Determination of lead(II) by thermal lens spectroscopy (TLS) using 2-(2′-thiazolylazo)-p-cresol (TAC) as chromophore reagent

Saavedra, R.; Soto, César; Gómez, R.; Muñoz, Ariana

doi:10.1016/j.microc.2013.04.019

Cited by 18 publications

(6 citation statements)

References 35 publications

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“…Dual-beam TLS also differs in the direction of laser beam propagation through the sample. Three options are possible: (i) collinear (the beams are strictly co-axial) [ 31 , 38 ], (ii) the beams intersect in the sample at a small angle (usually 1.5°) [ 34 , 39 ], and (iii) the crossed-beams configuration (an angle of 90°) [ 15 , 40 ]. The latter case is relatively rarely used in thermophysical studies due to the difficulty of aligning the beams relative to each other and the small sample volume.…”

Section: Introductionmentioning

confidence: 99%

Accuracy of Measurements of Thermophysical Parameters by Dual-Beam Thermal-Lens Spectrometry

2023

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Thermal-lens spectrometry is a sensitive technique for determination of physicochemical properties and thermophysical parameters of various materials including heterogeneous systems and nanoparticles. In this paper, we consider the issues of the correctness (trueness) of measurements of the characteristic time of the thermal-lens effect and, thus, of the thermal diffusivity determined by dual-beam mode-mismatching thermal lensing. As sources of systematic errors, major factors—radiation sources, sample-cell and detector parameters, and general measurement parameters—are considered using several configurations of the thermal-lens setups, and their contributions are quantified or estimated. Furthermore, with aqueous ferroin and Sudan I in ethanol as inert colorants, the effects of the intermolecular distance of the absorbing substance on the correctness of finding the thermophysical parameters are considered. The recommendations for checking the operation of the thermal-lens setup to ensure the maximum accuracy are given. The results obtained help reducing the impact of each investigated factor on the value of systematic error and correctly measure the thermophysical parameters using thermal-lens spectrometry.

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Section: Introductionmentioning

confidence: 99%

Accuracy of Measurements of Thermophysical Parameters by Dual-Beam Thermal-Lens Spectrometry

2023

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“…Hence, residual elemental impurities controls are required in voriconazole drug substance for regulatory requirements. Several colorimetric and spectrometric methods for determination of Lead [17][18][19], Palladium [20][21][22][23], and Zinc [24][25][26][27][28] was reported. In view of this, we have developed and validated the inductively coupled plasma optical emission spectroscopy (ICP-OES) method and presented in this research paper.…”

Section: Introductionmentioning

confidence: 99%

Development and validation of a simple and rapid ICP-OES method for quantification of elemental impurities in voriconazole drug substance

et al. 2021

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Background The aim of the present study was to develop and validate an inductively coupled plasma optical emission spectroscopic (ICP–OES) method for quantification of elemental impurities, i.e., Lead, Palladium, and Zinc, in voriconazole drug substance, and this method was employed for the regular sample analysis of Lead, Palladium, and Zinc in voriconazole drug substance for pharmaceutical use. The method has been validated using RF power of 1150 W, auxiliary gas of 0.5 L/min, and nebulizer flow of 0.4 L/min and plasma view at axial mode for Lead and Palladium and radial mode for Zinc. The wavelength was monitored for Lead, Palladium, and Zinc at 220.3 nm, 340.4 nm, and 213.8 nm respectively. Results The method is selective and is capable of detecting desired elemental impurities with regulatory acceptance limits in the presence of other elements. The validation experiments involve the demonstration of system suitability, specificity, LOD and LOQ, linearity, precision, and accuracy experiments. The linearity results obtained ˃ 0.9990 for all three impurities. Conclusion The proposed method is simple, sensitive quality control tool for the simultaneous quantitative determination of Lead, Palladium, and Zinc at low levels in voriconazole drug substance. Graphical abstract

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“…[31][32][33][34] The method can also be used to study thermal and optical properties of polymers and glasses, [35][36][37][38][39][40] in addition to the pharmacological and biological applications and determination of heavy metals. [41][42][43][44][45] There have been several reviews on TL applications in the literature. [46][47][48][49][50] In this work, we use the high sensitivity and remote measurement characteristics of the time-resolved TL technique to investigate the photoconversion of pHyp to Hyp.…”

Section: Introductionmentioning

confidence: 99%

From Protohypericin to Hypericin: Photoconversion Analysis Using a Time-Resolved Thermal Lens Technique

et al. 2019

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Hypericin (Hyp) is a natural compound with interesting photophysical and pharmacological properties, which has been used in photodynamic therapy and photodynamic inactivation of microorganisms. Its synthesis is based on a series of chemical processes that ends with a light–drug interaction by the photoconversion of protohypericin (pHyp) to Hyp. Although this photosensitizer is used in a variety of medical applications, the photophysical and photochemical mechanisms involved in the final step related to the photo production of Hyp are not completely understood at the molecular level. Protohypericin concentration, solvents, light irradiation under different wavelengths, and a sort of variables could play an important role in predicting the yielding of this photoconversion process. Here, we used the high-sensitive and remote measurement characteristics of the time-resolved thermal lens technique to investigate the relation between the light-induced photoconversion rate of pHyp to Hyp and the initial concentration pHyp. The results show a linear dependence of the photoreaction rate with the concentration of pHyp, indicating that the overall reaction process includes steps comprising the formation of distinct intermediate species. We demonstrate the applicability of the thermal lens technique for the photochemical characterization of photosensitive drugs at low concentration levels.

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Determination of lead(II) by thermal lens spectroscopy (TLS) using 2-(2′-thiazolylazo)-p-cresol (TAC) as chromophore reagent

Cited by 18 publications

References 35 publications

Accuracy of Measurements of Thermophysical Parameters by Dual-Beam Thermal-Lens Spectrometry

Accuracy of Measurements of Thermophysical Parameters by Dual-Beam Thermal-Lens Spectrometry

Development and validation of a simple and rapid ICP-OES method for quantification of elemental impurities in voriconazole drug substance

From Protohypericin to Hypericin: Photoconversion Analysis Using a Time-Resolved Thermal Lens Technique

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