Element Determination in Pharmaceuticals Using Direct Solid Analysis-Electrothermal Vaporization Inductively Coupled Plasma Optical Emission Spectrometry

Abstract

A solid sampling electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP OES) method for determination of As, Cd, Cr, Cu, Mn, Mo, Ni, Pb, Pd, Pt, Rh, Ru and V in pharmaceuticals is proposed. Tricyclic pharmaceuticals were directly analyzed due to their difficult decomposition with acids. Pyrolysis and vaporization temperature, sample mass, and reaction gas (Freon) flow rate were evaluated. The effect of organic and inorganic compounds was evaluated for matrix matching. The limits of detection ranged from 0.04 µg g −1 (Cu) to 107 µg g −1 (As) and the relative standard deviation was lower than 10%. The investigated elements were not detected in the analyzed samples with the exception of Cr in cyclobenzaprine hydrochloride. Since there was no certified reference materials available for metals and metalloids in pharmaceuticals, the accuracy of the method was evaluated by an independent technique and by analyte recovery. Inductively coupled plasma mass spectrometry was employed for analyte determination after sample decomposition by microwave induced combustion. The agreement of the results found by both techniques was better than 87% and analyte recoveries ranged from 91 to 103%.

Improvements in the direct analysis of advanced materials using ICP-based measurement techniques

“…12,59 In case of metallic samples, not only trace impurities were analyzed, 11,60 but also chlorine, 47 as well as the isotopic composition of the matrix metal tungsten. 44 Synthetic organic materials such as polymers and pharmaceutical components were analyzed for the presence of trace elements 42,51,61 as well as for bromine. 62 All of the mentioned sample types have in common that they are difficult to dissolve, hence the choice of ETV.…”

Feasibility of Rare Earth Element Determination in Low Concentration in Crude Oil: Direct Sampling Electrothermal Vaporization-Inductively Coupled Plasma Mass Spectrometry

“…Electrothermal vaporization-inductively coupled plasma mass spectrometry (ETV-ICP-MS) has been used for the determination of REE in several matrices, since it allows sample introduction with a minimum pretreatment, reducing reagent consumption, mainly by avoiding the use of concentrated acids, and the generation of residues. − Another advantage of ETV-ICP-MS is the possibility of obtaining low LOQs (in the ng g –1 range) since it combines the good sensitivity of ICP-MS technique with the direct sampling by ETV, which has higher transport efficiency (20–80%) than pneumatic nebulization (1–5%). ,− It is important to notice that the aerosol formed in the electrothermal vaporizer is a dry vapor, minimizing spectral interferences from the formation of oxides and hydroxides in the determination of REE by ICP-MS. ,, Some limitations of ETV system have been reported for calibration step and sample representativeness. Low-sample masses (0.1–5 mg) are generally used. , However, matrix effects can sometimes hamper the calibration with aqueous reference solutions. − , These limitations can be overcome by optimizing the operating conditions of the ETV system, such as the heating program, the gases flow rate, the use of modifiers and the sample amount. ,,− Another limitation of the use of ETV system is related to the need of a high degree of the analyst’s know-how to develop a method. , On the other hand, after optimization, the application of ETV-ICP-MS method requires the same degree of analyst training of a method based on ICP-MS technique using pneumatic nebulization. ,, …”