How ACS Reagent Chemicals Define Lab Standards

How ACS Reagent Chemicals Define Lab Standards


In the expansive field of chemistry, understanding the foundational concepts and purposes of chemical grades is crucial. These grades do more than just indicate specific qualities or suggest purity; they offer insights into a reagent's suitability for various applications. These applications range from food preparation to medical treatments, emphasising aspects such as potential risks, metal detection, and the existence of bioactive impurities.

The establishment of these grading criteria is based on thorough research, not arbitrary decisions. They stem from detailed monographs, representing rigorous benchmarks that explain a chemical's characteristics, from its appearance to its purest composition. Notable organizations, including the United States Pharmacopeia and the American Chemical Society (ACS), advocate for these monographs, underscoring the importance of quality control.

Within this framework, ACS Reagent Chemicals hold a significant position, serving as a benchmark in maintaining quality and precision.


What are ACS Reagent Chemicals?

The specifications prepared by the Committee on Analytical Reagents of the American Chemical Society (ACS) aim to serve reagents and standard-grade reference materials used in precise general analytical work1. The term "reagent-grade chemical" implies a substance of sufficient purity to be used in most chemical analyses or reactions.

On the other hand, standard-grade reference materials are suitable for the preparation of analytical standards used in various applications, including instrument calibration and quality control1. It is essential to understand that, despite the comprehensive specifications provided by the ACS, there may be occasions when the analyst may need to further purify reagents for certain specialised uses.

The ACS has left an indelible mark on the professional lives of many scientists, not only through its publications and professional services but also in improving the quality of the chemicals and reagents used in labs worldwide2.

Before the creation of the Committee on Analytical Reagents (CAR), scientists had no easy way to determine the purity of a chemical compound. From the first chemical standard published in 1925 to the current ACS Reagent Chemicals, the aim has been to provide an accessible way for chemists to verify a compound's purity2.


ACS Reagent Chemicals | ACS Reagent Chemicals


ACS Reagent Chemicals and the Pharmaceutical Industry

 The United States Pharmacopoeia–National Formulary (USP–NF) tests support a wide range of drug development and manufacturing processes3. These tests, which are referenced and enforced by bodies like the Food & Drug Administration (FDA), depend on ACS Reagent Grade chemicals, considered the "gold standard" in quality analytical reagents and reference materials.

 Proper planning and acquisition are essential for efficient pharmaceutical development, especially in a field where standards change with new technologies. ACS Reagent Chemicals, available online, is constantly updated, providing easy access to the latest information, essential for the pharmaceutical industry.


Advantages of Using ACS Grade Chemicals

In chemical research and processes, the calibre of substances used can significantly affect the results. ACS grade chemicals, characterised by their stringent quality standards, offer certain advantages that address key concerns in laboratory settings:

  • Reliability and Consistency: ACS grade chemicals ensure high purity, guaranteeing precise and consistent outcomes in experiments and processes, avoiding inaccuracies and saving both time and resources.
  • Safety: These high-purity chemicals decrease the risks of contamination and accidents, providing a safer laboratory environment for staff.
  • Regulatory Compliance: Utilising ACS grade chemicals ensures adherence to industry standards and regulations. This is essential in industries such as pharmaceutical and food production that follow strict guidelines.
  • Cost-Efficiency: While they might seem pricier at the outset, their quality and dependability can result in long-term savings by reducing failed experiments, costly retests, and potential accidents.


DC Fine Chemicals and our Commitment to Tailoring Quality to Diverse Laboratory Needs:

  • Chemical grades signify more than just a general expectation of quality; they align with quality standards tailored for particular applications.
  • While some producers set their own unique grades and standards, they usually provide clarity on how to decipher their definitions.
  • Chemical grades offer producers a roadmap for the consistent creation of essential laboratory reagents.
  • Gaining insight into the distinctions between chemical grades can help determine potential suitable alternatives for specific situations.


At DC Fine Chemicals, we understand the importance of using high-quality reagents. Therefore, we are proud to announce that we offer a variety of products that meet the ACS Reagent Chemicals standard. Our goal is to ensure that every customer receives products that exceed their expectations in terms of quality and performance.

If you are interested in learning more about our ACS quality products or have any inquiries, please do not hesitate to contact us.




