Rapid method for the determination of vitamins A and E in foods using ultra-high-performance liquid chromatography

A rapid and novel ultra-HPLC (u-HPLC) method for the determination of vitamins A (retinol) and E (alpha-, gamma-, and delta-tocopherol) in foods was validated in terms of its precision, accuracy, and linearity. The u-HPLC separation was performed on an RP C18 column (particle size 2 microm, id 2 mm, and length 75 mm), followed by fluorescence detection. The recovery of retinol was more than 84.58%; the LOD and LOQ of the u-HPLC analysis were 0.015 and 0.045 mg/kg, respectively. The intraday and interday precision was less than 9.12%. The recoveries of alpha-, gamma-, and delta-tocopherol were more than 81.37%; the LOD and the LOQ were 0.014, 0.002, and 0.001 mg/kg and 0.042, 0.005, and 0.004 mg/kg, respectively. All calibration curves had good linearity (r2 = 0.99) within the test ranges. The novel, rapid method coupled to u-HPLC can provide significant improvements in the speed, sensitivity, and resolution compared with a conventional HPLC method.     

Determination of capsaicin and dihydrocapsaicin in Capsicum fruit samples using high performance liquid chromatography

The aim of the present study was to determine the content of capsaicin and dihydrocapsaicin in Capsicum samples collected from city markets in Riyadh (Saudi Arabia), calculate their pungency in Scoville heat units (SHU) and evaluate the average daily intake of capsaicin for the population of Riyadh. The investigated samples consisted of hot chillies, red chillies, green chillies, green peppers, red peppers and yellow peppers. Extraction of capsaicinoids was done using ethanol as solvent, while high performance liquid chromatography (HPLC) was used for separation, identification and quantitation of the components. The limit of detection (LOD) of the method was 0.09 and 0.10 μg/g for capsaicin and dihydrocapsaicin, respectively, while the limit of quantification (LOQ) was 0.30 and 0.36 μg/g for capsaicin and dihydrocapsaicin, respectively. Hot chillies showed the highest concentration of capsaicin (4249.0 ± 190.3 μg/g) and the highest pungency level (67984.60 SHU), whereas green peppers had the lowest detected concentration (1.0 ± 0.9 μg/g); green peppers, red peppers and yellow peppers were non pungent. The mean consumption of peppers for Riyadh city population was determined to be 15.5 g/person/day while the daily capsaicin intake was 7.584 mg/person/day.     

Rapid confirmatory method for the determination of 11 nitroimidazoles in egg using liquid chromatography tandem mass spectrometry

A rapid confirmatory method has been developed and validated for the simultaneous identification, confirmation and quantitation of 11 nitroimidazoles in eggs by liquid chromatography tandem mass spectrometry (LC–MS/MS). The method is validated in accordance with Commission Decision 2002/657/EC and is capable of analysing metronidazole (MNZ), dimetridazole (DMZ), ronidazole (RNZ), ipronidazole (IPZ) and their hydroxy metabolites MNZ-OH, HMMNI (hydroxymethyl, methyl nitroimidazole), IPZ-OH. The method is also capable of analysing carnidazole (CRZ), ornidazole (ORZ), tinidazole (TNZ) and ternidazole (TRZ). MNZ, DMZ and RNZ have been assigned a recommended level (RL) of 3 μg kg⁻¹ by the Community Reference Laboratory (CRL) in Berlin. The developed method described in this study is easily able to detect all the nitroimidazole compounds investigated at this level and below. Egg samples are extracted with acetonitrile, and NaCl is added to help remove matrix contaminants. The acetonitrile extract undergoes a liquid–liquid wash step with hexane; it is then evaporated and reconstituted in mobile phase. The reconstituted samples are analysed by liquid chromatography tandem mass spectrometry (LC–MS/MS). The decision limits (CCα) range from 0.33 to 1.26 μg kg⁻¹ and the detection capabilities (CCβ), range from 0.56 to 2.15 μg kg⁻¹. The results of the inter-assay study, which was performed by fortifying hen egg samples (n = 18) on three separate days, show the accuracy calculated for the various analytes to range between 87.2 and 106.2%. The precision of the method, expressed as %CV values for the inter-assay variation of each analyte at the three levels of fortification (3, 4.5 and 6.0 μg kg⁻¹), ranged between 3.7 and 11.3%. A Day 4 analysis was carried out to examine species variances in eggs from different birds such as duck and quail and investigating differences in various battery and free range hen eggs.     

