The use of polypropylene materials in industry for food packaging is increasing. The presence of additives in the polymer matrix enables the modification or improvement of the properties and performance of the polymer, but these additives are potential risk for human health. In this context, an efficient analytical method for the quantitative determination of three antioxidants (2,6-di-tert-butyl-4-methylphenol (BHT), dibutylhydroxyphenylpropionic acid stearyl ester (Irganox 1076), and tns-(2.4-di-tert-butyl)-phosphite (Irgafos 168)) and five ultraviolet stabilizers (2-(2′-hydroxy-5′-methylphenyl) (UV-P), (2′-hydroxy-3′-tert-5′-methylphenyl)-5-chloroben zotriazole (UV-326), 2-(2′-hydroxy-3′,5′-di-tert-butylphenyl)-5-chlorobenzotriazole (UV-327), 2-(2H-benzotriazol- 2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol(UV-329), and 2-hydroxy-4(octyloxy) benzophenone (UV-531)) in polypropylene food packaging and food simulants by high-performance liquid chromatography (HPLC) has been developed. Parameters affecting the efficiency in the process such as extraction and chromatographic condition were studied in order to determine operating conditions. The analytical method showed good linearity, presenting correlation coefficients (R ≥ 0.9977) for all additives. The limits of detection and quantification were between 0.03 and 0.30 μg mL−1 and between 0.10 and 1.00 μg mL−1 for eight analytes, respectively. Average spiked recoveries in blank polypropylene packaging and food simulants were in the range of 80.4–99.5% and 75.2–106.7%, with relative standard deviations in the range of 0.9–9.1% and 0.2–9.8%. Dissolving the polypropylene food packaging with toluene and precipitating by methanol was demonstrated more effective than ultrasonic extract with acetonitrile or dichloromethane for extracting the additives. The method was successfully applied to commercial polypropylene packaging determination, Irgafos 168 and UV-P were frequently found in six commercial polypropylene films, and the content ranged from 166.47 ± 5.11 to 845.27 ± 29.31 μg g−1 and 2.10 ± 0.29 to 19.23 ± 1.26 μg g−1, respectively.
Authors:Y. Wang, M. Wang, J. Li, S. Yao, J. Xue, W. Zou, and C. Hu
An improved ion-pairing reversed-phase high-performance liquid chromatography method coupled with evaporative light scattering detection (HPLC-ELSD) was developed to determine spectinomycin and its related substances in commercial samples. The method was validated in accordance with International Conference on Harmonization (ICH) guidelines. The specificity of the HPLC-ELSD method was similar to that of the European Pharmacopoeia (Ph. Eur.) method, and repeatability and robustness were markedly improved relative to other reported methods due to our empirical evaluation of separation columns. Indeed, it is a more specific assay of spectinomycin than traditional microbiological techniques. The HPLC-ELSD method was used to evaluate the impurity profiles of eight compounds in seven spectinomycin batches from five different companies. Liquid chromatography coupled with electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) was employed to characterize the structures of these compounds. Though the HPLC-ELSD method was not as sensitive as the Ph. Eur. method, its limit of quantitation (LOQ) (0.16%) was lower than the disregard limit (0.3%) described by the Ph. Eur. 7.0. This suggests that the HPLC-ELSD method is appropriate for routine analysis of spectinomycin and its related substances.
Authors:Y. Zhou, Y. Yang, X.L. Li, Z.Y. Chen, Q.B. Liu, X.L. Zhu, and J. Yang
An efficient and sensitive analytical method based on precolumn derivatization and gas chromatography—mass spectrometry—selected ion monitoring (GC—MS—SIM) was proposed and validated for analysis of two cembrenediols (CBDs) which are α-cembrenediol and β-cembrenediol in tobacco samples. CBDs in tobacco samples were extracted by sonication with 50 mL dichloromethane for 10 min before derivatized with 2:3 (v/v) bis(trimethylsilyl)trifluoroacetamide (BSTFA)—pyridine at 20 °C for 100 min. CBDs’ level in tobacco samples was analyzed by GC—MS—SIM and quantified by the internal standard method. The linear range for α-CBD and β-CBD was 13.6–554.6 μg mL−1 and 4.11–162.6 μg mL−1, and the correlation coefficients of both were 0.9998. The limit of detection (LOD) and limit of quantification (LOQ) of α-cembrenediol and β-cembrenediol were 0.40 μg g−1 and 1.34 μg g−1, and 0.27 μg g−1 and 0.90 μg g−1, respectively. Average recoveries of α-CBD and β-CBD were 94.4–99.9% and 91.9–98.2% while the relative standard deviations (RSDs, n = 5) were ranged from 2.67 to 5.6% and 2.04 to 4.22%, respectively. This proposed analytical method has been successfully applied to analyze CBDs in tobacco samples.
Authors:X.R. Zhi, Z.Y. Zhang, R.Y. Li, L. Chang, P.P. Jia, N. Sheng, and L.T. Zhang
A new, sensitive, and selective high-performance liquid chromatography-tandem mass spectrometric method (HPLC-MS/MS) has been developed for the quantification of six flavonoids (sophoricoside, genistin, genistein, rutin, quercetin, and kaempferol) in rat bile and urine. The sample pretreatment was simple by liquid-liquid extraction. Sulfamethalazole was used as internal standard (IS). During method development, the effect of extraction volume, mobile phase composition, column temperature, and injection volume were varied to optimize sensitivity and achieve a run time as short as possible. Chromatographic separation was accomplished on a C18 column with a simple linear gradient elution within 9 min. Full validation of the assay was in accordance with the requirement of the validation of the method in vivo and implemented including specificity, linearity, accuracy, precision, recovery, and matrix effect. This is the first report on determination of the major flavones in rat bile and urine after oral administration of Fructus Sophorae extract. The method has been used successfully in excretion studies of six major flavonoids in rat bile and urine.
Authors:W. J. Duan, Q. Liu, R. X. Zhao, Y. Mu, L. P. Guo, D. P. Li, and X. Wang
A method was developed for the preparative separation of two alkaloids from the crude extract of the radix of Rauvolfia verticillata (Lour.) Baill. in a single run. The two-phase solvent system composed of petroleum ether–ethyl acetate–methanol–water (5:5:2:8, v/v), where triethylamine (40 mmol/L) was added to the upper organic phase as the stationary phase and hydrochloric acid (10 mmol/L) was added to the lower aqueous phase as the mobile phase, was selected for this separation by pH-zone-refining counter-current chromatography (PZRCCC). For the preparative separation, the apparatus was rotated at a speed 850 rpm, while the mobile phase was pumped into the column at 2 mL/min. As a result, 112 mg of reserpine and 21 mg of yohimbine were obtained from 3 g of crude extract in a single run. The analysis of the isolated compounds was determined by high-performance liquid chromatography (HPLC) at 230 nm with purities of over 91.0%, and the chemical identification was carried out by the data of electrospray ionization–mass spectrometry (ESI–MS) and nuclear magnetic resonance (NMR) spectroscopy. The technique introduced in this paper is an efficient method for preparative separation of reserpine and yohimbine from devil pepper radix. It will be beneficial to utilize medicinal materials and also useful for the separation, purification, and pharmacological study of Chinese herbal ingredients.