  1. Tyner, T. (Chair), & Francis, J. (Secretary). (2017). Part 1, Introduction and Definitions. ACS Committee on Analytical Reagents. eISBN: 9780841230460.
  2. Sweedler, J. V. (2018). A Resource for Our Reagents: ACS Reagent Chemicals. Chem., 90(9), 5511.
  1. Expedite pharmaceutical Development. ACS reagent chemicals is a trust reference for analytical reagents.



Article written by Sherry Cacay, Marketing Manager of DC Fine Chemicals


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Chromogenic Substrates Overview

Chromogenic Substrates Overview

Enzyme-Substrate Specificity

Enzymes are proteins that catalyze most of the chemical reactions that occur in the body, allowing these reactions to occur at neutral pH and body temperature. Enzymes are not modified or consumed during reactions, thus enabling their reuse in biochemical processes and their detection and study in the field of Clinical Microbiology and Biotechnology.

The chemical compound on which the enzyme exerts its catalytic activity is called a substrate. Each specific enzyme binds to its corresponding substrate and modifies it, promoting its transition from a reactive state to a product state. This substrate-enzyme interaction is fundamental for a large number of biological functions and metabolic processes. Enzymes are usually named according to the molecules they interact with - substrates - and their names typically end with the suffix "-ase".


What are chromogenic substrates?

Chromogenic substrates are colourless soluble molecules consisting of a chromophore - a chemical group that, after enzymatic cleavage, releases colour - and a specific enzymatic substrate. They are synthetically produced and are designed to possess a selectivity similar to the natural substrate for the enzyme. These compounds are useful for enzymatic detection, as chromogenic substrates specifically bind with the target enzyme. This reaction allows the enzyme to catalyze the separation of the chromophore group, resulting in an insoluble product with a distinctive colour - releasing the chromophore - that confirms the existence and activity of the enzyme under study. This colour change can be followed spectrophotometrically and is proportional to the proteolytic activity of the enzyme.

Chromogenic substrates facilitate the quantitative and qualitative identification of enzymes and proteins in laboratory experiments, thanks to their visible colour change. This chromatic transition, whose intensity can be quantified, allows the precise measurement of the enzymatic or protein target in chromogenic assays. Its use is common in techniques such as Western blot, ELISA, immunohistochemistry, enzymatic assays, and microbial detection in culture media.

Common enzymes in chromogenic assays are Alkaline Phosphatase (AP), β-Galactosidase, and Horseradish Peroxidase (HRP).

DC Fine Chemicals, an international supplier dedicated to providing high-quality fine chemicals for production, that meet the needs of their customers, presents a new range of chromogenic products:

  • Lapis Substrates (Deep Blue)
  • X-Substrates (Blue Green)
  • Magenta Substrates (Magenta to Lilac)
  • Salmon Substrates (Pink)
  • Other Chromogenic Substrates


Clasification DCFC Code Substrates Synonims CAS Enzyme
Lapis Substrates

(Deep Blue)

125290 5-Bromo-3-indolyl phosphate disodium salt Blue-phos 16036-59-2 Alkaline phosphatase

(Blue Green)


125030 5-Bromo-4-chloro-3-indolyl-β-D-cellobioside X-Cellobioside 177966-52-8 β-Cellobiosidase
125000 5-Bromo-4-chloro-3-indolyl caprylate X-Caprylate 129541-42-0 Esterase
125220 5-Bromo-4-chloro-3-indolyl-α-D-galactopyranoside X-α-Gal, X-α-D-Galactoside 107021-38-5 α-Galactosidase
124980 5-Bromo-4-chloro-3-indolyl-α-D-glucopyranoside X-α-Glucoside 108789-36-2 α-Glucosidase
124960 5-Bromo-4-chloro-3-indolyl-N-acetyl-β-D-glucosaminide X-N-Acetyl-β-D-glucosaminide; X-Glucosaminide 4264-82-8 N-Acetyl-β-D-glucosaminidase
Magenta Substrates (Magenta to Lilac)


125020 5-Bromo-6-chloro-3-indolyl-β-D-glucopyranoside Magenta-glucoside 93863-89-9  β-Glucosidase
125010 5-Bromo-6-chloro-3-indolyl-α-D-glucopyranoside Magenta-α-D-glucoside 878495-64-8 α-Glucosidase
124990 5-Bromo-6-chloro-3-indolyl phosphate disodium salt Magenta-phos 404366-59-2 Alkaline phosphatase
124970 5-Bromo-6-chloro-3-indolyl-β-D-galactopyranoside Magenta-gal 93863-88-8 β-Galactosidase
125240 5-Bromo-6-chloro-3-indolyl-β-D-glucuronide, cyclohexylammonium salt Magenta-GlcA CHA salt, Magenta-gluc CHA salt 144110-43-0 β-Glucuronidase
Salmon Substrates



