

25 Water Purification Unit
Simplified flow schematic combining purification technologies Tank Pretreatment cartridge Reverse Osmosis cartridge Electrodeionization module Resistivity cell Feed water Pump To analyzer UV Germicidal Ion exchange resins Drain The electrodeionization module is not present in some purification units

26 Connecting the Water Purification Unit to the Clinical Analyzer
Water is delivered in its purified state to a harsh environment within the chemistry analyzer bottle Water bottles inside analyzer are not frequently decontaminated Electronics, mechanical hardware, pumps all create heat within the analyzer cabinet, thus raising the interior temperature of the water bottle. Increased temperatures enhance the growth of bacteria and biofilm within the instruments manifolds and tubings.

27 Conclusions Water is a reagent.
The quality of water has an impact on the testing method.

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