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Molar Mass and Mass Percent Composition Calculator
Assay Analysis Tool
Periodic Table of the Elements
Mass Molarity Calculator
HPLC Method Transfer Calculator
Normality & Molarity Calculator
Isotope Molecular Weight Calculator
Solution Dilution Calculator
Vapour Pressure Calculator
The concentration of a solution is a measure of the number of particles of the solute (a dissolved solid) that are in the solvent (the liquid in which the solute is dissolved). The concentration of a solution can vary based on whether the solution is concentrated or diluted.
The number of particles in a concentrated solution will be greater than the number of particles found in a diluted solution. For example, when a drink is sweetened by adding sugar. The more sugar that is added to the sweeter the drink will taste. This can be calculated by using two formulae and the accompanying formula triangles.
Finding the concentration of a solute is extremely important in order to determine the rate at which molecules will react to each other.
The first way of calculating is to use moles and mount the chemical substance and divide it by its volume. Here is the formula triangle for this: Most of the time volumes are measured in cubic centimeters. 1000 centimeter cubed = 1 decimeter cubed (1 liter)As an example:
500 cubic centimeter = 0.5 decimeter cubed.
1000 cubic centimeter = 1.0 decimeter cubed.
1500 cubic centimeter = 1.5 decimeter cubed.
2000 cubic centimeter = 2.0 decimeter cubed.
If you are trying to find the value of any of the following three: Concentration (mol/decimeter cubed), Moles (mole), or Volume (decimeter cubed).
In the case of concentration you can find the value by dividing the moles by the volume.
Example: If you have 2 moles of salt and it is dissolved in 2 liters of water. What would the concentration be?
Answer: 2 mol / 2 liters = 1 mole/decimeter cubed.
In the case of the Mole you can find the value by multiplying the other values.
The second way of calculating is very similar. However, in this case, we will use the mass of the substance divided by the volume in order to find the concentration instead of the mole of the substance.
The formula is (mass/volume)(The concentration has the unit grams/decimeter cubed rather than moles/ decimeter cubed).
Example: You have 10 gram/ decimeter cubed solution and must dissolve it to 250cc. What would the mass of salt need to be divided by?
Answer: 10g/ decimeter cubed x (250/1000)=2.5g.
Half-life (t1/2) is the amount of time needed to reduce the concentration of a substance by half. Understanding how half-life works is important when trying to determine the excretion rate of a specific chemical. All chemicals have different half-lives; however, they all follow the same concept: once a half-life has passed, 50% of the chemical amount is eliminated from the body. The symbol for the half-life is T½.
How to calculate half-life
For example, 200mg of a chemical with a 1-day half-life is administered, the following can be estimated:
1 day after administration, 100mg remains.
2 days after administration, 50mg remains.
3 days after administration, 25mg remains.
4 days after administration, 12.5mg remains.
5 days after administration, 6.25mg remains.
In theory, after 5 days we can see that almost 97% of the chemical has been eliminated. Chemicals are considered to have a negligible effect after about 4-5 half-lives. However, even if there is a negligible effect after such time, the chemical can still be detected.
Molecular weight is the complete atomic weight of a molecule. The MW (molecular weight) is found by adding the mass of all individual atoms that are in a molecule. In this guide, we will show the steps needed to calculate MW.
The key is to find the molecular formula for the compound you are calculating. This means the number of atoms that the compound consists of. (You can find this information in any chemistry book or even online.)
As an example, the molecular formula for Vitamin D3 is C27H44O. The molecular formula can be used to find the number of atoms of each element that form the compound.
For C27H44O there are 27 atoms of Carbon, 44 atoms of Hydrogen, and 1 atom of Oxygen.
Locate the atomic mass of all elements that are in the compound. All periodic tables will have the atomic mass listed below the symbol for the element. Once you have located the atomic mass on the periodic table, multiply those masses by 1gram/mole.
The atomic masses for the elements in Vitamin D3 are Carbon, 12.011 g/mol, Hydrogen 1.008 g/mol, and Oxygen 15.999 g/mol.
Calculate the total molar mass of the individual elements in the compound. Do this by multiplying the molar mass by the number of atoms of the element in the compound. This way you will be able to see how much each element contributes to the compound.
