Guide Lab Water

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AGuide

ToLaboratory

Water

Purification



Introduction

Water is a reagent that has often been taken forgrant ed. It falls from the sky, it flows in t he r ivers,it is available at the tap at the turn of the faucet,we drink it, bathe in it — if it looks clear and tastesokay we are accustomed to thinking of it as beingpure. However, in the laboratory, potable water isoften not pure enough.

It is common for analytical and experiment alscientists to be concerned with elements andcompounds in the parts per billion (ppb) and partsper t rillion (ppt) r ange. Life science research isoften very sensitive to many contaminants,especially heavy metals and dissolved organics.High performance liquid chromatography (HPLC)requires ultrapure water in many of itsapplications, including calibration of detector baselines and elut ion of reverse phase columns. Traceelement analysis requires water that is free of theelements in question.

What kind of work are you doing with pure water?__________________________________________

How are you purifying your water now?__________________________________________

Is the water in your laboratory pure enough for thesensitivity of your analytical procedures?__________________________________________

Foreword

This booklet has been prepared by LabconcoCorporation to serve as a basic guide in theselection of water purification equipment . Theinformation presented is “generic” in nature. Thatis, while experienced Labconco personnel havecompiled this booklet, it is our intention to providea non-biased review of water quality standards,common water contaminants and pur ificationmethods. The purpose of this booklet is to h elp youmake an informed choice for your laboratorysituation.

Our Method

We begin our discussion of water purification by

looking at current water quality standards whichhave been established by several scient ific groups.Secondly we examine the many types of contaminants commonly found in water suppliesand why their removal is important to variouslaboratory procedures. Next, purification methodsare compared for effectiveness and ease of use.Throughout these discussions are QualifyingQuestions which will help you determine whatlevel of water purity is needed for your laboratoryprocedures and what purification methods aremost practical to achieve these levels of pur ity.

Finally, towards the end of this guide is a list of problems associated with traditional approaches towater purification and a brief discussion of howLabconco’s water purification systems addressthese problems.



Wat er Stan dards

In response to developments in scientifictechnique and technology and the increasingsensitivity of research, several professionalorganizations have established water qualitystandards. These groups include the AmericanChemical Society (ACS), the Amer ican Society forTesting and Mater ials (ASTM), the NationalCommit tee for Clinical Laboratory Standards(NCCLS), and the U.S. Pharmacopeia (USP).

As an example, th e NCCLS has specified threetypes of water — I, II, III — and Special Purpose,which are listed below with their int ended uses.

NCCLS Water Types and Applications

Type I - Test m ethods requiring minimalinterference and maximum precisionand accuracy:Atomic absorpt ionFlame emission spectrometr yLigand assaysTrace metalsEnzymatic procedures sensitive to trace metalsElectrophoretic procedures

High sensitivity chromatographic proceduresFluorometric proceduresBuffer solutionsStandard solutions

Type II - Test methods in which the presence of bacteria can be tolerated:General reagents without preservativesMicrobiology systems (not to be sterilized)Test methods for which requirementsleading to the choice of Type I orSpecial Pu rpose waters do not apply:Stains and dyes for histologyGeneral reagents with preservativesMicrobiology systems (to be ster ilized)

Type III - General washing and feedwater forproducing higher grade water, as wellas bacteriological media preparation.

Special Purpose - Procedures r equiring removalof specific contaminan ts:Removal of pyrogens for tissue/cell culturesRemoval of trace organics for HPLC

Reproduced with permission of National Committee for Clinical Laboratory Standards, Villanova, PA.

A summary of the various Type I water quality

Type I Water Quality StandardsNCCLS ASTM

Resistivity 1,megohms-cm, at 25° C, minimum 10.0 18.0

Conductivity,microsiemens/cm, maximum 0.1 0.056

Silicate, mg/l, maximum 0.05 .003

Particulate matter, µm filter 0.22 0.2

Microorganisms, seecolony forming units per milliliter 10 note 2

1 Resistivity and conductivity of Type I water m ust bemeasured in-line. Measuring in a container will giveinaccurate r eadings.

2 For ASTM: Type IA water - 10/1000 mlType IB water - 10/100 ml

Type IC water - 100/10 ml

Conta mina nt s an d Wat er Testing

For a better idea of what these standards mean,let us examine the kinds of contaminants t hat maybe found in water.

First of all, water is an excellent solvent and themedium of most life processes on t his planet . Thatis why water gets contaminated with just abouteverything it encounters and why microorganismsgrow in it so well. The aforement ioned is whypurifying water is a much more difficult procedurethan it in itially might seem to be.

