Solubility of DNA in water

This would seem to be an easy to answer question, but I was unable to find an answer (in g/L) for generic double-stranded DNA or plasmid neither on Google nor on BioNumbers. I would expect the solubility to vary slightly based on the sequence or length, but it probably wouldn't affect it very much due to the relative hydrophobicity of the bases.

I know I have made solutions of plasmid maxipreps of at least 1µg/µl, and the Nanodrop DNA quantifier datasheet has a maximum DNA detectable limit of 15µg/µl, but can anyone find a source for the maximum solubility level of generic DNA? For example, the solubility of a specific plasmid of approx. 5kb in length would be a good ballpark answer for this question.

DNA is a bit more complicated than some molecules due to it's length and composition variability.

In water.

According to Integrated DNA technologies:

DNA oligos can be resuspended to a near maximum concentration of 10mMolar; to achieve such a high concentration will require a lot of vortexing and it may take up to a day for the oligo to go into the solution.

DNA is a polar molecule and as far as I have experienced dissolves in water very readily. However there doesn't seem to be an exact quantifiable number for DNA solubility in water. If I correctly understand it, this paper claims that a 200,000Da-8,000,000Da oligonucleotide is soluble in water, however they never quantify this. An answer on a related question pointed out that high molecular weight DNA oligomers, like genomic DNA, is enhanced in solutions with dilute monovalent cations.

Cleaver & Boyer (1971) have some data on this, however it is somewhat outdated, and they were only using this solubility to demonstrate dialysis in water was capable of desalting the oligonucleotides.

Oligonucleotides larger than 5 bases in length remained within the dialysis bag (Fig. 2) and losses of 10% and 40% occurred for tetra- and trinucleotides, respectively.

There is a lot of work done on optimal temperature and pH for solubility of DNA so perhaps a more specific query might throw up some results.

In ethanol.

Ethanol precipitates at least 10-20 % of all classes of oligonucleotides. Oligonucleotides longer than 15-16 nucleotides are precipitated to about 65%.

Practical Work for Learning

Class practical or demonstration

You can extract DNA – to see what it is like – from some plant and some animal material using equipment and chemicals you might find in a kitchen. For more thorough analytical work, you need more control over the components of your chemicals, and it may be worth investing in a kit from one of the major suppliers. This is a rough and ready method that should give reasonable quantities of DNA from quite large quantities of material.

Lesson organisation

You can run this as a demonstration, or as small group work. Or you could prepare enough of each of several materials to allow groups to take samples from which they extract the DNA.

Apparatus and Chemicals

For each group of students:

Access to water bath at 60 °C (optional)

Test tube, 1, for each sample to be used

Ice cold ethanol (IDA), 10 cm 3 for each sample to be used

Wooden spill, straw, glass rod or inoculating loop, 1 per sample

For the class – set up by technician/ teacher:

Blender for each material to be used
or knives to chop material and a mortar and pestle to grind material for each working group

Ice bath to keep materials cool as necessary (Note 1)

Source/s of DNA (Note 2) – to produce 10-20 cm 3 of blended material per sample

Table salt, a pinch (or 1 cm 3 ) for every 300 cm 3 sample (Note 3)

Strainer for each material to be used

Detergent, 30 cm 3 for each 300 cm 3 of blended material to be processed

Protease, for example, pineapple juice, contact lens cleaner, pinch of meat tenderiser

Health & Safety

  • Take care with ethanol IDA (see CLEAPSS Hazcard) – which is highly flammable and harmful through skin contact because of the presence of methanol.
  • Protease (see CLEAPSS Hazcard) is harmful as a powder and irritant in solution. Wear eye protection and wash off skin promptly.
  • Electrical equipment: Any electrical appliances used in the lab should be checked according to your employer’s systems. Use a blender dedicated for laboratory activities, not one that will be used later to process food for human consumption.