Carbon, 12.011 g/mol x 27, Hydrogen 1.008 g/mol x 44, and Oxygen 15.999 g/mol x 1.
Add the molar mass of all elements in the compound. Now you will be able to determine the molar mass for the whole compound. Using the numbers obtained in Step 3, you can add them together to calculate the molar mass.
Carbon, 324.297 g/mol + Hydrogen 44.352 g/mol + Oxygen 15.999 g/mol = 384.64
“pH” is an abbreviation for “potential of hydrogen”. It is a unit of measurement that stands for the concentration of hydrogen ions that are within a solution. When an acid or base is mixed with water, the compound disassociates into ions. In acids one of the ions is a hydrogen ion (H+), In acids, one of the ions is a hydroxide ion (OH-). The concentration of ions is commonly described by the pH scale as a numeric value.
In this guide, we will be going over a few different ways to find pH, pOH, acid concentration, and base concentration OH-.
Given [H+] = 4.1 x 10-4M, find the following: We have the concentration and will attempt to find: pH, pOH, and OH-. To find the pH we will use the following formula using the given acid concentration: pH = – log (4.1 x 10-4M)
Note that the number of sig figs will be the number of decimal places pH and pOH should be rounded to
Answer: pH = 3.39
As we have found the pH we can now use the following formula to find the pOH: 3.39 + pOH = 14. After subtracting 3.39 from both the pH and 14 we will get the pOH.
Answer: (3.39 – 3.39)+(14 – 3.39)= pOH 10.61
As we have found the pOH, we will now go ahead with finding the base concentration OH-. To do this can use the following formula: OH- = 10-10.61
Answer: OH- = 2.5 x 10-11M
Pharmaceutical excipients are substances other than the active pharmaceutical ingredient that is added during the manufacturing process or is contained in the final dosage. In the formulation of pharmaceutical suspensions, excipients are added with the active pharmaceutical ingredients in order to:
- Protect, support, or enhance the stability of the formulation.
- Bulk up the formulation in case of a potent chemical for assisting in the formulation of an accurate dosage form.
- Improve acceptance.
- Help improve the bio-availability of active chemical.
- Enhance the overall safety and effectiveness of the formulation during its storage and use.
Solvents (or vehicles) are used as a base in which chemicals and other excipients are dissolved or dispersed. Purified water is the most commonly used vehicle for the formulation of suspensions. This is because of its lack of toxicity, physiological compatibility, and good solubilizing power (high dielectric constant).
In certain cases, viscous nonaqueous solvents, such as propylene glycol and polyethylene glycols, are used in order to impart stability to suspended chemical particles. The choice of solvent used depends on the nature and physicochemical properties of the chemical substance and the intended use of the formulation.
Other examples of solvents used in suspension formulation include alcohol, acetic acid, acetone, ethyl acetates, etc.
The purpose of a Co-solvent is to promote the solubility of the solute in solvents and they act by decreasing the inter-facial tension between predominantly aqueous solutions and hydrophobic solutes. Sorbitol, dextrose, etc. are often added as solubilizers, as well as base sweeteners. Other examples of co-solvents include Ethanol, Sorbitol, Glycerin, Propylene glycol, etc.
Buffers are a mixture of a weak acid or base and one of its salts which when dissolved in a solvent will resist any change in pH when an acid or base is added. Buffering agents/ pH modifiers are added to suspensions to
- Ensure physiological compatibility.
- Maintain/optimize chemical stability.
- Maintain/optimize anti-microbial effectiveness.
- Optimize solubility (or insolubility if the taste is an issue).
Normally, the pH of pharmaceutical suspension should be kept between 7.0 – 9.5 preferably between 7.4 – 8.4. Substances commonly used buffering agents in suspensions include salts of week acids such as carbonates, citrates, gluconates, phosphate, and tartrates.
Amongst these, citrates and phosphates are commonly used in suspensions. Citrate buffers are used to stabilize suspensions in the pH range of 3 – 5, while phosphate buffers are used in the pH range of 7 – 8.
When conducting laboratory research it is imperative that proper safety procedures and rules are followed in order to prevent accidents and or injuries. In this guide, we will be going over the safety procedures and rules that we must follow in a laboratory. We will also cover the necessary safety and PP equipment that is needed in every laboratory.
