ZH
KR
JP
ES
RU
DEUV Absorption Spectroscopy and UV Spectrophotometry
UV Absorption Spectroscopy and UV Spectrophotometry, Total:169 items.
In the international standard classification, UV Absorption Spectroscopy and UV Spectrophotometry involves: Education, Analytical chemistry, Jewellery, Optics and optical measurements, Water quality, Waxes, bituminous materials and other petroleum products, Edible oils and fats. Oilseeds, Organic chemicals, Petroleum products in general, Environmental testing, Construction materials, Products of the chemical industry, Fibre optic communications, Photography, Soil quality. Pedology, Physics. Chemistry, Air quality, General methods of tests and analysis for food products, Vocabularies, Biology. Botany. Zoology, Solar energy engineering, Optoelectronics. Laser equipment, Fertilizers, Protection against crime.
Professional Standard - Light Industry, UV Absorption Spectroscopy and UV Spectrophotometry
- QB/T 2334-1997 Qualitative determination of ultraviolet absorbers in cosmetics by ultraviolet spectrophotometry
Professional Standard - Education, UV Absorption Spectroscopy and UV Spectrophotometry
- JY/T 022-1996 General rules for ultraviolet and visible absorption spectroscopic methods
- JY/T 0570-2020 General rules for ultraviolet and visible absorption spectrometry
AENOR, UV Absorption Spectroscopy and UV Spectrophotometry
- UNE 55047:1973 FATS. SPECTROPHOTOMETRIC MEASURE OF ABSORPTION IN THE ULTRAVIOLET AREA.
- UNE 77401:1992 ECOTOXICOLOGY. DETERMINATION OF UV-VIS ABSORPTION SPECTRA.
- UNE-EN ISO 3656:2011 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction (ISO 3656:2011)
- UNE 84124:2014 Cosmetic raw materials. Determination of UV-filters by spectrophotometric absorbance.
- UNE-ISO 4735:2009 Oils of Citrus. Determination of CD value by ultraviolet espectrometric analysis
- UNE-EN ISO 3656:2011/A1:2017 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction - Amendment 1 (ISO 3656:2011/Amd 1:2017)
Professional Standard - Agriculture, UV Absorption Spectroscopy and UV Spectrophotometry
- JJG(教委) 022-1996 Verification Regulations for Ultraviolet and Visible Absorption Spectrometers
- 67藥典 四部-2015 0401 UV-visible spectrophotometry
- 47藥典 四部-2020 0401 UV-visible spectrophotometry
- 197藥典 三部-2020 Spectrophotometry 0401 UV-Vis Spectrophotometry
- 772獸藥典 二部-2015 Appendix Contents 0400 Spectroscopy 0401 UV-Vis Spectrophotometry
- 775獸藥典 一部-2015 Appendix Contents 0400 Spectroscopy 0401 UV-Vis Spectrophotometry
- 153藥典 三部-2010 Appendix Ⅱ Spectrophotometry ⅡA UV-Vis Spectrophotometry
- 1759藥典 一部-2010 Appendix VA UV-Vis Spectrophotometry
- 2297藥典 二部-2010 Appendix IV A UV-Vis Spectrophotometry
- 178藥典 三部-2015 Spectrophotometry 0401 UV-Vis Spectrophotometry General Principles 19
- NY/T 1597-2008 Animal and vegetable fats and oils. Determination of ultraviolet absorbance expressed as specific UV extinction
- NY/T 1279-2007 Determination of Nitrate in Vegetables and Fruits UV-spectrophotometer
- NY/T 1116-2006 Fertilizers-Determination of nitrate nitrogen content.UItraviolet spectro-photometric method
Professional Standard - Medicine, UV Absorption Spectroscopy and UV Spectrophotometry
- YY 91060-1999 Vocabulary of biochemical instruments.UV-VIS spectrophotometry
General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China, UV Absorption Spectroscopy and UV Spectrophotometry
- GB 9721-1988 Molecular Absorption Spectrophotometry of Chemical Reagents General Rules (Ultraviolet and Visible Parts)
- GB/T 9721-2006 chemical reagent General rules for the molecular absorption spectrophotometry (ultraviolet and visible)
- GB/T 42645-2023 Jewelry and Jade Identification by Ultraviolet-visible Absorption Spectroscopy
- GB/T 9721-1988 Chemical reagent--General rules for the molecular absorption spectrophotometry(ultraviolet and visible)
- GB/T 11081-2005 Standard test method for ultraviolet adsorption of white oils
- GB/T 14571.4-2008 Ethylene glycol for industrial use.Determination of ultraviolet transmittance.Ultraviolet spectrophotometric method
- GB/T 26798-2011 Single beam UV/VIS spectorphotometer
- GB/T 26813-2011 Double beam UV/VIS spectrophotometer
- GB/T 11081-1989 White oils--Determination of ultraviolet absorption