1 Using ice-cold ethanol and ice-cold water increases the yield of DNA. Low temperatures protect the DNA by slowing down the activity of enzymes that could break it apart. A cell’s DNA is usually protected from such enzymes (DNases) by the nuclear membrane which is disrupted by adding detergent. DNases in the cytoplasm would destroy the DNA of viruses entering the cell. Cold ethanol helps the DNA to precipitate more quickly. Chill the ethanol in a screwcap plastic bottle in the prep room freezer. Below 4 °C ethanol is below its flashpoint so this is safe even if your freezer is not spark proof.

2 You can use a variety of substances for this extraction. The original of this protocol recommended split peas, but onions, and fish eggs or fish sperm (milt) are commonly recommended. It is important to check that your source material contains enough DNA. Kiwi fruit, strawberries and bananas are often recommended, but it is reported (see NCBE article Discovering DNA in the Links section) that the white strands produced here are usually pectin rather than DNA. Kiwi fruit temptingly contain protease that could help to digest the proteins surrounding DNA and make the addition of further protease unnecessary. Some foods (such as grapes) contain a lot of water and will make a watery ‘soup’. In this case, go back to the first step and add less water. You need an opaque cell ‘soup’ for good yields. The amount of DNA you will get will depend on the ratio of DNA to cell volume rather than the number of chromosomes in your material. Plant seeds (such as peas) contain a high proportion of DNA.

3 The salt added helps the DNA to precipitate (as it clumps together) when it meets the ethanol phase.

4 It is important to allow time for each step to complete. The detergent must sit for at least 5 minutes to disrupt the cell membranes and nuclear membranes.

5 If you don’t think you can see any DNA, dip your stick or rod into the surface of the ‘soup’ and then move it gently upward into the ethanol layer. Also, look closely at the ethanol layer for bubbles – sometimes clumps of DNA are loosely attached to the bubbles. If you can leave the mixture for 30-60 minutes, you may see more DNA precipitate.

6 Confirm that what you have is DNA by using a stain for DNA. (It may well be a mixture of DNA and RNA.) Confirm that what you have is not pectin by adding pectinase. If it dissolves it was pectin!


SAFETY: Wear eye protection when handling the enzyme solution.

Avoid skin contact with ethanol and with enzyme solutions or powders.

Wash any spills off your skin promptly.


a Chill your ethanol by placing in a freezer for at least 2 hours, or overnight. Keep it on ice throughout the procedure (Note 1).


b Make a thick ‘soup’ by blending your source material with a little table salt and some cold water (Notes 1, 2, 3). For example, use 100 cm 3 of split peas, with 200 cm 3 of cold water and a pinch of table salt (around 1 cm 3 – Note 2). Blend on high for 15 seconds.

c Strain your ‘soup’ through a mesh strainer and collect the liquid part in a beaker.

d Add 2 tablespoons (30 cm 3 ) of washing-up liquid and swirl to mix.

e Let the mixture settle for 5-10 minutes (Note 4). Some protocols recommend carrying out this stage in a water bath at 60 °C. This may increase yield by increasing the breakdown of cell and nuclear membranes, or reduce yield if it stimulates the action of DNase enzymes (Note 1).

f Pour the mixture into test tubes or other small glass containers, to make each about one third full.

g Add some protease enzymes to each test tube. You could use a pinch of meat tenderizer, a few drops of fresh pineapple juice, or some contact lens cleaning solution.

h Tilt your test tube to 45° and slowly pour well-chilled ethanol (IDA) into the tube so that it forms a layer on top of your ‘soup juice’ – about the same volume as you have of ‘soup/ juice’. Ethanol is less dense than water and will float on top. DNA is soluble in water, but salted DNA does not dissolve in ethanol and will form white clumps where the water and ethanol layers meet (Note 5).

i Use a wooden stick or a straw (or a glass rod) to collect the DNA. Dip the stick into the tube and touch the white layer. Twirl the rod and the DNA should ‘spool’ onto the rod. DNA is a long, stringy molecule. As you pull on one end of the strand, it pulls more DNA into the ethanol layer where it will precipitate. (Note 3 and 5)

j Dry the sample on a paper towel if you want to measure the mass of product, or simply save the DNA by placing it in ethanol in any suitable small container with a lid.

