Asphaltene content by the in-line filtration method

• The in-line filtration method to determine asphaltene content takes less than 10 min.
• The method has high repeatability and a detection limit of 13 ppm of asphaltenes.
• The method uses a standard HPLC instrument and filters that are widely available.
• Results correlate with results obtained using traditional gravimetric techniques.

In this work, we report the development of an improved analytical method for the evaluation of asphaltene content. This method uses high performance liquid chromatography (HPLC) but, instead of using a conventional column, it uses a commercially available filter to retain the precipitated asphaltenes that are to be quantified. The in-line filtration method represents a significant improvement with respect to previous methods that use a column packed with an inert packing material to perform the analysis, being more repeatable and reproducible with better sensitivity and as a consequence, lower detection and quantification limits. Additionally, the improved method works at lower flow rates making possible the use of a larger variety of different HPLC detectors and opening the possibility to directly couple it with other analytical techniques such as GPC, MS, ICP that require low flow rates. Filters are commercially available, cheaper, and show low variability that drives a more consistent performance than inert/handmade columns. This in-line filtration method requires small amounts of sample and can take less than 10 min. These characteristics make the use of filters an excellent candidate for monitoring processes in the oil industry where evaluation of asphaltenes is important.