These Reference Materials can be used to qualify HPLC UV Detectors for wavelength accuracy and for absorbance accuracy and linearity over the wavelength range 200 – 650 nm. They can also be used to qualify UV-visible spectrophotometers when used with flow cells, sipper systems or other sampling accessories that significantly mask the light beam. 

Description and Discussion

Spectrophotometer calibrations made at full aperture may not be acceptable when the beam is masked by flow cells or microcells, as with HPLC UV detectors. Starna Gold references enable a holistic approach to instrument qualification by allowing measurements using the same flow cell, sipper system or other sampling accessory used in the actual analysis, and over the same wavelength range. The references are supplied in vials with crimp closure and can be transferred to the instrument under test using a syringe without disturbing the cell alignment, often critical in such systems. Each vial contains 4.0 ml of solution. 

Four different solution references are available to check wavelength and absorbance accuracy and absorbance linearity in the UV region, or in the UV and visible regions. 

The references are:

Wavelength references:

RM-LCUV/RE– Starna Cerium oxide solution (RM-RE) in dilute sulfuric acid 
5 characteristic peaks covering the wavelength range from 200 nm to 270 nm. 
Approximate peak wavelength values (in nm) are: 
201, 211, 223, 240, 254

RM-LCUV/HL – Starna holmium oxide solution (RM-HL) in dilute perchloric acid
14 characteristic and well-defined peaks covering the wavelength range from 240 to 650 nm. 
Approximate peak wavelength values (in nm) are: 
241, 250, 278, 288, 334, 346, 361, 385, 417, 451, 468, 485, 537, 641

Absorbance reference:

RM-LCUV/NA– Four Starna nicotinic acid solutions: RM-06A, RM-12A, RM-18A, RM-24A (6, 12, 18 & 24 mg/l) in dilute (0.1 M) hydrochloric acid. Supplied with a 0.1 M hydrochloric acid blank (RM-LCUV/00A). Covers the wavelength range 210 nm to 260 nm.


Nicotinic acid has peaks at 213 and 215 nm. Typical absorbance values at these wavelengths for the different concentrations are as follows:

  Concentration 213 nm 261 nm
RM-LCUV/06A  6 mg/L 0.24 0.28
RM-LCUV/12A 12 mg/L 0.48 0.56
RM-LCUV/18A 18 mg/L 0.73 0.85
RM-LCUV/24A 24 mg/L 0.99 1.15

Note: the above three references are all recognised by major pharmacopoeias for instrument qualification.

Wavelength and Absorbance reference:

RM-LCUV/SG – Four Starna Green dye solutions, RM-25G, RM-50G, RM-75G, RM-100G,with nominal concentrations of 25, 50, 75 and 100 respectively.   Supplied with a solvent blank (RM-LCUV/00G).


References with sharp absorption bands are unsuitable for qualification of broad bandwidth instrumentation. Starna Green is a specially formulated dye solution with three broad but well-defined peaks that can be certified for both wavelength and absorbance value in the UV and visible regions, from 250 nm to 650 nm, at bandwidths up to 20nm.

  Nominal Concentration Nominal Wavelength and Absorption values
258 nm 416 nm 630 nm
RM-LCUV/25G  25 0.259 0.259 0.259
RM-LCUV/50G 50 0.514 0.56  
RM-LCUV/75G 75 0.757 0.85  
RM-LCUV/100G 100 1.007 1.15

Catalogue Number

  Catalogue Number
Starna Rhodamine Quantum Counter Cell  4-TB/RHB



These cell-based reference materials are designed for the qualification of HPLC UV detectors that can accept conventional spectrophotometer cells, e.g. Waters.

Erbium Oxide Solution – Wavelength Qualification

9 well defined peaks from 230 nm to 660 nm. For HPLC UV detectors that can accept conventional spectrophotometer cells, e.g. Waters.

Propyl Parabenz Solution – Photometric Linearity Qualification

Five concentrations (5 mg/l - 30 mg/l) of  Propyl Parabenz in methanol  . For HPLC UV detectors that can accept conventional spectrophotometer cells, e.g. Waters.



This material can be used to verify the photometric linearity of HPLC UV detectors (that can accommodate conventional UV cells) in compliance with published with HPLC qualification protocols 

Description and Discussion

Five solutions of Propyl Parabenz in methanol, in 10mm UV quartz cells that have been permanently sealed by heat fusion.

The use of Propyl Parabenz solutions in methanol for the validation of HPLC DAD detector linearity is well documented. Preparing these solutions in the laboratory can have hazards due to the volatility and toxicity of the methanol. Permanently heat sealed cells effectively isolate the operator from these problems.

The spectrum of propyl parabenz, when prepared in methanol, has an absorbance peak at 257 nm. Within the concentration range 5-30 mg/l, if the absorbance scale of a narrow bandwidth (<5 nm) UV detector is linear, the apparent absorbance of a series of concentrations measured at these peaks will be a linear function of concentration.

Typical spectra


Absorbance values are certified at 257 nm for concentrations of 5,10, 20, 25 and 30 mg/l, when measured against the supplied methanol blank



Catalogue Number

  Catalogue Number 

Starna Propyl Parabenz HPLC linearity set

5, 10, 20, 25 and 30 mg/land methanol blank cell




This material can be used to qualify the wavelength scale of HPLC Diode Array detectors that can accept a 10 mm path length spectrophotometer cell in the sample position.

Description and Discussion

Erbium Oxide (1% m/v) in 10% v/v perchloric acid, permanently sealed by heat fusion into a 10 mm far UV quartz cuvette.

The use of Erbium oxide solvated in perchloric acid for the validation of the wavelength scale of HPLC Diode array detectors is well documented. When prepared in perchloric acid, erbium oxide gives a spectral scan containing a seriesof 9 characteristic and well-defined peaks covering thewavelength range from 230 nm to 660 nm.

Approximate peak wavelengths (in nm) are:255, 364, 379, 405, 449, 487, 522, 541, 652.

In typical HPLC validation protocols (e.g Waters) the threepeaks at 255, 379 and 522 nm are used.


Typical spectra


Note: The above values are for guidance only. Because the absorption bands are asymmetric, measured values will bespectral bandwidth dependent. The Calibration Certificateaccompanying each Starna Erbium Reference gives actual values measured at bandwidths of 1.00 and 5.00 nm, andonly these certified values should be used for instrument qualification. On request, Starna can provide certifiedvalues at other wavelengths and bandwidth values.


Catalogue Number

  Catalogue Number 

Erbium perchlorate reference cell