was assayed three times at each sampling point in order to  calculate standard deviation and provide an estimate of pre› cision. When returning the vials to the isothermal oven, the  headspace of each vial was purged briefly with UHP argon, as  before.  The cycling temperature profile specified in AR 70-38 also  was studied. An oven (Fisher Scientific model No. 48) was  outfitted with a programmable temperature controller  (Omega Engineering model CN3251) and a small fan in order  to provide air circulation. Temperature data acquisition was  performed using a HOBO data logger (Onset Computer  Corp., model HTEA -39+ 123°  C.). The temperature control- ler was programmed to meet the specifications of AR 70-38  Sec. II, Table 2-2 (Storage and Transit Conditions). Specifi› cally, the oven was programmed to remain above 66°  C. for at  least 5 hrs and to reach a peak temperature of71 °  C. for not  more than 1 hr. The programmed parameters appear below in  Table 1.  nic acid was to a 25-mL volumetric flask and brought to  volume with HPDI water. The solution was transferred to a  50-mL beaker with a stir bar and pH adjusted using 10.04N  NaOH, monitored with a calibrated pH meter. Aliquat 336fi  (Cognis) (also suitable is Aliquat 134fi) (N-methyl-tri-(n› octyl)ammonium chloride), (N-methyl TOA) or "HEPA"  chelating pH Buffer: 2.5-µL  ofN-methyl TOA was added to  5 mL of pH 7 HEPA buffer and sonicated for 1 minute. pH 7  Sodium Dodecyl Sulfate (SDS)/HEPA Buffer: 10 mg of SDS  was added to 5 mL of pH 7 HEPA buffer and sonicated for 1  minute. pH 8 SDS/HEPABuffer: l0mgofSDS was added to  5 mL of pH 8 HEPA buffer and sonicated for 1 minute.  Calcium Deficient Hydroxyapatite (HAP) Disk Examples:  A. A tea stained disk was placed into the bowl of the bowl of  a watch glass and 100 µL  of pH 7 HEPA buffer was pipetted  onto the disk surface. 3.7 mg of potassium ferrate(VI) was  added to the disk surface and mixed gently. The surface  liquid appeared black. The color changed to amber in about  4 minutes with red particles suspended in the liquid. The  disk was rinsed at 10 minutes with HPDI water. The disk  was stained purple with rust stains. Color Space coordinate  readings were found to be li.E (versus tea stain)=13.57;  L *=72 (lightness/darkness); a*=2.6 (blue/red); and b*=- 1.1 (yellow/green). The reflectance of visible light was  recorded as 44.547 at 450 nm, and 61.521 at 750 nm  respectively.  Observation: Rust stains, possibly from direct deposition  of rust formed by chemical reduction of ferrate(VI)  when it oxidizes organic stain-forming color bodies,  such as the tannins, and the like of tea and other foods.  B. A tea stained disk was placed into a 50 mL centrifuge tube.  1 mL of pH 7 HEPA buffer was added followed by 9 mL of  HPDI water. 9.7 mg of potassium ferrate(VI) was added.  The tube was gently hand shaken for 10 minutes. The disk  was removed and rinsed with HPDI water. The disk was  stained purple with rust stains. Color Space coordinate  readings were found to be li.E (versus tea stain)=8.29;  L*=79.1 (lightness/darkness); a*=l.6 (blue/red); and  b*=-2 (yellow/green). The reflectance of visible light was  recorded as 57.457 at 450 nm, and 69.889 at 750 nm  respectively.  Observation: Rust stain formation, possibly from precipi- tation of brown ferric hydroxide formed from reduction  of ferrate(VI) during the de-staining reaction ( consistent  with "b" values). This result supported the contention,  validated in the testing below, that rust stains can be  prevented by providing a solubilizing and/or ferric ion  bleaching agent in the formulation along with the ferrate  (VI) ion. Hence the most preferred such complexing  agent would also be oxidation resistant, at least for the  duration of the oxidation reaction with ferrate(VI).  C. 10 mg of potassium ferrate(VI) was added to 1 mL of pH  7 HEPA buffer in a 50 mL centrifuge tube. 9 mL HPDI  water was added, and the solution was shaken for a few  seconds followed by the addition of a tea stained HAP disk.  The disk was removed at 10 minutes and rinsed with HPDI  water. The disk was stained purple.  Observation: Discovery and Confirmation that solubiliza› tion and chelation control of ferrate(III) in solution, pro› duced from ferrate(VI) during destaining, prevents or at  least minimizes rust staining. Hence ferrate(VI) is  shown here, and further below, that it can be used to  destroy stains, especially problematic food stains such  as tea, coffee, grape juice, cranberry juice, and the like,  without the formation of rust stain from the iron product.  Oxidation resistant chelating buffer: 0.25M 1-Hydroxy› ethylidenediphosphonic acid ( etridonic acid) (Dequestfi  2010, Thermphos) (HEPA) was pH adjusted by microtitration  with 1 ON NaOH. 1.28 g of 1-Hydroxyethylidenediphospho- Tea staining Procedure: A calcium-deficient hydroxyapa› tite (HAP) disk (Clarkson Chromatography Products) was  placed into a 50-mL centrifuge tube with 10 mL of tea solu› tion. The centrifuge tube was gently shaken by hand for 15  minutes. The tea solution was decanted and replaced with 10  mL of HPDI water and vortexed for 30 seconds. The water  was decanted and replaced with 10 additional mL of HPDI  water and vortexed for 30 seconds. The disk was removed  with forceps and patted  dry  with a tissue. The disk was  allowed to air  dry  at room temperature for at least one hour.  Color Space coordinate readings were found to be L *= 103 .3  lightness/darkness); a*=-2.8 (blue/red); and b*=-3.7 (ye!- low/green) for the unstained disc. The reflectance of visible  light was recorded as 112.352 at 450 nm, and 101.312 at 750  nm respectively for the unstained disc. li.E=21.35; L *=84.7  (lightness/darkness); a*=5.5 (blue/red); and b*=2.7 (yellow/  green) for the stained disc. The reflectance of visible light was  recorded as 61.768 at 450 nm, and 85.023 at 750 nm respec› tively for the stained disk. The unstained disc appeared pure  white and the stained disc a medium brown color.  Tea staining Solution: 200 mL of high-purity deionized  (HPDI) water was heated to boiling in a 500-mL beaker. The  beaker was removed from heat and 4 Lipton™ tea bags were  added. The tea bags were allowed to soak for 5 minutes. The  tea bags were pressed with a spatµLa  upon removal to remove  liquid. The tea was allowed to cool to room temperature  whereupon heavy turbidity occured.  Stain Removal from Calcium Deficient Hydroxy Apatite 35  Disks (Human Tooth Model) Using Potassium Ferrate(VI)  TABLE 1  EXAMPLE2  Cycling Oven Programmed Parameters  Programmed Induced  Clock Time  Air Temperature(°  C.)  0:00  35  6:30  35  12:30  66  15:00  71  17:30  66  23:30  35  28  US 8,663,607 B2  27  D.An unstained HAP disk was placed into the bowl of a watch  glass and 100 µL  of pH 7 HEPA buffer was pipetted onto 