Teaching notes

Each cell in the human body contains 46 chromosomes. If you unravelled the DNA from each chromosome and put the 46 segments end-to-end, each cell would contain about 2 metres of DNA. Each piece of DNA is around 4-5 cm long.

What happens at each step?

  • blending with salt and water: breaks the cells apart from one another and increases the surface area exposed to reagents such as detergent. It also begins to disrupt some of the cell walls of plant material.
  • adding salt: means the DNA is more likely to clump together when it meets the ethanol layer.
  • adding meat tenderiser: meat tenderiser commonly contains bromelain or papain – protease enzymes extracted from pineapple and papaya respectively. It will digest proteins associated with the DNA and so may help to purify the sample.


  • which sources give the most DNA? how will you measure the sources and the product accurately for comparison?
  • do you get better yields if you keep things cool throughout, or if you heat the blended mixture with detergent at 60 °C?
  • which detergent works best?
  • does the meat tenderiser make a difference? with every source?
  • try extracting DNA from things which might not contain it
  • how could you prove that this was indeed DNA? (what is the effect on it of stains which act on DNA such as toluidine blue or acetic orcein?)

Several companies produce kits for DNA extraction (for example Edvotek and NCBE – links below). The advantage of using kits is that any enzymes, salts, surfactants and buffer solutions provided will be pre-tested to ensure consistency from batch to batch, and hence reliability of the outcome of the procedure. They will also probably be cheaper than if you tried to source such materials directly. For a simple ‘bulk’ extraction like this, using many domestically available chemicals, it may not be necessary to use a kit. However, if you want clean DNA for further analysis, the kits are recommended. Some kits allow students to extract DNA from their own cheek cells and to encapsulate that DNA in a small plastic pendant (on a chain). Many students respond very positively to this personal dimension in the protocol, and it may make the procedure more memorable.

Health & Safety checked, March 2009

Web links
This website provides a clear, simple procedure and useful FAQs.
Edvotek is a biotechnology education company providing kits and workshops to support teaching and learning in biotechnology. They produce a simple DNA extraction kit (What does DNA look like?) and a kit (Genes in a tube) for extracting DNA from student cheek cells and making the sample of DNA (in a microcentrifuge tube) into a pendant.
The NCBE has an international reputation for developing innovative educational resources and making sophisticated biotechnology techniques accessible to classroom teachers and students. They provide courses and materials for a wide range of biotechnology practicals – including a DNA pendant kit using which students can store the DNA collected from their own cheek cells in a glass vial. Their website also contains a link to a protocol for extracting DNA from frozen peas (at

The article Discovering DNA (in particular a paragraph headed DNA your onions?) on the NCBE site ( explains that fruits yield pectin rather than DNA.

(Websites accessed October 2011)

© 2019, Royal Society of Biology, 1 Naoroji Street, London WC1X 0GB Registered Charity No. 277981, Incorporated by Royal Charter

Hydrogen Bonding

Hydrogen bonds provide many of the critical, life-sustaining properties of water and also stabilize the structures of proteins and DNA, the building block of cells. When polar covalent bonds containing hydrogen form, the hydrogen in that bond has a slightly positive charge because hydrogen&rsquos one electron is pulled more strongly toward the other element and away from the hydrogen. Because the hydrogen is slightly positive, it will be attracted to neighboring negative charges. When this happens, an interaction occurs between the &delta + of the hydrogen from one molecule and the &delta&ndash charge on the more electronegative atoms of another molecule, usually oxygen or nitrogen, or within the same molecule. This interaction is called a hydrogen bond. This type of bond is common and occurs regularly between water molecules. Individual hydrogen bonds are weak and easily broken however, they occur in very large numbers in water and in organic polymers, creating a major force in combination. Hydrogen bonds are also responsible for zipping together the DNA double helix.

