Download File - Midwest Water Analysts Association

High Purity Water for Critical Laboratory Applications
Brian Rhoades
Water Analysis and Purification Specialist
Proprietary & Confidential
The world leader in serving science
Overview
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Explain the standards of water purification
Review impurities in water
Review technologies to remove those impurities
Discuss the technologies utilized to produce different qualities of water
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Water Purification Standards
• There are several agencies that
publish industry standards for the
different types of water
• We will cover the most commonly
referenced standards:
• ASTM – American Society for
Testing and Materials – D1193
• CLSI – Clinical and Laboratory
Standards Institute
• ISO – International Organization for
Standardization – ISO 3696
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Reagent Grade Water Types
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Clinical and Laboratory Standards Institute (CLSI) Laboratory
Water Standards
• Clinical Laboratory Reagent Water - CLRW
Contaminant
Unit of Measure
Standard
Ions
Resistivity
(megohm)
> 10
Organics
TOC (ppb)
< 500
Bacteria
Bacteria (cfu/ml)
< 10
Particles
Microns
0.2 micron filter
• CLSI also sets standards for clinical analyzer feed water, bottled water,
special reagent water, and autoclave water
• Please refer to the entire guidelines as provided by your client
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Water Standards – ISO 3696
• ISO standards measure in grades
• ISO only concerns resistivity and conductivity
Type
I
Grade
Grade
Grade
Type
Type
Type
1
2
3
IV
II
III
(ISO)
(ISO)
(ISO)
Conductivity - 0.056
0.100
1.000
1.000
0.250
5.0
5.0
Resistivity - (min. 18.0
10.0
1.0
1.0
4.0
0.2
0.2
(max. µS/cm)
MΩ•cm)
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Appropriate Use of Water
Feed for lab
equipment
Ultrapure
water
Water for cell culture
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Water for
chromatography
Appropriate Use of Water
Feed for lab
equipment
Reverse Osmosis
water
Water for cell culture
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Water for
chromatography
Limitations & Capabilities
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Ion Impurities in Water
Dissolved Ionized Solids
Major
Calcium - Ca++
Cations
Magnesium - Mg++
Sodium - Na+
------------------------------------------------------------------Chloride - ClMajor
Sulfate - SO4=
Anions
Bicarbonate - HCO3Silica/Silicate - HSiO3 -
Highest purity Resistivity: Deionization with Semiconductor
grade
• High grade mixed bed resin formulated to have a low TOC
Service DI: regenerated resins – not high purity
Distillation: Ionized gases could reabsorb
RO: % removal technology
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Monitoring Resistivity - Ions
Conductivity
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Resistivity
Conductivity
Resistivity
Organics
• Total organic carbon monitoring organic compounds.
• Low TOC = higher purity
• NOT the same as bacteria!
• Sources include:
• Plant and animal decay
• Agricultural and manufacturing byproducts
• Phthalates or plasticizers increase flexibility and transparency of plastic
• Best removed from water with UV and carbon.
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Bacteria
Found: Everywhere – air and water
Bacteria
Potentially interferes with:
Measured off-line by micro
culture methods
• Lab equipment – clogs filters (HPLC)
• Sensitively biological methods such as
cell culture, tissue culture, and bacterial
studies
• Source for pyrogens/endotoxins
• Source for nuclease (RNase/DNase)
Removed with final filter, RO, UV
• Likes to grow in water systems!
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A natural contaminant in feed
water
Measured in CFU/mL
Nuclease and Pyrogens (Endotoxins)
• Endotoxins (pyrogens): Pieces
of Gram negative bacteria
• Interfere with growth of mammalian
cell or tissue cultures
• Nucleases: Enzymes RNase and
DNase
• Degrade and breaks down RNA and
DNA
• Sensitively biological methods
such as cell culture, tissue culture,
and bacterial studies
RNase/DNase Measured offline by fluorometric assay
Enzyme that cleaves bonds
within nucleic acids
Measured in ng/mL (ppb) or
pg/mL (ppt)
Pyrogens
Measured off-line by LAL
spectrophotometric assay
•Bacterial cell walls
•Can retard cell or tissue growth
Measured in units/mL (EU/mL)
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Particulates
Typical tap water
• Ruins RO membranes
• Lab equipment – can leave a deposit,
plug valves
• Affect gravimetric methods
• Prefilters remove particulates
Rust
Sediment
Plumbing debris
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• Measured by turbidity meter – should
be below 1 N.T.U.
Limitations & Capabilities
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Deionization or Ion Exchange
• Removes ions from water
through the use of synthetic resins.
