basic requirements of water testing laboratory 1

Basic Requirements of Water Testing Laboratory 1

2 A Technical Manual for Water and Westewater Analysis

Dr. Sunil P. PandeDirector-grade-Scientist (Retired),

NEERI, Nagpur.

Dr. (Mrs.) Leena DeshpandeTechnical Officer,NEERI, Nagpur.

A TECHNICAL MANUALFOR WATER AND

WASTEWATERANALYSIS

MUMBAI NEW DELHI NAGPUR BENGALURU HYDERABAD CHENNAI PUNE LUCKNOW AHMEDABAD ERNAKULAM BHUBANESWAR INDORE KOLKATA GUWAHATI


Published by : Mrs. Meena Pandey for Himalaya Publishing House Pvt. Ltd.,“Ramdoot”, Dr. Bhalerao Marg, Girgaon, Mumbai - 400 004.Phone: 022-23860170/23863863, Fax: 022-23877178E-mail: [email protected]; Website: www.himpub.com

Branch Offices :New Delhi : “Pooja Apartments”, 4-B, Murari Lal Street, Ansari Road, Darya Ganj,

New Delhi - 110 002. Phone: 011-23270392, 23278631; Fax: 011-23256286Nagpur : Kundanlal Chandak Industrial Estate, Ghat Road, Nagpur - 440 018.

Phone: 0712-2738731, 3296733; Telefax: 0712-2721215Bengaluru : No. 16/1 (Old 12/1), 1st Floor, Next to Hotel Highlands, Madhava Nagar,

Race Course Road, Bengaluru - 560 001.Phone: 080-32919385; Telefax: 080-22286611

Hyderabad : No. 3-4-184, Lingampally, Besides Raghavendra Swamy Matham,Kachiguda, Hyderabad - 500 027.Phone: 040-27560041, 27550139; Mobile: 09390905282

Chennai : No. 8/2, Modley 2nd Street, Ground Floor, T. Nagar, Chennai - 600 017.Phone: 044-28144004/28144005; Mobile: 09345345051

Pune : First Floor, "Laksha" Apartment, No. 527, Mehunpura, Shaniwarpeth(Near Prabhat Theatre), Pune - 411 030. Phone: 020-24496323/24496333;Mobile: 09370579333

Lucknow : Jai Baba Bhavan, Church Road, Near Manas Complex and Dr. Awasthi Clinic,Aliganj, Lucknow - 226 024 (U.P.). Phone: 0522-2339329, 4068914;Mobile: 09307501550

Ahmedabad : 114, “SHAIL”, 1st Floor, Opp. Madhu Sudan House, C.G. Road, Navrang Pura,Ahmedabad - 380 009. Phone: 079-26560126; Mobile: 09377088847

Ernakulam : 39/104 A, Lakshmi Apartment, Karikkamuri Cross Rd., Ernakulam,Cochin - 622011, Kerala. Phone: 0484-2378012, 2378016; Mobile: 09344199799

Bhubaneswar : 5 Station Square, Bhubaneswar - 751 001 (Odisha).Phone: 0674-2532129, Mobile: 09861046007

Indore : Kesardeep Avenue Extension, 73, Narayan Bagh, Flat No. 302, IIIrd Floor,Near Humpty Dumpty School, Indore - 452 007 (M.P.). Mobile: 09301386468

Kolkata : 108/4, Beliaghata Main Road, Near ID Hospital, Opp. SBI Bank,Kolkata - 700 010, Phone: 033-32449649, Mobile: 09910440956

Guwahati : House No. 15, Behind Pragjyotish College, Near Sharma Printing Press,P.O. Bharalumukh, Guwahati - 781009, (Assam).Mobile: 09883055590, 09883055536

DTP by : HPH, Editorial Office, Bhandup. (Krunali)Printed at : Geetanjali Press Pvt. Ltd., Nagpur, On behalf of HPH.

First Edition : 2012

© AUTHORSNo part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means,electronic, mechanical, photocopying, recording and/or otherwise without the prior written permission of the publishers.


Preface

Presently, there are many agencies involved in water supply in India and each agencyhas its own laboratory test practices. In view of the demand for a comprehensive manual byvarious water quality testing laboratories at Central, State, District, Block and Gram Panchayatlevels, effort has been made to prepare a technical manual for water and wastewater analysiswhich can cater to the needs of various laboratories. The main objective of this manual is toensure quality control in water testing laboratories.

