medical & scietific
Pharmaceutical Water
Water is a key component in the pharmaceutical industry. It functions as an ingredient, a cleaning agent, a reagent, a solvent and a product, throughout the drug discovery process, from the initial identification of potential drug targets, all the way to the manufacture and quality control of the final product.
Within the production processes of the Pharmaceutical Industry, the water is one of the most used elements being the main component of the different formulations, cosmetics, lotions and other pharmaceutical products. In fact, water is considered as the main raw material within the applications to produce pharmaceuticals. Water for pharmaceutical uses is not only used as a raw material, but it is usually used for the cleaning and rinsing processes required in the processing plant, being also a regular agent for cleaning of reactors and other pharmaceutical equipment.
There are many different grades of water used for pharmaceutical purposes. Several are described in USP monographs that specify uses, acceptable methods of preparation, and quality attributes. These waters can bedivided into two general types: bulk waters, which are typically produced on site where they are used; and packaged waters, which are produced, packaged, and sterilized to preserve microbial quality throughout their packaged shelf life. There are several specialized types of packaged waters, differing in their designated applications, packaging limitations, and other quality attributes. Different grades of water quality are required depending on the different pharmaceutical uses.
Applications of purified water in pharmaceuticals range from rinsing equipment to being one of the main constituents in several products and processes. Some of these include:
Production of oral and topical products
Granulation process for tablets and capsules
Being the feed water for WFI (Water for Injection)
Being the feed water for pharmaceutical grade clean steam
Preparation of cleaning
Related Information
> Guideline on the quality of water for pharmaceutical use
Medical Water
Water plays an important role in the health care field. From washing surgical tools and equipment to creating a soothing environment for patients to have hydrotherapy, water is essential to the effectiveness of the health industry. However, moist environments and liquid solutions can create a favorable setting for the growth of many bacterial and some protozoal microbes.
Water Use In Dialysis
During an average week of hemodialysis, a patient can be exposed to 300-600 liters of water, providing multiple opportunities for potential patient exposure to waterborne pathogens. For the health and safety of hemodialysis patients, it is vital to ensure the water used to perform dialysis is safe and clean.
The Association for the Advancement of Medical Instrumentation (AAMI) in conjunction with the International Standards Organization (ISO) have established chemical and microbiological standards for the water used to prepare dialysate, substitution fluid, or to reprocess hemodialyzers for renal replacement therapy. The AAMI standards address:
Equipment and processes used to purify water for the preparation of concentrates and dialysate and the reprocessing of dialyzers for multiple use.
The devices used to store and distribute this water.
The allowable and action threshold levels of water contaminants, bacterial cell counts, and endotoxins. Refer to specific reference listed for full details on maximum allowable chemical contaminates and bacterial/endotoxin limits.
Related Information
> AAMI Water Quality Standard for Hemodialysis
In 2001, AAMI released the first version of RD62 water for dialysis and then again in 2006. Since then this has become a standard followed by many dialysis providers and is recognized throughout the world. This standard, although addressed to industry, has been adopted by most dialysis facilities.
RD52 recommends that the dialysate be tested for bacteria and endotoxin monthly, similar to the water recommendation. The level of bacteria and endotoxin that should be met is the same as that of the water system. AAMI committee considered RD62 “Water treatment equipment for hemodialysis applications” the manufacturers requirements and RD52 the users requirements. Parts of both RD52 and RD62 are the same as it relates to water.
Laboratory Water
Purified water has a very wide range of uses in chemical and biochemical laboratories, from glassware washing to autoclave filling. It provides a more consistent, less contaminated reagent than potable water leading to improved reproducibility.
A major use of purified water is in glassware washing. This can require relatively high volumes delivered rapidly on demand. Heating baths are another common requirement for purified water. Microbiology labs need water to refill autoclaves, while steam generation is used for sterilization and clean-room humidification. Stills and ultra-pure water polishers also benefit from a purified water feed. Routine preparation of reagents and standards for non-trace work, along with general purpose chemical and physical testing, such as pH, are further suitable applications for general lab water.
Laboratory water is the most used solvent. Used in almost all laboratories, it is an important component of a wide range of applications such as preparation of buffers, samples, media and other solutions, and as feed water for laboratory devices.
Why Would You Use General Lab Water?