125260 6-Chloro-3-indolyl-α-D-galactopyranoside Salmon-α-gal 198402-61-8 α-Galactosidase
103380 6-Chloro-3-indolyl-β-D-galactopyranoside Salmon-gal 138182-21-5 β-Galactosidase
125250 6-Chloro-3-indolyl-β-D-glucopyranoside Salmon-glucoside 159954-28-6 β-Glucosidase
125230 6-Chloro-3-indolyl-β-D-glucuronide, cyclohexylammonium salt Salmon-glcA CHA salt, Salmon-gluc CHA salt 138182-20-4 β-Glucuronidase
Other Chromogenic Substrates

(Blackish purple)

125210 5-Bromo-4-chloro-3-indolyl phosphate disodium salt X-Phosphate disodium salt, BCIP 102185-33-1 Alkaline phosphatase, often in conjunction with NBT
125270 Nitro blue tetrazolium NBT, Nitro BT 298-83-9 Alkaline phosphatase

Use of BCIP-NBT substrates

The substrates Bromo-4-chloro-3-indolyl phosphate disodium (BCIP) and Nitro blue tetrazolium chloride (NBT) are commonly used together as a combination of chromogenic substrates. In experiments using BCIP-NBT, the corresponding enzyme linked to the probe antibody is alkaline phosphatase (AP). BCIP-NBT can be used in Western blot techniques, immunohistochemistry (IHC), and can be added to solid microbiological media to detect AP activity in microbial cultures.

The product formed is a dark purple colour that can be easily visible.

Figure 1: Chromogenic reaction using BCIP-NBT as substrate.

What are their applications?

Chromogenic substrates have a wide range of applications, mainly in:

  • Microbiology: They are used in culture media, clinical laboratories for diagnostic tests and identification of microorganisms, and in the food industry.
  • Biotechnology: Chromogenic substrates are vital in colourimetric detection. They are simple to use and suitable for a variety of immunotechniques, from immunohistochemistry to Western blot and ELISA.

Figure 2: Culture Media with chromogenic substrates from CHROMagar™  for detection of carbapenem-resistant Enterobacteria (CRE).


If you are interested in fine chemicals, be sure to visit our website, where you can also find chemical products that suit your business. If you need to know more about our chromogenic substrates or any other product, please contact us:



  1. Manafi, M. (29 November 1995). Fluorogenic and chromogenic enzyme substrates in culture media and identification tests. Hygiene Institute,University of Vienna.
  2. Druggan, P., & Iversen, C. (2014). Chromogenic Agars. In University of Dundee. Elsevier Ltd.
  3. Perry, J. D., & Freydière, A. M. The application of chromogenic media in clinical microbiology. Journal of Applied Microbiology.
  4. Jackson ImmunoResearch Laboratories,INC. Chromogenic Detection for Western Blot, IHC, and ELISA.


Article written by Sherry Cacay, Marketing Manager of DC Fine Chemicals


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Ácido Tricloroacético Ph. Eur.: Propiedades y aplicaciones en bioquímica, cosmética y medicina

Trichloroacetic Acid Ph. Eur.: Properties and Applications in Biochemistry, Cosmetics, and Medicine

Trichloroacetic acid is a solid organic compound with the chemical formula C2HCl3O2. It is also known as trichloroethanoic acid and as TCA. It is a monocarboxylic acid in which the hydrogens of the second carbon atom have been replaced by chlorine.

At DC Fine Chemicals, we specialise in supplying fine chemical products. Our catalog offers a wide variety of solutions for your business. We look forward to serving you soon!

Applications for Trichloroacetic Acid

Trichloroacetic acid (CAS 76-03-9) is a colorless, crystalline deliquescent solid. It is very soluble in water and is exothermic in dissolution. The solution is a strong acid, corrosive to both tissues and metals.

Trichloroacetic acid is a versatile compound used in various fields due to its strong, stable acidic nature. Its applications span areas such as biochemistry, clinical chemistry, and the cosmetics industry.

