a) guiding a first solvent with a sample through an SPE cartridge for concentrating the sample in the cartridge;

b) positioning the cartridge in a carrier, the carrier structured to accommodate a plurality of cartridges;

c) repeating steps a) and b) for a desired number of samples;

d) drying the samples through evaporation or vaporization of residual first solvent following steps a) through c), wherein all the samples are simultaneously dried together using a gas flow which streams through the cartridges while the cartridges with samples are positioned in the carrier, wherein the gas flow is divided into individual partial flow paths, with each cartridge having its own individual partial flow which is guided to and/or from the cartridge, wherein the partial flow paths through each cartridge are sealed from ambient surroundings, with a flow resistance being provided in each partial flow path that is larger than a maximum flow resistance of any cartridge with dissolved sample;

e) dissolving each sample in a second solvent;

f) transferring the dissolved samples from the cartridges to a spectrometer; and

g) acquiring a spectrum of each sample.