An ICP‐MS, equipped with an ultrasonic nebulizer and active‐film multiplier detector, is used to attempt to determine 54 trace elements directly in ground water. Lithium, arsenic, rubidium, strontium, barium, and antimony are found in the microgram‐per‐liter (part‐per‐billion = ppb) range. Most of the other elements are present at nanogram‐per‐liter (part‐per‐trillion = ppt) concentrations. Ion exchange preconcentration is utilized in order to improve the sensitivity for measuring the rare earth elements that exist at concentrations as low as 0.05 ppt for lutetium, thulium, and terbium. The formation of molecular species in the plasma produces false positive results for some of the elements. The presence of silicon or carbon dioxide interferes with the measurement of scandium, strontium interferes with rhodium and palladium, and barium interferes with europium. Correction procedures for these interferences are discussed. All together, the concentrations of the 54 elements in water from four Nevada springs span almost seven orders of magnitude.

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A microfluidic gas-intake device for measurement of gaseous substances was fabricated and tested. The gas-intake device has a window that provides direct absorption of gas into liquid in microchannels the membrane-type microfluidic device which uses a gas permeability of the PDMS membrane for gas-intake is fabricated and compared gas intake efficiency to the gas-intake device using the dissolution velocity of oxygen into DI water channel. The degree of oxygen saturation was significantly improved (17.5 %) in case of the pillar-type device. This indicates that the pillar-type microstructure is effective for the gas-intake purpose.

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