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The ammonia/ammonium buffer pair has a pK of 9.0, resulting in the combination of highly alkaline, ammonia-rich urine. Symptoms attributable to struvite stones are uncommon. More often, women present with UTI, flank pain, or hematuria, and are found to have a persistently alkaline urine pH (>7.0).
The pH range is commonly given as zero to 14, but a pH value can be less than 0 for very concentrated strong acids or greater than 14 for very concentrated strong bases. [2] The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. [3]
In the fetus, the normal range differs based on which umbilical vessel is sampled (umbilical vein pH is normally 7.25 to 7.45; umbilical artery pH is normally 7.18 to 7.38). [2] Fetal metabolic acidemia is defined as an umbilical vessel pH of less than 7.20 and a base excess of less than −8.
The pH of tears shift throughout a waking day, rising "about 0.013 pH units/hour" until a prolonged closed-eye period causes the pH to fall again. [15] Most healthy individuals have tear pH in the range of 7.0 to 7.7, where bicarbonate buffering is the most significant, but proteins and other buffering components are also present that are ...
Soils with pH values that are higher than 7.3 are usually defined as being alkaline. These soils can occur naturally due to the presence of alkali salts. Although many plants do prefer slightly basic soil (including vegetables like cabbage and fodder like buffalo grass ), most plants prefer mildly acidic soil (with pHs between 6.0 and 6.8), and ...
Amniotic fluid normally has a pH of 7.0 to 7.5. [7] Because pH in the upper vagina is normally acidic (pH 3.8–4.5), a vaginal pH test showing a pH of more than 4.5 strengthens a suspicion of rupture of membranes in case of clear vaginal discharge in pregnancy. [7]
Buffer capacity falls to 33% of the maximum value at pH = pK a ± 1, to 10% at pH = pK a ± 1.5 and to 1% at pH = pK a ± 2. For this reason the most useful range is approximately p K a ± 1. When choosing a buffer for use at a specific pH, it should have a p K a value as close as possible to that pH.
Increasing the urine pH to a value higher than 7.0 may increase the risk of calcium phosphate stone formation, though this concept is controversial since citrate does inhibit calcium phosphate crystallization. Testing the urine periodically with nitrazine paper can help to ensure the urine pH remains in this optimal range. Using this approach ...