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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. 

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Stain Removal from Calcium Deficient Hydroxy Apatite 35 Disks (Human Tooth Model) Using Potassium Ferrate(VI) 

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. 

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. 

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- 

## EXAMPLE2 

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. 

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 

