Limit Tests for Impurities Detection
Limit test is defined as a quantitative or semi-quantitative test designed to identify and control small amounts of impurities that may be present in pharmaceutical raw materials and finished products. In general, limit tests apply to a wide range of pharmacopoeias such as United States Pharmacopoeia (USP), European Pharmacopoeia (EP), Japanese Pharmacopoeia (JP), and Food Chemicals Codex (FCC). In simple terms, limit test refers to the identification of impurities by comparing a solution of an unknown sample with a standard solution containing the limiting impurity of the product. Typically, these tests usually rely on visual assessment by a technician, although some tests may rely on instrumental analysis of the sample.
At BOC Sciences, we conduct limit tests to determine the presence of a variety of inorganic impurities and microorganisms in samples.
Purpose of Limit Test
- Determine the harmful amount of impurities
- Determine the allowable/unallowable amount of impurities
Limit Tests for Inorganic Impurities
Limit Test of Chloride
Limit test of chloride is developed based on the precipitation reaction. The precipitation of chloride occurs when soluble chloride reacts with silver nitrate in the presence of dilute nitric acid to form silver chloride, which appears as solid particles in solution. The intensity of turbidity depends on the amount of chlorides present in the test substance/sample.
Limit Test of Sulphate
We perform this test to control the impurity due to sulphate in inorganic substance. The test is carried out based on the precipitation of SO42-, with barium chloride in the presence of hydrochloric acid and traces of barium sulphate. And the opalescent solution so obtained is compared with a standard turbidity containing a known amount of SO42- ion.
Limit Test of Arsenic
The test is designed based on the procedure in which all arsenic if present is converted into arsine(AsH3) by reduction with zinc and hydrochloric acid. The reaction of the issuing gases with mercuric chloride paper producers a yellow stain which can be compared with that produced form a known amount of arsenic.
Microbial Limit Test (MLT)
Our team works in a state-of-the-art controlled and HEPA-filtered microbiology laboratory facility, providing the scientific expertise necessary to quickly and efficiently complete microbial limit testing programs in pharmaceuticals.
BOC Sciences' microbial limit test workflow consists of two parts. The quantitative phase, microbial enumeration, determines the total number of aerobic organisms as well as the total number of yeasts and molds on the product. The qualitative phase, which is a test designed to determine the presence of specific undesirable organisms in the product.
Method Validation
Prior to performing MLT on the product, our experts validate the method to ensure that the product does not have microbial inhibitory properties that could lead to false negatives. This validation test is referred to as the MLT Method Suitability Test. If these antimicrobial properties are present, they can be eliminated by dilution, filtration, neutralization or inactivation prior to testing the product. Our MLT is typically performed on non-sterile pharmaceutical products ranging from raw materials to finished products.
Available Pharmaceutical Microbial Limit Test Services
At BOC Sciences, microbial limit test is typically performed in accordance with cGMP and performed in a GMP microbiology laboratory.
- MLT Method Suitability Test
- Microbial Enumeration (Total Aerobic Microbial Count and Total Yeast and Mold Count)
- Screening Tests for Specified Microorganisms
Pseudomonas aeruginosa
Escherichia coli
Staphylococcus aureus
Salmonella
Bile tolerant gram negative bacteria
C.albicans
Clostridium
B. cepacia complex (Bcc)