This manual includes the methods for physico-chemical, microbiological, and biologicalparameters which can be practiced in all the laboratories. Due emphasis has been given inthis manual to basic requirements in water testing laboratory and sampling procedures whichare important factors for water and wastewater testing. More than one analytical method hasbeen described for the testing of physico-chemical parameters. Appropriate analytical methodcan be adopted by the concerned water testing laboratory depending on the equipment/instrument availability. A separate chapter in the manual describes some useful tests for drinkingwater treatment. WHO Guidelines and Indian Standards for drinking water have been given asannexures in this manual.

The contributions and suggestions of all the scientific and technical staff involved in waterand wastewater analysis at the National Environmental Engineering Research Institute (NEERI)is greatly acknowledged. We cannot thank them enough for their cooperation and manygestures.

We hope this technical manual will go a long way in providing valuable guidance to all thechemists/analysts who are involved in water and wastewater analysis in this country.

Dr. Sunil P. Pande

Dr. Leena S. Deshpande


Detailed Contents

No. Chapter Name Page No.

1. BASIC REQUIREMENTS OF WATER TESTING LABORATORY 1 - 6 Analytical Quality Control

2. SAMPLING PROCEDURES 7 - 18 Introduction Selection of Sampling Locations Sampling Frequency

– Number of Samples

Sampling Equipment– Sample Containers

Sample Collection– Other Points Requiring Attention

Sample Preservation, Handling and Transport– The Physico-chemical Determinands of Interest are – SampleRequirements and Methods of Preservation for Nutrient Group– Sample Requirements and Methods of Preservation for Basicand Optional Determinands – Sampling and Preservation ofSamples of Organic Groups – Prevention of SampleContamination

3. PHYSICO-CHEMICAL ANALYSIS 19 - 21 Introduction Analytical Procedures Types of Analysis

4. MINERAL PARAMETERS 22 - 61 Temperature Procedure pH

– Electrometric Method

Conductivity Turbidity Colour

– 1. Platinum Cobalt Method – 2. Photoelectric Method


Solids– 1. Filtration Method – 2. Centrifugal Method – SettleableSolids

Alkalinity Chloride

– Argentometric Method

Fluoride– 1. SPADNS Method – 2. Ion Selective Electrode Method

Silica Sulphate Sulfide

– Introduction – Qualitative Estimation – Quantitative Estimation

Total Cyanide– Calibration Graph

Hardness– A. Total Hardness – B. Calcium Hardness – C. MagnesiumHardness – Alkaline (Carbonate) Hardness and Non Alkaline(Non Carbonate) Hardness

Sodium and Potassium– Equipment

5. DEMAND PARAMETERS 62 - 74

Dissolved Oxygen– A. The Winkler Method wi th Azide Modif icat ion– B. Membrane Electrode Method – C. Open Reflux Method

Chemical Oxygen Demand

Biochemical Oxygen Demand

Total Organic Carbon– Combustion-Infrared Method

6. NUTRIENT PARAMETERS 75 - 87 Total Kjeldahl Nitrogen

Ammonia Nitrogen

Nitrite Nitrogen

Nitrate Nitrogen– Phenol Disulphonic Acid (PDA) Method – UVSpectrophotometric Method


Phosphate — Total and Other Forms– Preparation of Calibration Graph

7. METALS 88 - 142 Introduction

Preliminary Digestion for Metals– Open Digestion – Microwave Digestion System

Estimation of Metals – A. Inductively Coupled Plasma (ICP) Method – Equipment– Flame Atomic Absorption Spectrophotometry – Procedure– B. Flame Atomic Absorption Spectrophotometry

Aluminum (Al)– Scope and Application – Methods for Analysis

Arsenic (As)– Scope and Application

Boron– Introduction – 1. Curcumin Method – 2. Carmine Method

Cadmium

Chromium

Copper

Iron– Phenanthroline Colorimetric Method

Lead– Dithizone Method – Preparation of Calibration Curve

Manganese

Mercury– Cold Vapour Atomic Absorption Method

Nickel

Selenium– Colorimetric Method

Zinc– Calibration Curve – Procedure


8. ORGANIC ANALYSIS 143 - 170

Introduction– Sources and Significance

Analytical Instrumentation– Chromatography – General Basis for Gas Chromatography– Sample Injection – Detection of Eluted Compounds (Detector)– Identification and Quantification

