Water for pharmaceutical use shall be free from any cations, anions, heavy metals & any other impurities why?

   Water for pharmaceutical must be free from inorganic as well as organic impurities, minerals, and heavy metals. Some impurities like calcium, magnesium, ferrous are responsible for degradation of drug molecule, many cations like ferrous and calcium magnesium act as catalysts in degradation reaction of drug molecule, anions like chloride are highly active they participate in nucliophylic substitution reactions, where in they break a double bond between -C=C- in to a single bond as CL –CH-CH2- , which a reason why we observe that color dies tend to fed in presence of chlorine as most of the dies used are diazo compounds which has plenty of places for nucliophylic substitution reactions, which is also a reason why stability of drug is drastically affected in presence of cations and anions from mineral origin present in water.

    Heavy metals like lead and arsenic are highly cumulative neurotoxic metals, heavy metals are not eliminated out of our body easily like other drugs and molecules but heavy metals bind with proteins and tend to get accumulated in fatty tissues, nerve tissue is most likely to get damaged by heavy metals, heavy metal causes nervous tissue damage there for water must be free from heavy metals.

Why water for pharmaceutical use is always kept in close loop in continuous circulation?

Water is very important & essential medium for any pharmaceutical preparation. So this use very carefully.

      Water is a best medium for most microorganisms, microorganism can be a highly pathogenic which causes serious diseases(many diseases are  water born), these pathogens infect after consumption of contaminated water, microorganisms tend to settle on a surface if water is allowed to stand in a stagnant position for few hours, these settled microorganism form a film over the surface of vessel and piping, such film formed by microorganisms is also called as bio-film, bio-films are very difficult of remove, once a bio-film is formed at a particular point then that point may form a bio-film again even after cleaning very easily as seed from this point is may not completely get removed effectively.

   Bio-films then can become a source of microbial contamination's, therefore purified water after collection in a distribution system is always kept in a closed loop in a continuous circulation.

      A continuous circulation is also not enough at some points, therefore it is aided with high temperature range from 65 °C to 80°C, a minimum temperature of 65 °C is considered a self sanitizing, but better assurance is obtained with a temperature of 80°C.

      Purified water collected should be stored in a stainless still vessel which must facilitate distribution to the point of use in a closed loop of continuous circulation, tank should be made of corrosion free material of construction, and must facilitate sanitization and easy cleaning. Thank's

Difference between Karl Fischer Titrator and Loss on drying (LOD).

Actually Karl Fischer titration and loss on drying (LOD) are the methods, which is used for determining moisture content in a product. We detect LOD by moisture analyzer machine.

Karl Fischer Titrator:  KF is a method, which measures only the water content (i.e. it's water-specific) in a product sample. Karl Fischer titration is a chemical method. It involves adding a reagent to the sample to cause a reaction that converts the water in a product to a non-conductive chemical.

Karl Fischer Titrator

LOD-Loss On Drying: LOD that means loss on drying we determine lod by the moisture analyzer machine, lod measures the total change in weight of a material as a result of drying. For some products, components such as alcohol or fat evaporate with the water. Therefore, the LOD method measures both the water and volatile impurities such as those mentioned previously Loss on Drying compares the weight of a product before and after it is dried. This difference in weight is taken as the percentage of moisture in the product.

Moisture Analyzer 

Finally, we can say by the Karl Fischer Titrator we only detect what amount of water into the substance, but by the moisture analyzer we can not detect what amount of water like any other liquid substance into the materials. So here we detect what percentage of any kind liquid present into the materials. 

For Example: (LOD-Loss On Drying) Suppose 50 gm materials used in moisture analyzer machine after drying determine how percentage weight loss of this 50 gm materials, so we say loss on drying.