Photodiode array wavelength

Fig. 1.7. Instantaneous spectrum of the GC-AED photodiode array wavelength rang for tin detection, showing primary and secondary emissions. (Reproduced by permission from R.L. Firor, American Lo6., 1989, 21(5), 1989 copyright, 1989, International Scientific Communications, Inc.)...

An optical detector with appropriate electronics and readout. Photomultiplier tubes supply good sensitivity for wavelengths in the visible range, and Ge, Si, or other photodiodes can be used in the near infrared range. Multichannel detectors like CCD or photodiode arrays can reduce measurement times, and a streak camera or nonlinear optical techniques can be used to record ps or sub-ps transients. 

Figure 5.8 Scheaatic optical diagram of a variable wavelength dual beam absorption detector. A, and a photodiode array detector with reverse optics, B.

Figure 3.5 Three-dimensional display of the photodiode array absorbance data obtained by HPLC/PDA/MS for a M. truncatula extract. The first dimension is HPLC retention time, second is wavelength, and third is absorbance. The data can be rapidly previewed for specific absorbance regions characteristic of functional groups.

SPE with Amberlite XAD 2/4/8 mixture, elution with dichloromethane and RP-HPLC-UVD with a photodiode-array at their optimum wavelength LOD is ca 50 ng/L with 85-105% recoveries, depending on the compound445. 

Duverneuil and coworkers (2003) have developed a method for the determination of 11 of the most commonly prescribed non-tricyclic antidepressants and some of their metabolites these include paroxetine, fluoxetine, norfluoxetine, sertraline, citalopram, fluvoxamine mirtazapine, venlafaxine, and 0-des-methylvenlafaxine. The method involves an LLE procedure followed by an HPLC separation with photodiode-array UV detection at three different wavelengths (220, 240, and 290 nm). The total run time was 18 min. The extraction recoveries were calculated to be in the range of 74-109% and the lower limit of detection (LLOD) reported was 2.5-5 ng/ml. A method published by Tournel and associates (2001) also reported the simultaneous determination of several newer antidepressants by RP-HPLC with UV detection. The compounds were isolated from human serum using an LLE process. The LLOQ ranged from 15-50 ng/ml depending on the analyte of interest. The total run time for all compounds eluted was approximately 20 min. 

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