WATER TESTING KITS
FOR FIELD USE
Water is tested in laboratories to find out
the minerals present in it along with parameters like pH, conductivity, colour
and turbidity. The tests help establish the presence of any parameter and the
extent to which it is present in a particular water. Most of the tests are done
using the time tested method of titration, using laboratory glassware like
burettes, pipettes, conical flasks and beakers. This method still prevails
although modern instruments like spectrophotometers, chromatographs, etc have
started making their presence felt for testing parameters where the titration
method cannot be used.
Since it is not possible to carry delicate
glassware out into the field for field tests, several companies/agencies/NGOs/Government
laboratories have done a lot of work to bring out kits which use the titration
principles but are light, can stand up to rough 'travel' and still give fairly
accurate results. These are field test kits which can be used anywhere and by anyone
who can read the instructions. Titration involves using a chemical solution of
a known strength in a burette to be added to a sample of water to be tested in
a beaker/conical flask. A chemical indicator solution is also added to the
water before titration. The solution from the burette is added to the sample in
carefully controlled drops with the sample being continuously stirred. This
addition is stopped when the colour of the sample changes. The burette reading
taken after colour change is multiplied by a specific numerical factor. This
gives the quantity of the parameter tested for in the water in terms of
mg/litre or parts per million (pm). All titration tests are colorimetric tests
where a change in colour is an indication that the presence/absence of the
parameter being tested had been ascertained.
Most of the field test kits operate on the
same principle. The kit consists of a sample bottle with a marking on it to
indicate that the sample to be tested must be filled up to that mark. Another
bottle contains the required chemical solution (which in a lab would be in the
burette). This bottle would have a dropper fitted on it. Depending on the
parameter to be tested, there would be a small dropper bottle containing the
indicator solution (tests for certain parameters may not need such an
indicator).To use this kind of a kit, the sample bottle is first rinsed with
the water to be tested and then filled up to the mark. The solution from the
dropper bottle is added to this sample after adding the recommended drops of
indicator solution, a drop at a time, counting each drop. When the colour of
the sample changes, the addition of the solution is stopped, number of drops
added is multiplied by a factor given in the instruction manual to arrive at the
quantity of the parameter in mg/litre of water or ppm.
Test kits used for testing the
bacteriological content in water are slightly different. Some have a bottle in
which the sample of water to be tested is put and into which another solution
is added. It is then shut and kept for a period of several hours or overnight.
If, at the end of this period, the sample has acquired a colour as given in the
instructions, it indicates that the sample is bacteriologically contaminated,
otherwise not. Another kit used for such tests is called a 'dip slide'. It
consists of a slide made of an inert plastic material coated with a nutrient
which is kept inside a sealed container. This slide is taken out of the
container by breaking the seal of the container, dipped into the sample of
water to be tested and then kept aside for several hours or overnight. If, at
the end of this period, the slide has acquired or changed colour it is an
indication that the sample is contaminated. Tests for bacteriological
contamination using such kits only indicate the presence or absence of
contamination (also called a GO/NO GO result) and not its extent.
It is important to remember that all such
kits have a shelf life. Once this has expired, the kits must not be used as
results will be wrong or inconsistent. Given below is a table of the kits
available in the market indicating the parameter, name and
manufacturer/supplier from whom they can be procured. The accuracy of the
results may not be as accurate as those done in a laboratory. It may be in the
range of +/- 5. In the table below, where a multiparameter kit is indicated but
not the parameters, it is usually for the parameters which determine the
potability of water.
List
of Kits :
|
Type
/ Name of Kit
|
Parameter
|
Cost
(Rs.)
|
|
Kits
made / sold by Development Alternatives
|
||
|
Jal TARA WTK-14
|
14 parameters
|
7913.00*
|
|
Jal TARA WTK-11
|
11 parameters
|
7238.00*
|
|
Jal TARA Mini Kit-I
|
Fluoride
|
1220.00*
|
|
Jal TARA Mini Kit-II
|
Nitrate
|
1474.00*
|
|
Jal TARA Mini Kit-III
|
Iron
|
1475.00*
|
|
Jal TARA Mini Kit-IV
|
Free chlorine
|
1138.00*
|
|
Jal TARA Mini Kit-V
|
Arsenic
|
3073.00*
|
|
Jal TARA - Set of 10 tests
|
Coliform bacteria
|
290.00* per set
|
|
* The cost is inclusive of Basic price,
Applicable tax (VAT/CST) and Freight charges.
|
||
Important:
All prices for Jal Tara Kits are inclusive of tax and
freight.
Manufacturer
Details:
Development
Alternatives,
Technology
and Action for Rural Advancement (TARA)
B-32
Tara Crescent, Qutab Institutional Area,
New
Delhi - 110 016, INDIA
Tel:
+91-11-685-1158, 696-7938
Fax:
+91-11-686-6031;
Website:
http://www.devalt.org
References:
http://www.cleanindia.org/jaltarakit.htm
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