超高效液相色谱-二极管阵列检测法同时测定化妆品中22种防晒剂

建立了一种超高效液相色谱-二极管阵列检测法同时测定不同种类化妆品中22种防晒剂的方法.样品首先加入少量四氢呋喃,涡旋、分散、混匀(蜡质化妆品可于50℃超声,以便分散完全),然后加入0.1％(v/v)甲酸乙醇溶液振摇、超声提取,稀释、过滤后经Poroshell 120 EC-C18(100 mm×4.6 mm,2.7μm...     

Quantitative determination of capsaicin in liniments by microemulsion liquid chromatography

A technique for the quantitative determination of capsaicin in liniments by the microemulsion liquid chromatography method is proposed. Due to the absence of the homogenization, extraction and filtration stages, the procedure of sample pretreatment takes 5 minutes, which is much more rapid in comparison with the variants described in the literature (from 30 minutes to 12 hours). The full time of the analysis (including the procedure for sample pretreatment) is 20 minutes. The graduation curve is linear in the range from 0.02 to 240 mg/l. The limit of determination of capsaicin was 8 μg/I.     

Gas chromatographic analysis of capsaicin in Gochujang

A sensitive, precise, and specific gas chromatographic (GC) method was developed for the analysis of capsaicin in Gochujang and validated by comparing with a column high-performance liquid chromatographic (HPLC) method (AOAC 995.03). The method validation parameters yielded good results, including linearity, precision, accuracy, and recovery. The GC separation was performed on a (5% phenyl)-methylpolysiloxane column [length 30 m, internal diameter (id) 250 microm, film thickness 0.25 microm] followed by flame ionization detection. The conditions of temperature programming were initially 220 degrees C for 1 min, ramp at 5 degrees C/min to 270 degrees C, and hold for 10 min. The recovery of capsaicin in Gochujang was more than 92%, and the detection limit and lower determination limit of the GC analysis were 1.0 and 5.0 microg/g, respectively. The calibration graph for capsaicin was linear from 1 to 250 microg/mL for GC and 0.5 to 50 microg/mL for HPLC. The interday and intraday precisions (relative standard deviations) were <4.02%.     

Rapid immunoaffinity-based method for determination of zearalenone in corn by fluorometry and liquid chromatography

An immunoaffinity-based method was developed to determine zearalenone in corn. Corn samples were extracted in acetonitrile-water (90 + 10, v/v), applied to an immunoaffinity column, and eluted with methanol. The isolated toxin was quantitated either by reaction with aluminum chloride hexahydrate (AlCl3.6H2O) prior to measurement with a fluorometer or injection into a liquid chromatographic (LC) system with a fluorescence detector. Performance was evaluated in terms of antibody specificity, limit of detection, percentage recovery, precision, column capacity, assay linearity, and comparison with AOAC Official Method 985.18. With the immunoaffinity column cleanup procedure, only zearalenone and its metabolites were recognized by the antibody (> or = 75% recovery). Limits of detection were 0.10 microgram/g for the fluorometer and 0.10 or 0.0025 microgram/g (sensitive method) for the LC method. Percentage recovery averaged 105% (fluorometer) and 93% (LC method), with average relative standard deviations (RSDs) of 15.7 and 9.3%. Naturally contaminated samples gave comparable RSDs of 8.3 and 9.9% for the fluorometer and LC methods, respectively. Column capacity was 4.0 micrograms with 89% recovery. Assay linearity was comparable for both methods (r2 = 0.998). Optimum assay ranges were 0.10-5.0 micrograms/g for the fluorometer and 0.10-50 or 0.0025-5.0 micrograms/g (sensitive method) for the LC method. Comparative analysis of 17 naturally contaminated corn samples using Zearala Test LC and the official AOAC LC method for detection of zearalenone showed that Zearala Test is statistically comparable to the AOAC Official Method 985.18 (r2 = 0.747).     

Rapid sample preparation method for the determination of chloramphenicol in swine muscle by high-performance liquid chromatography

A simple and rapid sample preparation method for the determination of chloramphenicol in swine muscle tissue at the 10 micrograms/kg level is described. The method comprises sonication-aided extraction with ethyl acetate, addition of hexane to the extract and cleaning up and concentration of the extract on a small column packed with silica gel. Analysis was performed by high-performance liquid chromatography on a ChromSep column with ChromSpher C8 using acetonitrile-sodium acetate buffer as the mobile phase. Detection was performed at 280 nm. Mean recoveries from spiked muscle samples were 79 +/- 3% (10-50 micrograms/kg). The distribution of chloramphenicol in different muscle and fatty tissues from a pig to which a single dose of chloramphenicol was administered was also investigated.