General lab water is used where water is required that has had most of the impurities in drinking water removed. Typically, this water will contain sub-ppm levels of ionic and organic impurities. Using this water avoids the variability, contamination and down-time associated with using drinking water but minimises the costs associated with producing higher purity water. Methodologies may also specify certain grades of water for certain operations.
The more sensitive the analyses being carried out the more critical is the purity of the water both for use in the analyses but also in ancillary roles such as water baths, humidification and, especially, glassware washing. Too many impurities in rinse water can degrade various aspects of laboratory work the cause of which can be difficult to trace.
Several Key Factors Describing The Various Properties Of Water
The Conductivity of Water
Conductivity is reported as microSiemens per centimeter (µS/cm) at 25oC and is the reciprocal of resistivity and provides a measure of a fluid's ability to conduct electrical current. Conductivity is typically used when assessing water ranging from 'raw water' through to 'drinking water' and provides a valuable, non-specific indication of the level of ions in the water.
The Resistivity of Water
Reported as Mega-Ohms per centimeter (MO-cm) at 25oC, resistivity is related to conductivity: a high resistivity equals a low conductivity. As such, it also provides a measure of the water's ionic content. Unlike conductivity, resistivity is primarily used in the assessment of ultrapure water.
Organic Compound Levels in Water
Organic compounds can exist in water in numerous forms and so measuring every single one individually is impractical. Instead, the most useful indicator is considered to be the total organic carbon (TOC) content of the solution. This is measured via a process that oxidizes the organic compounds present and then quantifies the oxidation products generated. TOC is as close as we can currently get to a 'universal indicator' for the presence of organic impurities.
Alternatively, chromatographic techniques may be employed to determine the specifics of organic content, but this is frequently considered both too expensive and time-consuming to be used in general monitoring workflows.
Biological Contamination of Water
The presence of biological contaminants such as bacteria and other microorganisms is a common issue in untreated water. Bacterial levels reported as colony forming units per milliliter (CFU/ml) are kept low via filtration, UV treatment and sterilant solutions.
Following an incubation period in suitable growth media, individual bacterial species and total viable cell counts can be determined. Bacteria counts may also be monitored through the use of epifluorescence testing to rapidly detect and distinguish between dead and living microorganisms.
In addition to the bacteria themselves, endotoxins produced from the cell wall of gram-negative microorganisms (reported as endotoxin units per milliliter, EU/ml; 1 EU/ml approximately equal to 0.1 ng/ml) can be assessed using standard tests based on Limulus Amebocyte Lysate activity.
Impurities Of All Types Can Affect General Lab Water
1. Organic Compounds
The most common organic impurities in purified water are residuals of the more common low molecular weight organics in feed water, organics weakly held on ion-exchange resin and compounds leached from within the water purification system or produced by bacteria within the system. The actual compounds present have been found to vary widely.
Organic compounds are typically present in the feed water used to supply water purification systems at between 1000 to 3000ppb C (TOC – see below). Water purification systems are made very largely from plastics to avoid contamination by metals. These can release monomers, release agents etc. if suitable virgin materials are not used. Organics can also be released from ion-exchange (IX) and other media within the purification system. Organics from any or all of these sources will carry over into the product purified water if they are not removed effectively.
Clearly, the presence in the water of a compound being determined will directly affect the accuracy of the results of analysis. Other compounds with overlapping chromatographic peaks or isotopic masses will also interfere with HPLC and LC-MS analyses respectively. Higher concentrations of less soluble species can lead to degradation in spray characteristics for these techniques and can degrade column and detector performance in HPLC. Impurities can also affect ionisation and form multi-atom ions in ICP-MS and LC-MS.
The only on-line method of monitoring for total organic impurities in purified water is by measuring its total oxidisable carbon content (TOC). The organics are oxidised (usually by short-wavelength UV light) and a change is monitored.
The significance of impurities depends on the application. For ultra-trace analysis even very low (ppb) levels of organics can interfere significantly. TOC of less than 5ppb is recommended. For less sensitive analyses higher TOC levels may be acceptable - <10 or <50ppb. For historical reasons pharmacopoeia specify <500ppb but many laboratories work to much tighter standards.