Sample Processing

Oil and Grease (Mineral Oil)– 1. Partition-Gravimetric Method – 2. Soxhlet ExtractionMethod

Phenols– Introduction – 1. Chloroform Extraction Method – 2. DirectPhotometric Method

Polynuclear Aromatic Hydrocarbons– Introduction

Trace Organics– Liquid-Liquid Extraction Gas Chromatographic/MassSpectrometric Method – Experimental Procedure – InstrumentConditions

9. PESTICIDES ANALYSIS 171 - 179 Introduction

Estimation of Pesticides– Interference – Sample Processing – Florisil Clean-up

10. MICROBIOLOGICAL ANALYSIS 180 - 207 Preamble

– 1. Coliform Bacteria – 2. Faecal Coliform Bacteria – 3. FaecalStreptococci – 4. Clostridium Perfringens 5. Pseudomonasaeruginosa – 6. Hydrogen Sulphide (H2S)-producing Bacteria– 7. Coliphages and Other Bacteriophages

Composition of Common Bacteriological Culture Media– 1. MacConkey Broth – 2. Brilliant Green Lactose Bile Broth– 3. EC Broth – 4. EC-MUG Medium – 5. Indole Medium– 6. MacConkey Agar: (w/o crystal violet and NaCl, w/o Sodiumtaurocholate)


Test Procedures– A. H2S

-strip Test (Rapid Field Test for Bacteriological Qualityof Drinking Water) – B. Multiple Tube Fermentation Techniquefor Coliform Bacteria (MPN test) – C. Membrane FiltrationMethod for Total Coliforms and Thermotolerant (Faecal)Coliforms – D. EC-MUG Test for Confirmation of E. coli – E.Identification/Differentiation of Coliform Bacteria EncounteredDuring Bacteriological Testing of Water

Bibliography

Detection of MS2 Bacteriophages– Agar Overlay for the Detection of MS2 Bacteriophages

11. BIOLOGICAL ANALYSIS 208 - 226

Phytoplankton– Introduction – Methods for Analysis – Apparatus andEquipment – Sample Collection, Preservation and Storage– Calibration and Standardisation – Data Analysis andCalculations – Method Performance and Quality Control– Pollution Prevention and Waste Management

Zooplankton– Introduction – Apparatus and Equipment – Sample Collection,Preservation and Storage – Calibration and Standardisation– Data Analysis and Calculations – Method Performance andQuality Control – Safety – Pollution Prevention and WasteManagement – Bibliography

12. SEDIMENT ANALYSIS 227 - 238

Sample Collection– General Considerations – Sampling Design – Sampling ofSediments

pH

Cation Exchange Capacity

Carbon, Hydrogen, Nitrogen, and Sulphur13. USEFUL TESTS FOR DRINKING WATER TREATMENT 239 - 257

Testing for Residual Chlorine– Introduction – Analytical Methods – Sample Collection,Preservation and Storage – Calibration and Standardisation– Data Analysis and Calculation – Method Performance andQuality Control – Calibration and Standardisation – MethodPerformance and Quality Control – Pollution prevention and


Waste Management – Diethyl-p-phenylene-diamine (DPD)Method – Sample Collection, Preservation and Storage– Method Performance and Quality Control – Stabilised NeutralOrthotolidine (SNORT) Method – Equipment – SampleCollection, Preservation and Storage

Testing for Bleaching Powder– Bleaching Powder – Estimation of Available Chlorine

Testing for Alum (IS: 260-1969)– Methods of Test for Aluminium Sulphate, Non-ferric –Sampling of Aluminium Sulphate, Non-ferric – Determinationof Insoluble Matter – Determination of pH – Determination ofAluminium – Bibliography

Jar Test– Purpose of the Test – Sampling – Equipment – LaboratoryStirring equipment for coagulation and Flocculation or Jar Test

ANNEXURES 258 - 269I. WHO Guideline Values for Chemicals of Health

Significance in Drinking Water (2004)

