Silicone Extraction from Nitrile Compounds and Analyzing Using FTIR-ATR

Silicone Extraction from Nitrile Compounds and Analyzing Using FTIR-ATR

What is Fourier Transform infrared spectroscopy?

Silicone is worldwide used in many industries which produce a wide variety of products, among them disposable glove industry claims their finished products as silicone-free, hence silicone analysis is an essential test in above industry to identify the presence and absence of silicone. Silicone need to be extracted from the product in order to analyse and match its’ chemical structure with Fourier Transform Infrared spectroscopy (FTIR) signature spctrum, hence silicone extraction is carried out using n-hexane as the solvent while giving ultrasonic vibrations to the mixture, after the extraction process extracted silicone is dissolved in the n-hexane solvent, hence n-hexane should be filtered and eliminated using evaporation in order to obtain silicone as a paste, thereafter the obtained paste is analyzed using Fourier Transform Infrared ATR method to get the fingerprint structure of silicone

Benefits of Silicone

Silicone is commonly a fluid or an adaptable, rubberlike plastic, and has various helpful properties, for example, low poisonousness and high warmth opposition. It additionally gives great electrical protection. In the clinical field, silicone can be found in inserts, catheters, contact focal points, gauzes and an assortment of different things. You can likewise discover silicone in various individual things, including shampoos, shaving cream, cosmetics and greases.

Usually nitrile disposable gloves are claimed as silicone free to reduce the product contamination with silicone. But in industrial scale, there might be slight chances for silicone to get into production lines and then into the finished product. Even though the raw materials used in the production process are silicone free, there are many ways to enter silicone into gloves. Hence, testing for the presence of silicone is essential.

fourier transform infrared spectroscopy

Silicone extraction from Nitrile compounds

Silicone extraction process is carried out using n-hexane as the solvent. The material that need to check the presence of silicone, should have a weight of 25 g and it should be cut into smaller pieces, approximately 1 cm2 pieces. Cutting these sized pieces gives more surface area and makes the extraction more efficient. Thereafter they should be put into a beaker. Appropriate amount of N-hexane should be poured into the beaker while ensuring the n-Hexane amount used can cover or submerge all the cut pieces.

The amount of n-hexane depends on the amount of sample pieces used in the extraction process. After putting enough n-hexane to submerge all the samples, seal the beaker with a polythene or cellophane to avoid the evaporation of n-Hexane. Thereafter the beaker with samples should be kept in an ultra- sonicator and sonicate for 2 hours at 700C. Sonication gives ultrasonic vibrations to samples. With ultrasonic vibrations, silicone inside the sample pieces break their bond with samples and get extracted into the n-Hexane solution. After sonicating for 2 hours, the extraction should be kept to cool down. Thereafter n-hexane should be filtered, and the filtrate should be evaporated until a fine paste of extracted silicone remains at the bottom of the beaker.

Fourier transform infrared spectroscopy

fourier transform infrared spectroscopy
The photo credit goes to - Stigmatella aurantiaca at English Wikipedia / CC BY-SA (
Fourier transform spectrometer comprises a Michelson interferometer with a movable mirror. A Fourier transform converts the interferogram into the actual spectrum.

The remained paste should be analyzed using FTIR (Fourier-transform infrared spectroscopy).  FTIR Analysis or FTIR Spectroscopy, is an investigative procedure used to distinguish natural, polymeric, and, at times, inorganic materials. The FTIR examination strategy utilizes infrared light to test and observe chemical properties.

The Fourier-transform infrared spectroscopy instrument sends infrared radiation of around 10,000 to 100 cm-1 through a sample, with some radiation consumed and some went through. The consumed or absorbed radiation is changed over into rotational as well as vibrational vitality by the sample’s atoms. The subsequent sign at the detector presents as a range, typically from 4000 cm-1 to 400cm-1, representing a molecular fingerprint of the sample.  Every functional group or chemical structure will deliver an extraordinary unique fingerprint like spectral impression, making FTIR examination an incredible instrument for substance identification.

Once the extracted silicone is put on the crystal, which is the analyzer and sample holder of the FTIR, the detector detects its’ significant chemical signature. By looking at the spectrum obtained and comparing it with the standard silicone signature spectrum, it can be concluded whether the sample contains silicone depending on the presence of peaks relevant to chemical structure of silicone. FTIR method is being used by scientists and researchers worldwide to get rapid and accurate results.

Article By,

Erandi Ranasinghe – Chemist

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