- GB/T 25481-2010 On-line ultraviolet/visible spectrum analyzer
- GB/T 24369.1-2009 Characterization of gold nanorods.Part 1:UV-Vis-NIR absorption spectroscopy
- GB/T 22500-2008 Animal and vegetable fats and oils.Determination of ultravolet absorbance expressed as specific UV extinction
- GB/T 32737-2016 Determination of nitrate nitrogen in soil - Ultraviolet spectrophotometry method
- GB/T 24370-2009 Characterization of CdSe quantum dot nanocrystals.UV-Vis absorption spectroscopy
- GB/T 16077-1995 Workplace air--Determination of phosgene--Ultraviolet spectrophotometric method
- GB/T 43297-2023 Fourier transform infrared spectroscopy and UV/visible spectroscopy methods for evaluating photoaging properties of plastic polymers
- GB/T 19267.2-2003 Physical and chemical examination of trace evidence in forensic sciences--Part 2: Ultraviolet-visible absorption spectroscopy
- GB/T 19267.2-2008 Physical and chemical examination of trace evidence in forensic sciences.Part 2:Ultraviolet-visible absorption spectroscopy
Professional Standard - Machinery, UV Absorption Spectroscopy and UV Spectrophotometry
NO-SN, UV Absorption Spectroscopy and UV Spectrophotometry
SCC, UV Absorption Spectroscopy and UV Spectrophotometry
- NS 9462:2006 Water quality — Determination of UV-absorbance
- DANSK DS/EN ISO 3656:2011 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction
- UNE 84170:1983 OIL OF LEMON. ULTRA-VIOLET SPECTROPHOTO METRIC ANALYSIS
- DANSK DS/EN ISO 3656/A1:2011 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction
- BS EN ISO 3656:2002 Animal and vegetable fats and oils. Determination of ultraviolet absorbance expressed as specific UV extinction
- UNE-EN ISO 3656:2002 Animal and vegetable fats and oils. Determination of ultraviolet absorbance expressed as specific UV extinction. (ISO 3656:2002)
- SPC GB/T 37186-2018 Gas analysis -- Determination of sulfur dioxide and nitrogen oxides -- Ultraviolet differential optical absorption spectroscopy (TEXT OF DOCUMENT IS IN CHINESE)
- 10/30197374 DC BS ISO 3656. Animal and vegetable fats and oils. Determination of ultraviolet absorbance expressed as specific UV extinction
- AWWA WQTC64141 Comparison between the UV Action Spectrum of Bacillus subtilis Spores and the Standard DNA Absorbance Spectrum
- UNE 84124:2000 Cosmetic raw materials. Determination of UV-filters by spectrophotometric absorbance.
- NS-EN ISO 3656:2002 Animal and vegetable fats and oils — Determination of ultraviolet absorbance expressed as specific UV extinction (ISO 3656:2002)
- AWWA WQTC58864 The Search for the Origins of Specific UV Absorbance
- NS-EN ISO 3656:2011 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction (ISO 3656:2011)
- AENOR UNE-EN ISO 3656:2011 Oils and fats of animal and vegetable origin. Determination of ultraviolet absorbance expressed as specific UV extinction. (ISO 3656:2011)
- DANSK DS/ISO/TS 17466:2015 Use of UV-Vis absorption spectroscopy in the characterization of cadmium chalcogenide colloidal quantum dots
- DIN EN ISO 3656 E:2010 Draft Document - Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction (ISO/DIS 3656:2009); German version prEN ISO 3656:2009
- DANSK DS/ISO/TS 10868:2017 Nanotechnologies – Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
- BS PD ISO/TS 10868:2017 Nanotechnologies. Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
- AENOR UNE-EN ISO 3656/A1:2017 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction - Amendment 1 (ISO 3656:2011/Amd 1:2017)
- AS 3753:1990 Recommended practice for chemical analysis by ultraviolet/visible spectrophotometry
National Metrological Verification Regulations of the People's Republic of China, UV Absorption Spectroscopy and UV Spectrophotometry
- JJG 689-1990 UV-VIS-NIR Spectrophotometer
- JJG(地質) 1002-1990 Verification Regulations for UV/Visible Spectrophotometer
- JJG 178-2007 Verification Regulation of Ultraviolet, Visible, Near-Infrared Spectrophotometers
- JJG 682-1990 Verification Regulation of Double Beam UV-VIS Spectrophotometers
- JJG 375-1996 Verification Regulation of Ultraviolet Visible Range Spectrophotometer in Single Beam
GSO, UV Absorption Spectroscopy and UV Spectrophotometry