• Divided into two classifications –
cation and anion.
• Only technology that produces
18.2 megohm water.
• Mixing cation and anion resins
achieve maximum purity.
Benefits
• Removes dissolved inoragnics
(ions), very effectively.
• Water resistivity above 18.0MΩ
-cm
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Limitations
• Limited capacity – once all ion
binding sites are occupied ions are
no longer retained
• Does not remove organics, particles,
pyrogens or bacteria
Ion Exchange and Regeneration
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Electrodeionization
• Removes ions from water using
electricity and resin.
• Continuously regenerates
automatically (though has a finite
life)
• The technology that produces 515 megohm water.
Benefits
• Removes dissolved inoragnics
(ions), very effectively.
• Water resistivity 5-15Megohm cm
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Limitations
• Finite capacity
• Expensive replacement
• Does not remove organics, particles,
pyrogens or bacteria
Distillation
Water is heated to the boiling point.
Water vapor rises to the condenser
where it is cooled and condensed.
The purified water is stored for use.
Benefits
• Offers the broadest removal
capabilities of any single form of
water purification
• Requires no consumables
Pure water
Limitations
• Requires periodic maintenance
and cleaning of system to
maintain water purity
• Requires cooling water
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Distillation
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Reverse Osmosis
• Most economical method of
removing up to 99% of all
contaminants.
• Water is pushed through a semi
permeable membrane
• Most impurities do not pass
through the membrane, they
collect on the surface and are
flushed
Benefits
• To varying degrees, removes all
types of contaminants.
• Requires minimal maintenance
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Limitations
• Limited flow rates through the membrane
require intermediate storage devices to
meet user demand
• Membrane susceptible to:
• Scaling – CaCO3
• Fouling – Organics & Colloids
• Piercing – hard particles
Reverse Osmosis - Rejection Characteristics
Good for pretreatment of
tap water
(Concentrate)
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Reverse Osmosis Spiral Wound Membrane
(Permeate)
(Concentrate)
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Carbon Adsorption
Process: Water is passed
through activated carbon
which organics and chlorine
adhere to
Benefits: Carbon can be
combined with resin to
achieve low TOC’s or is a
good first step to clean up
feed water high in chlorine
Limitations: Activated carbon
will not remove ions and
particulates
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Depth and Screen Filtration
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Final Filters
•0.2 micron POU designed to
removes bacteria and particles
Important Tips:
•Rinse filter before sampling
•Change frequently minimum 1-2X
per year
•Purge – upon installation or if flow
rate from dispenser, release air
with vent port purge air bubbles.
•Slow flow rate can also
indicate filter needs
replacement.
•Avoid adding tubing to final filter,
touching tip of final filter.
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Endotoxin-free Type 1 Water
• Ultrafilters:
• Remove endotoxins in water
• <0.001 Eu/ml
• Polysulfone hollow fibers
• Large surface area
• In water line – away from potential environmental
contamination
• Combination of UV light and
Ultrafiltration (UF)
• Excellent way to reduce nuclease and endotoxin:
• Ultrafilter hollow fiber filters trap impurities
• System rinse remove them from the system
• UV light – oxidizes bacteria and organics
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UV Photo-Oxidation and Bacteria Reduction
• Built into systems with UV photo-oxidation:
• Type 1 systems – dual wavelength UV:
• 185/254 nm organic compounds
• 254 nm controls microorganisms
• Type 2 systems and storage tanks:
• Use 254 nm only to discourage growth
• Effective in the flow path
• Thermo Scientific UV lamps – up to a 2-year lifetime
There is a 20 minute “minimum on time” safety regulation in the
software for the UV Bulb.
The UV Bulb is only on during the “Non-Stop” or “Production” modes
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Limitations & Capabilities
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Example Water Treatment Flow from Tap to Type 1
Flow Inside POU System
POU Water System being supplied type
2 water from resin bed in basement
UV Lamp
Oxidizes organics /
Kills bacteria
Pump
Moves H2O through
System
2nd Floor Lab Bench
Deionization Removes ions and
Cartridge
dissolved gases
Ultrafilter
Resin Bed in Basement producing 8
megohm quality water (type 2)
Main water line with
potable incoming water
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Removes particles,
bacteria, pyrogens
Conductivity
Cell
Measures resistivity
and shows on system
display
Final Filter
Removes particles
larger than 0.2 micron
END
RESULT:
18.2
megohm
water with
TOC levels
below 5ppb,
nucleases,
pyrogens,
bacterial
levels
extremely
low
Thank you
Questions?
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