Boron isotopes are widely used as a proxy of marine carbonate in paleoclimatology to reconstruct seawater pH and atmospheric pCO₂, and precise and accurate boron isotopic analysis is required for this purpose. Determination of boron isotopic composition is susceptible to contamination, especially for sample analyses with small amounts of boron; however, sources of experimental and laboratory contamination are not clearly evaluated. In this study, boron and boron isotope contamination during the analysis of small carbonate samples were examined in detail during sample cleaning, sample storage, chemical separation, and isotope measurement. Repeated cleaning of foraminifera shells using H₂O with ultrasonication effectively minimized boron contamination from clay-rich material; however, an additional cleaning step with methanol and H₂O₂ is recommended to obtain repeatable precise δ¹¹B, δ¹⁸O, and Mg/Ca values. Boron contamination during sample storage in a glass vial was far greater than expected. Glass-derived boron attached to foraminifera shells could not be completely removed by any physical or chemical cleaning process and influenced the δ¹¹B value significantly. Even when a low-boron HEPA, boron-free HEPA, or ULPA filter was used for air-handling in the laboratory, airborne contamination by gaseous boron can still be significant, with seasonal variation in abundance and isotopic composition. Although this affects the procedural blank of boron during chemical separation, an acid-removing chemical filter can reduce the airborne boron flux. An autosampler in the MC-ICPMS analysis might be an additional source of airborne boron contamination.

硼同位素在古气候学中被广泛用作海洋碳酸盐的替代物，以重建海水的pH值和大气中的p CO ₂，为此需要精确而准确的硼同位素分析。硼同位素组成的测定容易受到污染，特别是对于少量硼的样品分析而言；但是，没有明确评估实验和实验室污染的来源。在这项研究中，在样品清洁，样品存储，化学分离和同位素测量过程中，对小型碳酸盐样品分析过程中的硼和硼同位素污染进行了详细检查。使用H ₂重复清洁有孔虫壳用超声波处理的O可有效地减少富含粘土的材料对硼的污染；然而，用甲醇和H额外的清洁步骤₂ ö ₂建议以获得可重复的精确δ ¹¹ B，δ ¹⁸ O，和镁/钙值。样品在玻璃小瓶中存储期间的硼污染远远超出预期。附连到壳有孔虫玻璃衍生硼无法通过任何物理或化学清洗过程可以完全除去，影响了δ ¹¹B值明显。即使在实验室中使用低硼HEPA，无硼HEPA或ULPA过滤器进行空气处理时，气态硼在空气中的污染仍然很显着，其丰度和同位素组成随季节变化。尽管这会影响化学分离过程中硼的程序空白，但除酸化学过滤器可以减少空气中的硼通量。MC-ICPMS分析中的自动进样器可能是空气中硼污染的另一个来源。