- GSO ISO 3656:2015 Animal and vegetable fats and oils -- Determination of ultraviolet absorbance expressed as specific UV extinction
- BH GSO ISO 3656:2016 Animal and vegetable fats and oils -- Determination of ultraviolet absorbance expressed as specific UV extinction
- BH GSO ASTM E958:2022 Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers
- GSO ASTM E958:2021 Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers
- GSO ISO 4735:2015 Oils of Citrus -- Determination of CD value by ultraviolet spectrometric analysis
- GSO ISO/TS 17466:2017 Use of UV-Vis absorption spectroscopy in the characterization of cadmium chalcogenide colloidal quantum dots
- GSO ISO/TS 10868:2013 Nanotechnologies -- Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
- OS GSO ISO 4735:2015 Oils of Citrus -- Determination of CD value by ultraviolet spectrometric analysis
- NB/SH/T 0966-2017 Determination of aromatics content in white oil - UV spectrophotometry
- OS GSO ISO/TS 10868:2013 Nanotechnologies -- Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
- GSO ASTM G130:2010 Standard Test Method for Calibration of Narrow- and Broad- Band Ultraviolet Radiometers Using a Spectroradiometer
- BH GSO ISO/TS 10868:2016 Nanotechnologies -- Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
Professional Standard - Energy, UV Absorption Spectroscopy and UV Spectrophotometry
- NB/SH/T 0415-2013 Standard test method for ultraviolet absorbance and absorptivity of petroleum products
Group Standards of the People's Republic of China, UV Absorption Spectroscopy and UV Spectrophotometry
Professional Standard - Petrochemical Industry, UV Absorption Spectroscopy and UV Spectrophotometry
German Institute for Standardization, UV Absorption Spectroscopy and UV Spectrophotometry
- DIN EN ISO 3656:2017-08 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction (ISO 3656:2011 + Amd 1:2017); German version EN ISO 3656:2011 + A1:2017
- DIN EN ISO 11151-1:2000 Lasers and laser-related equipment - Standard optical components - Part 1: Components for the ultraviolet, visible and near-infrared spectral range (ISO 11151-1:2000); German version EN ISO 11151-1:2000
Danish Standards Foundation, UV Absorption Spectroscopy and UV Spectrophotometry
- DS/EN ISO 3656:2011 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction
- DS/ISO/TS 10868:2011 Nanotechnologies - Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
International Commission on Illumination (CIE), UV Absorption Spectroscopy and UV Spectrophotometry
- CIE 151-2003 SPECTRAL WEIGHTING OF SOLAR ULTRAVIOLET RADIATION
Professional Standard - Water Conservancy, UV Absorption Spectroscopy and UV Spectrophotometry
- SL 93.2-1994 Determination of oil and grease (Vitraviolet spectrophotometric method)
- SL 84-1994 Determination of nitrogen (nitrate)(Ultraviolet spectrophtometric method)
British Standards Institution (BSI), UV Absorption Spectroscopy and UV Spectrophotometry
- BS EN ISO 3656:2011+A1:2017 Animal and vegetable fats and oils. Determination of ultraviolet absorbance expressed as specific UV extinction
- BS EN ISO 3656:2011 Animal and vegetable fats and oils. Determination of ultraviolet absorbance expressed as specific UV extinction
- PD ISO/TS 17466:2015 Use of UV-Vis absorption spectroscopy in the characterization of cadmium chalcogenide colloidal quantum dots
- BS PD ISO/TS 17466:2015 Use of UV-Vis absorption spectroscopy in the characterization of cadmium chalcogenide colloidal quantum dots
- PD ISO/TS 10868:2017 Nanotechnologies. Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
- BS EN ISO 11151-1:2015 Lasers and laser-related equipment. Standard optical components. Components for the UV, visible and near-infrared spectral ranges
American Society for Testing and Materials (ASTM), UV Absorption Spectroscopy and UV Spectrophotometry
- ASTM E958-13(2021) Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers
- ASTM E958-93(2005) Standard Practice for Measuring Practical Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers
- ASTM E2193-16 Standard Test Method for Ultraviolet Transmittance of Monoethylene Glycol (using Ultraviolet Spectrophotometry)
