Buffers are widely used when performing soil enzyme assays, either to measure specific soil enzyme activities based on a standard protocol or to determine the pH optima of a soil enzyme. However, few studies have tested whether the existent buffer-making protocol they followed actually obtains the target pH during their enzyme assays. To test the pH stabilization capacity of modified universal buffer (MUB) commonly used in soil enzyme assays, four different soils with varying buffering capacity (proxied by contrasting soil pH and clay content) were used for phosphomonoesterase assays using a 1:5 (m/v) soil:buffer ratio, as per common practice for chromogenic enzyme assays. The original MUB working solution deviated from the target pH by as much as 1.6 units. Deviations were greatest when the soil and buffer had contrasting pH. Increasing MUB concentration by fourfold did not mitigate this pH discrepancy to a satisfactory level (± 0.1 unit). For the standardly used MUB concentration (1 ×), the deviation between the target pH and the assay pH was greatest when the difference between the target pH and the soil pH was > 1 unit. Therefore, forcing pH to a specific value in soil enzyme activity assays (1:5 soil:MUB) appears to be difficult for many soils, and increasing MUB concentration risks reducing enzyme activities due to higher ionic strength. Thus, the use of MUB to assay enzyme activity presents a tension between maintaining the target pH and maximizing the sensitivity of the assay.

缓冲液在进行土壤酶检测时被广泛使用，可以根据标准协议测量特定的土壤酶活性，也可以确定土壤酶的最佳 pH 值。然而，很少有研究测试他们遵循的现有缓冲液制备方案是否在酶测定过程中实际获得了目标 pH 值。为了测试土壤酶测定中常用的改良通用缓冲液 (MUB) 的 pH 稳定能力，使用 1:5 (m/ v) 土壤：缓冲液比例，按照显色酶测定的常规做法。原始 MUB 工作溶液偏离目标 pH 值高达 1.6 个单位。当土壤和缓冲液具有相反的 pH 值时，偏差最大。将 MUB 浓度增加四倍并没有将这种 pH 差异减轻到令人满意的水平（± 0.1 单位）。对于标准使用的 MUB 浓度 (1 ×)，当目标 pH 值与土壤 pH 值之间的差异 > 1 个单位时，目标 pH 值与测定 pH 值之间的偏差最大。因此，在土壤酶活性测定 (1:5 土壤:MUB) 中强制 pH 值达到特定值对许多土壤来说似乎很困难，并且由于更高的离子强度，增加 MUB 浓度有降低酶活性的风险。因此，使用 MUB 来测定酶活性呈现出维持目标 pH 值和最大化测定灵敏度之间的张力。当目标pH值与土壤pH值之间的差异> 1个单位时，目标pH值与测定pH值之间的偏差最大。因此，在土壤酶活性测定 (1:5 土壤:MUB) 中强制 pH 值达到特定值对许多土壤来说似乎很困难，并且由于更高的离子强度，增加 MUB 浓度有降低酶活性的风险。因此，使用 MUB 来测定酶活性呈现出维持目标 pH 值和最大化测定灵敏度之间的张力。当目标pH值与土壤pH值之间的差异> 1个单位时，目标pH值与测定pH值之间的偏差最大。因此，在土壤酶活性测定 (1:5 土壤:MUB) 中强制 pH 值达到特定值对许多土壤来说似乎很困难，并且由于更高的离子强度，增加 MUB 浓度有降低酶活性的风险。因此，使用 MUB 来测定酶活性呈现出维持目标 pH 值和最大化测定灵敏度之间的张力。