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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2018/11/23 08:00:43」(JST)

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Refractometry is the analytical method of measuring substances' refractive index (one of their fundamental physical properties) in order to, for example, assess their composition or purity. A refractometer is the instrument used to measure refractive index ("RI"). Although refractometers are best known for measuring liquids, they are also used to measure gases and solids; such as glass and gemstones.

The RI of a substance is strongly influenced by temperature and the wavelength of light used to measure it, therefore, care must be taken to control or compensate for temperature differences and wavelength. RI measurements are usually reported at a reference temperature of 20 degrees Celsius, which is equal to 68 degrees Fahrenheit, and considered to be room temperature. A reference wavelength of 589.3 nm (the sodium D line) is most often used. Though RI is a dimensionless quantity, it is typically reported as nD20 (or n20
D ), where the "n" represents refractive index, the "D" denotes the wavelength, and the 20 denotes the reference temperature. Therefore, the refractive index of water at 20 degrees Celsius, taken at the Sodium D Line, would be reported as 1.3330 nD20.

Refractometers are frequently used by grape growers and kiwifruit growers for Brix testing of sucrose levels in their fruit. Refractometry is also used in the gelatin industry. To convert the RI of a gelatin sol (reported in Brix) to a gelatin concentration, one need only multiply by eight-tenths (0.8). A sol with a 10.0 RI would therefore be 8% gelatin by weight. This is known to be a reliable conversion for gelatin sols as low as 1% up to over 50%.

Types of refractometers

There are four main types of fluid refractometers: traditional handheld refractometers, digital handheld refractometers, Abbe refractometers, and inline process refractometers.

External links

Refractometry - Gemstone Buzz methods for measuring refractive index.

English Journal

Evaluation of Possible Relationship Between COL4A4 Gene Polymorphisms and Risk of Keratoconus.

Saravani R1, Hasanian-Langroudi F, Validad MH, Yari D, Bahari G, Faramarzi M, Khateri M, Bahadoram S.
Cornea.Cornea.2015 Mar;34(3):318-22. doi: 10.1097/ICO.0000000000000356.
PURPOSE: Keratoconus (KC) is a genetically heterogeneous corneal dystrophy with unknown etiology that causes loss of visual acuity. Evidence has shown that corneas from patients with KC contain reduced amounts of total collagen proteins, and collagen type IV has been suggested as a candidate gene in
PMID 25651396

Monitoring change in refractive index of cytosol of animal cells on affinity surface under osmotic stimulus for label-free measurement of viability.

Park J1, Jin SI2, Kim HM2, Ahn J3, Kim YG4, Lee EG4, Kim MG5, Shin YB6.
Biosensors & bioelectronics.Biosens Bioelectron.2015 Feb 15;64:241-6. doi: 10.1016/j.bios.2014.09.007. Epub 2014 Sep 6.
We demonstrated that a metal-clad waveguide (MCW)-based biosensor can be applied to label-free measurements of viability of adherent animal cells with osmotic stimulation in real time. After Chinese hamster ovary (CHO) and human embryonic kidney cell 293 (HEK293) cells were attached to a Concanavali
PMID 25232665

Corneal collagen cross-linking in keratoconus - long-term prospective study.

Nicula C1, Nicula D2, Popescu R2, Saplonţai-Pop A3.
Journal francais d'ophtalmologie.J Fr Ophtalmol.2015 Feb 11. pii: S0181-5512(15)00003-0. doi: 10.1016/j.jfo.2014.10.007. [Epub ahead of print]
PURPOSE: To determine the refractometric, keratometric and functional results 3 years after cross-linking therapy in patients with keratoconus.PATIENTS AND METHODS: Eighty-one patients in various stages of keratoconus were studied, all meeting eligibility criteria for the cross-linking technique.RE
PMID 25682565

Japanese Journal

小児に対するアトロピン硫酸塩点眼薬による副作用の発現率と症状

日本視能訓練士協会誌 43(0), 213-218, 2014
NAID 130004822886

Correlation of Serum IgG Concentration in Foals and Refractometry Index of the Dam's Pre- and Post-Parturient Colostrums: An Assessment for Failure of Passive Transfer in Foals

Journal of Veterinary Medical Science 74(11), 1387-1395, 2012
NAID 130001879721

Optical Scattering Spectral Thermometry and Refractometry of a Single Gold Nanoparticle under CW Laser Excitation

JOURNAL OF PHYSICAL CHEMISTRY C 116(29), 15458-15466, 2012
NAID 120005609400

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