- ASTM E958-13 Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers
- ASTM E2193-23 Standard Test Method for Ultraviolet Transmittance of Monoethylene Glycol (using Ultraviolet Spectrophotometry)
- ASTM E958-93(1999) Standard Practice for Measuring Practical Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers
European Committee for Standardization (CEN), UV Absorption Spectroscopy and UV Spectrophotometry
- EN ISO 3656:2011 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction (ISO 3656:2011)
- EN ISO 3656:2011/A1:2017 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction - Amendment 1 (ISO 3656:2011/Amd 1:2017)
International Organization for Standardization (ISO), UV Absorption Spectroscopy and UV Spectrophotometry
- ISO 3656:2011 Animal and vegetable fats and oils. Determination of ultraviolet absorbance expressed as specific UV extinction
- ISO 3656:2011/Amd 1:2017 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction; Amendment 1
- ISO/TS 17466:2015 Use of UV-Vis absorption spectroscopy in the characterization of cadmium chalcogenide colloidal quantum dots
- ISO/TS 10868:2011 Nanotechnologies - Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
- ISO 4735:2002 Oils of citrus - Determination of CD value by ultraviolet spectrometric analysis
- ISO/TS 10868:2017 Nanotechnologies - Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
- ISO 11151-1:2000 Lasers and laser-related equipment - Standard optical components - Part 1: Components for the UV, visible and near-infrared spectral ranges
- ISO 11151-1:2015 Lasers and laser-related equipment - Standard optical components - Part 1: Components for the UV, visible and near-infrared spectral ranges
DIN, UV Absorption Spectroscopy and UV Spectrophotometry
- DIN EN ISO 3656:2002 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction (ISO 3656:2002)
Association Francaise de Normalisation, UV Absorption Spectroscopy and UV Spectrophotometry
- NF T60-223*NF EN ISO 3656:2011 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction.
- NF EN ISO 3656:2011 Fatty substances of animal and vegetable origin - Determination of ultraviolet absorbance, expressed in the form of specific extinction in ultraviolet light
- NF T60-223/A1*NF EN ISO 3656/A1:2017 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction - Amendment 1
- NF T75-122*NF ISO 4735:2002 Oils of Citrus - Determination of CD value by ultraviolet spectrometric analysis.
- NF ISO 4735:2002 Citrus essential oils - Determination of the CD value by ultraviolet spectrometric analysis
CEN - European Committee for Standardization, UV Absorption Spectroscopy and UV Spectrophotometry
- EN ISO 3656:2002 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction
Korean Agency for Technology and Standards (KATS), UV Absorption Spectroscopy and UV Spectrophotometry
- KS B 5570-2017 Performance test for UV/Vis spectrophotometer
- KS B 5570-2022 Performance test for UV/Vis spectrophotometer
- KS H ISO 4735-2019 Oils of Citrus－Determination of CD value by ultraviolet spectrometric analysis
- KS H ISO 4735-2014(2019) Oils of Citrus－Determination of CD value by ultraviolet spectrometric analysis
- KS H ISO 4735:2014 Oils of Citrus－Determination of CD value by ultraviolet spectrometric analysis
- KS H ISO 4735:2011 Oils of Citrus-Determination of CD value by ultraviolet spectrometric analysis
- KS M 9102-1996 Water quality-Determination of total mercury by flameless atomic absorption spectrometry(Method after pretreatment with ultraviolet radiation)
- KS B ISO 11151-1:2003 Lasers and laser-related equipment-Standard optical components-Part 1:Components for the UV, visible and near-infrared spectral ranges
- KS B ISO 11151-1-2015(2020) Lasers and laser-related equipment ― Standard optical components ― Part 1: Components for the UV, visible and near-infrared spectral ranges
- KS B ISO 11151-1:2015 Lasers and laser-related equipment ― Standard optical components ― Part 1: Components for the UV, visible and near-infrared spectral ranges
- KS B ISO 11151-1:2013 Lasers and laser-related equipment ?; Standard optical components ?; Part 1: Components for the UV, visible and near-infrared spectral ranges
Lithuanian Standards Office , UV Absorption Spectroscopy and UV Spectrophotometry
