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Merck

179922

Sigma-Aldrich

Potassium phthalate monobasic

ACS reagent, acidimetric standard

Synonym(s):

KHP, Phthalic acid monopotassium salt, Potassium biphthalate, Potassium hydrogen phthalate

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About This Item

Linear Formula:
HOOCC6H4COOK
CAS Number:
Molecular Weight:
204.22
Beilstein:
3637128
EC Number:
MDL number:
UNSPSC Code:
12352100
PubChem Substance ID:
NACRES:
NA.21

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grade

ACS reagent

Quality Level

Assay

99.95-100.05% dry basis

form

crystals

quality

acidimetric standard

impurities

≤0.002% S compounds
≤0.003% Cl compounds
≤0.005% insolubles

pH

4.00-4.02 (25.0 °C±0.2 °C, 0.05 M)

mp

295-300 °C (dec.) (lit.)

cation traces

Fe: ≤5 ppm
Na: ≤0.005%
heavy metals: ≤5 ppm (by ICP)

functional group

carboxylic acid

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1 of 4

This Item
NIST185I1.04874NIST2185
assay

99.95-100.05% dry basis

assay

-

assay

≥99.5% dry basis (perchloric acid titration)

assay

-

Quality Level

200

Quality Level

100

Quality Level

300

Quality Level

100

grade

ACS reagent

grade

certified reference material

grade

-

grade

certified reference material

pH

4.00-4.02 (25.0 °C±0.2 °C, 0.05 M)

pH

-

pH

4.0 (20 °C, 50 g/L in H2O)

pH

-

cation traces

Fe: ≤5 ppm, heavy metals: ≤5 ppm (by ICP), Na: ≤0.005%

cation traces

-

cation traces

Cu: ≤0.0002%, Fe: ≤0.0005%, Na: ≤0.01%, Pb: ≤0.0005%, heavy metals (as Pb): ≤0.0005%

cation traces

-

Application

Potassium phthalate monobasic may be used as a primary standard in acidimetric titration[1] and also to prepare potassium phthalate buffer solution for pH calibration.[2][3]

Storage Class Code

13 - Non Combustible Solids

WGK

WGK 1

Flash Point(F)

387.1 °F - Pensky-Martens closed cup

Flash Point(C)

197.3 °C - Pensky-Martens closed cup

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

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Determination of standard pH values for potassium hydrogen phthalate reference buffer solutions in 10, 20, 50, 64 and 84.2 wt per cent methanol/water mixed solvents at temperatures from 283.15 to 313.15 K.
Mussini T, et al.
Electrochimica Acta, 28(11), 1593-1598 (1983)
2, 4, 6-Trinitrobenzoic acid as a primary standerd in acidimetry.
Smith GF and Wilkins DH.
Analytica Chimica Acta, 8, 209-216 (1953)
J M Padró et al.
Talanta, 107, 95-102 (2013-04-20)
Dispersive ionic liquid-liquid microextraction combined with liquid chromatography and UV detection was used for the determination of two antichagasic drugs in human plasma: nifurtimox and benznidazole. The effects of experimental parameters on extraction efficiency-the type and volume of ionic liquid
Randi J Bertelsen et al.
Environmental health perspectives, 121(2), 251-256 (2012-11-21)
High-molecular-weight phthalates in indoor dust have been associated with asthma in children, but few studies have evaluated phthalate biomarkers in association with respiratory outcomes. We explored the association between urinary concentrations of phthalate metabolites and current asthma. In a cross-sectional
Martha M Téllez-Rojo et al.
The Science of the total environment, 461-462, 386-390 (2013-06-12)
Previous studies suggest that prenatal phthalate exposure affects neurodevelopment and behavior during the first years of life. To evaluate the effect of maternal urinary concentrations of phthalate metabolites during pregnancy on mental and psychomotor development in children 24-36 months of

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