A sample handling system comprising: a sample-liquid input for a sample liquid; an encapsulating-liquid input for an encapsulating liquid; a carrier-liquid conduit for a carrier liquid; wherein the sample liquid has a density between that of the carrier liquid and the encapsulating liquid and the carrier liquid has a density higher than that of the encapsulating liquid; a liquid-handling system comprising a control tube and a driver; and a controller operably connected to the liquid-handling system; wherein the controller is programmed to cause the liquid-handling system to: (i) draw an encapsulating liquid from the encapsulating-liquid input; (ii) discharge the drawn encapsulating liquid onto a free surface of a carrier liquid in the carrier-liquid conduit, the encapsulating liquid being immiscible with the carrier liquid, so that the discharged encapsulating liquid does not mix with the carrier liquid, and floats on top of the carrier liquid; (iii) draw a sample liquid from the sample-liquid input; and (iv) discharge the drawn sample liquid, the sample liquid being immiscible with the encapsulating liquid and with the carrier liquid, so that the sample liquid does not mix with the encapsulating liquid or with the carrier liquid; and wherein the controller is programmed to actuate the driver to cause the control tube first to carry out step (i) to draw an encapsulating liquid, then to carry out step (iii) to draw a sample liquid, then to carry out step (i) again to draw additional encapsulating liquid, then to carry out step (ii) to discharge the additional encapsulating liquid, then to carry out step (iv) to discharge the drawn sample liquid, and then to carry out step (ii) again to discharge the encapsulating liquid, so that the encapsulating liquid, the sample liquid, and the additional encapsulating liquid are discharged as a unit from the control tube and onto the free surface of the carrier liquid in the carrier-liquid conduit, the encapsulating liquid and the additional encapsulating liquid thereby merging and surrounding the sample liquid to form a composite liquid cell. a sample-liquid input for a sample liquid; an encapsulating-liquid input for an encapsulating liquid; a carrier-liquid conduit for a carrier liquid; wherein the sample liquid has a density between that of the carrier liquid and the encapsulating liquid and the carrier liquid has a density higher than that of the encapsulating liquid; a liquid-handling system comprising a control tube and a driver; and a controller operably connected to the liquid-handling system; wherein the controller is programmed to cause the liquid-handling system to: (i) draw an encapsulating liquid from the encapsulating-liquid input; (ii) discharge the drawn encapsulating liquid onto a free surface of a carrier liquid in the carrier-liquid conduit, the encapsulating liquid being immiscible with the carrier liquid, so that the discharged encapsulating liquid does not mix with the carrier liquid, and floats on top of the carrier liquid; (iii) draw a sample liquid from the sample-liquid input; and (iv) discharge the drawn sample liquid, the sample liquid being immiscible with the encapsulating liquid and with the carrier liquid, so that the sample liquid does not mix with the encapsulating liquid or with the carrier liquid; (i) draw an encapsulating liquid from the encapsulating-liquid input; (ii) discharge the drawn encapsulating liquid onto a free surface of a carrier liquid in the carrier-liquid conduit, the encapsulating liquid being immiscible with the carrier liquid, so that the discharged encapsulating liquid does not mix with the carrier liquid, and floats on top of the carrier liquid; (iii) draw a sample liquid from the sample-liquid input; and (iv) discharge the drawn sample liquid, the sample liquid being immiscible with the encapsulating liquid and with the carrier liquid, so that the sample liquid does not mix with the encapsulating liquid or with the carrier liquid;