The five types of contaminant s th at may befound in water are:

1. Part iculates2. Dissolved inorganics (solids and gases)3. Dissolved organics4. Microorganisms5. Pyrogens

PARTICULATES include silt, plumbing pipe

debris, and colloids. These suspended part icles canplug filters, valves, lab tubing, reverse osmosismembranes and conductivity meters. Particulatesare visible as cloudiness or tu rbidity, and aredetected using filtration and gravimetric means, ormicroscopic methods. A 10 to 20 micron prefilteris often placed as the first component in a waterpurification system to filter out the largerparticles. Smaller part icles are removedsubsequent ly by reverse osmosis, submicron filtersand ultr afiltration membranes.

DISSOLVED INORGANICS include calcium and

magnesium ions dissolved from rock formations(these two ions make water hard), gases such ascarbon dioxide that ionize in water (carbon dioxide



There are several tests for identifying specificdissolved inorganics. The simplest test is a directmeasurement of electrical conductivity orresistivity. Most dissolved inorganics are eithernegatively charged (anions) or positively charged(cations), and will transmit a current when avoltage is applied to electrodes inserted in thewater. The more ions present, the greater theconductivity, or the lower the resistivity of thesample water .

This figure shows the standard configuration of aconductivity cell and the movement of the anions (-) and cations (+) toward the charged poles.

Reprinted from Handbook of Water Purification 1981 bycourtesy of Walter Lorch, editor, and McGraw Hill,

publisher.

Conduct ivity is expressed in microsiemens/cmand is used to measure water with a large numberof ions present. Resistivity is expressed inmegohms-cm and is used in t he measurement of water with few ions. Conduct ivity and r esistivityare reciprocals of each other . Thus, at 25° C, 18.2megohm water, which is the highest purity waterobtainable with today’s technology, also has aconduct ivity of 0.055 microsiemen/cm.

Resistivity 0.1 1.0 10.0 18.24 megohm-cm

Conduct ivity 10.0 1.0 0.1 0.055 microsiemens/cm

Does your analytical work require that your waterbe free of dissolved inorganics? ________________

DISSOLVED ORGANICS may include pesticides,herbicides, gasoline, and decayed plant and animaltissues. Dissolved organics may also include theplasticizers leached out of plumbing lines, fittingsand storage tanks.

Note the sources of the last organic

contaminant — all are from improperly designedwater purification systems. Thus, a waterpurification system mu st both remove the

electrophoresis, and fluoroscopy, or in researchinvolving tissue cultures.

There are several ways of measuring dissolvedorganic levels. The potassium permanganate(KMnO

4) color retention time test is a qualitative

organic test that may be used. The premise of thistest is t hat the bright purple-colored potassiumpermanganate, a powerful oxidizing agent , willchange color to clear if there are sufficientorganics present in the water to be oxidized. Thedrawbacks of this test are that it is slow, it is notsensitive to very low levels of organics (that m ightstill be too h igh for HPLC purposes), and it is notquantitative — it doesn’t tell how many parts perbillion of organics are present.

Total Organic Carbon (TOC) analyzers, whichoxidize the organics and measure th e CO

2liberated, are being used more and more todetermine organic levels in Type I water due totheir low-level detection sensitivities. A low TOClevel is very important for HPLC users.

Are you doing HPLC? ________________________

Is it important to you to have very low levels of dissolved organics? __________________________

MICROORGANISMS con stit ut e another groupof contaminants found in water. Surface water may

contain a wide variety of microorganisms,including bacteria, protozoa, algae, amoebae,rotifers, diatoms and others. Since most laboratorywater comes from municipal water treatmentplants, which is extensively treated to removemicroorganisms, th e chief microbes of concern forwater purification systems are bacteria. A typicalbacterial level for a potable laboratory water supplyis one colony forming unit per milliliter (cfu/ml).

The challenges for an ultra-pure waterpurification system are to:

a) remove the bacteria present in the feedwaterb) prevent bacteria from entering the system

and contaminating itc) ensure that no bacteria are in the product waterd) inhibit bacterial growth through proper

design and operation.

Bacteria are one celled organisms that multiplyat exponential rates, thrive in standing water, andmay be present on many surfaces and in the air.Bacteria subsist on a variety of substrates in purifiedwater including dissolved organics such as plasticizersand dissolved inorganics such as iron and sulfur.

Bacteria will enter an unprotected waterpurification system from the feedwater, any breaksin the system, or th rough the dispenser. Once in

1cm

1cm1cm

ELECTRONFLOW

Weak solution ofsodium chloride

Sodium ion

Chloride ion



Purification MethodsEight different methods are commonly used to

purify water. These are:1. Distillation2. Deionization3. Reverse osmosis4. Activated carbon filtration5. Microporous filtration6. Ultrafiltration7. Ultraviolet oxidation8. Electrodialysis

The following NCCLS chart compares theeffectiveness of seven of these technologies for theremoval of the various contaminants found in water.(Electrodialysis was not listed in this NCCLS chart.)

