PH Meter Final

PH Meter
• What is the PH:

• PH is a unit of measure which describes the degree of acidity or alkalinity of a
solution. It is measured on a scale of 0 to 14.
• PH provides needed quantitative information by expressing the degree of
activity of an acid or base in terms of its hydrogen ion activity.
• What is the PH meter:

• A PH meter is a scientific instrument that measures the hydrogen-ion activity
in water-based solutions, indicating its acidity or alkalinity expressed as PH.
and that is done by measures the difference in electrical potential between a
PH electrode and a reference electrode in solution.
Applications of PH Meter:
1. To measure the pH of biological fluids such as blood, urine, gastric
acid etc. to ascertain type of biological conditions and Diagnosing
medical conditions such as diabetes, heart and lung diseases,
poisoning, and others.
2. PH Meter is very crucial in Agriculture industry for soil evaluation.
Major crops require alkaline environment
3. It is also used in Food industry especially for dairy products
4. It becomes mandatory for chemical and pharmaceutical industries and
detergents.
5. PH level monitoring is essential in water treatment.
TYPES OF PH METER
There are three main types of pH meter available:
1- PH electrodes, also known as pen testers, are the cheapest and easiest to
use on the market. The electrode is housed in a glass pen-like container with a
tip that is sensitive to hydrogen ions.
• The small size of the electrode meter means that it can be transported and
used anywhere, although it does have limitations compared to heavier grade
meters. pH electrodes are often used on the go for testing in construction,
hydroponics, food manufacturing and pool maintenance.
• The primary working mechanism of this pH meter is based on the exchange of
ions from the sample solution to the inner solution (pH seven buffer) of the
glass electrode through the glass membrane that generates electric voltage.
Therefore, the result of the pH meter is based on the combined relation
between electric voltage, ion concentration, and pH reading.
•
2- Handheld PH meters
• are more heavy duty than their pen tester counterparts. These meters consist of a
handheld device for display and calibration features as well as an interchangeable
electrode probe component. Handheld pH meters are often used in field work by
environmental officers and in aquaculture, agriculture and water treatment industries.
Many recent models also feature Bluetooth and wireless technology for easy
transmission of data to mobile devices.
3-Benchtop pH meters
• are often found in laboratories and professional industries. These are the
largest types of meter available and are usually either desk or wall
mounted. Benchtop meters provide the highest degree of accuracy when
measuring pH levels and are commonly found in food processing
facilities, quality assurance, water testing and environmental testing.
The main parts of PH meter:
• Probe: The probe, designed as a three-in-one combination, consists of a glass
electrode, reference electrode, and temperature probe. One end of the probe consists
of a sensitive tip glass that detects the solution’s acidity or alkalinity. In contrast,
another end of the probe is connected to the electronic meter that measures and
displays the pH value. The temperature detector in a probe helps to detect the
temperature of the solution. The pH value of the test or buffer solution should be only
measured at room temperature (i.e., 25°C).
• Glass electrode: It is a narrow tube-like structure usually made up of glass consisting
of a highly sensitive glass bulb at the end. It also includes a silver wire coated with
silver chloride immersed in an electrolyte (potassium chloride pH 7) as an electrode.
The glass electrode helps measure potential changes across the glass membrane.
• Reference electrode: It is a glass tube-like structure consisting of a metallic conductor
made of silver chloride immersed in an electrolyte solution, potassium chloride of pH
7. This electrode only comes in contact with the test solution through a ceramic
junction. The reference electrode is used to provide a stable zero voltage connection
and helps to complete the circuit. Therefore, it is insensitive to the solution’s pH.
• Electrometer/Voltmeter: It is attached to the pH electrode that can measure minimal
differences in electrical potential in a circuit.
• Filling hole: It is an opening used to refill the electrolyte.
Block diagram
Procedure for the operation of the PH meter
• Turn on the pH meter and wait for an adequate time for it to initialize (check your pH meter
operating manual for the exact time).
• Remove the electrode from the storage solution and clean it with deionized water.
• After rinsing, blot the dry electrode with non-abrasive Kimwipes or Shurwipes to remove
excess water.
• Maintain the temperature of the sample at 25°C for appropriate reading.
• Place the electrode in a test solution, stir the test solution and also press the measure button
to measure the pH value.
• Then, wait until the reading gets stabilized for 1 to 2 minutes.
• Once the reading gets stabilized press the measure button and record the pH value and also
the temperature.
• When done, remove the electrode, rinse it with deionized water, and blot dry with a Kimwipes.
• Lastly, immerse the probe in a 3M potassium chloride storage solution.
Advantages
• Pocket-sized portable PH meters are easy to carry and measure accurately.
• Lab-scale pH meters are easy to use and occupy less space.
• With proper maintenance and periodic calibration.
• It can be used in a wide variety of protein solutions, viscous preparations and
also solutions with strong oxidants and reductants.
• If properly handled, it can be used for a longer duration of time.
• pH meter provides highly accurate and more precise values than a pH strip.
• Do not require high installation charges. Therefore, they are cost-effective.
Challenges and limitations :
• It needs extra care and attention towards the pH sensing bulb of the electrode and
reference junctions from getting dried. It always needs to be stored in a pH storage
solution.
• PH meter electrodes quickly tend to clog, get coated with sample and becomes dirty.
Cleaning electrodes is a challenge without which the life of the electrodes becomes
short.
• The temperature of the solutions always affects the pH readings. Extra attention
needs to be taken to ensure the temperature of the solution is at room temperature all
time, and also the temperature probe is calibrated before testing the sample for PH.
• Requires regular calibration that consumes an extra amount of time
• Electrodes must be cleaned regularly to remove deposits.
• It is equipped with a highly sensitive probe. Therefore, proper handling is required.
• Fluctuation in reading might occur due to temperature variations and carbon dioxide
absorption.
• They are more expensive than PH strips.

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PH Meter

• What is the PH:

• What is the PH meter:

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