NDMA and others

Home / Services / Nitrosamines (NDMA)

Nitrosamines (NDMA)

SAL(ND) is one of the testing laboratory in the field of transformer.

In September 2019, the U.S. Food and Drug Administration (FDA) published a statement of NDMA found in samples of ranitidine, a drug used to treat peptic ulcer disease, gastroesophageal reflux disease and Zollinger-Ellison syndrome.

NDMA is a substance from the class of compounds known as Nitrosamines and is well documented to be an environmental contaminant found in water and foods, including various meats, dairy products, and vegetables.

In late September 2019, the FDA alerted health care professionals and patients to a voluntary recall of ranitidine medicines. Nevertheless, it turned out that some methods for the detection of NDMA residues were using elevated temperatures which induced the artificial synthesis of NDMA.

In November 2019, the FDA published a list of laboratory results of NDMA in ranitidine and nizatidine products that clearly showed all samples tested positive for NDMA residues. Although detectable levels of NDMA were found in each

sample, the concentration varied significantly between the different products. The FDA has set the acceptable daily intake limit for NDMA at 0.096 micrograms or 0.32 ppm for ranitidine – which is exceeded by several products tested.

Nitrosamine impurities such as N-nitrosodimethylamine (NDMA)  have been highlighted by the US FDA and other regulatory authorities as an area for concern. These impurities, classified as a probable human carcinogen, became a focus in July 2018, when the FDA announced a recall of some angiotensin II receptor blocker (ARB) medicines.  In 2019, some over-the-counter medicines used to prevent and relieve heartburn such as ranitidine, were also the the subject of some recalls with the HSA in Singapore and Swissmedic laboratory (OMCL) also detecting levels of contamination with NDMA in certain metformin preparations, used in the treatment of type 2 diabetes. More recently the FDA has issued an alert following the recall of some nizatidine products in association with suspected low levels of NDMA

List of available Nitrosamines

  • N-Nitrosodi-n-butylamine (NDBA)
  • N-Nitrosodimethylamine (NDMA)
  • N-Nitrosomorpholine (NMOR)
  • N- Nitrosodiethanolamine (NDELA)
  • N-Nitrosodi-n-propylamine (NDPA)
  • N-Nitrosodiphenylamine (NDPhA)
  • N-Nitrosopiperidine (NPIP)
  • N-Nitrosodiethylamine (NDEA)
  • N-Nitrosomethylethylamine (NMEA)
  • N-Nitrosopyrrolidine (NPYR)

Liquid Chromatography-Mass Spectrometry (LC-MS/MS) Method for the Determination of NDMA in Ranitidine and other Drug Substances

This method is a liquid chromatography-mass spectrometry (LC-MS/MS) method for the determination of NDMA in ranitidine drug substance and other drug products.

At Standard Analytical Laboratory (ND) Pvt Ltd Since 1989 (Approved by ISO 17025 and FDA-Delhi, GLP), we are experts at method development and validation of suitable analytical procedures, we also help clients overcome the challenges of low detection levels, difficult matrices and identification of unknowns in the course of pharmaceutical impurities analysis. 

As it is vital to obtain the necessary data in short time, Standard Analytical Laboratories guarantee a maximum turnaround time of 3 business days.

Dissolved Gas Analysis

The use of DGA as a powerful diagnostic tool is a critical & important aspects of determining the condition and health of a transformer. DGA is a very reliable and proven techniques to detect the internal faults in working transformers. The fault diagnosis by the gas chromatography is based upon the types & relative quantities of various hydrocarbon gases which can get dissolved in the oil under various fault.

Electric Strength

A measure of the ability of an insulating fluid to withstand electric stress (voltage) without failure. Fluids with high dielectric strength (usually expressed in volts or kilovolts), are good insulators.

Water Content

The water content of an oil sample is measured using an automatic Mitsubishi moisture meter, which is based on the Karl Fischer titration &coulometric end-point. All laboratories use these instruments now to measure dissolved water & probably over 90% use the Mitsubishi model. The instrument is calibrated electronically but is checked with the aid of standard water in methanol solutions. The water content is given in mg/kg (ppm). For an oil sample originating from a 33kv transformer, the water content is normally considered to be a little high when it reaches 25mg/lg(ppm) and too high when it reaches 30mg/kg(ppm). These limits vary depending upon the source of the oil sample.

