Fabric Dyeing White polyester satin was donated by Jo-Ann Fabrics (Woodland, CA) and dyed with disperse dyes. A stovetop dyeing recipe was obtained (ProChemical and Dye, Somerset, MA; http://www.prochemical.com/directions/Prosperse_ImmersionPolyester.htm) and used with minimal alterations. Approximately 0.2 g swatches of fabric were used in the dyeing of all samples. The fabric was added to 100 mL water at 60°C with 0.043 g Na2CO3 and 50 μL of dish soap (Dawn, Procter and Gamble, Cincinnati, OH). This was stirred for 2 min, followed by rinsing the fabric with water. A solution of 200 mL water at 50°C, 50 μL of 30% acetic acid (EM Science), and 0.075 g of dyestuff filtered with 50 mL of boiling water was stirred, and the fabric was added. The dyebath temperature was raised to boiling and held for 30 min. The fabric was removed and plunged in 20°C water. This was stirred for 30 sec. The fabric was then removed and plunged in 70°C water with 50-μL dish soap and stirred for 30 sec. The fabric swatch was removed and rinsed with water. Finally, any unfixed dye adsorbed on the fabric was removed using a 50:50 methanol and acetone rinse at 40°C for 30 sec. Various colors of acrylic fibers with unknown dyes were obtained. TLC was performed on the fibers (13) to confirm that the dyes were basic. Dye Extraction Single acrylic fibers (≤0.5 cm) were extracted at 100°C for 45 min with 50 μL of a 1:1 formic acid and water solution for LC/MS analysis (13). Disperse dyes were extracted from polyester fabric swatches with a mass of 0.005 g each. Samples to be analyzed by the LC/MS method were extracted with 100 μL, while samples for the spectrophotometer were extracted with 250 μL. All swatches were extracted at 120°C for 60 min using acetonitrile and water (4:3) or pyridine and water (4:3) (pyridine from Pierce Chemicals Co., Dallas, TX). Swatches were then removed and the extracts were diluted with 400 μL of methanol for HPLC/UV-Vis and 2250 μL for spectrophotometer analysis. Basic Dye Chromatography Optimization All basic dye standards were initially run on an un optimized gradient of 2–98% acetonitrile for 22 min (9) to determine each dye's base ion and absorption spectrum. Then, the mass spectrometer was optimized to maximize the abundance of each dye's base ion. Finally, the HPLC gradient was optimized for separation of all 15 basic dyes. HPLC parameters (flow rate, solvent composition, and column temperature) were optimized using a mix (50 μL each) of 15 basic dye standards. This mix was then injected, and dye peaks were located using mass spectral and UV–Vis data. Finally, the UV–Vis detector was optimized by finding the λmax of each dye peak. The Agilent Chemstation™ software is limited in that it can only monitor five wavelengths for data manipulation. Therefore, the λmax values of each dye standard within a 100 nm range were averaged together. For example, all dyes that absorbed in the 400 nm range were averaged, the 500 nm range averaged, and the 600 nm averaged. These were then selected as monitoring wavelengths.
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