II. CPHEEO (Ministry of Urban Development, Govt. ofIndia) Regulations for Drinking Water Quality (1999)

III. Bureau of Indian Standards/Specifications for DrinkingWater (IS: 10500, 1992)

IV. CPCB Guideline Values for Classification of InlandSurface Waters (1982)


The role of laboratory in analysis of water and wastewater samples can hardly be overemphasized. Laboratories are the essential corner-stones of effective and reliable water andwastewater testing programmes. The analytical laboratories provide qualitative as well asquantitative data for use in decision-making. For generating this valuable data with a desiredaccuracy to quantify the properties and concentration of the constituents present in the samplessubmitted to the laboratory, the laboratory should have the desired facilities and capabilitiesto achieve the above goal. The erroneous data are worse than no data at all because thesemay mislead the decision-maker and ultimately lead to wrong decisions. The errors in analysismay arise due to various factors like lack of proper preservation, improper sample containers,inferior quality of chemicals or glassware, impurities in distilled water, instrumental errors,improper selection of analytical method, personal error etc. Hence, in order to producemeaningful and reliable analytical data it is necessary that the laboratory should have goodinfrastructural facilities of a minimum acceptable quality and the relevant designed expertise.Regular analytical quality control programmes are necessary to ensure the reliability ofanalytical data.

Quality control of analytical data of water and wastewater analysis generated in alaboratory requires control of many variables that may affect the production of reliable data.The laboratory should have sufficient space properly designed, interior furbishing, properventilation, dust free atmosphere etc. Regular and proper supply of some of the essentialneeds like water and electricity is to be ensured for the smooth functioning of the laboratory.In addition to these, other important factors like facilities for weighing, cleaning of glassware,quality of chemicals, fire fighting facilities, laboratory safety and first-aid facilities are essentialrequirements of a water and wastewater testing laboratory. These factors are briefly describedin following paragraphs:

Distilled Water: Distilled or demineralized water is used in the laboratory for preparationof reagents, dilution and final rinsing of glassware / polytheneware. Ordinary distilled watermay be contaminated by dissolved gases, materials leached from the container in which it isprepared or stored. Hence for specific determinations distilled water may require further

CHAPTER

1 BASIC REQUIREMENTS OF WATERTESTING LABORATORY


purification. However, selection of still, storage tank and any associated piping needs carefulselection to ensure minimum contamination. Generally, distilled water with conductivity around2.0 mhos/cm or less is considered as reasonably pure for routine work. The degree of puritycan be further classified as:

Degree of purity Maximum conductivity Approximate concentrationµ mhos/cm of electrolyte (mg/L)

Pure 10 2 – 5

Very pure 1 0.2 – 0.5

Ultra pure 1 0.01 – 0.02

Theoretically pure 0.05 0.00

Generally, metal stills made of stainless steel are reliable source of distilled water. Forspecial purposes, like analysis of heavy metals, pesticides, organic compounds, glass distillationunit is better. When the salinity/dissolved solids in incoming feed water is high it is requiredthat preliminary softening by a mixed-bed ion exchanger be carried out.

Water Supply: The water is an essential need of the laboratory without which work ofthe laboratory is likely to be hampered. Hence, the laboratory should be provided with acontinuous water supply either from a direct supply source or through storage tanks. It ispreferred, if a separate water storage tank is made available for exclusively laboratory purpose.

Electricity Supply and Electrical Services: Similar to water supply, regular and properelectric supply (220 – 230 Volts) is essential for smooth functioning of the laboratory. Necessaryand adequate provisions should be made for continuous supply, proper constant voltage,adequate load, desired level of illumination, proper electrical fittings etc.

Some instruments like spectrophotometer, flame photometer, atomic absorptionspectrophotometer, gas chromatograph etc., require constant voltage to maintain stabilityand drift-free instrument operation. For such instruments voltage regulation is necessarywhich can be achieved through stabilizers and UPS systems.

Weighing Facilities: The most important equipment in any analytical laboratory is theAnalytical Balance. The degree of accuracy of the balance is reflected in the accuracy of alldata related to weight-prepared standards and gravimetric determinations. The balance shouldtherefore be the most protected and cared instrument in the laboratory. Each type of balancehas its own place in the scheme of laboratory operation. But analytical single pan balanceplays the most important role in the production of reliable data. The analytical balance shouldbe mounted on a heavy shock proof table located away from the other equipments, in a dustfree zone. Normally, analytical balance with an accuracy and readability of 0.01 mg and weighingcapacity up to 200 g is suitable for analytical laboratories.