Aqueous solutions containing organic cosolvents

Nucleic acids are soluble in aqueous solutions mixed with water-soluble organic cosolvents. Studies using circular dichroism (CD) and electron paramagnetic resonance (EPR) spectroscopy have shown that the addition of various cosolvents at 20 wt% or higher does not substantially change the overall conformation of short duplexes or hairpins (2�-mers) but does alter the conformations of single-stranded DNA and RNA (Nakano et al. 2008, 2014b). Nuclear magnetic resonance (NMR) analyses indicate that a relatively low concentration of cosolvent, such as 1,4-dioxane at 10 vol% or DMSO at 5 vol%, disrupts weak noncanonical interactions in the group II intron ribozyme (Furler et al. 2009) and in the transactivation response element RNA from human immunodeficiency virus type 1 (HIV-1) (Lee et al. 2013). Thus, organic cosolvents in amounts of up to a few tens of percent by volume or weight do not significantly affect base pairing but do disrupt weak interactions of flexible residues.

There are many reports on the stability of oligonucleotide structures in mixed solutions. In most cases, the thermal stability of base pairing decreases in the presence of cosolvents (discussed further below). This destabilization effect under reduced water content is proposed to be relevant to the function of DNA unwinding enzymes such as helicases (Cui et al. 2007). Moreover, the ability of organic cosolvents to decrease the thermodynamic stability of base pairs has the practical benefit of regulating oligonucleotide structure formation in various applications: For example, the efficiencies of polymerase chain reaction (PCR) and DNA sequencing are improved by the addition of 10 % DMSO, which inhibits reassociation of template DNA strands (Winship 1989 Jensen et al. 2010). Detection of target sequences using molecular beacons is also improved by addition of cosolvents (methanol, ethanol, isopropanol, acetonitrile, formamide, DMF, DMSO, ethylene glycol, and glycerol), showing a 70-fold rate enhancement in 56 vol% ethanol compared with the rate in the absence of cosolvents, as a result of decreasing the activation energy for the hybridization (Dave and Liu 2010). Likewise, the rate of strand replacement in a 30-base-pair DNA duplex is enhanced by the addition of cosolvents such as isopropanol, ethanol, and DMSO e.g., a 15-fold enhancement was observed in 20 vol% isopropanol (Zhang et al. 2015). It is worth noting that, in contrast to the case of oligonucleotide duplexes, the stability of 9- and 10-mer duplexes of peptide nucleic acids (PNAs) having a non-ionic backbone are not disrupted by the addition of DMF or dioxane up to 70 % (Sen and Nielsen 2006, 2007) or of methanol, ethylene glycol, or low-molecular-weight PEGs at 20 wt% (Nakano et al. 2012b). These observations suggest an important role of the nucleotide backbone in the destabilization of oligonucleotide duplexes.

There are several possible explanations for the effects of cosolvents on the stability of nucleic acid structures. When the molarity of cosolvent is high (e.g., about 2 M for the 20 wt% solution of a compound with the molecular weight of 100), binding interactions with nucleotides might be significant. The single-stranded conformation may have greater capability to interact with cosolvents than the base-paired duplex in which bases are stacked within the helix. Particularly, formamide, DMSO, and diethylsuloxide (e.g., at 40 vol%) destabilize DNA base pairing because of the formation of multiple hydrogen bonds and hydrophobic interactions with the nucleotide bases (Escara and Hutton 1980 Blake and Delcourt 1996 Markarian et al. 2006). On the other hand, the enhancement of the renaturation rate of base pairs formed by E. coli and bacteriophage λ DNAs in the solutions with DMSO and formamide has been attributed to the effect of the dielectric constant (Escara and Hutton 1980). To clarify how the solvent properties affect the stability of nucleic acid structures, it is preferable to employ cosolvents that have no strong specific interactions with nucleotides. In addition, although experiments using varied concentrations of a single species of cosolvent have been used to correlate particular solvent properties with base-pair stability or hybridization kinetics, such experiments can be misleading when multiple solvent properties are simultaneously changed. Systematic comparisons of the effects of different types of cosolvents such as ethylene glycol derivatives, small primary alcohols, and aprotic solvents are useful as certain cosolvents have similar dielectric constant but different water activities and vice versa (Fig.  2 ). Many studies have emphasized the importance of the osmotic pressure effect arising from the reduced water activity and of the dielectric constant effect on nucleic acids. Several examples are given in the following sections.

