Fluorimetric determination of some basic antibiotics at very low concentrations

1974 ◽  
Vol 271 (4) ◽  
pp. 288-288 ◽  
Author(s):  
J. Kušnír ◽  
K. Barna
Keyword(s):  
Fluorimetric Determination ◽  
Low Concentrations

FLUORIMETRIC DETERMINATION OF ADRENAL CORTICOSTEROIDS: OBSERVATIONS ON INTERFERING FLUOROGENS IN HUMAN PLASMA

1964 ◽  
Vol 30 (2) ◽  
pp. 255-263 ◽  
Author(s):  
J. R. DALY ◽  
J. SPENCER-PEET
Keyword(s):  
Experimental Data ◽  
Human Plasma ◽  
Plasma Volume ◽  
Fluorescence Intensity ◽  
Plasma Sample ◽  
Accurate Estimation ◽  
Fluorimetric Determination ◽  
Low Concentrations ◽  
Theoretical Considerations

SUMMARY Simple fluorimetric methods for the determination of corticosteroids are not sufficiently specific to allow the accurate estimation of low concentrations in plasma. It has been noted previously and is confirmed here, that the measured fluorescence is not proportional to the volume of plasma used, but includes a component which is relatively independent of the plasma volume extracted. This gives rise to a positive intercept on the fluorescence axis when fluorescence intensity is plotted against volume. The suggestion that the determination of plasma corticosteroids can be made specific by subtracting the value of this intercept from the measured fluorescence intensity of the plasma sample has been examined. In the light of experimental data and certain theoretical considerations presented here, this suggestion is rejected. It is concluded that the inaccuracy due to interfering fluorogens can be reduced by taking fluorimeter readings within 5 min. of extraction into the fluorescence reagent, but that even then specificity is not complete.

The fluorimetric determination of cerium and terbium

1989 ◽  
Vol 54 (3) ◽  
pp. 616-621 ◽  
Author(s):  
Záviš Holzbecher
Keyword(s):  
Rare Earth ◽  
Detection Limit ◽  
Rare Earth Elements ◽  
Fluorimetric Determination ◽  
Fluorescence Maximum ◽  
Relative Standard ◽  
And Shifts ◽  
Hcl Medium ◽  
Fold Excess

It has been found that phosphoric acid decreases the first excitation maximum of Ce(III) at 256 nm, increases the second excitation maximum at 297 nm and shifts the fluorescence maximum from 350 to 346 nm. Under optimum conditions, with λexc = 297 nm and λem = 346 nm, Ce(III) can be determined fluorimetrically with a detection limit of 1.2 ng ml-1 in 12M-H3PO4 medium. No interference was observed from a 20-200 fold excess of HCl, H2SO4, Na, K, NH4+, Al and the rare earth elements. HNO3 interferes and Ce(IV) and Fe(III) interfere strongly. It follows from the stereofluorograms of Ce and Tb that the spectra of the two elements are practically independent. The detection limit for Tb(III) in 0.02-2.5M-H2SO4 medium for λexc = 222 nm and λem = 494 nm is 33 ng ml-1. No interference was observed from a 5-20 fold excess of Al3+ and the other rare earth elements. The determination is slightly less sensitive in H3PO4 or HCl medium. The relative standard deviation of the measurement for 10 ng ml-1 Ce(III) or 50 ng ml-1 Tb(III) is about 3%.

scholarly journals The Double Face of Ketamine—The Possibility of Its Identification in Blood and Beverages

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 813
Author(s):  
Magdalena Świądro ◽  
Paweł Stelmaszczyk ◽  
Irena Lenart ◽  
Renata Wietecha-Posłuszny
Keyword(s):  
Date Rape ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Heroin Addiction ◽  
Assisted Extraction ◽  
Low Concentrations ◽  
High Concentrations ◽  
Rosé Wine ◽  
Tof Ms

The purpose of this study was to develop and validate a high-sensitivity methodology for identifying one of the most used drugs—ketamine. Ketamine is used medicinally to treat depression, alcoholism, and heroin addiction. Moreover, ketamine is the main ingredient used in so-called “date-rape” pills (DRP). This study presents a novel methodology for the simultaneous determination of ketamine based on the Dried Blood Spot (DBS) method, in combination with capillary electrophoresis coupled with a mass spectrometer (CE-TOF-MS). Then, 6-mm circles were punched out from DBS collected on Whatman DMPK-C paper and extracted using microwave-assisted extraction (MAE). The assay was linear in the range of 25–300 ng/mL. Values of limits of detection (LOD = 6.0 ng/mL) and quantification (LOQ = 19.8 ng/mL) were determined based on the signal to noise ratio. Intra-day precision at each determined concentration level was in the range of 6.1–11.1%, and inter-day between 7.9–13.1%. The obtained precision was under 15.0% (for medium and high concentrations) and lower than 20.0% (for low concentrations), which are in accordance with acceptance criteria. Therefore, the DBS/MAE/CE-TOF-MS method was successfully checked for analysis of ketamine in matrices other than blood, i.e., rose wine and orange juice. Moreover, it is possible to identify ketamine in the presence of flunitrazepam, which is the other most popular ingredient used in DRP. Based on this information, the selectivity of the proposed methodology for identifying ketamine in the presence of other components of rape pills was checked.

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