Water Purification Process Comparison

E = Excellent (capable of complete or neartotal removal)

G = Good (capable of removing largepercentages)

P = Poor (little or no removal)

Permission to reprin t portions of C3-A2, “Preparationand Testing of Reagent Water in t he Clinical Laboratory

— Second Edition; Proposed Guideline,” has beengranted by the National Comm ittee for Clinical

Laboratory Standards. NCCLS is not responsible for errors or inaccuracies. The complete current standard may be obtained from NCCLS, 771 E. Lancaster Avenue,Villanova, PA 19085.

(1) The resistivity of water purified by distillation is an orderof magnitude less than that produced by deionization,due mainly to the presence of CO 2.

(2) The residual concentration of dissolved solids isdependent on the original concentrat ion in the feedwater.

(3) Activated carbon will remove chlorine by chemisorption.(4) Special grades of carbon are available which exhibit

excellent trace organic removal capabilities.(5) Ultrafiltration will remove organics based on molecular

weight cu toff of ultrafilter m embrane.

filter and cultu ring t he filter on a suitable mediumfor several days. Bacteria coun ts are usuallyreported in colony forming units per milliliter(cfu/ml).

Bacteria can be killed with disinfectant s likehydrogen peroxide, hypochlorite, andformaldehyde. However, when bacteria die, theirpolymeric secretions and lipopolysaccharidecellular fragments remain and may be a source of contamination if not removed.

A culture of bacteria (one organism per m illiliter) inglucose medium after a lag of about 4 hours growsexponentially with a doubling time of one hour.

Reproduced with permission of Blackwell ScientificPublications, Oxford, England.

Pyrogens, are t ypically gram-negative bacterialcell wall fragments or lipopolysaccharides. Wheninjected into a mammal, pyrogens cause a rise inbody temperature. Thus pharmaceutical gradewater must be pyrogen-free. Pyrogens also have adetrimental or lethal effect on tissue cultures.

Pyrogens are detected either by injecting the

sample water in to specially bred rabbits andmonitoring them for a body temperature rise, orwith the LAL (Limulus Amoebocyte Lysate) test, asensitive test for very low concentrat ions of lipopolysaccharides.

Have you analyzed your feedwater and productwater for bacterial and pyrogen levels? __________

Have you had problems with bacteria proliferatingin your water purification system? ______________

Do you r equire that your water be bacteria-free? __

__________________________________________Do you r equire that your water be pyrogen-free? __

0 4 8 12 16 20 24 28 32 36

0

1

2

3

4

5

6

7

8

9

10

10

10

10

10

10

10

10

104 x 10No. of cells per ml.

Hours

log 10 No. of cellsper ml.9

9

8

7

6

5

4

3

2

1 D i s s o l v e d S o l i d s

D i s s o l v e d G a s e s

D i s s o l v e d O r g a n i c s

P a r t i c u l a t e s

M i c r o o r g a n i s m s

P y r o g e n s D I

S T I L L

A T I O

N

D E I O

N I Z A

T I O N

R E V E

R S E O

S M O S

I S

C A R B

O N F I L T R

A T I O N

M I C

R O P O

R O U S

F I L T R A T

I O N

U L T R

A F I L T R

A T I O

N

U . V .

O X I D A T

I O N

EG(1)

EG(6)

EG(4)

P

PP

PPP

PP

P

PP

P

P(3)

P

P

PP

PEE

E

EE

E

EE

EEE

EE

G

G

P

P

P

G(7)

G(5)

G(2)



DISTILLATION has several positive features.The equipment is relatively inexpensive, there areno expendables other than replacement glasswareand heating elements, and it produces water of generally good quality. Distillation typicallyproduces water of Type II or III quality, with aresistivity of about 1.0 megohm.

Distillation has several drawbacks, however, andbecause of these, is not as widely used as in thepast. Distillation is not an on-demand process.Because of th is aspect, a quantity of water must bedistilled and stored for later use. If the storagecontainer is not made of an inert material, ions orplasticizers will leach out of the water containerand recontaminate the water. Bacteria are knownto grow well in standing water. The bott les may besterilized and t he collected water autoclaved.However, once the bott le is opened, it is exposed tobacteria and contamination begins.

Distillation has other drawbacks, includingbeing highly wasteful of energy and water —typically only 5% of the water u sed in the processends up as product water. Stills require regularcleaning due to build-up of mineral deposits fromthe feedwater.

