Laboratory Mathematics - Reagent Preparation (Lecture)

- Dilution factor, Percent Solutions, Molecular Weight, Molarity, and Molality and -Reagent Preparation

Percent Solutions:

• % (W/V)

• % (V/V)

• % (W/W)

Molarity

Number of Moles of solute dissolved in one liter solution.

Molarity is widely used in:

• Clinical chemistry

• Analytical chemistry

• Instrument preparation

• Buffer Preparation

Most common type of solution in percent solution

Weight/Volume

These are commonly used for disinfection and reagent preparation

v/v %

w/w % purpose:

• Preparation of powder

• Commercial reagent manufacture

• Dry chemical formulations

Normality

Expresses the concentration of a solution in terms of Number of grams equivalent per Liter of solution.

Normality is commonly used for:

• Acid-base

• Oxidation-reduction

Molality (m)

Number of moles of solute dissolved in One kilogram of solvent.

• It is independent of the temperature

• Primarily used in PHYSICAL CHEMISTRY and studies involving COLLIGATIVE PROPERTIES.

Molality (m)

Based on Mass of the Solvent, Not the volume of the solution.

Molality (m)

pH and POH

Formula mentioned above and below

1. [H+]

2. [OH]

1. 30% w/w

2. 10 g

3. Solution: 55.56 g & Solvent: 50.56

% v/v

1. 10% v/v

2. 2 mL

3. 20 mL

How to get molecular weight?

• Add the atomic weight

1 mole

1. 0.55 mol/L

2. 30 g

3. 52.65 g

Normality is commonly used as:

• Acid-base

• Oxidation - reduction

Most commonly used reagent in the clinical laboratory? (water specifications)

• High Purity Water

Unsuitable for Lab Applications? (water specifications)

Tap Water

Most procedures, reagent and control preparations requires substantially, which is ?

Purified water, known as Reagent - Grade Water.

Type 1 (water)

critical, highly sensitive analytical procedures requiring absolute measurement precision.

Type 2 (water)

General clinical laboratory testing procedures and Standard active chemical reagent preparations.

Type 3 (water)

General lab glassware, pre-rinsing and direct feed lines feeding automated purification equipment.

Water to rinse your everyday laboratory glassware, and connect this same water supply directly to your automated chromatography machine via a dedicated pipe or tube.

Type 3

Distilled Water

• Purified by boiling & vaporizing water.

• Impurities remain in the boiling apparatus.

• Water collected after condensation has less contamination

• Distillation cycles can be repeated to remove additional impurities

Ultrafiltration and Nanofiltration remove:

• Particles

• Microorganisms

• Endotoxins

What is a Dilution Ratio?

A parts-to-parts comparison format written as Solute :Solvent

What does a 1:4 dilution ratio mean?

Combine 1 part solute with 4 parts solvent (giving 5 total parts).

What is a Dilution Factor ?

A parts-to-total fraction format written as Solute/Total Volume or a whole number multiplier.

What is the golden dilution equation used to mix solutions?

Deionized Water

• Has some or all ions removed from water

• Not considered pure or sterile

• Produced Using anion- or caution- exchange resins.

• Excellent at removing dissolved ionized solids and dissolved gas.

Water that is excellent at removing dissolved ionized solids and dissolved gases.

Deionized Water

List Chemical Use for Reagent Preparation

1. Analytical Reagent Grade

2. Ultrapure Reagents

3. Chemically pure (CP) or Pure Grade

4. Technical or Commercial Grade

5. United States of Pharmacopoeia (USP) and National Formulary (NF)

Reference material : purpose

Standard with Assigned value

Calibrator : purpose

Adjust instrument response

Control Material

Monitor assay performance

Important for qualitative and quantitative analyses; essential for accuracy

AR (analytical reagent grade

It is not recommended for research and analytical chemistry unless further purification or a reagent blank is included

CP (chemically pure or pure grade

Reagent put through additional purification

Ultrapure Reagents

It is used primarily in MANUFACTURING.

Technical or commercial Grade

Uses for Drug Manufacturing

USP and NF