Analytical instruments and sample handling procedures have steadily improved during the last decade in pursuit of accurate boron concentrations in biological matrices. Boron values reported at the mg/kg level are now generally reliable; however, g-B/kg level determinations remain a challenge in many biological matrices. The detection limits for boron by isotope dilution mass spectrometry (IDMS), inductively coupled plasma mass spectroscopy (ICP-MS), neutron activation mass spectrometry (NA-MS), ion-coupled plasma emission spectroscopy (ICP-ES), and prompt gamma activation analysis (PGAA) are usually adequate. Rather, limiting factors include establishing boron-clean laboratory environments, the implementation of appropriate quality control, and foremost, maintaining proper precautions in handling and preparing samples for instrumental analysis. At the g-B/kg level, particular care is required to prevent boric acid interchange during sample handling and while bringing biological matrices into solution. Specific knowledge of boron's chemical pathway in the laboratory is essential. For example, because boric acid is relatively volatile, it persists as an environmental source of contamination and as a transport mechanism for loss. Although boron concentration levels in purified water start below 1 g/kg, they can exceed 15 g/kg before a noticeable change in electrical conductivity is registered. Thus alternative procedures for controlling boron "break-through" are necessary. Likewise, "inert" Teflon containers appear boron free, but they serve as a significant source or repository of boric acid. These examples and others illustrate that despite instrumental values being accurate, serious errors are unwittingly incurred, which can alter the sample before analysis. The need for extraordinary vigilance and innovation throughout the experimental procedure is essential.