DEIONIZATION is commonly used inlaboratories for producing purified water ondemand. Deionization systems have typicallyconsisted of one to four cylindrical cartr idgeshooked up to plumbing lines and hanging on awall near a sink.

Deionization functions by exchanging hydrogenions for cationic contaminant s and hydroxyl ionsfor anionic contaminants in the feedwater. Thedeionization resins are tiny spherical plastic beadsth rough which the feedwater passes. After a periodof time, cations and anions from the water displaceall the active hydrogen and hydroxyl groups in thebeads and the resin must be replaced orregenerated.

Deionization has several advantages (overdistillation) for the production of purified water. Itis an on -demand process supplying purified waterwhen needed. Nuclear grade deionization r esin orpolishing mixed bed resin removes almost all theionic material in the water to a maximumresistivity of 18.2 megohm-cm (at 25° C).

Deionization alone, however, does not produceabsolutely pure water. Tiny fragments of the ionexchange resin are washed out of the systemduring operation and stagnant water in thecartridges may allow excessive bacterial growth.Deionization also does not remove all dissolvedorganics from the feedwater, and in fact, dissolvedorganics can foul the ion exchange resin. Finally,deionization cart ridges can be an expensive optionfor labs that choose to replace their cartridgesrather than regenerate them.

There have been many attempts to overcomethe shortcomings of deionization and distillation.In some setups, distillation has precededdeionization — the cartridges last much longer,but the problems of bacterial contaminationremain.

REVERSE OSMOSIS is a process whichovercomes many of the shortcomings of distillation and deionization.

Reverse osmosis can be explained better afterunderstanding the natural process of osmosis.Osmosis is the movement of water across asemipermeable membrane from the lessconcentr ated (purer) side to the moreconcentrated (saltier) side. This movementcontinues until the concentrations reachequilibrium or the pressure on the moreconcentr ated side becomes high enough to stopthe flow. Osmosis is the n atural process by whichwater is drawn into a plant’s root , or moved fromone cell to another in our bodies.

H+

H+H+

H+H+

H+ H+

OH-

OH-OH-

OH-OH-

OH- OH-

Cl-

Na +Cl-

Cation Resin Anion ResinH+ + OH -

Na +



If a pressure greater t han t he osmotic pressureis applied to t he more concentr ated solut ion, usinga high pressure pump, water molecules are pushedback across the membrane t o the less concentratedside, yielding pur ified water . This is the process of reverse osmosis.

Reverse osmosis typically removes 90-99% of most contaminant s. A table of reverse osmosisperformance characterist ics follows:

Contaminant Removal Efficiency

Suspended solids 100%Bacteria 99.5%Viruses 99.5%Pyrogens 99.5%Organics, molecular 97-99.5%

weight > 250 Daltons

Monovalent inorganics 94-96%Divalent inorganics 96-98%Trivalent inorganics 98-99%

Because of its exceptional purifying efficiency,reverse osmosis is a very cost effective technologyand is often used to pre-purify tap water for furtherpurification by other technologies. Since reverseosmosis removes a high percent age of bacteria andpyrogens, it is often combined with ion exchangeto significantly prolong th e life of the deionization“polishing” cartr idges. In addition, a system which

allows dispensing of the reverse osmosis watergives a source of high quality pre-purified water,which is suitable for many routine laboratorypurposes.

ACTIVATED CARBON FILTRATION removeschlorine by chemisorption and dissolved organicsby adsorption and is often found at two places in awater purification system. Because thin filmcomposite reverse osmosis membranes aresensitive to chlorine, and to a lesser degree, foulingfrom dissolved organics, act ivated carbon is oftenplaced before th e RO membrane to remove these

contaminants.

A granu lar activated carbon filter is also oftenplaced in the polishing loop of a water purificationsystem to r emove trace amoun ts of dissolvedorganics for water quality suitable for HPLC work.

MICROPOROUS FILTRATION or submicronfiltration uses a membrane or hollow fiber with anabsolute pore size of 0.2 micron that prevent s anycontaminant larger t han 0.2 micron from passingthrough it. The submicron filters retain carbonfines from the carbon cartridge, resin fragmentsfrom the deionization cartridges and any bacteriathat may have entered the system.

NCCLS considers water to be particulate freewhen it has been passed through a 0.2 micronfilter. Microporous membranes are generallyconsidered to be indispensable element s of a waterpurification system, unless th ey are replaced by anultrafilter.

Do you n eed laboratory water t o be particulate-free per Type I standards? _______________________________________________________________

ULTRAFILTRATION uses a membrane verysimilar in design to reverse osmosis systems exceptthat the ultrafilter’s pores are slightly larger. Theultrafilter is used to remove pyrogens and otherlong chain organic molecules such as RNase fromthe purified water.

