Validation of Thin Layer Chromatographic Methods

Thin-layer and high-performance thin-layer chromatography (TLC/HPTLC) methods for assaying compound(s) in a sample must be validated to ensure that they are fit for their intended purpose and, where applicable, meet the strict regulatory requirements for controlled products. Two validation approaches are identified in the literature, i.e. the classic and the alternative, which is using accuracy profiles.Detailed procedures of the two approaches are discussed based on the validation of methods for pharmaceutical analysis, which is an area considered having more strict requirements. Estimation of the measurement uncertainty from the validation approach using accuracy profiles is also described.Examples of HPTLC methods, developed and validated to assay sulfamethoxazole and trimethoprim on the one hand and lamivudine, stavudine, and nevirapine on the other, in their fixed-dose combination tablets, are further elaborated.

Measurement of ratios of fragmentation fractions for bottom hadrons in pp̄ collisions at s=1.96TeV

This paper describes the first measurement of b-quark fragmentation fractions into bottom hadrons in Run II of the Tevatron Collider at Fermilab. The result is based on a 360pb-1 sample of data collected with the CDF II detector in pp̄ collisions at s=1.96TeV. Semileptonic decays of B̄0, B-, and B̄s0 mesons, as well as Λb0 baryons, are reconstructed. For an effective bottom hadron pT threshold of 7GeV/c, the fragmentation fractions are measured to be fu/fd=1.054±0.018(stat)-0.045+0.025(sys)±0. 058(B), fs/(fu+fd)=0.160±0.005(stat)-0.010+0.011(sys)-0.034+0.057(B), and fΛb/(fu+fd)=0.281±0.012(stat)-0.056+0.058(sys)-0.087+0.128(B), where the uncertainty B is due to uncertainties on measured branching ratios. The value of fs/(fu+fd) agrees within one standard deviation with previous CDF measurements and the world average of this quantity, which is dominated by LEP measurements. However, the ratio fΛb/(fu+fd) is approximately twice the value previously measured at LEP. The approximately 2σ discrepancy is examined in terms of kinematic differences between the two production environments. © 2008 The American Physical Society.