Monitoring Phenothiazine Exposures - Heterocyclic Compounds Used as Medication, Insecticides, Dyes

Thiazine and related phenothiazine derivatives are an important class of compounds with diverse

biological characteristics, including anti-tubercular, anti-fungal, anti-bacterial, analgesic, and anti-inflammatory properties [1-3]. Thus, these compounds are constituents of many biomolecules and drugs [4]. These compounds are also constituents of insecticides, livestock treatment, and textile dyes. Methylene blue, the most well-known and widely used thiazine compound [1, 3], is also a well-known textile dye.

Thiazine is a six-member heterocyclic compound containing two heteroatoms (N and S) in the heterocyclic ring [3]. For example, methylene blue is a cationic tricyclic phenothiazine salt (see Figure). High concentrations of these compounds are known to be toxic to aquatic life. Thus, its continuous discharge into water bodies is considered a threat to the environment and human health.

These compounds can be extracted from wastewater employing various chemical (e.g., oxidation, ozonation), electrochemical (e.g., electrolysis), biological (microbes or enzyme-based bleaching), and physical (e.g., flocculation, filtration, adsorption) techniques or their combination [5]. All these methods are helpful if the goal is to remediate wastewater. These methods either remove or degrade these compounds. However, suppose the goal is to extract and monitor the presence and concentration of these compounds in wastewater. In that case, the compounds cannot be degraded. For such applications, solid phase extraction (SPE) stands out as one of the most widely used methods to remove and recover these compounds from wastewater [6] [7]. These recovered compounds can then be characterized and quantified using analytical tools (spectroscopy or other methods).

Millennial Scientific has used methylene blue as a representative phenothiazine compound and developed a solid phase extraction (SPE) method using its all-carbon reverse phase media. Its optimized protocol allows 95% recovery efficiency. Get in touch to discuss how we can support your extraction needs for heterocyclic thiazine and other dye compounds.

Please email us at, call us at 855 388 2800 or fill in our online form.


1. Asif, M., Chemical and Pharmacological Potential of Various Substituted Thiazine Derivatives. Journal of Pharmaceutical and Applied Chemistry, 2015: p. 49-64.

2. CS, P.S.a.D., Synthesis And Biological Evaluation Of 1,3-Thiazines- A Review. Pharmacophore, 2013. 4(3): p. 70-88.

3. Vincent Girly, M.V.B., Joseph Jini, Chandran Meena, Bhat AR. and Kumar K. Krishna A Review on Biological Activities of Thiazine Derivatives. International Journal Of Pharmaceutical And Chemical Sciences, 2014. 3(2): p. 341-348.

4. Badshah, S.L. and A. Naeem, Bioactive Thiazine and Benzothiazine Derivatives: Green Synthesis Methods and Their Medicinal Importance. Molecules, 2016. 21(8).

5. Roy, M. and R. Saha, 6 - Dyes and their removal technologies from wastewater: A critical review, in Intelligent Environmental Data Monitoring for Pollution Management, S. Bhattacharyya, et al., Editors. 2021, Academic Press. p. 127-160.

6. Nekouei, F., et al., Efficient method for determination of methylene blue dye in water samples based on a combined dispersive solid phase and cloud point extraction using Cu(OH)2 nanoflakes: central composite design optimization. Anal Bioanal Chem, 2017. 409(4): p. 1079-1092.

7. Sipi, A.K.M. and S.H. Chang, Extraction of Methylene Blue from Aqueous Solutions by Waste Cooking Oil and its Back-Extraction. IOP Conference Series: Materials Science and Engineering, 2020. 811(1): p. 012001.