In biochemistry and clinical chemistry, trichloroacetic acid is essential for preparing and purifying macromolecules like proteins and nucleic acids, which is important for advancing scientific research and developing new medications and therapies. Furthermore, trichloroacetic acid can be used in amino acid analysis and protein quantification, as it precipitates proteins from dilute solutions.

In the cosmetics industry, trichloroacetic acid is a key ingredient in treatments like tattoo removal and chemical peels. Its ability to destroy and remove the top layers of skin facilitates the elimination of pigments and dead cells, promoting cell renewal and improving skin appearance. Salts and esters of Trichloroacetic acid also exhibit useful properties in these treatments, acting as antimicrobial and anti-inflammatory agents.

As a strong acid, Trichloroacetic acid is used topically to treat warts. This process effectively removes warts without significantly damaging surrounding tissue.

Given its highly corrosive nature, Trichloroacetic acid must be handled carefully with appropriate personal protective equipment as recommended by the MSDS.

Industrial Production of Trichloroacetic Acid: Chlorination Process and Catalysts

Industrial production of trichloroacetic acid is carried out through the chlorination of acetic acid (CH3-COOH) using chlorine (Cl2). This process involves the substitution of the three hydrogen atoms in the methyl group of acetic acid with chlorine atoms, resulting in trichloroacetic acid (CCl3-COOH).

The chlorination process can be performed in the presence or absence of catalysts; however, using catalysts can improve reaction efficiency and increase production speed. Some common catalysts in this process include red phosphorus and iodine, which facilitate the substitution reaction and promote the formation of the desired product.

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Novák, P., & Havlíček, V. (2016). Protein Extraction and Precipitation. In Proteomic Profiling and Analytical Chemistry (Second Edition).

Cox, S. E., & Butterwick, K. J. (2005). Chemical Peels. In Surgery of the Skin.

Nandakumar, M. P., Shen, J., Raman, B., & Marten, M. R. (2003). Solubilization of Trichloroacetic Acid (TCA) Precipitated Microbial Proteins via NaOH for Two-Dimensional Electrophoresis. Journal of Proteome Research, 2(1), 89–93.

What is Tris(hydroxymethyl)aminomethane (Tris Buffer)?

Tris buffer is a biological buffer used in biochemistry, microbiology, molecular biology, and pharmacy. Buffers are chemicals that absorb acid or alkali so that the pH of a solution does not change if acid or alkali is added. Tris(hydroxymethyl)aminomethane (CAS 77-86-1) is also known as Tromethamine, Trometamol and Trizma.

At DC Fine Chemicals, fine chemical suppliers in Spain and the United Kingdom, Tris buffer is the biological buffer that we supply most regularly. On our website, you can find the fine chemical raw materials you need, including biological buffers such as Tris.

Uses and Applications of Biological Buffers

Tris(Hydroxymethyl)aminomethane (CAS 77-86-1) is an organic compound that exhibits buffering properties in aqueous solutions. Its chemical formula is C₄H₁₁NO₃, and its molecular structure consists of a central amino group (NH₂) bonded to three hydroxymethyl groups (CH₂OH). These hydroxymethyl groups grant it a unique ability to act as an effective buffer in in the pH range of 7.2 to 9.0.

Tris buffer is a common reagent in biochemistry, used in DNA purification, protein solubilization, and nucleic acid separation by electrophoresis.

It is used in bacteriology, often in conjunction with inorganic buffers, to allow acid sensitive organisms to grow in multi strain cultures where acid producing organisms are present.

In the pharmaceutical industry, Tris buffer is also widely used as an excipient in injection and infusion solutions, eye drops, creams, and gels, helping to stabilize these products. 

Tris can also be used for the treatment of metabolic acidosis and urine alkalinization, in cases where the patient is intoxicated by weakly acidic substances like barbiturates. Its administration is via intravenous injection, as it has a respiratory depressant effect, making its use contraindicated in patients with respiratory insufficiency.

Key Factors in Using Chemical Buffers

There are different biological buffers which are chosen depending on the required pH working range. Many organic chemicals have buffering properties, such as amino acids, but biological buffers tend to have a greater capacity to counteract the effects of added acid or alkali. Organic buffers are distinct from inorganic buffers, such as phosphate and carbonate buffer.

