Detection in Daylight

Under long-wavelength UV light (A = 365 nm) the chromatogram zones fluoresce yellow to yellow-green, they are sometimes detectable in daylight as colored zones, too. 

Detection and result The chromatogram was freed from mobile phase and dipped for 1 s in solution I and after drying for 1 min in a stream of cold air it was dipped in a solution of liquid paraffin — -hexane (1 + 2) in order to stabilize and increase the intensity of fluorescence by a factor of 1.5—2.5. The derivatives which were pale yellow in daylight after drying fluoresce pale blue to turquoise in long-wave... 

The hypotensive and sedative drug reserpine (256) has long been known to decompose in daylight. The photolysis has been studied in aqueous solution under a mercury discharge tube [ 159] and in chloroform at 360-370 nm [ 160]. The conclusions were essentially the same. The derivatives detected were isoreserpine (the C-3 epimer of reserpine), 3,4-dehydroreserpine (257) and lumireserpine which was shown to be 3,4,5,6-tetradehydroreserpine (258). 

A very serious safety deficiency of methanol is that it bums without a visible flame in daylight which makes fire detection and fire fighting difficult. The invisible flame is an indication of the soot-free combustion properties of methanol. A moderate safety advantage of methanol flames is that they have low radiant heat transfer, meaning that surfaces close to a methanol flame will not get as hot as compared to a luminous flame such as from gasoline. 

Vitamin E compounds can be detected (about 20 /tg) as dark spots in UV light. They appear violet and detection is appreciably more sensitive (0.02 /tg) on layers that contain 0.02% Na-fluorescein. Moreover, these are visible in daylight as reddish spots (limit of detection 2 fig). The same effect is produced by spraying with fluorescein or dichlorofluorescein reagent. Nonspecific visualization procedures for tocopherols and tocotrienols are based on spraying with sulfuric acid, molybdophosphoric add, antimony(V) chloride, dipyridyl-iron reagent, nitric add, and copper(II) sulfate-phosphoric add [1-4]. 

It has been reported that passing a mixture of carbon monoxide and dichlorine through a solution of aluminium(III) chloride in trichloromethane at 30-35 C results in the catalytic formation of phosgene [1628], Experiments in our own laboratories [1589b] show that there is no observable reaction in the dark, and that, in daylight, the presence of aluminium(lll) chloride solution had no detectable effect. 

Evaluation after derivatization does not only involve assessment of the chromatogram in daylight or measurement in light of wavelength >400 nm there are also a large number of reactions whose products are detected in 254-mn or 365-nm UV light. 

Thus, a large set of data obtained by McWilliams (1969) in clean air (W. Ireland) by means of expansion chambers showed that the concentration of Aitken particles is lower in the winter than in the summertime. Furthermore, McWilliams observations also demonstrated that more aerosol particles can be detected during daylight than at night. This finding was confirmed by the investigations of Vohra et... 

The five solutions were found to be stable [except for As(III)] for four months if kept in the dark at +4 °C. Storage in the dark at +40 °C led to the formation of As(III) in some solutions. Arsenobetaine resulting from the degradation of arsenocholine was observed to occur significantly when solutions were stored at +20 °C in daylight but no trace of degradation was detected at +4 °C in the dark. 

Vitamin E compounds can be detected (about 20 p-g) as dark spots in UV light. They appear violet, and detection is more sensitive (0.02 pg) on layers that contain 0.02% Na-fluorescein. Moreover, these are visible in daylight as... 

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