Since a high percentage of the water brought tothe ultrafilter passes through it, it will eventuallyplug if not maintained. In a properly designedsystem, the ultrafilter is regularly and tangentiallywashed free of contaminants. With th is type of design, ultr afiltration is an outstanding technologyfor ensuring very consistent ultrapure waterquality.

Does your work require that you use pyrogen-freewater? _______________________________________________________________________________

OsmoticPressure

OsmoticPressure

PumpPressureOsmotic Head

(pressure)

PureWater

PureWater

PureWater

H2O ➝

H2O ➝

H2O ➝

H2OH2OH2O ➝

➝

➝

➝

➝

➝

➝

➝

➝

➝

➝SaltSolution

SaltSolution

FeedWater



Crossflow filtration in an u ltrafilter showing pyrogensand particles larger than 0.002 micron being retained,while only pure water molecules pass through t he pores.

Courtesy of OSMONICS, INC., Minnetonka, MN, USA.

ULTRAVIOLET OR PHOTO OXIDATION usesultraviolet radiation at the biocidal wavelength of 254 nanometers to eliminate bacteria from thesystem. It also cleaves and ionizes certain organicsat 185 nanometers for subsequent removal by the

deionization and organic adsorption cartridges inthe polishing loop.ELECTRODIALYSIS (ED) removes impurities

from water using an electrical current to drawionic contaminants through ion selectivemembranes (ion exchange resin in sheet form) andaway from the purified water. Used occasionally toproduce potable water from clean brackishfeedwater, ED is cost competitive with reverseosmosis.

To produce laboratory grade water, however, EDhas several drawbacks and, as such, is rarely used

in lab settings. First, the contaminants ED canremove are limited. ED cannot removecontaminants such as certain organics, pyrogensand element al metals which have weak ornonexistent surface charges because they are notattracted to the membranes. Second, ED requires askilled operator and routine maintenance. Largemolecules which bear a significant charge such ascertain colloids and detergents can plug themembranes’ pores, reducing their ionic transportability and requiring frequent cleaning. Duringoperation, ED liberates caustic soda which may

cause scaling, and hydrogen gas which ispotent ially dangerous. Finally, ED is relativelyexpensive. As ionic contaminants are r emoved

Pr oblems With The Tra ditiona lApproaches

While t he water purification systems available

today are often complex, they rely on traditionalmethods and are not problem-free.

The most common problems are:

1. Inconsistent quality.a) water quality that is good on Friday, bad

on Mondayb) bacteria-free water one day, bacteria-

ridden water th e next, often to levels thatare non-potable

c) unpredictable pyrogen levelsd) difficult to monitor water quality —

conductivity meters unrealistic or semi-functional

2. Lack of quality control with central systems.a) reliance on others to maintain the

system could resu lt in several days’wasted work due t o neglect or errors inregeneration of resins

b) difficulty in getting the system plumbedproperly by trained personnel using inertmaterials

c) product water contaminated by plumbing

and bacteria en r oute to the dispenser

3. System that makes product water of poorerquality than the feedwater.a) organics leaching out of the system

rather than being removed by thesystem, thus the water is unsuitable forHPLC purposes

b) carbon fines, resin fragments, andfiberglass fibers appearing as particulatematter in the product water

4. Traditional modular system designs.a) heavy wall-mounted units that require

professional maintenance crews to installb) difficult to servicec) leaks likely when trying to service the unitd) no sound insulation — very noisye) excessive costs for replacing cartr idges

and submicron filters

5. Improper specification of a water pur ificationsystem.a) inadequate investment in equipment

resulting in system with low productionrate or need for frequent cartridgechanges

b) inconsistent water quality with components

FEED FLOW

CONCENTRATE FLOW

P E R M E AT E F L O W

P E R M E A T

E

F L O W



Labconco’s Conceptsin Wat er P ur if ication

Labconco has developed three point-of-usewater purification systems that directly address theshortcomings found in traditional approaches towater purification. The concepts that Labconcobrings to the field of water pu rification, along withits h igh standards of quality construction of laboratory equipment and excellent service, are:

a) Recirculation th roughout the polishing system ,to the dispenser(s), to minimize bacterial buildupfound in standing water.b) Unique dispensing gun for sensit ive one-handcontrol of flow rates and enhanced flexibility.c) Informative diagnostic panels to relay systemstatus and performance.d) Higher capacity filters providing longer life,requiring fewer filter replacements, and reducingoperating costs.e) Highest quality materials , including spiralwound thin film composite reverse osmosismembranes, nuclear grade resins, and all inertmaterials of construction, such as virginpolypropylene in the water pathway.f) Timed dispense feature , which automaticallyshuts off the dispenser once user set time haselapsed, to allow for unattended operat ion.

