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The Most Common Grades of Reagents and Chemicals

It is imperative that everyone in the custody supply chain know and understand the different grades of reagents and chemicals used in the laboratory and their uses

by
Aaron Schieving

Aaron Schieving is the founder and managing director at ABS Testing Solutions. He has about 20 years of medical device, pharmaceutical, biopharmaceutical, organ and tissue, cell therapy and regenerative medicine...

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Chemicals and reagents play a critical role in the manufacturing and testing of pharmaceutical products, medical devices, biologics, cell- and tissue-based products, and many other health care-related solutions. Laboratories and researchers who use chemicals and reagents trust that their manufacturers have properly identified the grades of each chemical and ensured that the chemicals have met all regulatory and compliance standards for their intended use. It is imperative that everyone in the custody supply chain know and understand the different grades of reagents and chemicals and their uses, which are explained in this article.

Grades of reagents and chemicals used in the laboratory

When making a solution, the manufacturer must first decide what degree of chemical purity is needed based on the intended use. The following list describes the seven most common grades of reagents and chemicals, from highest to lowest grade/purity:

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  1. ACS grade meets or exceeds purity standards set by the American Chemical Society (ACS). This grade is acceptable for food, drug, or medicinal use and can be used for ACS applications or for general procedures that require stringent quality specifications and a purity of ≥95%.
  2. Reagent grade is generally equal to ACS grade (≥95%) and is acceptable for food, drug, or medicinal use and is suitable for use in many laboratory and analytical applications.
  3. USP grade meets or exceeds requirements of the United States Pharmacopeia (USP). This grade is acceptable for food, drug, or medicinal use. It is also used for most laboratory purposes, but the USP being followed should always be reviewed prior to beginning to ensure the grade is appropriate for that methodology.
  4. NF grade meets or exceeds requirements of the National Formulary (NF). The USP and the NF (USP– NF) jointly publish a book of public pharmacopeial standards for chemical and biological drug substances, dosage forms, compounded preparations, excipients, medical devices, and dietary supplements. The listings here should be reviewed to determine which would be considered equivalent grades.
  5. Laboratory grade is the most popular grade for use in educational applications, but its exact levels of impurities are unknown. While excellent for teaching and training, it is not pure enough to be offered for food, drug, or medicinal use of any kind.
  6. Purified grade, also called pure or practical grade, meets no official standard; it is not pure enough to be offered for food, drug, or medicinal use of any kind.
  7. Technical grade is used for commercial and industrial purposes; however, like many others, it is not pure enough to be offered for food, drug, or medicinal use of any kind.

ACS, Reagent, and USP-NF grades are typically equivalent and interchangeable but, even so, appropriateness should always be confirmed before application. This can be done by reviewing the applicable regulatory requirements.

Lab, purified, and technical grades of reagents and chemicals have their own uses. For example, lab-grade chemicals, because of their low cost and good chemical purity, are used widely in educational applications, such as teaching laboratories at both the secondary school and college levels; however, lab-grade chemicals would not be appropriate for use in the quality control laboratory of a pharmaceutical or medical device manufacturer. ACS-, USP-, or reagent-grade chemicals should be applied in this setting, because they have fewer impurities that could ultimately impact patients taking the drugs made with those chemicals.

With seven different and inequivalent grades of reagents and chemicals, it is crucial to understand how they can impact products. Using a lower-purity grade than a product’s intended use requires could be a costly mistake. Similarly, using a higher-purity grade when not required could result in unnecessary costs. Add in the increased regulatory scrutiny and it becomes even more important to have a complete understanding of the components that your process requires.

Grades of reagents and chemicals: Frequently Asked Questions

Q: What is LR and AR grade?

A: LR grade chemicals refer to chemicals that meet the specifications outlined by the Laboratory Reagent (LR) grade. LR grade chemicals are often used in laboratory settings for analytical and research purposes. These chemicals are of high purity, with impurities specified and controlled to ensure accuracy and reliability in experimental work. 

AR grade chemicals, also known as Analytical Reagent grade chemicals, are chemicals that meet the specifications outlined for analytical applications in laboratories. These chemicals are of high purity, typically exceeding 95 percent, with impurities specified and controlled to ensure accuracy and reliability in analytical procedures. AR grade chemicals are suitable for a wide range of analytical techniques, including titrations, spectrophotometry, chromatography, and other analytical methods. They are often used in research, quality control, and educational laboratories where precise and consistent results are essential.

Q: What is the most acceptable chemical grade?

A: The most acceptable chemical grade depends on the specific requirements of the intended application. However, in many cases, the highest purity grade available is preferred to ensure accuracy, reproducibility, and reliability of results. For most laboratory analytical work, the highest grades such as ACS (American Chemical Society) grade, AR (Analytical Reagent) grade, or equivalent are typically considered the most acceptable. These grades offer the highest level of purity and are suitable for a wide range of analytical techniques and applications.

It's important to note that the choice of chemical grade should be based on the specific needs of the experiment or process. For some applications where extreme levels of purity are not necessary, lower grades such as LR (Laboratory Reagent) grade may be acceptable and more cost-effective. Ultimately, selecting the appropriate chemical grade involves considering factors such as purity requirements, budget constraints, and the intended use of the chemicals.

Q: What do I need to consider when purchasing different grades of chemicals?

A: While there are a variety of considerations when purchasing different grades of chemicals for your lab, here are five important ones:

  • Specifications: Review the specifications provided by the supplier for each grade of chemical. Pay attention to impurity levels, assay values, and other relevant parameters to ensure they meet your requirements.
  • Application compatibility: Ensure that the grade of chemical you choose is compatible with your specific application. Some applications may require higher purity grades to avoid interference or contamination.
  • Regulatory compliance: Consider any regulatory standards or guidelines that apply to your industry or application. Choose chemicals that comply with relevant regulations and safety standards.
  • Budget: Evaluate the cost differences between different grades of chemicals. Balance the need for high purity with budget constraints to find the most cost-effective option.
  • Supplier reliability: Choose a reputable supplier known for providing high-quality chemicals and reliable service. Consider factors such as reputation, certifications, and customer reviews when selecting a supplier.

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