顶空气相色谱法测定烟用胶中残余单体

采用顶空气相色谱(HS-GC)法对卷烟用胶中甲基丙烯酸甲酯、甲基丙烯酸乙酯、甲基丙烯酸丁酯、丙烯酸甲酯、丙烯酸乙酯、丙烯酸丁酯和乙酸乙烯酯7种残余单体进行了分析。方法采用DB-VRX石英弹性毛细管色谱柱分离,氢火焰离子化检测器检测。7种单体能够完全分离,线性良好,线性相关系数在0.9985～0.9992之间,检测限在0.0030～0.0039mg/mL范围,相对标准偏差(RSD)小于1.92%。该方法操作简便、快速、高效、准确、灵敏度高,实用性强,可用于胶粘剂中残余单体的测定。     

大口径毛细管气相色谱法测定硅丙树脂中的残余单体

用甲醇为聚合物沉淀剂,利用反相沉淀法使聚合物与残余单体分离,避免了聚合物进入色谱柱的现象出现,延长了色谱柱的使用寿命;选用高惰性抗氧化交联二硝基苯二甲酸聚乙二醇酯(FFAP)大口径毛细管色谱柱,以丁酸丁酯为内标,采用程序升温色谱对硅丙树脂中的5种残余单体进行了分析,测定结果的相对标准偏差为1.90%-10.19%,回收率为91.30%-101.20%;最低检出限为2-150 μg/g。     

Effects of Sequence Structure of Polycarboxylate Superplasticizers on the Dispersion Behavior of Cement Paste

Different AA-OEGMA copolymers with random and block distributions were synthesized using free radical polymerization and reversible addition-fragmentation chain transfer polymerization, respectively. Studies on the dispersion ability, adsorption isotherm, adsorption conformation, and zeta potential revealed that the random and block architecture behaved differently. Sequence structure of polycarboxylate polymers (PCPs) had a significant influence on its performance. Both monomer ratio and sequence structure had influences on the dispersion of cement paste. Compared with random PCPs, PCPs with block distribution adsorbed faster on cement particle surfaces because of the higher density of exposed carboxylic groups. For random PCPs, the adsorption was a thermodynamic spontaneous process and driven by entropy, while it was driven by Gibbs free energy for block PCPs. Besides, the hydrodynamic radius of random PCPs in solution was larger than the block PCPs. However, the adsorbed layer thickness of random PCPs was close to that of block PCPs. Furthermore, the zeta potential illustrated that the PCPs with block distribution may adopt a more extended conformation compared with random PCPs. All these findings found from the differences between random PCPs and block PCPs will help the researchers to explore high-performance PCPs.     

丙烯腈-丁二烯-苯乙烯(ABS)塑料中残留单体的溶解沉淀-气相色谱法测定

建立了溶解沉淀-气相色谱同时测定丙烯腈-丁二烯-苯乙烯（ABS）塑料中9种有毒有害残留单体的分析方法。以N,N-二甲基甲酰胺为溶剂溶解ABS树脂,然后用甲醇作沉淀剂将高聚物进行沉淀,使残留单体与高聚物进行分离而继续留在溶液中,取溶液进行气相色谱分析。通过优化气相色谱的分离条件,实现了9种残留单体的成功分离,9种残留单体的平均回收率为91％～110％,测定结果的相对标准偏差为1．27％～3．16％,检出限（S／N=5）为0．936～1．639mg／kg。该方法比国家标准GB／T 5009．152-2003具有更广的适应性,应用此方法对4种牌号的ABS塑料中9种残留单体进行测定,获得满意的结果。     

Simultaneous RP-LC Determination of Additives in Soft Drinks

A reverse-phase HPLC method for the simultaneous determination of the main artificial sweeteners, preservatives and dyes present in soft drinks is proposed. It involves the use of a 10 μm LiChrosorb RP18 column and a binary eluent consisting of aqueous 0.1 M phosphate buffer (pH 4.0) added with methanol, according to a suitable gradient elution program. Good separations were obtained within less than 20-min run-time, with a satisfactory precision. The sensitivity of spectrophotometric detection was optimised by adopting a wavelength switching technique, thus achieving for all the additives considered detection limits ranging from 0.1 to 3.0 mg L^?1, well below the maximum permitted levels. The method was applied to some commercial soft drinks, whose analysis required minimum pre-treatment before direct injection.     

