Analytical GC-FID Method for the Determination of Organic Solvents in Radiopharmaceutical

Background:: Organic solvents play an indispensable role in most of the radiopharmaceutical production stages. It is almost impossible to remove them entirely in the final formulation of the product. Objective:: In this presented work, an analytical method by gas chromatography coupled with flame ionization detection (GC-FID) has been developed to determine organic solvents in radiopharmaceutical samples. The effect of injection hold time, temperature variation in the injection port, and the column temperature on the analysis time and resolution (R ≥ 1.5) of ethanol and acetonitrile were studied extensively. Methods:: The experimental conditions were optimized with the aid of further statistical analysis; thence, the proposed method was validated following the International Council for Harmonisation (ICH) Q2 (R1) guideline. Results:: The proposed analytical method surpassed the acceptance criteria for the linearity > 0.990 (correlation coefficient of R2), precision < 2%, LOD, and LOQ, accuracy > 90% for all solvents. The separation between ethanol and acetonitrile was acceptable with a resolution, R > 1.5. Further statistical analysis of Oneway ANOVA revealed that the increment of injection holds time and variation of temperature at the injection port did not significantly affect the analysis time. Nevertheless, the variation of injection port temperature substantially influences the resolution of ethanol and acetonitrile peaks (p < 0.05). Conclusion:: The proposed analytical method has been successfully implemented to determine the organic solvent in the [18F]fluoro-ethyl-tyrosine ([18F]FET), [18F]fluoromisonidazole ([18F]FMISO), and [18F]fluorothymidine ([18F]FLT).

Optimization of Silylation for Parabens Determination by Gas Chromatography-Mass Spectrometry

A low cost, environmental friendly and convenient method for parabens derivatization using Gas Chromatography-Mass Spectrometry (GC-MS) analysis is investigated. Derivatization is needed to enhance the thermal stability, detectability, and volatility of parabens to make them amenable for gas chromatographic analysis. This method involved on-line derivatization by silylating reagent: N-Methyl-N-tert-butyldimethylsilyltrifluoroacetamide (MTBSTFA), N,O-bis (trimethylsilyl) trifluoroacetamide (BSTFA), N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA), and N,O-bis(trimethylsilyl)acetamide (BSA). The variables affected the derivatization process, such as, types and volumes of silylating reagents, injection port temperature, and purge-off time, were evaluated to obtain the optimal condition for determination of parabens. The Relative Response Factors (RRF) was used as a parameter of parabens derivatization efficiency to obtain the best compromise condition of each variable. On a comprehensive level, a comparison of the optimal condition of each silylating reagent was evaluated. Moreover, 1 µL of MSTFA at 260°C of injection port temperature and 2.5 min purge-off time (in splitless mode) obtained the most effective of derivatization process.

Determination of CO2 in Wines by Gas Chromatography

A fast and direct method is presented for the determination of CO2 in wines. Partial pressures from other ingredients of alcoholic beverages do not interfere. The method was compared to the manometric procedure under vacuum. An F & M Model 450 Gas Chromatograph with a filament detector was used for C02 determinations. Components were separated by a column 9” long and 1/8” o.d. using charcoal (60—80 mesh) as solid adsorbent. Injection port temperature was ambient; detector and column temperatures were 40°C. Helium was used as a carrier gas at the rate of 50 ml/min. Approximately 50 μ1 samples of standard and unknown solutions were used for the respective determinations.