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. Author manuscript; available in PMC: 2014 Oct 24.
Published in final edited form as: Anal Chim Acta. 2013 Sep 12;800:50–55. doi: 10.1016/j.aca.2013.09.008

Fig. 2.

Fig. 2

Acid digestion procedure for measuring total soluble Cr. HNO3 is deposited on a 10 mm filter punch and digested using a commercial microwave. The digested punch is placed on the µPAD and acetate buffer (pH 4.5) is added to the paper substrate through the PDMS lid. The buffer elutes Cr ions from the MCE filter to the detection zones.