Determination of metal elements in the feces of Periplaneta americana by inductively coupled plasma optical emission spectrometry

To develop a method for the simultaneous determination of various metallic elements in the feces of Periplaneta americana L., samples were dissolved by microwave, with mixed metal ion standard solution as the control. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine the contents of 11 metal elements, including arsenic (As), cadmium (Cd), aluminum (Al), nickel (Ni), copper (Cu), mercury (Hg), chromium (Cr), cobalt (Co), lead (Pb), manganese (Mn) and iron (Fe). The linearity of the target elements was good in the concentration range with the correlation coefficient r≥0.9990. The detection limits of the method were 0.001~0.067 μg/mL, and the average spiked recoveries were 96.37%~102.01% with the RSDs in the range of 2.82%~13.49%, and the RSDs of the repeatability and precision were both less than 5.0%. Six elements, including Al, Ni, Cu, Cr, Mn, and Fe, were detected in the feces of both nymphs and adults of P. americana. The average content followed the order of Fe > Al > Mn > Cu > Ni > Cr. The content of each element in nymphs was slightly lower than that in adults, while the other five elements, As, Cd, Hg, Co, and Pb, were not detected. The ICP-OES method enabled simultaneouse determination of the content of multiple metal elements in the feces of P. americana, which contained six elements including Al, Ni, Cu, Cr, Mn, and Fe, with their content slightly increasing as the insects aged. Harmful metal elements such as As, Cd, Hg, and Pb were not detected. This study can provide a preliminary theoretical basis for the potential value and safety assessment of the feces of P. americana in medical applications.