a Organic solvents used for the preparation of mixed aqueous solutions. The properties of water activity a w and relative dielectric constant ε r of 20 wt% solutions are indicated. b Values of the water activity and the relative dielectric constant determined for the 20 wt% solutions of organic cosolvents containing 1 M NaCl (Nakano et al. 2004, 2012a)

Why are proteins water soluble and why do they become not water soluble after denaturation?

The solubility of a protein in water depends on the 3D shape of it. Usually globular proteins are soluble, while fibrous ones are not. Denaturation changes the 3D structure so the protein is not globular any more.

This has to do with the properties of the amino acids in the protein.


Proteins are buid up out of amino acids. All amino acids have a similar backbone structure, but differ in their side chains. These side chains have different properties, some are hydrophobic (not water soluble) whereas others are hydrophylic (water soluble).

To form a functional protein, the amino acid chain is folded in a way that the hydrophobic parts end up on the inside and the hydrophylic parts on the outside. This way a stable, water soluble protein is formed.

Denaturation changes the 3D shape of proteins and (parts) will unfold. This way some hydrophobic side chains, usually burried inside the protein, are exposed. The protein is then not soluble anymore.

What is the difference between 100%ethanol and 70% ethanol - (Aug/21/2007 )

1)what is the difference between 100%ethanol and 70% ethanol
seems like 100%ethanol is used to precipitate DNA while 70% ethanol is for wash salt but why and how does it work?

DNA is very soluble in water so to precipitate the DNA out of solution you need to change the properties of the solution to one where DNA is less soluble. The precipitation protocol involves 3 steps to reduce the solubility of the solution to make the DNA come out of solution:

1. Ethanol is added to the solution because DNA is poorly soluble in ethanol. Normally 2 to 2.5 volumes of 100% ethanol are added, which gives a final concentration of around 70%.
2. Charged groups/atoms give molecules solubility. In DNA, the negatively charged phosphate backbone is a major contributer to its solubility. Adding salt (a.g. NaAc) to the solution shields the charges on the DNA phosphate backbone because the Na+ will bond with the phosphate group. This reduces the solubility of the DNA
3. Lowering the temperature further reduces the solubilty as everything is less soluble at lower temperatures.

The combination of these things reduces the solubility of the DNA to the point that it precipitates as a solid out of solution and can be pelleted.

After pelleting, the DNA is washed with 70% ethanol to remove some (or ideally all) of the salt from the pellet. If water was used as the wash then DNA would dissolve again and if 100% ethanol was used the salt would not wash off because sodium salts are poorly soluble in ethanol.

thanks for help, but i still do not understand that why DNA favor on water not ethanol, since both has OH bond,


Water-soluble piano-stool arene ruthenium complexes based on 1-(4-cyanophenyl)imidazole (CPI) and 4-cyanopyridine (CNPy) with the formulas [(η 6 -arene)RuCl2(L)] (L = CPI, η 6 -arene = benzene (1), p-cymene (2), hexamethylbenzene (3) L = CNPy, η 6 -arene = benzene (4), p-cymene (5), hexamethylbenzene (6)) have been prepared by our earlier methods. The molecular structure of [(η 6 -C6Me6)RuCl2(CNPy)] (6) has been determined crystallographically. Analogous rhodium(III) complex [(η 5 -C5Me5)RhCl2(CPI)] (7) has also been prepared and characterized. DNA interaction with the arene ruthenium complexes and the rhodium complex has been examined by spectroscopic and gel mobility shift assay condensation of DNA and B→Z transition have also been described. Arene ruthenium(II) and EPh3 (E = P, As)-containing arene ruthenium(II) complexes exhibited strong binding behavior, however, rhodium(III) complexes were found to be Topo II inhibitors with an inhibition percentage of 70% (7) and 30% (7a). Furthermore, arene ruthenium complexes containing polypyridyl ligands also act as mild Topo II inhibitors (10%, 3c and 40%, 3d) in contrast to their precursor complexes. Complexes 46 also show significant inhibition of β-hematin/hemozoin formation activity.