There are 6 topics that will cover.
In a laboratory, it is possible for an unforeseen accident to happen. Your knowledge of the safety equipment is the best way to minimize the likelihood and damage of an accident. The safety equipment you have in the lab is designed to save lives if used correctly.
- Safety shower – Use in the event of a chemical spill as it will dilute any harmful chemical that you have come in contact with. It is imperative that you use the shower immediately after coming in contact with any hazardous chemicals as prolonged exposure can lead to permanent damages. Make sure to remove any clothes that have come in contact with the chemicals.
- Eye Shower – Be sure to rinse your eyes within 15 seconds of contact as any longer exposure can cause permanent damage to your Eye-site. (Make sure to keep both eyes open so that the stream can rinse your eyes for at least 15 minutes)
- First aid kit – Use in the event of any minor cuts or burns
- Fume hood – To be used when conducting an experiment that exerts fumes
- Fire extinguisher – To be used in case of fire
- Fire blanket – To be used in the event that lab personnel catches fire
When working in the lab it is imperative that you do so while conducting yourself professionally. It is important that all lab staff behave in the correct manner.
- Follow instructions
- No eating or drinking in the lab. (Doing so may cause contamination of your project or even cause ingestion of poisonous chemicals)
- Do no conduct experiments alone. Always have a lab partner.
- Conduct proper cleaning of your lab before after and during lab work.
- Always dispose of chemicals in the appropriate manner.
- In the event of a spill please refer to the Safety Data Sheet in order to see what the correct response should be.
- No fooling around in the laboratory.
- Be aware of others and their movement.
- Do no conduct unauthorized experiments, defined by your laboratory rules.
- When in doubt, ask for assistance.
When working in a laboratory it is important to be aware and understand the risks and hazards that are involved with chemicals. Many chemicals are toxic and corrosive to humans. The PPE and safety gear mentioned in section 3 must always be worn in order to prevent and mitigate any type of contamination or injury.
The main way that we can identify chemical hazards is by reading the SDS sheet. All chemicals in a lab are required to be accompanied by an SDS sheet, that is provided by the manufacturer of the chemical. It is important to know the location of the SDS sheets in your lab. The 16 sections that an SDS sheet covers are:
- Identification (chemical name, manufacture’s contact information)
- Hazard identification (warning symbols, signal words, and safety symbols)
- First-aid measures
- Fire-fighting measures
- Accidental release measures (instructions for containment and the clean-up procedures for chemical spills)
- Handling and storage
- Exposure controls and personal protection (This section provides information regarding the correct PPE that should be worn when working with the specific chemical)
- Physical and chemical properties (appearance, odor, pH, flash point & solubility)
- Stability and reactivity
- Toxicology (information regarding the possible routes of exposure and symptoms)
- Regulatory consideration
- Other information
An safety data sheet will provide plenty of useful information regarding a chemical, therefore it is important to read the document thoroughly before conducting research.
Safe Handling of Chemicals
It is important to prepare before working with chemicals by determining the possible risks and wearing the appropriate PPE. And be aware of the protective measures and emergency responses that relevant to the chemicals you are working with.
- When diluting acids or bases, always add the acid or base to the solvent, such as water. Not, the other way around. Doing so may cause a reaction causing injuries and burns.
- Never remove chemicals from the lab.
- Wear proper goggles. In some cases, Splash Goggles may be needed in order to protect yourself from splashes or spills. Splash Goggles should be marked with the code Z87.1.
- Wear a full chemical-resistant apron when dealing with splash hazards.
- When working with a corrosive chemical it is necessary to wear full arm-length rubber gloves.
- Some chemicals can harm you without contact with your skin, Therefore, it is important to be aware of inhalation exposure. DO NOT smell a chemical, always work with toxic chemicals under a fume hood.
- Be sure to tightly close any containers when not in use.
- Be sure to evacuate the lab immediately in the event of a large chemical spill.
- Always know the flammability and explosive potential for each chemical you work with.
- Separate flammables away from all ignition sources such as burners and hot plates.
- Store flammables in a separate cabinet that is grounded.
