Optimised ICP-MS quantification method for using animal faeces as a measure of protected area ecosystem health

Abstract

Pollution is a key threat to biodiversity and ecosystem health within protected areas. Using a non-invasive, multi-matrix approach, sediment, vegetation and faecal material from lion (Panthera leo) and giraffe (Giraffa camelopardalis) were collected and assessed for the simultaneous quantification of 20 trace elements using an optimised method for Inductively Coupled Plasma-–Mass Spectrometry (ICP-MS). Method Linearity was confirmed over an analytical range of 0.1–50 mg/kg for aluminium (Al) and iron (Fe); 0.4–400 µg/kg for vanadium (V), cobalt (Co), molybdenum (Mo), and cadmium (Cd); 0.5–5 µg/kg for mercury (Hg); and 1–1 000 µg/kg for elements arsenic (As), boron (B), barium (Ba), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), selenium (Se), tin (Sn), strontium (Sr) and zinc (Zn). Coefficient of determination (R2) was above 0.99 for all elements. Accuracy (% recovery) and precision (% RSD) of replicate measurements for certified reference material controls fell within 20% of expected value at lower concentrations and 15% at higher concentrations for all elements except Al. Results for instrument and method limit of detections (LOD), method limit of quantification (LOQ) and expanded uncertainty were satisfactory. Preliminary data indicate As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn were present in all matrices evaluated. This raises concerns regarding the combined action of multiple elements at concentrations that can adversely affect ecosystem and wildlife integrity.

• Sample quantity is reduced due to the power and sensitivity of ICP-MS. • The optimised method is capable of detecting differences in trace element concentrations over large orders of magnitude in animal faeces containing different amounts of organic content. • The method can be applied to the quantification of essential and potentially toxic elements in faeces across a wide range of terrestrial species.