液体顶空-气相色谱法测定食品接触苯乙烯聚合物中单体及溶剂残留

提出了液体顶空-气相色谱法测定食品接触苯乙烯聚合物中残留单体及溶剂的方法。采用N,N-二甲基乙酰胺溶解聚合物,使其中残留单体及溶剂完全释放,并在优化的工作条件下,以基体匹配校正法绘制工作曲线,有效消除基质效应。7种分析物检出限(3S/N)在0.2～4.1mg.kg-1之间。测得方法的回收率在93.2%～103.2%之间,测定值的相对标准偏差(n=6)在1.1%～5.6%之间。     

Simultaneous RP-LC Determination of Artesunate and Amodiaquine in Pharmaceutical Preparations

A simple, fast and precise reversed phase liquid chromatographic method was developed for the simultaneous determination of artesunate (AS) and amodiaquine (AD) in combined pharmaceutical dosage form. Chromatographic separation of the two drugs was performed on a BDS Hypersil C18, 100 mm × 4.6 mm, 3 μm particle size column as stationary phase with a mobile phase comprising of phosphate buffer (pH 3.0 with orthophosphoric acid) and acetonitrile in the proportion of 50:40 (v/v), at a flow rate of 0.8 mL min^?1 and UV detection at wavelength 210 nm for AS and 300 nm for AD using photo diode array detection. The proposed method was validated for specificity, accuracy, linearity, range, precision and was successfully applied to the simultaneous determination of AS and AD in the combined fixed dosage form without any excipient’s interference.     

Simultaneous Determination of Nine Major Flavonoids in Sophora flavescens by RP-LC

A liquid chromatographic method was applied to determine trifolirhizin, kushenol K, kushenol L, kushenol N, kushenol X, kurarinone, norkurarinone, isokurarinone and kushenol A in the roots of Sophora flavescens, namely Kushen in China. The samples were separated on a YMC-C₁₈ column (250 × 4.6 mm, 5 μm) with a gradient of methanol and 0.3% aqueous acetic acid (v/v) at a flow rate of 0.8 mL min^?1 and detected at 295 nm. The complete separation was achieved within 45 min for the nine major flavonoids. All calibration curves expressed good linearity (r ² > 0.999) within the test range. The recovery of this method was 92.3–106.9%. The assay was successfully applied to the quantification of nine flavonoids in 26 samples of Kushen. The results indicated that this developed LC assay could be readily utilized as a quality control method for the Chinese herb medicine Kushen.     

Determination of Dimenhydrinate Nasal Delivery System in the Blood by RP-LC

Dimenhydrinate (DM) is used therapeutically for the prevention of motion sickness associated with nausea and vomiting. The aim of this investigation is the development of a new, rapid, sensitive, simple and fully validated RP-LC procedure for the suitable assay of DM in pharmaceutical formulation applied in blood samples. The method was validated before the amount determination studies in order to confirm linearity, precision, accuracy, selectivity, determination and quantification limit and consistency. High determination coefficient (r ²  = 0.998) of the standard curve drawn in the linearity studies showed that the line equation can be used in the quantification of the DM. Literature was reviewed for the methods based on diphenhydramine (DIP), its metabolite dimenhydrinate, in the in vivo determination of dimenhydrinate amount. The most appropriate method to be used in LC was decided to be the method applied by benefitting from the fluorescence characteristic of DIP. Maximum excitation and emission wavelengths in the developed method were scanned using multiple wavelengths and, maximum excitation and emission wavelengths were found to be 215 and 300 nm, respectively. In the validation study used to prove validity of the method, determination coefficient of the developed standard curve was calculated as 0.998 (RSD %), and line equation was concluded to be appropriate for use in amount determination studies. BBS % (1.06, 1.84 %) values obtained as “<2 %” in the intra-day and inter-day precision studies proved the precision of the method. Selectivity study revealed that other materials used in the formulation did not exhibit absorbance in the same wavelengths. Detection and quantification limit were found as 1 and 5 ng mL^?1, respectively. The determination of DM plasma concentrations using the proposed and fully validated LC assay has allowed us to characterize DMPK in the sheep, as well as determine DM relative bioavailability.     

Simultaneous RP-LC Determination of Ketorolac and its Piperazinylalkyl Ester Prodrugs

A simple, rapid and selective RP-HPLC method was developed and validated for the determination of ketorolac and five piperazinylalkyl ester prodrugs. A binary isocratic mobile phase composed of a mixture of 65:35 (v/v) 0.02 M phosphate buffer (pH 5.4) and acetonitrile was used on a C₁₈ column (125 × 4 mm, 5 μm). The injection volume was 25 μL and the detection wavelength was 314 nm and the flow rate was 1.5 mL min⁻¹. The method exhibited excellent linearity with R ² of no less than 0.999 and intra-assay and inter-assay precision that were less than the maximum amount allowed according to Horwitz equation. The accuracy was found to be within the allowed ±15%. The limits of detection for the analytes were between 0.060 and 0.220 μg mL⁻¹ and the limits of quantification were between 0.183 and 0.667 μg mL⁻¹. This method was used successfully for the study of the solubility, stability and partition coefficients of piperazinylalkyl ester prodrugs of ketorolac.     