Temperature, reactivity, toxicity, and concentration are other crucial factors to consider. Temperature can affect a buffer's buffering capacity, and it is vital to ensure there are no adverse reactions and that the buffer is non-toxic to the test sample. Concentration can also alter the pH level, and it is important to take this into account in experiments.

Biological Buffers at DC Fine Chemicals

If you are looking for high-quality fine chemical products, DC Fine Chemicals is your solution! As international fine chemical suppliers, we offer a wide variety of biological buffers to meet your needs. Browse our catalog to find what you are looking for.

At DC Fine Chemicals, we strive to provide the best quality chemicals on the market to meet the demands of our industry. We look forward to helping you find the chemical products you need!


Good, N. E., Winget, G. D., Winter, W., Connolly, T. N., Izawa, S., & Singh, R. M. M. (1966). Hydrogen Ion Buffers for Biological Research. Biochemistry, 5(2), 467-477.

Ogden, R. C., & Adams, D. A. (1987). Electrophoresis in Agarose and Acrylamide Gels. In Methods in Enzymology (Vol. 152, pp. 61-87). Academic Press.

MOPS Sal Sódica en profundidad: Un análisis de sus usos y recomendaciones en bioquímica y biología molecular

MOPS Sodium Salt: An Analysis of Its Uses and Recommendations in Biochemistry and Molecular Biology

MOPS sodium salt, a biological buffer, is frequently used in the field of biochemistry and molecular biological research. Buffers are chemicals capable of absorbing acid or alkali, in solution, so that the addition of acid or alkali results in small changes in the pH of the solution.


MOPS sodium salt (CAS 71119-22-7), chemical name: 3-(N-morpholino)propanesulfonate, is a white powder at room temperature with excellent water solubility properties.

With a working pH range between 6.5 and 7.9, it is commonly used in biochemistry and molecular biology, mainly for protein extraction and purification, and RNA isolation by electrophoresis. Most of the material we supply is used in the production of culture media for growth and diagnosis of bacteria and yeast, especially for food microbiology.

Special Considerations in Specific Applications

For specific applications, the following should be considered:

  • Concentrations greater than 20 mM can affect growth in eukaryotic cell cultures.
  • MOPS can form complexes with metals, nucleic acids, and lipids, possibly affecting experiments.
  • In the presence of glucose, it can partially degrade upon autoclaving.

For more details about fine chemical products, please consult our product catalog. At DC Fine Chemicals, as fine chemical suppliers located in Spain and the United Kingdom, we offer products for multiple uses. If you cannot find the product you need, please ask. We will be delighted to help you!

Relevant bibliographic references

Taha, M., Gupta, B. S., Khoiroh, I., & Lee, M. J. (2011). Interactions of Biological Buffers with Macromolecules: The Ubiquitous "Smart" Polymer PNIPAM and the Biological Buffers MES, MOPS, and MOPSO. Macromolecules, 44(21), 8575-8589. c

Carson, S. D., Hafenstein, S., & Lee, H. (2017). MOPS and coxsackievirus B3 stability. Virology, 501, 183-187.

What are API active pharmaceutical ingredients?

The industries that deal with active pharmaceutical ingredients and their pharmaceutical applications must be aware of the new regulations regarding this type of components and substances, especially those that appear in the BOE (Official State Gazette). That is why at DC Fine Chemicals we always try to stay tuned to any updates. In several articles we have mentioned pharmaceutical APIs, but what are they? 

Throughout this article, as manufacturers of fine chemicals in Spain and the UK, we will talk about this type of substance and we will look at what aspects give it so much importance in modern medicine. But first, bear in mind that you can browse our extensive catalogue of chemical products and get your hands on the ones you need. 

What are APIs?

It is said that active pharmaceutical ingredients will change the world of medicine and are an essential factor for innovation, but... What are APIs? They are active pharmaceutical ingredients. In English it is ''Active Pharmaceutical Ingredient'', which results in the acronym API. According to the WHO, APIs are any substance used in pharmaceutical products. They are the main ingredients and the basis for the use and manufacture of pharmaceuticals and medicines. 

For many, APIs are a fundamental element for the production of innovative medicines and treatments. Some of them already exist and are currently under development. The aim of the active pharmaceutical ingredient is to help the patient by treating or preventing a disease. 

