Determination of the photodegradation products of basic yellow 2 by thermospray high-performance liquid chromatography and gas chromatography/mass spectrometry

Abstract

Like most dyes, Basic Yellow 2 (BY-2) fades upon prolonged exposure to light. Light-induced fading is a complex process that is also affected by beat and humidity. In order to better understand the photodegradation process and to identify the various photodegradation products of BY-2, fabric samples and solutions containing BY-2 were exposed to a variety of fading conditions. The analysis of faded BY-2 dyed fabric extracts by high-performance liquid chromatography/mass spectrometry (HPLC/MS) indicated the reduction and hydrolysis of the C=NH,+ group to form primarily benzophenone derivatives, as well as various demethylated products. Due to the absence of fragmentation in the thermospray spectra (only IM + HI+ ions were observed) the dye extracts were analyzed by gas chromatography/mass spectrometry (GC/MS) to confirm the identity of the degradation products. Many of the degradation products were sufficiently volatile for analysis by GC/MS. Mass spectra of the photodegradation products of BY-2 exhibited molecular ions and structurally important fragment ions to complement the thermospray data. The mass spectral data indicated that the most prevalent degradation product formed was ((CH,),NC6H,),C=0 (Michler's ketone). Hydrolysis of the C=NH, + group to C-0 is the main color-destroying reaction in the fading of BY-2. Demethylation products which can alter the shades of color were also detected in the faded BY-2 samples.

Determination of aromatic amines originating from azo dyes by chemical reduction combined with liquid chromatography/mass spectrometry

“…Table III lists the retention time and m/z values of the two isolated products (3,3'-dichlorobenzidine and 2V,/V'-dicyclohexylurea) of sludge II following SnCL treatment. Although both compounds were found in the untreated and treated (26); 119 (24); 90 (95); 89 (24); 78 (56); 63 (41); 62 (37); 52 (22) 17.9 277 (1); 239 (96); 237 (100); 191 (20); 184 (46); 155 (37); 8 125 (13); 76 (64) 28.9 330 (32); 315 (100); 281 (12); 232 (29); 174 (15); 165 (22); 20 152 (21); 119 (28); 103 (40); 91 (65); 77 (29) 28.9 480 (8); 478 (19) (reducing peak agent applied) no.6 I (NasSsOi) 0 ír = retention time in TIC chromatogram (min); m/z (relative intensity) reports the major peaks (>5%) of each product down to m/z 50. A maximum of 18 ions are reported in descending m/z.…”

“…Online HPLC/MS using thermospray has overcome some of these disadvantages in the analysis of environmental wastes (17)(18)(19)(20). Thermospray has proven to be a suitable technique for many azo dyes (25,(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32) with structural information obtained by MS/MS (25,22) or through repeller fragmentation (27,30,31). Furthermore, particle beam (PB) MS has been used to generate electron ionization (El) spectra on a series of commercial dyes (32)(33)(34)(35)(36).…”

Oxidative degradation of food dye E133 Brilliant Blue FCF

“…It is reported that some dyes are naturally decoloured as a consequence of prolonged exposure to sunlight: but in this case too the loss of colour does not mean complete mineralisation [17].…”

“…By HPLC-MS and GC-MS the main degradation products identified in the faded dye were the Michler's ketone, formed in the hydrolysis reaction of C NH 2 + group to C O and demethylation products [17]. Some authors report the formation of aromatic amines by exposure to natural light of some dyes [18][19][20][21][22][23][24][25], but this hypothesis must be discussed because aromatic amines are reported to be already present as impurities in many dye standards [18], as for example naphthylamine in amaranth [21] and p-cresidine and aniline in FD&C Red n. 40 [22].…”

HPLC‐MSn to Investigate the Oxidative Destruction Pathway of Aromatic Sulfonate Wastes

“…Many remediation processes have been in the past employed essentially aimed to decolorise the wastes. But a process or a chemical reaction able to transform a chromophoric group present in the molecular structure of the dye into a nonchromophoric group does not exclude the formation of toxic intermediates or products (Voyksner et al, 1989). These could be organic toxic species that do not absorb in the visible region.…”