The first of the th ree water purification systemsmanu factured by Labconco is the WaterPro ®

Softener . An ideal partner for any reverse osmosiswater purification system, the Softener extends thelife of the reverse osmosis membrane by protectingit from scaling due to hard water. The Softenermay also be connected to a glassware washer toprovide pretreated water to any cycle.

The WaterPro ® RO Station delivers laboratorygrade water for routine use or for furtherpurification by a polishing stat ion. Its reservoirholds 17 liters of water and dispenses up to 8.7liters per minu te (gravity fed). When the reservoiris empty, the WaterPro RO typically dispenseswater at a rate of one liter per minute (at 25° C).The RO Stat ion may be moun ted on a wall or onan accessory benchtop stand. It easily connects to

the WaterPro PS Polishing Station or toLabconco ’ s glassware washers. An accessory 70liter storage tank may be connected to the ROStation to provide additional water storage.

The WaterPro ® PS Polishing Station has adispensing center equipped with either adispensing valve or with a pistol t o typicallydispense up to 1.8 liters per minute of Type I water.Like traditional water purification systems, theWaterPro PS may hang on the wall or othervertical surface or be bench mounted using anaccessory stand. Various cartr idge configurationsare available to suit the needs of analyticalchemists, clinical and life scientist s, and HPLCanalysts. An optional dual wavelength ult ravioletreactor ensures both low TOC levels and bacter ia-free water.

In addition, an accessory mobile stand addsportability to pure water delivery. It accommodatesthe WaterPro RO Station on one side and theWaterPro PS Polishing Station on the other side.

Testing the feedwater before selecting a waterpurification system is essent ial. Labconco offersth e WaterProfile ™ Water Test Kit , a free analysis.For a WaterProfile Kit or additional assistance inthe selection of a water purification system,contact Labconco at 800-821-5525, 816-333-8811,or e-mail [email protected].

Labconco #9000501 WaterPro PS Polishing StationOn Support S tand #9077400



GlossaryACS: American Chemical Society

Activated Carbon: Aporous carbon material used for adsorption of organics and absorption of free chlorine.

Adsorption: The physical attraction and adherence of gas or liquidmolecules to the surface of a solid.

Anion: Anegatively charged particle or ion.

APHA: American Public Health Association.

BOD: Biological oxygen deman d.

CAP: The College of American Pathologist s.

Carbon fines: Very small particles of carbon that may wash out of anactivated carbon filter.

Cartridge: Aprepacked method for housing t he filtering components of awater purification system. Because of the modular design of filter element splaced in a cartr idge, the chan ging of exhausted filters is greatly facilitated.

Cation: Apositively charged particle or ion.

Cfu/ml: Colony forming units per milliliter; a measure of viable microbialpopulations in water.

Chemisorption: The formation of bonds between the surface molecules of carbon and chlorine coming in contact with it.

COD: Chemical oxygen demand.

Colloid: Astable dispersion of molecular aggregates in water that have asize ranging between one and two hundred millimicrons. Colloidal iron,aluminum, and silica are commonly found in water.

Concentrate: The reject water from a reverse osmosis membrane; calledthe concentr ate because it contains a higher level of contaminants t hanthe feedwater.

Conversion rate: Aquant ification of the r elationship between th e volumeof feed and product water of a reverse osmosis membrane.

Dalton: Aunit of molecular weight, 1.66 x 10 -24 grams: One Dalton isequivalent to the weight of one hydrogen atom. 1,000 Daltons areequivalent to a .0013 micron diameter for globular proteins.

Deionization: The process of removing the charged constitu ents orionizable salts (both organic and inor ganic) from solution. Apu rificationprocess that uses synthetic resins t o accomplish t he selective exchange of hydrogen or hydroxyl ions for the ionized impurities in the water.

Distillation: Apurification process involving the phase change of waterfrom liquid to vapor and back to liquid, leaving behind certain impurities.

Electrodialysis: Apur ification process that removes impurities from waterusing an electrical current to draw ionic contaminants thr ough ionselective membranes (ion exchange resin in sheet form) and away fromthe purified water.

Endotoxin: The lipopolysaccharide fragments of bacterial cell walls,ranging in size from 15,000 to one million Daltons in size; consideredpyrogenic if they have a fever inducing effect.

Endotoxin Units: EU; a quantification of endotoxin levels using the LAL test.

Exhaustion: The state in which an ion exchange resin is no longercapable of useful absorption: the depletion of the exchanger ’s supply of available ions. The exhaustion point is typically determined in terms of the reduction in quality of the effluent water as determined by aconductivity bridge which m easures the r esistance of the water to theflow of an electric current.

