PBX 9404, composed of 94 wt% HMX (1,3,5,7‐Tetranitro‐1,3,5,7‐tetrazoctane), 3 wt% NC (nitrocellulose), 2.9 wt% CEF (tris(beta‐chloroethyl) phosphate) and 0.1 wt% DPA (diphenylamine), has often been observed with a slight to entire blue discoloration of the manufactured prills. This blue discoloration has been observed since the formulation development of PBX 9404 in the late 1950s. In order to determine the source of the blue discoloration in PBX 9404, ultraviolet/visible (UV/Vis) absorbance of PBX 9404 and two potential candidates for the discoloration, p‐nitrosodiphenylamine (p‐NDPA) and N‐nitrosodiphenylamine (N‐NDPA) were evaluated. An absorbance band at 590 nm in PBX 9404 sample was attributed to the blue discoloration while p‐NDPA and N‐NPDA had different absorbance bands. Using the knowledge gained from the UV/Vis analysis, a semi‐targeted approach using ultrahigh pressure liquid chromatography coupled to UV/Vis detector and quadrupole time of flight mass spectrometry (UHPLC‐UV/Vis‐QTOF) was implemented. Investigating the UHPLC‐UV/Vis‐QTOF chromatograms at a wavelength of 590 nm, a single compound was tentatively identified as being the source of the blue discoloration. Targeted tandem mass spectrometry (MS/MS) on the compound and subsequent analysis indicated that 4,4′‐{[4‐(Phenylimino)‐2,5‐cyclohexadien‐1‐ylidene]methylene}bis(N‐phenylaniline), also known as Spirit Blue Base, was the source of the blue discoloration, which was confirmed using a standard. A theory on the formation of Spirit Blue Base in PBX 9404 involving DPA, nitric acid (HNO₃) / nitrogen oxide(s) NO_x, and formaldehyde is proposed.

中文翻译：

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超高压液相色谱-四极杆飞行时间质谱法鉴定PBX 9404中的蓝色变色

PBX 9404，由94 wt％的HMX（1,3,5,7-四硝基-1,3,5,7-四十六烷），3 wt％的NC（硝化纤维素），2.9 wt％的CEF（三（β-氯乙基））组成通常会观察到制造的小球有轻微到整个蓝色的变色，并观察到0.1％的DPA（二苯胺）和0.1wt％的DPA。自从1950年代末PBX 9404的配方开发以来，就已经观察到这种蓝色变色。为了确定PBX 9404中蓝色变色的来源，请使用PBX 9404的紫外线/可见光（UV / Vis）吸光度以及两个可能的变色候选物，对亚硝基二苯胺（p-NDPA）和N-亚硝基二苯胺（N-NDPA ）进行了评估。PBX 9404样品在590 nm处的吸光度带归因于蓝色变色，而p-NDPA和N-NPDA的吸光度带不同。利用从UV / Vis分析获得的知识，采用超高压液相色谱结合UV / Vis检测器和四极杆飞行时间质谱（UHPLC-UV / Vis-QTOF）的半目标方法。研究波长为590 nm的UHPLC-UV / Vis-QTOF色谱图，初步确定了一种化合物是蓝色变色的来源。针对该化合物的目标串联质谱（MS / MS）和随后的分析表明，4,4'-{[4-（苯基亚氨基）-2,5-环己二烯-1-亚甲基]亚甲基} bis（N-苯基苯胺），也称为精神蓝碱，是蓝色褪色的来源，已使用标准品进行了确认。提出了在PBX 9404中涉及DPA，硝酸（HNO ₃）/氮氧化物NO _x和甲醛的精神蓝碱形成的理论。