- When you are finished with the research be sure to properly dispose of any chemicals according to your local laws.
- Use chemical-resistant plastic or metal containers when disposing of chemicals.
- Do not use the fume hood as a method of disposal.
- Materials used for clean-up are also considered hazardous waste and must be disposed of accordingly.
Other General Hazards
So far in this article, we have covered a number of important topics regarding laboratory safety. However, there are still a few general lab hazards that we need to cover which are just as important.
- Electrical shock. Many pieces of equipment in a lab operate at high voltages. It is important to keep any liquid or water away from these instruments. Conduct routine checks of any electrical cords for fraying.
- Burns. Many instruments in the lab operate at high temperatures and can cause burns. It is important to use heat-resistant gloves when handling hot materials. Low temperatures can also be harmful to your skin. Wear insulated gloves when handling dry or ice or items stored in a freezer.
- Keep floors clean to prevent slips or falls. No items or instruments should be stored on the floor. Use “Wet Floor” signs to warm colleagues of any spill that has not yet been cleaned.
- Be sure to secure any gas cylinder with a heavy-duty clamp and strap. A gas cylinder head also must be secured with a protective cap when not in use.
A solution is described as a homogeneous mixture of a solute and a solvent. The term solution is commonly applied to a liquid, however, a solution can also be made using gas solids.
The purpose of preparing a solution is to make the drug easier to administer to the patient. Preparing a solution is done by dissolving a known mass of solute (often a solid) into a specific amount of a solvent. The most common way to express the concentration of the solution is M, or molarity, which is the number of moles of a solute per litre of solution.
In this example, we will be preparing a solution of Vitamin B12 dissolved into Water.
First, calculate the molar mass of Vitamin B12 (Molecular Formula C63H88CoN14O14P) which is the mass of a mole of all elements in the molecular formula. You can find the mole on nay periodic table (It is the number located beneath the element).
Example: C 756.7 + H 88.7 + Co 58.93 + N 196.09 + O 223.99 + P 30.97= 1355.36 g/mol
- Weigh out 1355.36 g Vitamin B12.
- Place the Vitamin B12 in a 1-litre volumetric flask.
- Add a small volume of distilled, deionised water to dissolve the Vitamin B12.
- Fill the flask to the 1 L line.
If different molarity is required, then multiply that number times the molar mass of Vitamin B12. For example, if you wanted a 0.5 M solution, you would use 0.5 x 1355.36 g/mol of Vitamin B12 in 1 L of solution or 677.68 g of Vitamin B12.
A suspension is a liquid dosage form that contains finely divided insoluble materials which are distributed evenly within the suspending medium offering a degree of solubility. This dosage form is normally used when it is needed to provide a liquid dosage form for a poorly soluble chemical. Additionally, it is ideal for chemicals that become unstable in an aqueous medium over time.
How to make a suspension
- Mortar and pestle
- Rubber spatula
- Metal spatula
- Graduated conical
- Weigh boats
- Place the specified number of tablets in your mortar and triturate until the tablets have become a fine powder. Using a firm twisting motion is the most efficient way to start the trituration process.
- Place your weigh boat onto the scale then tare the scale to zero.
- Place the powder into the weigh boat until you have the specified weight.
- Measure the required amount of suspending agent (Be sure to shake the suspending agent well before measuring) by pouring it into your graduated conical.
- Create a divot in the centre of your powder by firmly pressing down with your pestle. Pour a small amount of the suspending agent into the center of the divot. Use the pestle to begin the wetting process. *Rubber spatula can be sued if scraping is necessary.
- Continue to pour small amounts of the suspending agent into the mortar. *It is important to add the suspending agent otherwise clumping may occur in the suspension. *Use the rubber spatula to scrap your pestle and the sides of the mortar.
- Continue adding the suspending agent until there is a smooth consistency with no lumps. Once the consistency is smooth, you may add the suspending liquid more quickly. *The suspension should have no lumps inside.
- Pour your completed suspension into your prescription bottle. *Use the rubber spatula to scrape and remove all of the suspension from the mortar.
- Once you have finished placing all of the completed solution into the prescription bottle you may cap the bottle.
- Clearly label your bottle with the contents.