Determination of Dimenhydrinate Nasal Delivery System in the Blood by RP-LC

Dimenhydrinate (DM) is used therapeutically for the prevention of motion sickness associated with nausea and vomiting. The aim of this investigation is the development of a new, rapid, sensitive, simple and fully validated RP-LC procedure for the suitable assay of DM in pharmaceutical formulation applied in blood samples. The method was validated before the amount determination studies in order to confirm linearity, precision, accuracy, selectivity, determination and quantification limit and consistency. High determination coefficient (r ² = 0.998) of the standard curve drawn in the linearity studies showed that the line equation can be used in the quantification of the DM. Literature was reviewed for the methods based on diphenhydramine (DIP), its metabolite dimenhydrinate, in the in vivo determination of dimenhydrinate amount. The most appropriate method to be used in LC was decided to be the method applied by benefitting from the fluorescence characteristic of DIP. Maximum excitation and emission wavelengths in the developed method were scanned using multiple wavelengths and, maximum excitation and emission wavelengths were found to be 215 and 300 nm, respectively. In the validation study used to prove validity of the method, determination coefficient of the developed standard curve was calculated as 0.998 (RSD %), and line equation was concluded to be appropriate for use in amount determination studies. BBS % (1.06, 1.84 %) values obtained as “<2 %” in the intra-day and inter-day precision studies proved the precision of the method. Selectivity study revealed that other materials used in the formulation did not exhibit absorbance in the same wavelengths. Detection and quantification limit were found as 1 and 5 ng mL⁻¹, respectively. The determination of DM plasma concentrations using the proposed and fully validated LC assay has allowed us to characterize DMPK in the sheep, as well as determine DM relative bioavailability.

     

RP-LC Simultaneous Determination of Nebivolol Hydrochloride and Amlodipine Besilate in Bi-Layer Tablets

A simple and rapid LC method was developed and validated for simultaneous estimation of nebivolol and amlodipine in a bi-layer tablet formulation. Efficient chromatographic separation was achieved on (USP L10) Hypersil BDS cyano, 5 μm, 250 mm × 4.6 mm column with simple mobile phase composition delivered in isocratic mode. The method had requisite accuracy, selectivity, sensitivity, robustness and precision to assay nebivolol and amlodipine in pharmaceutical dosage form. Degradation products resulting from the stress studies did not interfere with the detection of nebivolol and amlodipine, these peaks remained pure and thus proved to be stability indicating. The mass balance of the stressed sample was in the range 99.0–100.2% for amlodipine and 99.3–100.3% for nebivolol.     

RP-LC Determination of Rutin in Amaranthus spinosus Linn. Whole Plant Powder

A simple, reproducible and efficient reverse phase high performance liquid chromatographic method has been developed for the determination of rutin in whole plant powder of Amaranthus spinosus Linn. The analysis was done with Waters Cosmosil C₁₈ column (150 × 4.6 mm i.d., 5 μm particle size) as stationary phase at a wavelength of 361 nm for detection and determination. The proposed HPLC method was validated for linearity, accuracy, precision and limit of quantitation.     

Simultaneous Determination of Etodolac and Acetaminophen in Tablet Dosage Form by RP-LC

A simple, specific, precise and accurate reverse phase liquid chromatographic (RP-LC) method has been developed for the simultaneous determination of etodolac and acetaminophen in tablet dosage form. The chromatographic separation was achieved on a BDS Hypersil C18, 100 mm × 4.6 mm, 5 μm column at a detector wavelength of 274 nm using an isocratic mobile phase consisting of a mixture of 0.05% aqueous orthophosphoric acid and acetonitrile in the ratio of 50:50 (v/v) at a flow rate of 1.0 mL min^?1. The retention times for etodolac and acetaminophen were found to be 1.32 and 4.24 min, respectively. The method was validated for the parameters like specificity, linearity, precision, accuracy and robustness. The method was found to be specific and stability indicating as no interfering peaks of impurities, degradent and excipients were observed. The square of correlation coefficients (R ²) for etodolac and acetaminophen were 0.9996 and 0.9998 while percentage recoveries were 101.32 and 100.94%, respectively. Intra- and inter-day relative standard deviations for both the components were <2.0%. The proposed RP-LC method can be applied for the routine analysis of commercially available formulations of these drugs either as such or in combination.     

