Figure 2

Example of FTIRμS analysis. Example of FTIRμS analysis. (a) The rectangular FOV of 160 × 40 μm² is aligned with the articular surface, and next a linear profile perpendicular to the articular surface with 20 μm intervals is scanned. The depth of the measurement is measured from the articular surface to the centre of the FOV. The first scan is at depth d₀ = 0 μm and only has AC for half of its FOV, the second scan is at d₁ = 20 μm and measures the first 40 μm of the superficial layer, the third scan is at d₂ = 40 μm and measures the FOV for 20 μm ≤ d ≤ 60 μm, etc. We do not present the results for the first scan at d₀. (b) Example of FOV aligned with the articular surface at d₀. (c) Example of a line scan with 20 μm intervals perpendicular to the articular surface. Crosses show the centre of the (aligned) FOV.