Rc. Back et al., MICROHOMOGENIZATION OF INDIVIDUAL ZOOPLANKTON SPECIES IMPROVES MERCURY AND METHYLMERCURY DETERMINATIONS, Canadian journal of fisheries and aquatic sciences, 52(11), 1995, pp. 2470-2475
A new method for processing zooplankton improves the accuracy and prec
ision of mercury (Hg) and methylmercury (MeHg) determinations and perm
its the analysis of Hg species and ancillary variables, such as dry we
ight and C, N, and protein contents on subsamples of the same tissue h
omogenate using clean technique. In this study, 10-50 individual zoopl
ankton were sorted from live samples, homogenized in 500 mu L of low-H
g water, subsampled, and then digested for analysis without contaminat
ion. Detection limits ranged from 4 to 12 pg for Hg and from 0.8 to 4.
3 pg for MeHg. Procedural blanks averaged 18.7 pg Hg and 5.3 pg MeHg.
Yield from certified reference materials was consistently high on smal
l masses of tissue homogenate (96% for Hg and 89% for MeHg), and recov
ery from spiked samples was good (99% for Hg and 92% for MeHg). We als
o present results for Daphnia and Chaoborus from Mud Lake, Wisconsin,
processed in this manner. The new method improves our ability to deter
mine the distribution of Hg species at lower levels of aquatic food we
bs and to investigate factors potentially regulating the bioaccumulati
on of Hg and MeHg in specific taxa.