Bis trimethylsilyl trifluoroacetamide bstfa

Biphenyl and benzoate were purchased from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China). PCBs were purchased from Accustandard Co., Ltd (USA), including 2-chloroBiphenyl (2-CB), 3-chloroBiphenyl (3-CB), 2,4′-dichloroBiphenyl (2,4′-DCB), 3,3′-dichloroBiphenyl (3,3′-DCB), 2,4,4′-trichloroBiphenyl (2,4,4′-TrCB), 2,4′,5-trichloroBiphenyl (2,4′,5-TrCB), 2,2′,3,3′-tetrachloroBiphenyl (2,2′,3,3′-TeCB), 2,2′,4,5′-tetrachloroBiphenyl (2,2′,4,5′-TeCB), 2,3′,4′,5-tetrachloroBiphenyl (2,3′,4′,5-TeCB) and 2,2′,4,4′,5,5′-hexachloroBiphenyl (2,2′,4,4′,5,5′-HCB). 2-chlorobenzoate (2-CBA), 3-chlorobenzoate (3-CBA) and 4-chlorobenzoate (4-CBA) were obtained from Aladdin Chemical Co., Ltd (Shanghai, China). A mixture of bis(trimethylsilyl)trifluoroacetamide (BSTFA) and trimethylchlorosilane (TMCS) (99:1, v/v), obtained from Sigma-Aldrich (Beijing, China), was used as the derivatization reagent. All other reagents and chemicals were of the highest purity commercially available. Soil samples were collected from the surface layer (0–30 cm) of a long-term e-waste recycling area in Taizhou, Zhejiang Province, China.

The chemical reagents, bis-(trimethylsilyl)-trifluoroacetamide (BSTFA) and saturated alkane standards (C7–C40) were purchased from Sigma Aldrich Trading Co., Ltd. (Shanghai, China). Chloroform was purchased from Shanghai Titan Technology Co., Ltd. (Shanghai, China). Sulfuric acid was purchased from the Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Trimethylchlorosilane, pyridine and methoxyamine hydrochloride were purchased from Myrell Chemical Technology Co., Ltd. (Shanghai, China). L-2-Chlorophenylalanine was purchased from Shanghai Bi De Pharmaceutical Technology Co., Ltd. (Shanghai, China). Quercetin 3-β-D-glucoside was purchased from Macklin Shanghai Macleans Biochemical Technology Co., Ltd. (Shanghai, China). Methanol and acetonitrile were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). Milli-Q system (Millipore, Bedford, MA, USA) was used to obtain ultrapure water for analysis. All purchased chemicals were HPLC grade ≥ 98%.

The saponification of the fatty oils in 1 g of roots and fruits CH₂Cl₂ extracts was done using 50% potassium hydroxide (5 mL)/ethanol (30 mL) at 90 °C for 60 min. Unsaponifiable fractions were separated using petroleum ether, and the soap-rich polar fractions were treated with hydrochloric acid to obtain free fatty acids, which were then collected using diethyl ether. Afterwards, the fatty acids were esterified using 98% sulphuric acid (1 mL)/methanol (150 mL, purity ≥ 99.9%) at 80 °C for 60 min to obtain volatile fatty acid methyl esters (FAME), which were then collected using petroleum ether. To analyze phytosterols and triterpenes, the unsaponifiable fractions (300 μL of 5 mg/mL solution in CH₂Cl₂) were treated with bis-(trimethylsilyl)-trifluoroacetamide (BSTFA; Sigma-Aldrich, St. Louis, MO, USA) (200 μL) and held at 60 °C for 60 min to obtain volatile trimethylsilyl (TMS) derivatives [70 (link)].

DMEM/Ham’s F12 with L-glutamine was purchased from PAA Laboratories GmbH (Pasching, Austria). Dulbecco’s modified eagle medium (DMEM), fetal bovine serum (FBS), minimal essential medium eagle (MEM) with L-glutamine, trypsin-EDTA, penicillin, streptomycin were purchased from Gibco (Thermo Fisher Scientific, Waltham, MA, USA). Calcium-free phosphate-buffered saline (PBS) was received from Biomed (Lublin, Poland). Bis(trimethylsilyl)trifluoroacetamide (BSTFA) with an addition of 1% trimethylchlorosilane, C10–C40 n-alkane standard solution, methylthiazolyl diphenyl-tetrazolium bromide (MTT), dimethyl sulfoxide (DMSO), pyridine, trichloroacetic acid, and trizma base were obtained from Sigma-Aldrich (St. Louis, MO, USA). Ethanol at 95% was obtained (AWW Group, Poland). The scintillation cocktail was purchased from PerkinElmer (Boston, MA, USA) and methyl-3H thymidine from MP Biomedicals, Inc. (Irvine, CA, USA).

Cholesterol standard (purity 98%), the internal standard (ISTD) 5α-cholestan-3β-ol (purity 98%), bis (trimethylsilyl) trifluoroacetamide (BSTFA) with 1% of trimethylchlorosilane (TMCS), heptane, dichloromethane (DCM) and methanol (all GC grade) were sourced from Sigma-Aldrich Co. (Arklow, Co. Wicklow, Ireland). Pyridine was supplied by Santa Cruz Biotechnology, Inc. (Dallas, TX, USA). Deionised water (DI) was sourced from a Millipore Elix 15 water purification system (Merck Millipore, Darmstadt, Germany).