2. Ions
The most common inorganic impurities in purified water are residuals of the more common ions in feed water – sodium, calcium, iron, magnesium, chloride, sulphate, nitrate – and ions weakly held on ion-exchange resin – silicates and borates. Bicarbonate ions will usually be present, as well, produced by the dissolution of atmospheric CO2 in the product water on exposure to the environment.
Inorganic ions are the most abundant of the impurities in the feed water used to supply water purification systems. These can carry over into the product purified water if they are not removed effectively. They can also be released from ion-exchange (IX) media within the purification system as the media IX capacities are used up.
Clearly, the presence of an impurity containing an element being determined will directly affect the accuracy of the results of elemental analysis. Other elements/compounds with overlapping spectral emissions or isotopic masses will also interfere with ICP-OES and ICP-MS analyses respectively. Higher concentrations of less soluble species can lead to degradation in spray characteristics for these techniques and AAS and can degrade column and detector performance in HPLC. Impurity ions can also affect ionisation and form multi-atom ions in ICP-MS and LC-MS.
The universal method of monitoring for ionic impurities in purified water is by measuring its electrical conductivity/resistivity. A resistivity of 18.2 MΩ.cm is essential for ultrapure water containing the lowest levels of impurities but, due to the slight ionisation of water into hydrogen and hydroxyl ions, even with 18.2 MΩ.cm resistivity water, ppb levels of impurity ions may be present.
The significance of impurities depends on the application. For ultra-trace analysis even very low (sub-ppb) levels of inorganic ions can interfere significantly. Type 1+ water with a resistivity of 18.2MΩ.cm is essential. For less sensitive analyses higher impurity levels may be acceptable (Type 2+ or 2 with resistivity respectively of 10 or 1MΩ.cm).
3. Bacteria and Particulates
The bacteria in purified water are residuals of those in feed water and those released by biofilms within the water purification system. The most common have been found to be opportunistic gram-negative non-fermenting rods such as Pseudomonas, Flavobacterium, and Acinectobacter ; they are very common in nature. Their presence in water treatment systems demonstrates an ability to adapt to environments with a low concentration of nutrients and to a large range of temperatures.
Some microorganisms and bacteria are present in the feed water used to supply water purification systems although previous treatments (chlorine, ozone etc.) will have reduced them to very low levels. As free chlorine will damage reverse osmosis (RO) membranes over time, any chlorine is usually removed by pre-treatment (often activated charcoal) as the first stage in a purification process. Unfortunately, this enables bacteria to grow in the water on and after the RO membranes.
Bacteria and their degradation by-products, such as endotoxins, can interfere with many bio processes including PCR, clinical analysis and testing. They provide alternative sources of biologically active material which can suppress or enhance results. Bacteria can also form biofilms which can build up and cause blockages in pumps, LC columns, detectors and tubing, causing problems with many techniques including HPLC and LC-MS.
There are no on-line methods of monitoring for bacteria in purified water that are rapid or sensitive enough. The usual procedure is to take samples and collect any bacteria on a filter which is subsequently incubated on a medium such as RA2 agar for several days before counting the colonies formed. The resultant value is the total viable count (TVC). As the bacterial count is not known when the water is used, it is essential to ensure that the water purification system is designed to minimise bacterial build-up and the systems are regularly monitored off-line.
The significance of impurities depends on the application. For highly sensitive work bacterial TVCs of 1CFU/mL or lower are needed. For less sensitive analyses higher TVC levels may be acceptable - <10 or <50. Pharmacopoeia have a guideline of <100CFU/mL but many laboratories work to much tighter standards.
Water Purity Requirements For General Lab
For most laboratory applications Type II/II+ water will be sufficient as shown in the table below. For high sensitive work Type I water is preferred even for glassware washing and sample preparation.
Application | Sensitivity Required | Resistivity (MΩ.cm) | TOC (ppb) | Filter (µm) | Bacteria (CFU/mL) | Endotoxin | Nuclease | Water Grade |
Glassware washing | General | >1 | <50 | <0.2 | <10 | NA | NA | Type II/II+ |
Steam generation | General | >1 | <50 | <0.2 | <10 | NA | NA | Type II/II+ |
Feed to Stills | Low | >0.05 | <500 | NA | NA | NA | NA | Type III |
Feed to pure water system | Low | >0.05 | <50 | NA | NA | NA | NA | Type III |
General | >1 | <10 | <0.2 | <10 | NA | NA | Type II/II+ |
Sample & reagent prep. | General | >1 | <50 | <0.2 | <10 | NA | NA | Type II/II+ |
Ultrapure Water
Ultrapure water (UPW) also known as Type 1 Water, is water that has been purified to high levels of specification. As a standard, the water contains only H20, as well as balanced number of H+ and OH- ions. It has a resistivity of 18.2 MΩ.cm, TOC < 10 ppb and bacterial count <10 CFU/ml. To be classified as ultrapure, water must not contain any detectable endotoxins. This level of purity makes it a perfect reagent for laboratory work.