- LST EN ISO 3656:2011 Animal and vegetable fats and oils - Determination of ultraviolet absorbance expressed as specific UV extinction (ISO 3656:2011)
RO-ASRO, UV Absorption Spectroscopy and UV Spectrophotometry
Military Standard of the People's Republic of China-General Armament Department, UV Absorption Spectroscopy and UV Spectrophotometry
PL-PKN, UV Absorption Spectroscopy and UV Spectrophotometry
- PN Z04200-02-1988 Air purity protection ests for oxalic acid etermination of oxalic acid by ltraviolet absorption spectrophotometry
- PN Z04171-02-1986 Air purity protection ests for picric acid etermination of picric acid n work places by UV pectrophotometry absorption
Shandong Provincial Standard of the People's Republic of China, UV Absorption Spectroscopy and UV Spectrophotometry
- DB37/T 4149-2020 Determination of water quality UV254 by ultraviolet spectrophotometry
- DB37/T 3786-2019 Determination of gaseous pollutants such as hydrogen sulfide in ambient air Open path ultraviolet absorption spectrometry
- DB37/T 4115-2020 Jewelry and jade identification by ultraviolet-visible spectroscopy
IN-BIS, UV Absorption Spectroscopy and UV Spectrophotometry
國家市場監督管理總局、中國國家標準化管理委員會, UV Absorption Spectroscopy and UV Spectrophotometry
- GB/T 14571.4-2022 Test method of ethylene glycol for industrial use—Part 4：Determination of ultraviolet transmittance—Ultraviolet spectrophotometric method
- GB/T 39114-2020 Nanotechnologies—Characterization of single-wall carbon nanotubes using ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopy
- GB/T 37186-2018 Gas analysis—Determination of sulfur dioxide and nitrogen oxides—Ultraviolet differential optical absorption spectroscopy
Standard Association of Australia （SAA）, UV Absorption Spectroscopy and UV Spectrophotometry
- ISO 3656:2011/Amd.1:2017 Animal and vegetable fats and oils — Determination of ultraviolet absorbance expressed as specific UV extinction AMENDMENT 1
YU-JUS, UV Absorption Spectroscopy and UV Spectrophotometry
- JUS E.K8.051-2000 Edible olive oil and edible olive-pomace oil - Determination of ultraviolet absorbance
工業和信息化部, UV Absorption Spectroscopy and UV Spectrophotometry
Professional Standard - Electron, UV Absorption Spectroscopy and UV Spectrophotometry
Shanghai Provincial Standard of the People's Republic of China, UV Absorption Spectroscopy and UV Spectrophotometry
National Metrological Technical Specifications of the People's Republic of China, UV Absorption Spectroscopy and UV Spectrophotometry
- JJF 1641-2017 Program of Pattern Evaluation of Ultraviolet—Visible Spectrophotometers
American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), UV Absorption Spectroscopy and UV Spectrophotometry
PH-BPS, UV Absorption Spectroscopy and UV Spectrophotometry
- PNS ISO/TS 17466:2021 Use of UV-Vis absorption spectroscopy in the characterization of cadmium chalcogenide colloidal quantum dots
NL-NEN, UV Absorption Spectroscopy and UV Spectrophotometry
- NEN 6306-1990 Vegetable and animal oils and fats Determination of extinction co?ffici?nt in the ultraviolet spectre
國家能源局, UV Absorption Spectroscopy and UV Spectrophotometry
- SH/T 0966-2017 Determination of aromatic hydrocarbon content in white oil by UV spectrophotometry
RU-GOST R, UV Absorption Spectroscopy and UV Spectrophotometry
- GOST ISO 4735-2015 Essential oils of citrus. Determination of CD value by ultraviolet spectrometric analysis
Professional Standard - Environmental Protection, UV Absorption Spectroscopy and UV Spectrophotometry
- HJ 756-2015 Determination of water quality butyl xanthate by UV spectrophotometry
- HJ 970-2018 Water Quality Determination of Petroleum by UV Spectrophotometry (Trial)
- HJ/T 346-2007 Water quality. Determination of nitrate-nitrogen. Ultraviolet spectrophotometry
中華人民共和國國家質量監督檢驗檢疫總局、中國國家標準化管理委員會, UV Absorption Spectroscopy and UV Spectrophotometry
- GB/T 34796-2017 Quantification and purity analysis of nucleic acid concentration in solution—Ultraviolet spectrophotometry
International Electrotechnical Commission (IEC), UV Absorption Spectroscopy and UV Spectrophotometry
Indonesia Standards, UV Absorption Spectroscopy and UV Spectrophotometry