Solubility of DNA in water - Biology

Summer Research Program for Science Teachers

DNA E xtraction F rom a V ariety of T issue S amples

GOAL : To use cooperative learning groups to extract very impure samples of DNA from a variety of tissues. [ 5-8 Content Standard E - Understandings about science and technology] To have students come to the realization that DNA in most organisms is biochemically identical. [ 5-8 Content Standard C - Structure and function in living systems] To show that recovered DNA can be frozen and later thawed for biochemical experimentation.

MATERIALS : Each group will be given a set of large filter papers (8 papers should be sufficient) , one small plastic cup, some toothpicks that have a flattened end (for stirring and scooping the DNA), a small amount of meat tenderizer, three small collection bottles (preferably ones that can be closed and placed in a freezer), a bottle of room temperature rubbing alcohol (isopropyl alcohol), liquid dishwashing soap, some liver, a few onions and an active yeast culture. [ Teaching Standard D - Make accessible science tools]

P ROCEDURE: Divide the class into cooperative groups. Have students list three features that they feel might be used to identify a substance as a DNA sample. Ask students to describe the differences that they would expect to find in DNA samples of an animal, a plant and a fungus. Inform students that they will extract DNA from Beef Liver, Onions and Yeast cells and compare and contrast the samples to see if their assumptions were verified.

The teacher should dissolve a teaspoonful of salt ( NaCl) in 500 ml of warm water, place the liver (repeat for other tissues) into the food blender and cover the liver with sufficient salt water to completely immerse the liver. Blend the mixture until it acquires the consistency of watery oatmeal (the yeast mixture will require much less water).

Pour the mixture into a beaker and slowly mix in approximately a half cup of dishwashing soap( the liquid varieties are often green - they contain SDS (sodium dodecyl sulfate) . Distribute to each group about one fourth of a cup of the tissue/saltwater/soap mixtures.

The groups should be told to design a method by which they could filter the liquid portion of the mixture from the solid portion and retain the liquid. [ 5-8 Content Standard A - Abilities necessary to do science inquiry] After a procedure has been discussed, outline it on the board. After each group has collected their three filtrates, hold an interim discussion. Inform students of the role of SDS in disrupting cell membranes. Ask why they feel the blender was used before the SDS was added. Ask what the appearance of the mixture was after the SDS was added. Direct the students to add a " pinch " of the meat tenderizer and observe any changes as they gently stir the mixture. Explain that DNA has a negative charge and the salt has many metallic ions that have positive charges (such as the sodium in the monosodiumglutamate of meat tenderizers) . There is an attraction of the positive ions for the negative ions which allows the solvation process to occur. Direct the students to pour an amount of isopropyl alcohol about equal in size to the amount of the mixture and observe any changes (they should see the DNA slowly separate and rise out of the original mixture).

Ask students to describe the substance that is beginning to enter the alcohol layer- ask if the substance appears to be the same in each of the three tissue samples. Have the students use a new toothpick (wide end) to spool up the stringy substance as if they were making cotton candy. Ask why they were able to separate the stringy substance from the alcohol. Hopefully , all three samples will look alike, leading to the conclusions that DNA is the same in all cells (as to biochemical make-up and properties), that DNA is soluble in water but not soluble in alcohol, that DNA is a transparent stringy substance (refer to double helix shape), that DNA has a negative charge and is attracted to salts dissolved in water solutions (sounds like a cell's contents). [ 5-8 Content Standard B - Properties and changes of properties in matter] See if any of their original guesses as to DNA's appearance, or any differences that might appear in different samples of DNA from different types of organisms were correct.