The presence of impurities and contaminants can have a serious impact on your data. By ensuring you use water meets a high level of purity you eliminate any sabotage to your data and ensure reliable, accurate results. Ultrapure water is an essential and critical reagent used in many highly sensitive scientific applications like HPLC, LC-MS, GC-MS, GFAAS, PCR and mammalian cell culture, as well as clinical analyzers.
UPW is used in the semiconductor and pharmaceutical industries the most, though it’s an ideal solution for any work in the lab. Its level of purification makes it versatile for highly sensitive applications.
Applications that use UPW include:
High Performance Liquid Chromatography (HPLC)
Liquid Chromatography – Mass Spectrometry (LC-MS)
Gas Chromatography – Mass Spectrometry (GC-MS)
Graphite Furnace Atomic Absorption Spectroscopy (GFAAS)
Polymerase chain reaction (PCR)
Immunochemistry (ICC)
Mammalian cell culture
Clinical analysers
Trace Analysis
Laboratory Water Quality Standards
Technical standards on water quality have been established by a number of organizations including the American Society for Testing and Materials (ASTM), International Organization for Standardization (ISO), United States Pharmacopoeia (USP) and the Clinical and Laboratory Standards Institute (CLSI) - previously known as the US National Committee for Clinical Laboratory Standards (NCCLS). CLSI outlines Clinical Laboratory Reagent Water (CLRW) guidelines.
ASTM Standards For Laboratory Reagent Water (ASTM D1193-91)
ASTM: American Society for Testing and Materials
| Measurement (Unit) | Type I | Type II | Type III | Type IV |
|---|
| Resistivity (MΩ-cm) | > 18 | > 1 | > 4 | > 0.2 (200KΩ) |
| Conductivity (µS/cm) | < 0.056 | < 1 | < 0.25 | < 5 |
| pH at 25˚C | N/A | N/A | N/A | 5.0 - 8.0 |
| Total Organic Carbon (TOC) ppb or µg/L | < 50 | < 50 | < 200 | N/A |
| Sodium (ppb or µg/L) | < 1 | < 5 | < 10 | < 50 |
| Chloride (ppb or µg/L) | < 1 | < 5 | < 10 | < 50 |
| Silica (ppb or µg/L) | < 3 | < 3 | < 500 | N/A |
The ASTM standards are further subdivided into A, B and C that can be used in conjunction with the type I, II, III or IV water above when bacteria levels need to be controlled.
Additional ASTM Sub-Standards For Laboratory Reagent Water
| Measurement (Unit) | A | B | C |
|---|
| Heterotrophic Bacteria Count (CFU/ml) | < 1 | < 10 | < 1000 |
| Endotoxin (units per ml) | < 0.03 | < 0.25 | N/A |
ISO 3696 Standard
ISO: International Organization for Standardization
| Parameter | Grade 1 | Grade 2 | Grade 3 |
|---|
| Conductivity µS/cm (temp corrected) | < 0.1 | < 1 | < 5 |
| pH at 25°C | N/A | N/A | 5.0 - 7.0 |
| Oxidizable matter Oxygen (02) content mg/L | N/A | < 0.08 | < 0.4 |
| Absorbance at 254 nm and 1 cm optical path length, absorbance units | < 0.001 | < 0.01 | N/A |
| Residue after evaporation on heating at 110°C mg/kg | N/A | < 1 | < 2 |
| Silica (Si02) mg/L | < 0.01 | < 0.02 | < N/A |
CLSI-CLRW Guidelines
CLSI-CLRW: Clinical and Laboratory Standards Institute - Clinical Laboratory Reagent Water
CLSI was formerly known as NCCLS (US National Committee for Clinical Laboratory Standards)
| Contaminant | Parameter and Unit | Type 3 | Type 2 | Type 1 | CLRW |
|---|
| Ions | Resistivity (MΩ-cm) | > 0.05 (50 KΩ) | > 1 | > 18 | > 10 |
| Organics | Total Organic Carbon (TOC) ppb | < 200 | < 50 | < 10 | < 500 |
| Pyrogens | (Eu/ML) | N/A | N/A | < 0.03 | --- |
| Particles | Particles > 0.2 µm (units/mL) | N/A | N/A | < 1 (0.22 µ filtration required) | Include 0.22 µ filtration |
| Colloids | Silica (ppb) | < 1000 | < 100 | < 10 | --- |
| Bacteria | Bacteria (cfu/mL) | < 1000 | < 100 | < 1 | < 10 |
These values are best used as guidelines, as many applications require further treatment based on other factors. For example, many molecular biology applications require Type 1 water that is free of DNase and RNase and simple washing of instruments (usually Type 3) might require water that is pyrogen free for critical applications (Type 1).
