Plant Growth Chambers

June 23rd, 2014 by Acmas No comments »

Plant Growth Chambers an approach to study the factors affecting the Plant growth


Growth
 is the process by which a plant increases in the number and size of leaves and stems. The growth of both plants and animals requires energy. Animals get their energy by digesting the plants they eat. Plants get their energy from the sun through photosynthesis.

Photosynthesis is the process where the green pigment in the plant’s leaf (chlorophyll) absorbs energy from sunlight and, using this energy, water, and carbon dioxide, produces oxygen and simple sugars. The plant then uses these sugars to make more complex sugars and starches for storage as energy reserves, to make cellulose and hemicellulose for cell walls or with nitrogen, to make proteins. How the plant uses its energy depends on the developmental stage of the plant and on environmental conditions.

Growth is determined by environmental factors, such as temperature, available water, available light, and available nutrients in the soil. Any change in the availability of these external conditions will be reflected in the plants growth. Biotic factors (living organisms) also affect plant growth.

Plant growth and geographic distribution are greatly affected by the environment. If any environmental factor is less than ideal, it limits a plant’s growth and/or distribution. For example, only plants adapted to limited amounts of water can live in deserts.

Either directly or indirectly, most plant problems are caused by environmental stress. In some cases, poor environmental conditions (e.g., too little water) damage a plant directly. In other cases, environmental stress weakens a plant and makes it more susceptible to disease or insect attack.

Environmental factors that affect plant growth include

  • Temperature; is a measure of the intensity of heat. Plant growth occurs in a fairly narrow range – 60 – 100 degrees F. Temperature directly affects the processes of photosynthesis, respiration transpiration  and absorption of water and nutrients.
  • Moisture supply; Plant growth is restricted by low and high levels of soil moisture as good soil moisture improves nutrient uptake. If moisture is a limiting factor fertilizer is not used efficiently.
  • Radiant energy; quality, intensity and duration (photoperiodism) of light are important for the plant growth. Photoperiodism is defined as the behavior of plant in relation to length of the day. On the basis of day period the plants can be:

a)      long day plants – flowering occur only if days are longer than same critical period – 12 hours e.g. Grains and clovers

b)      Short day plants – flowering occur only if days are shorter than critical period e.g. soybeans.

c)       Indeterminate – flowering occur over a wide range of day lengths. E.g. Tomato, cotton, buckwheat

  • Composition of the atmosphere; plant growth majorly depends on the amounts of gases present in the atmosphere such as carbon dioxide, nitrogen etc.
  • Soil aeration and soil structure; Compact soils of high bulk density and poor structure are aerated poorly. Pore space is occupied by air and water so the amount of air and water are inversely proportional to the amount of oxygen in the soil. On well drained soils, oxygen content is not likely to be limiting to plant growth.

There are many more environmental factors affecting plant growth some of them are:

  • Soil reaction
  • Biotic factors
  • Supply of mineral nutrients
  • Absence of growth-restricting substances

It is important to understand how these factors affect plant growth and development.

With a basic understanding of these factors, one (researcher/student) may be able to manipulate plants to meet required needs, whether for increased leaf, flower, or fruit production. By recognizing the roles of these factors, personnel also will be better able to diagnose plant problems caused by environmental stress.

Environmental chambers called Plant growth chambers are designed to study the effect of described different environmental factors such as humidity, temperature and light in various application tests. These plant growth chambers can be Rich in chambers or walk in chambers.

These plant growth chambers have their applications in the following areas;

  • Production of biotherapeutic proteins
  • Germplasm containments
  • Biotechnology
  • Agriculture
  • Tissue Culture Applications
  • Enzyme reaction applications
  • Fermentation analysis

Photostability Chamber Testing The Stability Of Drugs

June 23rd, 2014 by Acmas No comments »

Light-related adverse side-effects of drugs are now an important source of concern. In order that the mechanism underlying to such effects is recognized, an in-depth photochemical study must be carried out. ICH Q1B (The ICH rule Q1B defines the Irradiation dose for UV and white light) guideline is the harmonized effort to standardize photostability testing on new pharmaceutical drug substances and drug products. For companies developing or manufacturing pharmaceutical drugs, a robust photostability testing process is essential to ensure product quality and regulatory compliance.

Stability tests are an important step in the course of the development of new drugs and pharmaceutical substances. Photostability chambers are designed to carry out stability and shelf life studies on drug and drugs substances. These chambers are also known as Pharmaceutical Photostability Chamber. These chambers allow the photostability test in accordance with ICH guidelines. (The ICH rule Q1B defines the Irradiation dose for UV and white light). Photostability chambers are characterized by an ideal light, UV, temperature and humidity distribution.
Note: ICH stands for International Conference on Harmonization

Photostability Test

At first the actual substance without any modification is tested, after that the final product without any wrapping is tested. If the final product remains photostable, that is the changes caused by the light are negligible or acceptable or can be disregarded; the test is finished at this point.

