FTIR spectroscopy: Efficient biofluid analysis in the microliter range
Fig. 1: Urine spectra of 6 female wild-type mice aged 7 weeks
Preclinical research relies on reliable, reproducible data from biological models. Mice play a central role in this—not least because of their genetic proximity to humans and the possibility of controlling environmental and nutritional factors in a standardized manner. However, a limiting factor in many studies is the small amount of sample material available.
A recent study therefore evaluated the potential of Fourier transform infrared spectroscopy (FTIR) for analyzing minute volumes of mouse urine using the Harrick ConcentratIR2™ multiple reflection ATR accessory.
Analysis with only 2 microliters of urine
The study focused on evaluating the diamond-based multiple reflection system Harrick ConcentratIR2™, which was used in combination with a commercial FTIR spectrometer and DTGS detector. Urine samples from wild-type C3H mice (female, 7 weeks old) with a volume of only 2 µL were analyzed. After standardized drying of the sample using a nitrogen stream, the measurement was performed with high spectral resolution.
The spectra obtained (see Fig. 1) showed high internal reproducibility and strong agreement with previously published spectra of human urine (Fig. 2) – especially in the range from 3600 to 1100 cm- 1, which is characteristic of numerous biologically relevant molecular groups.
Fig. 2: Average spectra of human urine: children (red), young adults (blue), adults (green)
Despite individual variability with-in the animal group, structurally consistent band patterns were observed, for example in signals typical of urea and in areas of high absorption associated with proteins. The striking similarity between mouse and human samples underscores the translational potential of this methodology.
Methodological relevance for biomedical research
The ATR technique used here, combined with the Harrick ConcentratIR2™, enables the analysis of biofluids in the microliter range with high spectral quality. The absence of chemical labels or sample preparation makes the method particularly attractive for studies with limited sample material – for example, in toxicology, pharmacokinetics, or metabolomics. At the same time, spectroscopy provides deep insight into the molecular composition of biological fluids – non-invasively, quickly, and reproducibly.