Laboratory Water Purity Specifications 'Consolidated' Guidelines
| Contaminant | Parameter and Unit | Type 1 | Type 2 | Type 3 |
|---|
| Ions | Resistivity (MΩ-cm) | > 18 | > 1 | > 0.05 (50 KΩ) |
| Silica (ppb) | < 10 | < 100 | < 1000 |
| Organics | Total Organic Carbon (TOC) ppb | < 20 | < 50 | < 200 |
| Particles | Particles > 0.2 µm (#/ml) | < 1 | N/A | N/A |
| Bacteria | Particles > 0.2 µm (#/ml) | < 1 | < 100 | < 1000 |
| Endotoxin (Eu/ML) | < 0.001 | N/A | N/A |
Typical Uses For Each Type Are Outlined Below:
| Type 1 | Required for critical laboratory applications such as HPLC, Mobile Phase Preparation, blanks and sample dilution for analytical techniques such as GC, HPLC, AA, ICP-MS, etc. Preparation of buffers and media for mammalian cell culture and IVF. Production of reagents for molecular biology applications (DNA sequencing, PCR). Preparation of solutions for electrophoresis and blotting. |
| Type 2 | Used in buffers, pH solutions and microbiological culture media preparation and for preparation of reagents for chemical analysis. Used in clinical analyzers, cell culture incubators and weatherometers, etc. Also used as feed water to Type 1 systems. |
| Type 3 | Used for glassware rinsing, filling autoclaves and heating baths and humidifiers. Also used as feed water to Type 1 systems. |
Type 1 Water (Ultrapure Water)
Type I grade water, also known as Ultrapure Water, is the purest form of water to be produced. It’s used for the most critical applications and advanced analytical procedures.
This includes:
• Cell and Tissue Cultures
• Liquid Chromatography, including High Performance Liquid Chromatography (HPLC)
• Gas Chromatography
• Inductively Coupled Plasma Mass Spectrometry (ICP-MS)
• Molecular Biology
Type I can also be used in applications that require Type II water. This is quite a common practice that can help to avoid the generation of by-products during applications.
Type 2 Water
Type II water grade doesn’t have the same pureness of Type I, but still maintains high levels of purity. It is a good feed water for clinical analyzers as the calcium build-up is reduced with this water type.
It can also be used in applications such as:
• General Lab Practices
• Microbiological Analysis and preparation
• Electrochemistry
• FAAS
• General Spectrophotometry
It can also be used as feed water for Type I water production.
Type 3 Water (RO Water)
Type III grade water, also known as RO water, is water produced through the purification technology reverse osmosis. Of all the pure water types it has the lowest level of purity, but is typically the starting point for basic lab applications, such as cleaning glassware, heating baths or media preparation. It can also be used as a feed water for Type I water production.
USP Standards
USP: United States Pharmacopoeia
| Properties | USP 'Purified Water' | USP 'Water for Injection' & 'Highly Purified Water' |
|---|
| Conductivity (µS/cm @ 25°C) | < 1.3 | < 1.3 |
| Total Organic Carbon (TOC) ppb or µg/L | < 500* | < 500* |
| Bacteria (guideline) | < 100 cfu/ml | < 10 cfu/100ml |
| Endotoxin (EU/ml) | N/A | 0.25 EU/ml |
*Or pass oxidisable substance test