Exotoxin: Atoxic substance secreted by a bacterium, often causingdisease, such as tetanus or botulism.

Feedwater: The water brought to a filtering method before it is filtered;the water en tering a purification system.

GC: Gas chromatography.

Grain: Aunit of weight; 0.0648 gram, 0.000143 pound.

Hardness: The scale-forming and lather-inhibiting qualities which waterpossesses when it has h igh concentrations of calcium and m agnesiumions. Temporary hardness, caused by the presence of magnesium or

calcium bicarbonate, is so-called because it may be removed by boilingthe water to convert th e bicarbonates to the insoluble carbonates.Calcium sulfate, magnesium sulfate, and the chlorides of these twoelements cause permanent hardness.

Hydroxyl: The term u sed to describe the an ion (0H -) which is responsiblefor the alkalinity of a solution.

ICP: Inductively coupled plasma; a technique for analyzing a largenumber of different heavy metals simultaneously, usually preceded by adigestion u sing concentrated stron g acids.

Ion: Any nonaggregated particle of less than colloidal size possessing

either a positive or a negative electric charge.Kilohms: One thousand ohms.

KMnO 4: Potassium permanganate.

LAL: Limulus Amoebocyte Lysate, a test for pyrogen/endot oxin levels.LAL is an extract from the horseshoe crab which forms a gel in thepresence of sufficient pyrogens.

Mass Spectroscopy: Avery sophisticated technique for molecular analysisthat breaks a molecule into recognizable portions.

Megohm: Aun it of electrical resistance; one million ohm s.

Megohm-cm: The measure of electrical resistance across a onecentimeter gap, used as an indicator of ionic contamination.

Micron: 1 x 10 -3 millimeters; 1 x 10 -6 meters; also known as a m icrometer.

Microsiemen: Aunit of measure of conductivity; also called micromho;

the inverse of the megohm; 1 x 10 -6 siemens. One microsiemen is equalto one megohm; t en microsiemens are equal to 0.1 megohm.

Monovalent: An ion in solution that has given up or gained only oneelectron, represented by one plus or minus sign in front of the ion’ssymbol. Sodium ion (Na +), chloride ion (Cl -), and ammonium ion(NH4 +) are all monovalent ions.

Mixed Bed Ion Exchange: Acombination of anionic and cationicexchange resins m ixed together in one container.

Nanograms: 1 x 10 -9 grams; 0.000000001 gram.

NCCLS: The National Committee for Clinical Laboratory Standards.

Nuclear Grade Resin: The quality of deionizing resin material requiredfor the n uclear energy industry; the h ighest quality grade of resin.

pH: An expression of the acidity of a solution; the negative logarithm of the h ydrogen ion concentration. pH 1 is very acidic; pH 7 is neutr al, the

theoretical pH of water; and pH 14 is very basic. The electromotive forcebetween a glass electrode and a reference electrode when immersed in anaqueous solution as compared to t hat measured for a reference buffersolution.

Polish: The process of removing the r emaining contaminants from apreprocessed feedwater.

Polishin g Mixed Bed Resin: Amixed bed of cation and anion exchangeresins designed for use in high purity water systems.

Pyrogen: Athermostable component of gram-negative bacteria cell wallsthat may cause a fever when injected or infused.

Reject water: The water from a reverse osmosis membrane whichcontains a higher level of contaminants t han t he feedwater th at is carriedout the drain; the concentrate.

Reverse Osmosis: Aprocess in which water is forced under a pressuresufficient to overcome osmotic pressure th rough a semipermeablemembrane leaving behind a percentage of dissolved organic, dissolvedionic, and suspended impurities, typically 90-100%. Product water qualitydepends on feedwater quality.

Silt Density Index: SDI: also called the Fouling Index: a test used todetermine th e concentration of colloids in water; derived from the rate of plugging of a 0.45 micron filter r un at 30 psi pressure.

Specific Resistance or Resist ivity: The electrical resistance in ohmsmeasured between opposite faces of a one centimeter cube of an aqueoussolution at a specified temperature. Resistivity is usually corrected to25ºC an d expressed as megohm s-cm.

Total Organic Carbon: TOC; measures the degree of contamination bymicroorganisms and organic compounds.

Total Dissolved Solids: TDS; a semi-quantitative measure of the sum totalof organic and inorganic solutes in water.

Turbidity: Refers to the degree of cloudiness of the water caused by thepresence of suspended particulate or colloidal material. In a photometr icmethod, tu rbidity acts as an analyte by reducing th e transmission of light; measured in tur bidity units.