Medicines are made up of two main ingredients: the API and the excipient. The main active ingredient APIs are the fundamental ingredient to make the medicine and the excipient is an inactive substance that helps to apply the medicine in the formulation. One of the main and most important functions of excipients is the stabilisation of the API active pharmaceutical ingredients, as well as their preservation and maintenance under the right conditions. They prevent them from degrading and generating other potentially harmful and dangerous substances. 

In addition, the taste of active pharmaceutical ingredients is often unpleasant. With the help of excipients, it is possible to conceal it, providing a somewhat more palatable flavour for ingestion. Some API active ingredients do not work very well in solid form, so it is necessary to provide a more stable structure and to make them suitable for oral administration, e.g. in the form of a syrup. 

Find pharmaceutical products at DC Fine Chemicals

DC Fine Chemicals is dedicated to the manufacturing of fine chemical products in Spain and the United Kingdom. Our equipment and facilities are suitable, as well as being able to guarantee production on multiple scales. We always adapt to the requirements of our customers. 

We carry out exhaustive quality control to ensure that all our pharmaceutical products are in order and ready for our customers. We have a first class staff, which makes us a very competent team in our sector. Research is fundamental for us, so our projects are always focused on optimising existing processes. Take a look at our catalogue on our website, we are looking forward to seeing you!


Basic laboratory indicators

When we speak of laboratory indicators, we are referring to the diagnostic approach used in the laboratory to diagnose infectious diseases. Although there are multiple indicators, all of them are really useful to characterise and learn about new species and, as just mentioned, to detect infectious agents such as parasites, bacteria or fungi. 

As chemical suppliers, this article will talk about indicators and the different types that exist. You can find out much more useful information by visiting our blog and our extensive catalogue of chemical products - you can count on DC Fine Chemicals! 

Laboratory indicators: types and techniques

Staining can also be referred to as colouring. Since microorganisms are too small to be seen with the naked eye, a study under a microscope is necessary in order to know their structure, size or composition. It is also much easier to examine micro-organisms with dyes or stains, which makes it easier to observe them.

Humans live in constant contact with micro-organisms. In many cases they are part of the normal flora of our environment without posing a health hazard. However, on other occasions they can cause pathologies, or in other words, they can cause skin or bone infections, etc. This is why it is important to identify and treat them. 

Laboratory indicators thus describe the process by which various aspects of a bacterium, virus, protozoan, etc. can be identified with the help of dyes. They increase the distinctness of the sample and thus make the information obtained more reliable and accurate: they reveal its size and shape, trigger chemical reactions, and show the external and internal structures.  

Indicators can be classified into two major groups. Simple staining is characterised by the use of a single dye. In this way, the entire sample is stained with a single colour and the cell morphology of the micro-organism in question is known. A differential staining uses more than one dye, revealing differences between cells or parts of cells. Differential indicators include others such as Gram differential staining, Ziehl-Neelsen differential staining and Wirtz differential staining.

The most commonly used dyes in this field are methylene blue, safranin and crystal violet. These, among others, are combined with cellular components such as nucleic acids or acidic polysaccharides.

Gram stain: among the most commonly used stains

Each of them follows established guidelines. To give an example, we will explain what one of the best known and most commonly used stains is: Gram staining. It has been used in the field of microbiology for more than a century, due to the beneficial developments that science has undergone during this time.

Gram staining, like other types of indicators, is performed on bacteria in order to better observe them under a microscope. Depending on the cell wall that surrounds them, they stain differently. Those that do not stain are called Gram-negative bacteria, whose wall is thinner than Gram-positive bacteria, with a greater number of layers covering them. This procedure makes it possible to determine which antibiotic is appropriate, as well as its efficacy. The resulting antibiotic must be able to pass through bacterial walls, depending on whether the bacterium is Gram-negative or Gram-positive. 

The steps that must be followed to obtain a successful Gram stain are simple. First, the sample is collected using a swab. The sample is then spread on a slide and allowed to dry. Then, with the help of alcohol, the sample is fixated, after which the stain - in this case violet - is applied, and the stain is applied for about one minute. To continue the process, the sample is rinsed with water and lugol is applied. This solution is then capable of penetrating the wall of the micro-organism. After a few seconds, the slide should be washed again with a mixture of acetone and alcohol. 

Chemical suppliers

In conclusion, laboratory indicators and microbiology play a decisive role in the treatment of infectious diseases. By enabling the diagnosis of harmful agents, the right method must be practised to obtain the solution sought. These are elementary tools of universal use, thanks to which it is possible to find the most accurate treatment possible. 

