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confirmed by the control experiment to iden- tify the limits of detection of the NMR instru- ment (Supplemental Figure S3). XRD Analysis To confirm the FTIR and NMR results along with verifying the existence of inorganic ingredients, we used XRD analysis. The XRD diraction pattern of all inks revealed amor- phous and crystalline phases (Figure 4). The vehicles and organic pigments are associated with the amorphous phases of the inks. The diraction pattern of D-LY ink is similar to PY14 but not to PY65 or PB15, which further confirms the presence of PY14 (Figure 4). Furthermore, when comparing the XRD pat- tern of PO13 with that of GY and GR inks, the peaks diered, which was predicted and cor- responded with the FTIR and NMR findings. Additionally, TiO 2 has been recognized as one of the most common crystalline oxide peaks in both D-BO and D-GY inks. The intensity of TiO 2 peaks, however, was greater in D-BO ink than in D-GY ink, which might be because the quantity of TiO 2 was smaller in the D-GY ink than that in the D-BO ink, as per a November 20, 2018, clarification on the manufacturer’s website in the MSDS of these inks (INTENZE Advanced Tattoo Ink, 2025). The absence of the TiO 2 peaks in the D-LY ink, however, sug- gests that the amount of TiO 2 was smaller than the level detectable by XRD. These results from the XRD data analysis of the pigments and inks were compared with results from the refer- ence (Arl et al., 2019). The possible presence of BaSO 4 in the BO ink was evidenced by low- intensity peaks in the XRD analysis; however, this finding could not be confirmed using XRD alone, as some of these low-intensity peaks overlapped with the TiO 2 peaks. Raman Spectra Analysis Furthermore, Raman analysis was conducted to confirm the previous instrument examina- tion data and the presence of PY65, PO13, PB15, and the other inorganic ingredients (e.g., BaSO 4 and TiO 2 ), as shown in Figure 5. The full range of the spectra (2,500 cm -1 to 200 cm -1 ) can be found in Supplemental Figure S4. The Raman spectra analysis of the LY ink revealed that PY14 is a prominent component and that PY65 is not present. The challenge in resolving these separate pigments for this spe- cific shade of ink can be due to the quantity of PY14 versus PB15 (Supplemental Figure S5),
TABLE 2
Element Composition Analysis of Pigments and Inks Using EDX (Energy Dispersive X-Ray) Spectroscopy
Pigment/Ink
Element (%)
C N O Cl 66 19 14 2 62 20 14 –
Cu Ti
Ba S Si
Na Al
PY14 PY65 PB15 PO13 BaSO 4 TiO 2 D-LY E-LY D-GY E-GY D-GR E-GR D-BO E-BO
– – 2 – –
– – – –
– – – –
– – – –
– – – –
– – – – – – 3 – – –
– – – – – – – – – – – –
76 18 6 70 21 5
– 2
– 4
– 48 – 3 70 –
– 30 19 –
– 23 –
– – – – –
– – – – –
76 11 7 70 16 8
3 2
– – – – – –
3 – 4 – – –
– – – – – –
65 9 18 2 65 21 10 2 67 20 10 2 69 16 11 2 60 5 20 2 63 5 18 3
– 1.0 –
–
–
–
– 10 –
– 0.7 -
0.8
–
–
–
–
–
–
–
Note . EDX spectroscopy provides supportive evidence of the presence of certain pigments in inks and establishes a match between LY ink and PY14 pigment. The elemental percentage represents the average atomic percentages from surface analysis of three spots on a sample. Al = aluminum; Ba = barium; BaSO 4 = barium sulfate; C = carbon; Cl = chlorine; CU = copper; D-BO = dried ink, bright orange; D-GR = dried ink, golden rod; D-GY = dried ink, golden yellow; D-LY = dried ink, lemon yellow; E-BO = ink extract, bright orange; E-GR = ink extract, golden rod; E-GY = ink extract, golden yellow; E-LY = ink extract, lemon yellow; N = nitrogen; Na = sodium; O = oxygen; PB = pigment blue; PO = pigment orange; PY = pigment yellow; S = sulfur; Si = silicon; Ti = titanium; TiO 2 = titanium dioxide.
primarily, which causes signals from PY14 to overwhelm signals from PB15. Many aspects of the comparatively narrow PY14 spectrum corresponded with and overlapped with the few peaks (e.g., 1,598.5 cm -1 ) derived from PB15 due to similar structural vibrations. For example, the normally noticeable 1,332 cm -1 C-C bond stretching in PB15 (Scherrer et al., 2009) is hidden by a rather weak fea- ture in PY14 at 1,310 cm -1 . Additionally, the allocated peaks from PB15 at 1,414 cm -1 and 1,136 cm -1 were shifted to 1,456 cm -1 and 1,148 cm -1 , respectively. At the same time, the BP15 peak of 584 cm -1 was masked in the D-LY ink. Therefore, Raman spectra analysis results could not confirm the presence of PB15. Furthermore, the Raman spectra analysis of the GY and GR inks was consistent with previous characterization (e.g., IR, NMR, and XRD) studies and confirmed the absence of PO13 in these inks. This finding is because PO13 had a peak at 1,588 cm -1 and this peak
was shifted to 1,600 cm -1 in the GY and GR inks. The Raman spectra analysis of TiO 2 and BaSO 4 revealed two distinct peaks at 441cm -1 and 603cm -1 (Supplemental Figure S6), which were not observed on the Raman spectra analysis of the dried inks at the same region. This result could be because the quantity of elements was inadequate to be detected by Raman analysis. As a next step, therefore, we conducted an EDX analysis. EDX Analysis The pigments and dried inks were analyzed using EDX analysis to identify the element composition (Table 2 and Supplemental Fig- ures S7–S11). As expected, the pigment refer- ence samples contained carbon (C), nitrogen (N), oxygen (O), copper (Cu), barium (Ba), sulfur (S), and chlorine (Cl). The presence of Cl in the D-LY ink spectrum is further proof that PY14 is present in this ink. It was expected that Cu (from PB15) and Ba (from
14
Volume 88 • Number 2
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