Glassware/Polytheneware: Generally, glassware of borosilicate glass (corning makeBorosil) which is relatively inert, is used for the analytical work. Plastic bottles of polythene orpolypropylene are good for collecting and transporting water samples. Unless instructedotherwise, borosilicate (or polythene) bottles may be used for the storage of reagents andstandard solutions. Standard solutions of silica, boron and alkali metals are stored in polythenebottles. Wherever necessary, amber or dark coloured bottles are to be used for storing photo-reactive chemicals.


Cleaning of Glassware: The method of cleaning depend upon the substances that areto be removed from the glassware and the determination for which it is to be used. Normally,water soluble substances are simply washed out with hot or cold water and the glassware isfinally rinsed with successive small amounts of distilled water. Other substances which aremore difficult to remove may require the use of a detergent, organic solvent, chromic acid,nitric or aqua regain (1:3 : HNO3 : HCl). Glassware to be used for phosphate determinationshould not be washed with detergents containing phosphates.

Quality of Chemicals: The quality of chemicals / solvents used in the analytical laboratorymay vary from Laboratory Grade to Analytical or Guaranteed Grade (Analar or GR). Thequality of chemical/solvent may become one of the causes of erroneous data or may affectthe instrument or may lead to interferences in determinations. Hence, selection of a chemicalof an appropriate quality depending upon the role of that chemical in determination is mostimportant factor for achieving the result with desired accuracy. For preparation of all standardsolutions only ‘Analytical reagent Grade’ (Analar) or ‘guaranteed reagent’ grade (GR) shouldonly be used.

Fire Prevention/Fire Fighting: The laboratory should have adequate facilities for firefighting and fire escape. Generally, portable fire-extinguishers with a suitable extinguishingagent are provided in the corridors and laboratories, so that the extinguishers are always athand. Water showers in the wet laboratory are necessary to fight against the accidents or fire.Training to the staff on fire prevention and fire fighting measures is essential at regular intervals.

Laboratory Safety: Although safety in any laboratory requires continuous attention, thefollowing facilities may be essential to safeguard the health of the laboratory staff:

Multiple storey buildings and especially laboratory should have adequate exit doorsto escape in case of emergency

Adequate hood facilities for highly toxic or highly inflammable materials or gases Adequate number of exhaust fans for proper air-circulation Cleanliness and good house-keeping reduces frequency of laboratory accidents Adequate fire fighting facilities and training to laboratory personnel in its operation.

Laboratory personnel should also be trained regarding pertinent fire hazards withtheir work

Large gas cylinders should be securely fastened Laboratory personnel may get exposed to toxic chemicals by following ways:

- Contact with the skin and eyes

- Inhalation; and

- Swallowing

To avoid these exposures, hand gloves, vacuppets, gas masks, goggles etc. must beused wherever necessary.

First emphasis should be on preventing accidents by following the safe practices.However, inspite of all efforts, accidents may occur. Hence first aid charts should bedisplayed in the laboratory which may be helpful in case of accidents like burns,eye injuries, poisoning etc.


The laboratory staff should have adequate practical knowledge about the safetymeasure, fire fighting, first aid etc., to be taken in the laboratory when such accidentsoccur.

Proper labeling of reagents/chemicals should be practiced with information onCAUTION/WARNING notices as applicable.

Methods of Testing: Number of analytical methods are commonly available for themeasurement of any parameter. However, selection of a most appropriate method for a particulartype of a sample, keeping in mind, interference, accuracy detection limit, working range etc. ismost important. Uniformity of methodology within a single laboratory as well as among groupof participating laboratories is required to remove methodology as a variable, when there aremany data users. This aspect is particularly important when several laboratories participatein a single project to provide data to a common data bank, such as national and internationalprogramme (GAP, GEM, NAAQM, MINARS etc).

ANALYTICAL QUALITY CONTROL

To ensure reliability of the analytical results generated from the recognized laboratory, itis essential to conduct frequent Analytical Quality Control Programme, for the intra and interlaboratory checks. On the basis of the ‘Analytical Quality Control’ results, if required, thelaboratory should improve the performance to achieve the targeted accuracy.

Any study or a project always requires collection and comparison of data. The correctnessof these data are controlled by the size of errors in the results. Thus, it becomes theresponsibility of the laboratory to ensure the reliability and validity of the data reported by thelaboratory. Incorrect results are worse than no results because, these may lead to wronginterpretations or decisions thereby misleading, especially in a project or survey in which anumber of laboratories are involved and interpretation or decision are drawn from the overalldata received from different laboratories. In such projects, the erroneous data from even asingle or few laboratories may create confusion and lead to overall wrong interpretationsthereby spoiling the validity of the data reported by other laboratories also. Hence, it isnecessary to introduce a scheme to achieve a target accuracy, so that the results obtainedfrom different laboratories are comparable.