To find out more about other topics like this, you can read our blog. In addition, DC Fine Chemicals offers a wide range of chemical products among which you can find the ones you need. Contact us, we are your reliable partner when it comes to fine chemicals!

Bile acids

Bile acids are a group of biochemical substances that belong to the large family of steroids, molecules that have acquired a bad reputation over the last century due to their association with cardiovascular diseases, sports doping or uncontrolled intake of hormones or corticosteroid-type drugs.

However, steroids, with cholesterol as the main component, are absolutely essential for the proper functioning of cells, as their functions as a chemical substance are many and varied: regulatory, structural, mediating, emulsifying, precursors of other important molecules, etc.

As fine chemical suppliers, in this article we will briefly introduce their characteristics and properties, as this is a broad field of study and further in-depth study requires the consultation of a specialised bibliography.

Structure of bile acids

As mentioned above, bile acids are steroids and, therefore, their molecule contains the 4-fused ring system of the cyclopentane-perhydrophenanthrene (also called "gonane" or "sterane").

The carbon skeleton of sterane, the simplest steroid in existence. The numbering of the carbon skeleton is shown, following IUPAC recommendations.

The A and B rings are usually fused in cis-configuration, although the A ring can opt for a chair (more stable) or ship (less stable) conformation. On the other hand, the remaining rings, B/C and C/D, are fused in a trans configuration.

Structure of 5a-cholanic acid (left) and 5b-cholanic acid (right), showing the effect of the A/B cis and A/B trans conformations on the structure.

In terms of functionality, as fine chemical suppliers we can state that the hydroxyl group is common and can be found in the A, B and C rings, and in particular, it is usually present in the C3, C6, C7, C12  and C23 positions. It is also common to find methyl groups in the C10 and C13 positions.

The stereochemistry of steroids is very important. Based on the methyl chemical at C19, the hydrogens at C5 and C8 have cis-isomerism, while those at C9 and C14 have trans-isomerism.

Cholesterol structure with carbon skeleton numbering.

Finally, as fine chemical suppliers, it is common to find an aliphatic chain at the C17 position with varying degrees of functionality. The length and functionality of this chain, the presence of methyl and hydroxyl groups and the stereochemistry of the molecule are the main characteristics of this chemical that differentiate a particular steroid from others.

Biosynthesis and classification

In nature, the basic bile acid is cholanic acid, from which the various bile acids are obtained by the hydroxylation of various positions of the carbon skeleton. However, this acid is hardly found in mammals.

In fact, the main source of bile acids is cholesterol, a highly hydrophobic molecule despite its alcohol function, which is a major constituent of cell membranes. However, when the end of the aliphatic chain is oxidised, we obtain a bile acid, and this is the function performed by liver cells, providing what are known as the primary bile acids: cholic acid and chenodeoxycholic acid:

These acids pass into the digestive tract via the bile bladder, specifically into the duodenum, where there is a relatively acidic pH (5-6.5). However, the pKa of these acids is lower, between 3 and 5. As fine chemical suppliers, we know that this is a problem because under these conditions the acids will be mostly protonated, making them very poorly soluble in aqueous media. That is why, before being released into the intestine, the liver conjugates these acids with glycine or taurine, so that an ionic pair is formed which makes them soluble in aqueous media.

Later, the intestinal flora comes into play by breaking down this ionic pair and transforming these acids into new ones, the secondary bile acids, mainly by dehydroxylation of the C7 position. The intestinal flora can go further and undergo other transformations such as epimerisation or conjugation with N-acetylglucosamine, resulting in tertiary bile acids.

Finally, these acids can be recovered from the gut and returned to the liver to be reused again. This is known as enterohepatic circulation:

Functions of bile acids

Bile acids have surface-active properties when they are in a neutral or basic medium, with the aliphatic end, containing the carboxyl group, as the hydrophilic part, while the rest of the molecule is quite lipophilic. Therefore, its main function is to emulsify fats and non-polar substances into aggregates known as micelles, allowing them to be absorbed by the small intestine and remain soluble in the blood. This facilitates the work of lipases, enzymes that will degrade lipids to free fatty acids and glycerol.

In addition to their emulsifying function, these chemicals also act as chemical mediators, as they bind to various cell receptors in order to trigger important biochemical processes (cell signalling). They are even involved in mechanisms that regulate tissue inflammation.