BibliographyAmerican Chemical Society, Reagent Chemicals: American ChemicalSociety Specifications , 9th Edition, ACS, Washingt on, DC, 1999

American Public Health Association, American Water Works Association,

Water Pollution Control Federation, Standard Methods For The Examination of Water and Wastewater , 20th edition, published by APHA,1999

American Society for Testing And Materials, Standard S pecification for Reagent Water , D1193-99e1, © 2003

C. Clarine Anderson , A Comparison Of TOC Measurements In High-Purity Water Using Commercially Available Equipment ,Microcont aminat ion, April 1986

Brunswick’s The Filterite Cartridge Filtration Guide , Brunswick Corporation

Paul N. Cheremisinoff and Fred Ellerbusch, Carbon Adsorption Handbook , Ann Arbor Science Pu blishers Inc., Ann Arbor, MI: 1980

College of American Pathologist s, Reagent Water Specifications, © 1985,Commission on Laboratory Inspection and Accreditation

William V. Collentro, Water Purification Sy stems: Sim ilarities BetweenThe Pharmaceutical and Sem iconductor Industries , PharmaceuticalTechnology, September 1986

James F. Cooper, Draft LAL-Test Guidelines Welcomed by Industry ,P & MC Industry, September/October 1983

Fred Crowdus, System Economic Advantages of a Low Pressure Spiral RO System Using a Thin Composite Membrane , Ultrapure Water,July/August 1984

Helena Curtis, Biology , 5th Edition, Worth Publishers, Inc., © 1989

Filmtec Literature, Filmtec, 7200 Ohms Lane, Minneapolis, MN 55435

M.A. Floyd, A.A. Halouma, R.W. Morrow, R.B. Farrar, Rapid Multielement Analysis Of Water Samples By Sequential ICP-AES , AmericanLaboratory, March 1985

Marilyn C. Gould, Endotox ins in Vertebrate Cell Culture: Its Measureand S ignificance , Associates of Cape Cod, Inc., Woods Hole,Massachusetts

Reinhard Hanselka, P.E., Contamination S ources In Deionized Water Vessels and High-Purity Valving , Microcontamination, June/July 1984

Walter Lorch, editor, Handbook of Water Purification , McGraw Hill Book Co., © 1981

J. Mandelstam and K. McQullen, editors, Biochem istry of BacterialGrowth , Halsted Press, © 1973

Marc W. Mittleman, Biological Fouling of Purified Water Systems, Parts I and II , Microcontamination, October/November 1985

National Committee For Clinical Laboratory Standards, Preparation and Testing of Reagent Water in the Clinical Laboratory , 3rd Edition, August1997, NCCLS Vol. 17, No. 18

William H. Nebergall and William Robinson General Chemistry , 7thedition, Hought on Mifflin Company, Boston , MA, 2003

Thomas J. Novitsky, Ph.D. Monitoring and Validation of High PurityWater System s With The Lim ulus Amoebocyte Lysate Test For Pyrogens ,Pharmaceutical Engineering, March/April 1984

Osmonics literature, Osmonics Inc., 5951 Clearwater Dr., Minnetonka,MN 55343

Pall’s Principles of Filtration , Pall, Europa House, Havant Street,Portsmouth PO1 3PD, England

Pelczar, Michael J., Chan and Krieg, Microbiology: Concept and Applications , 1st Edition, McGraw-Hill Higher Education., © 1999

Robert R. Reich and Helen D. Anderson , Laboratory Application of Ultraviolet Irradiation , MD & DI August 1985

Rohm and Haas Technical Bulletinsa) Amberlite MB-1b) Amberlite MB-3c) Nuclear Grade Amberlite Ion Exch ange Resins

D. Dean Spat z, Methods Of Water Purification , presented to the AmericanAssociation of Nephrology Nurses and Technicians at the ASAIO-AANNTJoint Conference, Seatt le, WA, April 1972, © 1971

Ronald A. Tetzloff, Aseptic Process Validation , P & MC Industry,September/October 1983

Ultra Dynamics’ Technical Bulletin, Purification By Ultraviolet Radiation , Ultra Dynamics Corporation, 1631 Tenth Street, SantaMonica, CA 90404

The United States Pharmacopeia, 1996 Edition, -USP Convention, Inc.

Water Quality Association, Technical Papers Presented At WQA AnnualConvention, March 6-10 1985Water Quality Association Pu blications

a) A Glossary Of Termsb) Demin eralization by Ion Exchangec) Reverse Osmosis And Ultrafiltration

Water Quality Associat ion, 4151 Naperville Road, Lisle, IL 60532

David R. Lide, PhD, editor, Handbook of Chem istry and Physics , 81stedition, CRC Press, © 2000



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