Ultraviolet photometric detector

Although spectrophotometric, fluorometric, electrochemical, and mass spectrometric detectors have all been equally well used in liquid chromatographic analysis of -lactam antibiotics, most popular is the ultraviolet photometric detector. Penicillins do not have a specific ultraviolet chromophore and thus show an... 

Kirkland, J. J., A high-performance ultraviolet photometric detector for use with efficient liquid chromatographic columns. Anal. Chem. 40, 391-396 (1968). Kirkland, J. J., Controlled surface porosity supports for high speed gas and liquid chromatography. Anal. Chem. 41, 218-220 (1969). 

The UV detector is the most widely used detector for LC. It is a solute property detector that is suitable for those solute compounds that absorb radiation in the UV range ( 190-400 nm). Ultraviolet-photometric detectors are relatively insensitive to temperature and flow rate fluctuations. The sensitivity to solute detection is high (noise equivalent concentration 10 °g/ml).f Ultraviolet-photometric detectors are also well suited to applications that use gradient elution, given that many common LC solvents have low UV absorptivities. 

EC = electrical conductivity detector ECD = electron capture detector FPD = flame photometric detector GC = gas chromatography HPLC = high performance liquid chromatography NPD = nitrogen phosphorus detector TID = thermionic detector UV = ultraviolet spectroscopy... 

Differential refractometer-essentially all molecules are detected, but this method is not especially sensitive. Photometric detector—molecules that absorb in the ultraviolet or visible light region. Fluorescence detector-molecules that fluoresce. 

As with GC, numerous detectors have been developed for LC. Each can be categorized as one of two types of detectors solute property and bulk property. The two most commonly used detectors for LC are the ultraviolet-photometric (UV) detector and the refractive index (RI) detector. Wheals describes these and other common LC detectors. ... 

Photometric detectors are the most popular in CE instruments including diode array detectors. Laser-induced fluorescence (LIE) detection and electric conductivity detectors are also popular. LIE is particularly sensitive and powerful for detecting low concentration analytes. However, most analytes are not natively fluorescent and some derivatizations are necessary. Conductivity detector is useful for the detection of non-ultraviolet (non-UV) absorbing analytes such as inorganic ions or fatty acids. Both LIE detection and conductivity detectors are commercially available and easy to interface with conventional CE instruments. Electrochemical detectors are also useful for selective high-sensitivity detection. Several techniques have been developed to circumvent the problem of strong effects of electrophoretic field on electrochemical detection, but despite this, commercial electrochemical detectors are not used extensively. 

One of the major advantages of SFC is its compatibility with both GC and HPLC detectors. GC flame detectors, such as the flame ionization detector (FID) [11,12], nitrogen thermionic detector [12,13], and flame photometric detector [14] have all been interfaced with SFC systems using a capillary restrictor which, while maintaining supercritical conditions in the column, also effectively decompresses the fluid to ambient pressure just before it enters the flame tip [10,15]. HPLC detectors such as ultraviolet and fluorescence detectors are employed when pure organic mobile phases or modified mobile phases are used. With these detectors, analytes are detected spectroscopically in a flow-through cell prior to decompression [16]. 

Residues are determined in the purified extracts by chromatographic or immunochemical techniques. In the chromatographic systems, thin-layer chromatography (TEC), liquid chromatography (LC), and GC, the analytes are separated on plates or columns and determined by colorimetry, by spectrophotometry (ultraviolet (UV), infrared (IR, Fourier transform infrared (FTIR)), by fluorescence, by selective detectors (in GC analysis ECD, flame photometric (FPD), nitrogen/phosphorus (NPD, TSD), etc.), or by MS. Separations may also be achieved by... 

For routine HPLC analysis, the detection of flavins is carried out either spectro-photometrically, using variable- or fixed-wavelength HPLC detectors in the ultraviolet (e.g., 254 nm) or visible (e.g., 405 nm) region, or fluorimetrically. For riboflavin, the excitation wavelength for fluorimetric detection is usually 440 to 450 nm, and the emission wavelength 530 nm. The detection limit for fluorescence detectors is >1 pmol (0.38 ng) riboflavin, whereas <30 pmol (11 ng) can be detected spectrophotometrically at 254 nm. Photodiode array detectors are significantly less sensitive than normal HPLC spectrophotometers (38). 

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