ABSTRACT
Objective: To establish a new method for determining residual organic solvent DMF in imiquimod. Methods: The samples were injected into an Agilent HP-PLOT/Q capillary column(30 m × 0. 530 mm,40. 0 μm) by a headspace sampler and ana-lyzed with an FID detector, the carrier gas was nitrogen, the inlet temperature was 250℃, and the detector temperature was 270℃. The column temperature was programmed raised. Results: The resolution among the peaks of DMF and the other residual solvents could meet the requirements. There was a good linearity within the experimental concentration range. The average recovery was 94. 6%(RSD=4. 0%, n=9). The limit of quantification and the limit of detection was 4. 809μg·ml-1 and 0. 963μg·ml-1, respectively. Conclusion:The method is convenient, accurate and sensitive, which can be used in the determination of residual solvent DMF in imi-quimod.
ABSTRACT
A method for the determination of impurities in high pure Nd_2O_3 employing inductively coupled plasma mass spectrometry(ICP-MS) was established, and emphasise was put on the elimination of matrix induced NdO~+ and NdOH~+ spectral interferences using cell collision technology(CCT). Using 10% O_2-10% Ar-80% He as the reaction/collision gas and with proper adjustment of the instrumental parameters, ~(159)Tb,~(165)Ho,~(163)Dy could be quantified at ~(175)TbO,~(179)DyO and ~(181)HoO respectively, while the matrix induced NdO~+ and NdOH~+ spectral interferences could be reduced by 25-70 folds. In addition, different elements were tested as internal standards for matrix effect correction under the CCT mode, and it was found that Re was best. Other impurities including La, Ce, Sm, Eu, Gd, Er, Tm, Yb and Lu were detected under conventional mode, except that Pr was detected under high instrumental resolution mode to eliminate peak tailing interference from Nd. In combination with mathematic correction, the established method can be applied for the determination of impurities in 99.999% Nd_2O_3 products with satisfactory RSDs and recoveries.