FOLLOW-UP : Have students label three small sealable bottles and place their DNA samples in the appropriate bottles. Have all bottles placed in a box and place the box in a freezer. Ask the students to design an experiment in which they would use their DNA samples to verify differences in each organism's DNA as a homework assignment. [ Teaching Standard B - Orchestrate scientific discourse]

Difference Between Soluble and Insoluble

Solubility and insolubility of material in a solvent is very important. It is even the fundamental phenomenon for the generation of life on earth and the continuation of it. There should be various chemical and physical interactions for a substance to be soluble and insoluble. Here, we will consider these two terms in a broader perspective.

Solvent is a substance with dissolving capability, thus can dissolve another substance. Solvents can be in a liquid, gaseous or solid state. Solute is a substance that is soluble in a solvent in order to form a solution. Solutes can be in liquid, gaseous or solid phase. So, solubility/soluble is the ability of a solute to dissolve in a solvent. The degree of solubility depends on various factors like the type of solvent and solute, temperature, pressure, stirring speed, saturation level of the solution, etc. Substances are soluble in each other only if they are alike (“likes dissolve likes”). For example, polar substances are soluble in polar solvents but not in non-polar solvents. Sugar molecules have weak inter molecular interactions between them. When dissolved in water, these interactions will break, and molecules will be apart. Bond breakages need energy. This energy will be supplied by the formation of hydrogen bonds with water molecules. Because of this process, sugar is well soluble in water. Similarly, when a salt like sodium chloride dissolves in water, the sodium and chloride ions are released, and they will interact with polar water molecules. The conclusion we can arrive from the above two examples is that, the solutes will give their elementary particles upon dissolving in solubility. When a substance is first added to a solvent, first it will dissolve rapidly. After sometime, a reversible reaction establishes, and the dissolving rate will decrease. Once the dissolving rate and the precipitating rate are equal, the solution is said to be at solubility equilibrium. This type of solution is known as a saturated solution.

Insoluble means that cannot be dissolved. It is the opposite of soluble. As mentioned above, substances dissolve with each other if they “like” each other. When they “don’t like” each other they are insoluble. In other words, if two substances cannot interact with each other, they won’t be soluble. For example, polar substances and non-polar substances do not like each other therefore, there aren’t any interactions between them. So, non-polar solute will not be soluble in a polar solvent. For example, piece of rubber doesn’t soluble in water. Else sugar is not soluble in oil. Insoluble material can be separated easily by filtration method. As there are substances which are completely insoluble, there can be some which are partly soluble. If the solute and the solvent can make interactions for some degree, they are partly soluble.

What is the difference between Soluble and Insoluble?

• Soluble means capable of dissolving in a solvent whereas insoluble means incapable of dissolving in a solvent.

• Polar and non-polar substances are soluble in polar and non-polar solvents respectively, whereas polar and non-polar substances are insoluble when mixed with each other.

• When a solute is soluble in a solvent they may make a homogenous mixture, but if they are insoluble they may not.

• Separation of insoluble components in a mixture is easier than separating soluble components.


  1. “Chemistry of Protein Assay” Thermo Scientific Protein Methods Library.
  2. Ninfa, Alexander Ballou, David Benore, Marilee (2009). Fundamental Laboratory Approaches for Biochemistry and Biotechnology. Wiley. p. 111.ISBN978-0470087664.
  3. Fenk, C. J. Kaufman, N. and Gerbig, D. G. J. Chem. Educ. 2007, 84, 1676-1678.
  4. Smith, P.K. et al.: Measurement of protein using bicinchoninic acid. Anal. Biochem. 150 (1985) 76-85

Watch the video: How to Precipitate DNA (November 2021).