Review of use of keepers in solvent evaporation procedure during the environmental sample analysis of some organic pollutants

Analytical progress and challenges for the detection of oxygenated polycyclic aromatic hydrocarbon transformation products in aqueous and soil environmental matrices: A review

“…The addition of keeper solvents, which are less volatile than the primary sample solvent, such as heptane (Meyer et al 1999), dodecane (Fan et al, 2012;Li et al, 2014;Woudneh et al, 2016), and toluene Siemers et al, 2015) may be helpful in preventing losses due to excessive drying, but these have not been specifically evaluated, and could lead to reduced solubilisation of more polar analytes. In many cases, keeper solvent use during PAH analysis has not substantially improved recovery of the smallest targets (Dabrowski, 2016).…”

Evaluation of Solvents Used as Keepers in the Determination of Organic Pollutants by GC/MS

“…According to a previously published review paper [ 5 ], nonane and dodecane are the most commonly used keepers in the PCB determination procedure. In the latest works describing analytical procedures (for PCBs) using keepers, nonane was used by Sprague M. et al (2015) [ 15 ] and tetradecane was used by Arp H.P.H.…”

“…Although many miniaturized sample preparation techniques are popular, such as low density miniaturized homogenous liquid–liquid extraction (LDMHLLE) [ 1 ], single-drop microextraction (SDME) [ 2 ], dispersive liquid–liquid microextraction (DLLME) [ 3 ] and others [ 4 ], applications that require a "traditional" approach to the determination of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organic pesticides, with solvent evaporation, are still in use. Among several others, evaporation in a stream of nitrogen remains the most popular method when reducing a small volume of solvent or used as a second step in the evaporation procedure [ 5 ]. However, this stage is limited by the loss of analytes, especially volatile ones.…”

“…A keeper is usually a high-boiling-point liquid added to the extract in a small volume (usually 20–300 µL and above). According to the review paper on the use of keepers in the analysis of environmental samples published in 2016 [ 5 ], there are only a few works with basic studies on the application of keepers, i.e., for polycyclic aromatic hydrocarbons and their derivatives [ 6 , 7 ].…”

“…The determination of organic pollutants in samples of various types has been described in studies considering PAHs in contaminated soil samples [ 8 ] and particulate matter [ 9 ]; chlorpyrifos and other pesticides in river water and sediments [ 10 ]; pyrethroid metabolites in human urine [ 11 ]; organochlorine pesticides (OCPs) and PCBs in human serum [ 12 , 13 , 14 ]; PCBs and other persistent organic pollutants (POPs) in fish [ 15 ]; and PCBs in waste, leachate and aerosols [ 16 ]. In these and other works, the keeper was selected arbitrarily on the basis of previous works, recommendations, standards and regulations [ 5 ]. Nevertheless, there is a lack of basic research comparing different keepers (except [ 6 , 7 ]) and considering the influence of heating the sample during evaporation on analyte recovery.…”