Updates to the classic small volume (2-4L) 234Th analysis protocol

²³⁴Th measurements have been widely used in ocean sciences to study carbon removal processes in the upper ocean. Comparing the disequilibrium between the particle-reactive ²³⁴Th (half-life = 24.1 days) and its parent, ²³⁸U (half-life = 4.468×10⁹ years), with a defined element to ²³⁴Th ratio on sinking particles can provide insight into the amount of material, such as carbon, exported via the biological carbon pump. We focused on further optimization of the classic small volume (2–4 L) procedure in which ²³⁰Th is added as a yield monitor, ²³⁴Th is scavenged with a MnO₂ precipitate, and the precipitate is measured immediately via beta counting, with a final background beta count after 6 half-lives (144 days). Further experiments elucidate external factors that influence beta count rates including filtration time, volume of precipitation reagents used, as well as background interference by high-energy beta emitters from the ²³⁸U decay chain. Updates to the ²³⁰Th yield-monitor recovery procedure are also discussed. Additionally, a comprehensive accounting of ²³⁴Th and ²³⁰Th measurements at different points in the sample processing protocol indicate where sample loss can be best minimized. High temporal resolution measurements of beta count efficiency using ²³⁸U standards show the extent of measurement variation and uncertainty attributed to beta counters. Together, these updates present the most optimized and up-to-date techniques for accurately gathering high resolution ²³⁴Th data.