Accurate, real-time formation fluids analysis can be accomplished using the systems and techniques described herein. A fluid analyzer includes a first mode of analysis, such as an optical analyzer, configured to determine a physical (optical) property of a fluid sample. The fluid analyzer also includes another mode of analysis, such as a composition analyzer, such as a gas chromatograph, configured to determine a component composition of the fluid sample. A data processor is configured to determine a quantity, such as a weight percentage, of a target component of the fluid sample in response results obtained from the first and second modes of analysis. Beneficially, the results are obtained at least in near real-time, allowing for interim results, such as results from the first analyzer to be used for one or more of tuning the compositional analyzer and for implementing quality control.