Crystallisation is a separation technique that is used to separate a solid that has dissolved in a liquid and made a solution. solution that has as much solid dissolved in it as it can possibly contain is called a saturated solution. As the saturated solution is allowed to cool, the solid will come out of the solution and crystals will start to grow.
Unsourced material may be challenged and removed. (September 2007). Methemoglobinemia (or methaemoglobinaemia) is a disorder characterized by the presence of a higher than normal level of methemoglobin (metHb, i.e., ferric [Fe 3+ ] rather than ferrous [Fe 2+ ] haemoglobin) in the blood.igns and symptoms of methemoglobinemia (methemoglobin level above 1%) include shortness of breath, cyanosis, mental status changes (~50%), headache, fatigue, exercise intolerance, dizziness and loss of consciousness.
Advisory about methemoglobinemia with the use of benzocaine sprays durÂ­ ing medical procedures. Since then, FDA has received reports of 72 new cases of methemoglobinemia associated with the use of benzocaine sprays, including 3 resulting in death, bringing the total to 319 cases as of March 16, 2011. Of the 319 cases, 7 were deaths, 32 cases were categorized as life threatening, and 216 were categorized as serious. A review of the 319 cases indicated that the development of methemoglobinÂ­ emia after treatment with benzocaine sprays may not be related to the amount applied. In many cases, methemoglobinÂ­ emia was reported following the adminÂ­ istration of a single benzocaine spray. In other cases, methemoglobinemia resulted after excessive amounts were applied.