PH level implies the ratio between hydrogen ion [H+] and the hydroxyl ion [OH-] concentrations. That ratio shows the levels of acidic on one side and base activity on the other that can be measured by using the scale of 0 to 14.
When the H+ concentration is higher than OH-, the observed material is acidic and has a ph value that is less than 7. On the other hand, when the OH- concentration is higher than H+, the material is basic, with a pH value more than 7. In the case when the H+ concentration equals the one of H-, the material is neutral and has a pH value of 7.
Bases and acids are both consisted of free hydroxyl and hydrogen ions that form a constant for a certain set of conditions. As they coexist in the same solution, knowing one can help determine the other.
To measure the pH level, you can use several solutions such as PH Meter, OH buffer solution, pH test paper, and pH strips that use different techniques and provide different degrees of accuracy.
What is pH Meter?
It is estimated that pH meter provides the most accurate analyses of alkalinity and acidity. There are an analog and a Digital pH Meter, depending on which display the results are shown. It is comprised of three units: a reference electrode, pH measuring electrode, and high impendence input meter. The pH meter can be understood as a high impedance amplifier that measures the changes of electrode voltage that signal the pH levels. It displays results in pH units.
The pH measuring electrode represents a glass bulb that is hydrogen ion-sensitive. When its hydrogen ion concentration changes both inside and outside the bulb, it affects its millivolt output. On the other hand, those changes don’t affect the reference electrode output. The pH electrode has very high internal resistance, making the voltage change with pH difficult to measure. The input impedance of the pH meter and leakage resistances is therefore important factors.
Buffer Solutions
Buffer measurement has constant pH values for a certain level and can resist further changes. By using buffer solutions you can calibrate the pH Measurement System. There are premixed liquid and dry powder capsules buffers. When measuring pH levels only small differences can be found in the output of the meter. Thus, it is necessary to calibrate the system periodically. The meters mostly need calibration at several pH values. The best way to measure the pH level using the buffer solution is to select it as close as possible to the value of the sample that is measured.
What is pH test paper?
With pH Test Paper you can measure pH levels by simply soaking a paper in indicator to show an actual pH change. There are two types of pH Test Papers. One is a booklet where you can tear off just one leaf and another is a long real where you can tear off any required paper, length.
The benefits of pH paper tests are:
- Small samples– You only need one drop to measure the pH level, making the whole process faster.
- Measure difficult samples– By using the long reel, you can reach samples that are stuck at the bottom of the long test tubes.
- Specific tests– As they provide fast results, they are more popular with specific tests such as those that use Litmus paper and Phenolphthalein paper
What are pH test strips?
Test strips indicate the pH levels by changing the colors of their patterns. It has multiple pads that are placed on the plastic backing strip or a card.
In regard to the pH measuring, the paper strips have:
- High accuracy – They provide more accurate results than pH papers but they cover a smaller range that includes increments of 05 or less. Also, they do measure slower as you need to put a sample on each pad.
- Clearer results – As there are more color indicators, you can make a better judgment due to the fact that you can match pH values with the color of the pad.
- Non-bleeding strips – There are specialist strips that stop leaking in out of the sample, enabling you to use the same sample for other tests.
- Key displayed on the strip – Some of the strips have a color key that allows them to indicate results even when they are separated from the box.
Even though all the pH measurement tools provide results they all have disadvantages and advantages. The pH meter and buffer solutions are seen as more accurate than the pH paper and strips. However, Ph Strips and paper are handier and easier to use
Ref.
https://www.rscal.com/what-is-a-ph-meter-and-why-is-ph-meter-calibration-important/
https://in.omega.com/prodinfo/ph-meter.html
https://camblab.info/wp/index.php/whats-the-difference-between-ph-paper-and-ph-test-strips/
https://www.simplexhealth.co.uk/how-to-test-your-ph-cms-28.html