If unacceptable changes occur those modify the chemical structure of the test product, actions can be taken for the light protection of the specimens. The examinations are carried out once again e.g. in the first step the specimens are tested in a direct wrapping (like blister wrapping or glass), for further steps in sales packaging.

If the light stability is achieved with the taken action, normally this is seen in the storage tips, e.g. store only in the dark.

With such photostability examinations it is tested, how far the mentioned products change their chemical characteristics by light irradiation

One of the most important requirements in Photostability Tests is the homogeneous irradiation of the specimens. For this reason, all the specimens have to be positioned at the same distance from the light source.

cpH METER

June 17th, 2014 by Acmas No comments »

What is pH?

pH is a unit of measurement which is used to express the degree of acidity of a product or it can also be defined as negative logarithm of Hydrogen ion concentration i.e

pH= -log[H+]

The pH scale runs from 0 which means very acidic to 14 which means very basic.

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The scale is actually referring to the concentration of hydrogen (H+) ions in the product being tested. The more H+ ions that are present, the more acidic the product will be. The scale is logarithmic, meaning that each pH unit has 10 times more H+ ions than the one above it.pH can be measured using either pH indicators (like phenolphthalein) in form of solution or pH strips or using potentiometric method. Strips are very useful when all you need is 0.2-0.5 pH unit accuracy.

Tool for measuring pH with higher precision is the pH meter. Its working depends on the voltage that is caused by the H+ ions present in the product. A typical pH meter consists of a glass electrode connected to an electronic meter that measures and displays the pH value.

 

Parts of a pH meter:

pH meter consists of two or three parts that depends on the model(purchased)

  • Main Body Component; it houses the microchip used to process the measurements made by meter and the meter’s display.
  • A Probe commonly called an Electrode; it is the part where the measurement actually takes place, this part is consumable, sensitive and most expensive part of meter and should be handled with care.
  • Automatic Temperature Compensation (not present in all pH meters); some pH meters are equipped with the ability to measure the temperature of the solution being measured .This feature is called “Automatic Temperature Compensation.”Some ATC pH meters have the temperature sensor built into the electrode, and some have an independent thermometer probe which plugs into its own port on the back of the body of the meter.

How pH Meter works?

A pH meter is a precise voltmeter that measures the potential difference, in thousandths of a volt (mV), between the reference electrode and the measuring pH electrode. It’s scaled in such a way that it displays not the measured potential, but converts it to a display of pH. The pH meter calculates a value by measuring the voltage differences between the pH electrode (responsive to hydronium ion concentration) and the reference electrode (which provides a constant voltage). The meter must be calibrated in order to compensate for the difference in voltage output from different electrodes. It is recommended that at least two buffer solutions are used to calibrate the machine.(pH values 4,7 and 10).

According to Nernst equation (Nernst equation is a mathematical description of an ideal pH electrode behavior) a standard pH electrode generates a voltage of about 59 mV per pH, and at pH 7 (neutral pH) the electrode produces 0 volts. Acids produce positive and bases produce negative voltages.

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Calibration of a pH meter

This is required to calibrate the pH meter against a known set of values (e.g. pH= 4, 7 &10) so that it can yield accurate readings. For best results, calibrate pH with a buffer that is within 3 pH units of the test sample. Procedure:

1. Rinse the pH electrode in tap water.

2. Insert pH electrode in a fresh pH buffer solution.

3. Measure the temperature of the buffer solution.

4. Adjust the TEMP screw to the corresponding temperature value.

5. Observe the pH reading and adjust the “Cal” screw to pH 7 if required.

6. Remove pH electrode and rinse in distilled water.

7. Insert in a pH 4 if measuring an acid solution, or pH 10 bufsfer if measuring an alkaline solution.

8. Adjust the slope screw until the measurement value corresponds with the pH 4 or pH 10 buffer

What are the Types of pH meter?  

There are three different types of pH meters:

  • portable,
  • bench and
  • in-line.

    Portable devices are useful when there is a need to perform measurements outside the laboratory. Portable pH tester should be ergonomic, rugged and versatile.

    Bench tester is usually more precise and has more options. They are typically used in a laboratory where an interface for data communication and advance measurement features are         important.

    • In-line pH transmitters for process control are designed to with stand harsh environments.

Safety guidelines for pH meter

i) When it is not in use, it should be turned off and the electrode tip should be covered with the plastic cap.

ii) If the meter has not been used for some time, it should be soaked for several days in distilled water prior to use, with the power off. For effective soaking, the protective cap must be removed.

iii) The meter should ever not be placed in water deep enough to submerge any part of the upper body of the meter. this will ruin the electronics.

iv) After soaking, remove the pH meter from the water, dry the probe tip, and cap the probe until one is ready to use the meter again.

v) The meter may be laid on a paper towel on the bench top when not in use. However, under any circumstances the meter should not be inverted (turned probe-up); this may cause water inside the probe tip to run up into the meter electronics.

vi) Before using the meter to determine the pH of your analyte, it may be        necessary to standardize/caliberate it–that is, to immerse it in a buffer of known pH and adjust the meter to display the correct pH.