Application of Thin-Layer Chromatography for Determination of Residual Monomers in Homo-and Copolymers of N,N,N-Trimethyl-N-methacryloyloxyethylammonium Methylsulfate and Acrylamide

Russian Journal of General Chemistry - A method for determination of residual monomers in homo-and copolymers of acrylamide and N,N,N-trimethyl-N-methacryloyloxyethylammonium methylsulfate by means...     

RP-LC Determination of the cis-Isomer of Glimepiride in a Bulk Drug Substance

A rapid reversed-phase high-performance liquid chromatographic procedure is developed and validated for the resolution of the cis-isomer of 1-[[p-[2-(3-ethyl-4-methyl-2-oxo-3-pyrroline-1-carboxamido) ethyl] phenyl] sulfonyl]-3-(trans-4-methylcyclohexyl) urea, a dopamine agonist in bulk drugs. The cis-isomer and glimepiride were baseline resolved on a Waters Symmetry column (50 × 4.6 mm, 3.5 μm) using a mobile phase system containing water: tetrahydrofuran (75:25; v/v. The chromatographic resolutions between cis-isomer and glimepiride were found to be greater than two. The developed method was extensively validated and proved to be robust. The limit of detection and the limit of quantification of cis-isomer were 500 and 1,500 ng mL⁻¹, respectively, for 10 μL injection volume. The percentage recovery of the cis-isomer ranged from 97.3 to 102.0 in bulk drug samples of glimepiride. Glimepiride sample solution and mobile phase were found to be stable for at least 48 h. The proposed method was found to be suitable and accurate for the quantitative determination of the cis-isomer in bulk drugs.     

Stability Indicating RP-LC Method for the Determination of Gemifloxacin Mesylate

The present study describes the degradation of gemifloxacin mesylate under different International Conference on Harmonization prescribed stress conditions (hydrolysis, oxidation, dry and wet heat and photolysis) and application of a specific and selective stability-indicating reversed-phase liquid chromatography assay. Separation of drug and degradation products was successfully achieved on a HiQ-SiL C₈ column using 10 mM potassium dihydrogen orthophosphate (pH adjusted to 3.0 with o-phosphoric acid)–acetonitrile (65:35, v/v) at a flow rate of 1 mL min⁻¹ and detection at 273 nm.

     

RP-LC for Determination of Plastochromanol,Tocotrienols and Tocopherols in Plant Oils

An isocratic high performance liquid chromatographic method, with the application of C₁₈ and C₃₀ reverse-phase column and fluorescence detection, is described for the analysis of plastochromanol, tocotrienols and tocopherols in plant seed oils. The solvent systems have been optimized to obtain high resolution for all tocochromanols and relatively short analysis time. The use of reverse-phase columns for plastochromanol analysis, previously not reported, enables very sensitive and selective detection of plastochromanol which under the described separation conditions did not interfere with tocochromanols or any other compounds. The sample extraction method is fast, simple and highly efficient. The obtained results show that plastochromanol was present in most of the investigated seed oils. Its level was the highest in flax (17–30 mg/100 g oil), rape (8.5–9), camelina (4.3), peanut (1.95), corn (1.69) and grape (1.31) seed oils. Its level in the other investigated oils was below 1 mg/100 g oil, and only in sesame and coconut oils it was not detected. Tocotrienols were found in most of the oils but their content was usually very low (<<1 mg/100 g oil) with the exception of grape, milk thistle and corn oils where it reached >1 mg/100 g oil. Tocopherol content and isomer composition was within the earlier reported literature values for the investigated oils.

     

Simultaneous Determination of Six Active Compounds in Rhodiola L. by RP-LC

Rhodiola L. has a long history as traditional Chinese medicine (TCM) with a medicinal efficacy similar to Ginseng and Manyprickle Acathopanax roots. There exist three classes of important active constituents, i.e., phenylethanoids (salidroside, p-tyrosol), phenylpropanoides (rosarin, rosavin, rosin), and monoterpene (rosiridin) in this TCM. In this study, by optimizing the extraction, separation and analytical conditions, a sensitive and accurate high performance liquid chromatographic method has been developed for the simultaneous determination of the six active compounds in the different species of Rhodioa L. for the first time. The analysis was performed on a Purospher STAR C18 column at 30 °C using 20 mmol L⁻¹ aqueous ammonia acetate/methanol gradient system at a flow rate of 1.0 mL min⁻¹ and photodiode array detection (DAD ) at wavelengths 276, 250 and 205 nm, respectively. The optimized method provided good linear relation (r ² > 0.9993 for all the target compounds), satisfactory precision (RSD values less than 1.53%) and good recovery (from 96.3–104.8%). The limits of detection ranged between 0.012 and 0.047 μg mL⁻¹ for the different analytes. The developed method has been successfully applied to analysis and quality control of Rhodiola L.