A Rapid, Simple, and Low-Blank Pumped Ion-Exchange Column Chromatography Technique for Boron Purification From Carbonate and Seawater Matrices

Boron isotope ratios (delta 11B) are used across the Earth Sciences and are increasing analyzed by Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS). Accurate delta 11B MC-ICPMS analysis requires boron purification from the sample matrix using ion-exchange column chromatography. However, the traditional gravity-drip column method is time-consuming and prone to airborne contamination due to its long duration and open resin surface. To address these issues, we designed a novel, simple, and reliable column chromatography technique called "peri-columns." This method uses a peristaltic pump to generate vacuum on a commonly used column set up. This method uses sealed collection beakers and does not require solutions to pass through pump tubing, minimizing contamination. The duration is reduced by eight-fold, processing 12 samples in just 1.5 hr. It also yields low and consistent total procedural blanks, averaging 11 pg. The efficiency and efficacy of this method were tested by repeated boron purification from calcium carbonate and high-sodium matrices with international and in-house reference materials. The results matched those obtained using the gravity column method and fell within our laboratory long-term and international certified values. The mean delta 11B and 2SD (standard deviation) of repeatedly processed NIST 8301f were 14.57 +/- 0.26 parts per thousand (n = 31), NIST 8301c was 24.19 +/- 0.33 parts per thousand (n = 10), STAiG-F1 was 16.20 +/- 0.26 parts per thousand (n = 13), and seawater was 39.52 +/- 0.32 parts per thousand (n = 10). All the components of our techniques are commercially available, and it is easily adaptable to other laboratories and isotope systems. Scientists use boron isotope ratios to study changes in seawater acidity, atmospheric carbon dioxide levels, pollution, and volatile cycling in the Earth. To measure these changes, they need to purify boron from a carbonate matrix, such as foraminifera and coral fossils or seawater, using ion-exchange column chromatography. However, the traditional gravity-drip column method is time-consuming and prone to airborne contamination. To address this issue, we developed a new technique called "peri-columns," where we connect manufactured columns to a peristaltic pump. The pump creates a vacuum, which pulls the liquid through columns faster than gravity. This new method is around eight times faster than the existing gravity method and, due to the shorter timescale and the closed nature of the columns, produces lower levels of contamination. We tested this technique using several international and in-house reference materials and found that it produced the same boron isotope ratio results as the traditional method but faster and cleaner. New peristaltic pump-based boron ion-exchange column chromatography achieving eight-fold faster boron separation This technique produces lower total procedure boron blanks than gravity columns