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Reagent preparation and water specification in clinical chemistry lab

Todays clinical chemistry lab is fully automated, minimizing exposure to dangerous chemicals

In research and molecular diagnostic labs, the laboratorian may still face the problem of reagent preprations

Chemicals Analytic chemicals exist in varying grades of purity: 1. Analytic reagent (AR): Chemicals of this category are suitable for use in most analytic laboratory procedures2. Ultrapure: these chemicals have been put through additional purification steps for use in specific procedures such as chromatography, atomic absorption, immunoassays, molecular diagnostics, standardization, or other techniques that require extremely pure chemicals3. Chemically pure (CP): the impurity limitations for this group are not stated and that preparation of these chemicals is not uniform, so it is not recommended that clinical laboratories use these chemicals for reagent preparation unless further purification or a reagent blank is included4. United States Pharmacopeia (USP), and National Formulary (NF): these chemicals are used to manufacture drugs, so there are made to not being injurious to individuals. Chemicals in this group may be pure enough for use in most chemical procedures5. Technical or commercial grade: these are used primarily in manufacturing and should never be used in the clinical laboratory

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MSDS

MSDSMSDS is intended to provide workers and emergency personnel with procedures for handling or working with that substance in a safe manner, and includes information such as:- Physical data (melting point, boiling point, flash point, etc.) - Toxicity, health effects, and first aid - Reactivity - Storage, and disposal - Protective equipment, and spill-handling proceduresMSDS formats can vary from source to source depending on national requirements. So, It is important to use an SDS specific to both country and supplier, as the same product can have different formulations in different countries

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Water specificationsWater is the most frequently used reagent in the laboratoryBecause tap water is unsuitable for laboratory applications, most procedures, including reagent and standard preparation, use water that has been substantially purified

Water purification:Distilled water: water purified by distillation; which remove most organic materialsDeionized water: water purified by an anion or cation exchange resin, which remove some or all ionsReverse osmosis water: water pumped through a semipermeable membraneFilterated water: water purified by ultrafilteration or nanofilteration, are excellent in removing particulate matter, microorganisms, and any pyrogens or endotoxinsUltraviolet oxidation (removes some trace organic material) or sterilization processes (uses specific wavelengths), together with ozone treatment, can destroy bacteria but may leave behind residual products. These techniques are often used after other purification processes have been used

Reagent grade water: Production of reagent grade water largely depends on the condition of the feed water. Generally, reagent grade water can be obtained by initially filtering it to remove particulate matter, followed by reverse osmosis, deionization, and a 0.2-mm filter or more restrictive filtration process. Testing procedures to determine the quality of reagent grade water include measurements of resistance, pH, colony counts (for assessing bacterial contamination) on selective and nonselective media for the detection of coliforms, chlorine, ammonia, nitrate or nitrite, iron, hardness, phosphate, sodium, silica, carbon dioxide, chemical oxygen demand (COD), and metal detection. It is classified into one of six categories based on the specifications needed for its use rather than the method of purification or preparation

Distillation Water is boiled and vaporized, The vapor rises and enters into the coil of a condenser, a glass tube that contains a glass coil. Cool water surrounds this condensing coil, lowering the temperature of the water vapor. The water vapor returns to a liquid state, which is then collectedMany impurities do not rise in the water vapor, remaining in the boiling apparatus. The water collected after condensation has less contamination

Solution propertiesA solute is a substance that is dissolved in a liquid e.g. analyteA solvent is the liquid in which the solute is dissolve e.g. biologic fluid Solvent + Solute = SolutionProperties Concentration is expressed as percent solution, molarity, molality, or normality Colligative Properties are the properties of osmotic pressure, vapor pressure, freezing point, and boiling pointRedox potential or oxidation-reduction potential: is a measure of the ability of a solution to accept or donate electronsConductivity: is a measure of how well electricity passes through a solution. Resistivity is the reciprocal of conductivitypH and buffers: Buffers are weak acids or bases and their related salts that, as a result of their dissociation characteristics, minimize changes in the hydrogen ion concentration. Hydrogen ion concentration is often expressed as pH

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