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Potassium Hydrogen Phthalate

Muby Chemicals established in the year 1976, is pioneer in Manufacturing Chemicals for Oil and Gas Exploration, Hydraulic Fracturing (Fracking) and coiled tube Chemicals.Our advanced chemistry leading to an innovative and high-performance product range is coupled with effective on and off site management services.

We are manufacturer of Specialty chemicals, Pharmaceutical Excipients, Fragrance & Flavorchemicals in India, which are of IP, BP, USP, Ph. Eur., FCC or Food Grade, ACS, AR or Analytical Reagent Grade, LR or Laboratory Reagent Grade, Pure and Technical Grades of various chemicals.


Synonyms : Potassium acid phthalate, biphthalate; Phthalic acid monopotassium salt, potassium hydrogen phthalate, Potassium phthalate monobasic, potassium 2-carboxybenzoate, hydrogen potassium phthalate, phthalic acid potassium salt, potassium biphthalate.

Potassium hydrogen phthalate, often called simply KHP, is an acidic salt compound. It is white powder, colorless crystals, a colorless solution, and an ionic solid that is the monopotassium salt of phthalic acid. The hydrogen is slightly acidic, and it is often used as a primary standard for acid-base titrations because it is solid and air-stable, making it easy to weigh accurately. It is not hygroscopic. It is also used as a primary standard for calibrating pH meters because, besides the properties just mentioned, its pH in solution is very stable.

KHP can be used as a buffering agent (in combination with hydrochloric acid (HCl) or sodium hydroxide (NaOH) depending on which side of pH 4.0 the buffer is to be) but should not be used as a buffer for decarboxylation reactions, as these will degrade the KHP and mop up the conjugation groups. KHP is also a useful standard for total organic carbon (TOC) testing.

Specifications of standard potassium hydrogen phthalate:

Assay: 99.8% min
pH: (50g/L, 25C): 3.8~4.2
Clarify of solution: Conform
Water insoluble: 0.005%
Loss on drying: 0.05%
Chloride (Cl): 0.002%
Sulfate (SO4): 0.006%
Sodium (Na): 0.01%
Iron(Fe): 0.0005%
Heavy Metal (Pb): 0.0005%
Melting Point: 295-300 °C (decomposes)

Specifications of ACS Grade potassium hydrogen phthalate:

Grade: Analytical standard (for titrimetry)
Assay: 99.95-100.05% dry basis
≤0.002% S compounds
≤0.003% Cl compounds
≤0.005% insolubles
≤5 ppm Fe
≤0.005% Na
≤5 ppm heavy metals (as Pb)
pH: 4.00-4.02 (25.0 °C±0.2 °C, 0.05 M)
Melting Point: 295-300 °C (decomposes)