The test that are done under are :

Tests Significance
Dissolved Gas Analysis IS: 10593& IS: 9434 Check Internal Fault viz. Arcing, Hot Spot & Overheating Etc.
Electric Strength IS: 6792 Check Oil Insulation Value/ Level
Water Content IS:13567 Check Dissolved Moisture affecting Insulation
Resistivity IS: 6103 Affecting the insulation of core& Windings
Acidity IS: 1448 P-2 Paper Insulation Decomposition in oil
Sediments/ Sludge IS: 1866 Check dissolved Contamination
Flash Point IS: 1448 P-2 Fire Catching Point
Inter Facial tension IS: 6104 Aging of Oil
Furan IEC-1198-1993 Status of life of Transfamer
Kinematic Viscosity IS:1448(P-25) Flow and lubricating status of oil
Pour Point IS 1448(P-10) Condition of Oil at low temp.
Density IS:1448(P-16) Puritiy related parameter
Appearance Physical condition
Clarity and colour of oil Physical condition
SK Value IS:335


The resistivity of a liquid is a measure of its electrical insulating properties under conditions comparable to those of the test. High resistivity reflects low content of free ions & ion-forming particles and normally indicates a low concentration of conductive contaminants. These characteristics are very sensitive to the presence in the oil of soluble contaminants and ageing products. Resistivity is normally carried out at ambient temperature but useful additional information can be obtained if the test is carried out at ambient & a higher temperature such as 90degree celcius. Unsatisfactory results at both temperatures indicate a greater extent of contamination than a poor value at the lower temperature only, and the oil is therefore less likely to be restored to a satisfactory level by drying & low temperature filtration.


The acidity level of transformer oil is measured to IS: 1448 P-2. High acidities accelerate the degradation of the paper insulation & causes corrosion of the steel tanks. Oil analysis Services normally suggests changing the oil when the acidity approaches 0.3mgKOH/g, but expresses concern when it reaches 0.1mgKOH/g. It is believed that acidity increases exponentially with time.

Sediments/ Sludge

An estimation of the Sediment content in an oil sample is made by passing polarized light through the oil, clearly showing the fibres & any sediment which is present in the oil. The fibres are classed as being long (greater than 5mm), medium (2 to 5 mm) or short (less than 2 mm), & the number of fibres present is classed as few (1 to 5) or many (more than 10). Sediment is classed as being either light, medium or heavy. The presence of fibres in an oil sample, especially in combination with high water content, may result in a poor electric strength measurement. This is because wet fibres are drawn into the electrical field & cause arcing to occur. Fibres can easily be picked up during sampling & as such, it is important to ensure that sampling technique recommended by us, the oil sample will be more representative of the bulk oil in the transformer & test results will be more reliable.

Interfacial Tension

It is determine the interfacial tension between the oil sample & distilled water at a temperature of 25'C. The oil will float because its specific gravity is less than that of water. There should be a distinct line between the two liquids. The IFT number is the amount of force (dynes) required to pull a small wire ring upward a distance of 1 centimeter though the water/oil interface. A dyne is a very small unit of force equal to 0.000002247 pound. Good clean oil will make a very distinct line on top of the water & give an IFT number of 40 to 50 dynes per centimeter of travel of the wire ring.

Furan Analysis

A furan test should be included with yearly maintenance and trends developed to monitor the condition of the paper. Furan Test is used to detect the thermal, oxidative and hydrolytic breakdown of paper insulation. This Test, in Conjunction with our dissolved fault gas analysis, gives you the best overview of the state of your transformer. A rough approximation is that, for every 6' to 8' Celsius rise above normal operating temperatures, the life of the insulation is halved. Furans produced from these temperature build-ups are generated in two ways: the first being a localized area of high heat and paper damage, and the second being the general overall heating of the entire insulation system.

Dielectric strength

Dielectric is a measure of the electric strength of a material as an insulator. Dielectric strength defined as the maximum voltage required to produce a dielectric breakdown through tha material is expressed as volts per unit thickness.

Flash point

The flash point of a volatile material is the lowest temperature at which vapour of the material will ignite when given an ignition source. The flash point is a descriptive character that is used to distinguish between flammable liquid.