Analytical Quality Control (AQC) is a scheme introduced to minimize or control theseerrors or in other words, to achieve a target accuracy. The AQC scheme is generally taken upat two levels:

Within Laboratory AQC: Which is necessary basis for checking the precision andaccuracy of analytical results within laboratory.

Between Laboratory AQC: A group of laboratories has to achieve comparability ofresults by controlling the precision and accuracy of each laboratory.

WITHIN LABORATORY AQC

The various sequential stages involved for each parameter are:(i) Choosing an analytical method suitably free from bias and ensuring the complete

and unambiguous description of the method


(ii) Checking that satisfactory precision is obtained with the method(iii) Establishing a control chart as a continuing check on precision and some sources

of bias(iv) Ensuring accuracy of standard solution

Between Laboratories AQC (Inter-Laboratory)AQC tests between laboratories are necessary for the following reasons:(i) To test for possible bias caused by sources not already checked in within laboratory

AQC, and(ii) To provide direct-evidence that the required comparability of results between

laboratories has been achieved

Accuracy may deteriorate with time and hence subsequent regular tests are required asa continuing check on between laboratories bias.

Between-Laboratory Bias TestThe principle of such a test is that identical portions of the same sample are distributed

to different laboratories. Each laboratory analyses the portion it receives and the results fromthe various laboratories are examined by a coordinator who calculates the bias of the resultsof each laboratory. The ideal form, which inter laboratory bias test would take, involves thedistribution of portions of many types of samples to each participating laboratory. However, acompromise has to be drawn between what is technically desirable and practically feasible. Areasonable compromise is to distribute portions of standard solutions and two or three realsamples.

In order to achieve better Analytical Quality Control the following points are to be takeninto consideration while selecting the appropriate analytical method:

Calibration Curve: There is a great advantage in using the method for which calibrationcurve is linear because this simplifies the establishment and checking of calibration.

Limit of Detection: In any analytical method when very small concentrations are to bedetermined the analytical response for the sample and blank must be compared with thestandards.

Interferences: Very few analytical methods are completely specific for the determinandand effects of all substances likely to be present in samples in appreciable concentrationshould be known.

Accuracy of Data: Definition of accuracy required for analytical results is essential atthe first stage in AQC, which is generally used to denote the total error of the result, that isaccuracy represents the combined systematic and random errors of results and is said toimprove as the total error becomes smaller.

Standardisation of the Methods: Analytical results will be biased if the concentrationof the stock standard solution used for preparing calibration standards in the laboratory isinaccurate. The comparison of standards involves analyzing a suitable number of replicates.The difference between the standards should not exceed an agreed target which will be afraction of the maximum tolerable bias.


Control Charts: After AQC has been completed satisfactorily in the laboratory, acontinuing check on accuracy is required so that the time bound deterioration of data can bechecked. For this purpose the use of control chart is recommended. The minimum requirementis the analysis of control standard solution in each set of analysis and plotting of the resultson the control chart. The estimate of standard deviation from previous stage is used to calculatethe warning and control limits of the chart. The concentration of the control standard should beapproximately chosen. An example of the control chart is shown in Fig. 1.1

Other Sources of Errors: Errors in results may also arise through non-representativesampling and through charges in the sample between sampling and analysis. The first sourceof error must be controlled through the choice of appropriate time, location and procedure ofsample collection. The second source of error must be controlled by using appropriatetechnique of sample preservation and by analyzing samples without undue delay. Thespecification of appropriate sample preservation techniques must be an integral part of anyanalytical method and any effective AQC scheme must include all necessary precautionsrequired for sample preservation. The summary of sampling, preservation and sample handlingrequirements is described under Chapter 2.

Sequence of Results

X +3 SD

X +2 SD

X

X -2 SD

X -3 SD

Upper Control Limit

Lower Control Limit

Lower Warning Limit

Upper Warning Limit

Mean Value

1 2 3 4 5 6 7 8 9 10

Fig. 1.1 AQC Control Chart

basic requirements of water testing laboratory 1

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