Thus, among other functions, they are known to be involved in calcium mobilisation, activation of protein C kinase, synthesis of cyclic AMP and secretion of pro-inflammatory cytokines. They are also involved in oxidative processes in the mitochondria and are even involved in insulin receptor signalling. In addition, they regulate cholesterol levels or are involved in the elimination of catabolites such as bilirubin.

In short, bile acids have many functions, and although it may seem paradoxical today, we have seen that the presence of cholesterol is essential for the body to function properly. Provided, of course, that it is present in the right quantities then the problem is reduced to controlling the intake of this steroid. 




  • Kuhajda, K. et al, “Structure and origin of bile acids: an overview”, European Journal of Drug Metabolism and Pharmacokinetics 2006, Vol. 31, No.3, pp. I3S-143
  • Chiang, J.Y.L., “Bile acids: regulation of synthesis”, Journal of Lipid Research, Volume, 50, 2009, 1955-66.
  • Singh, J. et al., “A Review on Bile Acids: Effects of the Gut Microbiome, Interactions with Dietary Fiber, and Alterations in the Bioaccessibility of Bioactive Compounds”, J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b07306

Acetic acid

Acetic acid is an organic chemical substance, it is a colourless liquid with a very distinctive odour. One of its most common uses is in the composition of vinegar, although it is also used in cosmetics and pharmaceuticals, in the food, textile and chemical industries.

As chemical distributors and suppliers of fine chemicals in Spain and the United Kingdom, we would like to discuss the composition of acetic acid in relation to other substances in order to understand its different uses, as well as other information that may be of interest to the field.

What is acetic acid?

On an industrial level, acetic acid is produced through the carbonylation of methanol and is used as a raw material for the production of different compounds. It can also be obtained through the food industry by the acetic fermentation process of ethanol, or more commonly explained, through alcoholic fermentation and with the distillation of wood.

Pure acetic acid or glacial acetic acid, also known as CH 3 COOH, is a liquid that can be harmful to our health due to its irritating and corrosive properties and can cause severe skin, eye and digestive tract irritation. However, thanks to its combination with different substances, it is possible to obtain everyday products that may be familiar to everyone, such as vinegar.

Vinegar is a hygroscopic substance, i.e. it can absorb moisture from its surroundings. Therefore, when it is mixed with water, there is a very significant reduction in its volume. On the other hand, when acetic acid 100 % is exposed to low temperatures, the surface, also known as acetic essence, crystallises and forms ice-like crystals at the top.

Due to the chemical structure of this material, it has a very high boiling point. Furthermore, it is worth noting that acetic acid, being a carboxylic acid, has the ability to dissociate, but only slightly, as it is a weak acid [FC1] . Moreover, thanks to this ability to dissociate, it conducts electricity effectively.

Uses of acetic acid

As chemical distributors, the purposes for which this type of acid is processed are varied. As mentioned above, it can be found in many grocery shops as white vinegar. In such products, acetic acid cannot be found in its pure form, but only in small quantities. It is also present in foods such as canned and pickled foods, cheese and dairy products, sauces or prepared salads.

It is also commonly used in the pharmaceutical, cosmetic and industrial industries both to produce other substances and to regulate their properties, especially with regards to their pH. Due to its strong odour, one of its other main uses is in cosmetics as a regulator in the aroma of fragrances, i.e. it achieves a balance between sweet smells in particular. In the textile industry, it is used to dye fabrics and produce fabrics such as viscose or latex.

In the chemical industry, acetic acid is used in the production of cleaning products and, in the pharmaceutical industry, in supplements and some medicines, as it is capable of stabilising blood pressure and reducing blood sugar levels. It is also a common ingredient in ointments.

Acetic acid in everyday life

This substance is found in many everyday products as described above, such as food, cleaning products and cosmetics, among others. Of all of them, vinegar is one of the most important ones, as it has different uses, such as for cooking or cleaning. It is an infallible product when it comes to dealing with stubborn stains such as dog urine, rust or other dirt.

At DC Fine Chemicals, we as chemical distributors and suppliers offer a wide range of fine chemical products. If you are looking for a reliable partner throughout the entire process and product development, please contact us!

In this article, we have explained what acetic acid is, as well as its composition and use within the industry. Visit our blog for more info!