RSD For Reproducibility Research Articles

Validation of an UPLC-PDA Method for the Simultaneous Quantification of Phenol and Iomeprol in a Sterile Parenteral Preparation Used for Coeliac Plexus Block, and Its Application to a Pharmaceutical Stability Study.

Objectives: A commonly applied analgesic therapy for patients with severe abdominal pain due to cancer-related pain in the upper abdomen, is coeliac plexus neurolysis (CPN). Herein, a combination product of phenol and an iodine contrast agent are injected simultaneously. The chemical stability of such a combination product is unknown, and no chromatographic method is yet available that describes the simultaneous quantification of phenol and iomeprol. The aim of this study was to develop and validate a stability-indicating UPLC method for the simultaneous quantification of both phenol and iomeprol and to determine the chemical stability of a sterile 100 mg/mL phenol in 350 mg I/mL iomeprol solution for injection during shelf life. Methods: The product was compounded and sterilized in a GMP certified facility. The pharmaceutical analysis was validated by determination of the accuracy, precision, specificity, selectivity, carry-over and linearity. Pharmaceutical product stability was determined before and after sterilization, and during shelf life of 36 months at 25°C ± 2°C. Results: The accuracy for phenol and iomeprol was 97.1% to 99.3% and 100.0% to 100.2%, respectively. The RSD for repeatability and reproducibility for phenol were 0.65% and 1.17%, and for iomeprol 0.61% and 1.49%, respectively. All other tested parameters met the predefined validation criteria. All concentrations at all tested time points remained within ±2% of the initial concentrations for phenol and ±4% for iomeprol. No additional peaks were visible on the chromatograms. Conclusion: A stability-indicating method for the simultaneous quantification of phenol and iomeprol in a parental pharmaceutical preparation was developed and validated. This method was used to demonstrate the chemical stability of a newly developed sterile solution of 100 mg/mL phenol and 350 mg I/mL iomeprol. Chemical product stability was demonstrated during shelf life of up to 36 months.

Detection and Identification of Adulteration in Vinegar Samples Based on Reversed-Phase High-Performance Liquid Chromatographic (RP-HPLC) Strategies

Adulteration of vinegar to gain economic benefit has become a common practice in recent years. RP-HPLC strategies were proposed for the assurance of the concentration of acetic acid, rare organic acids (tartaric, malic, lactic and citric), and acetaldehyde in Egyptian vinegar samples. The flow rate was 0.5 mL/min using UV detection at 210 and 365 nm for organic acid and acetaldehyde, respectively. The linearity was 0.05–0.60 g/100 mL for acetic acid, 0.01–0.12 g/100 mL for citric, malic, and tartaric acids, 0.005–0.060 g/100 mL for lactic acid, and 0.02–0.16 mg/L for acetaldehyde with r2 > 0.999. Shortest retention time was at 2.38 min for acetic acid. %RSD for repeatability and reproducibility were <2%. The methods are accurate and precise with recoveries ranging from 94.20 ± 2.28 to 116.41% ± 3.70. The acquired information recommended that these techniques could successfully investigate diverse organic acids in real samples, and they have a wide extent of utilization.

Quantification and Analysis of Trace Levels of Phenicols in Feed by Liquid Chromatography\u2013Mass Spectrometry

A sensitive and reliable method using liquid chromatography–negative electrospray ionization mass spectrometry was developed for the simultaneous determination of chloramphenicol, florfenicol, and thiamphenicol at trace levels in animal feed. The analytes were extracted from grinded feed with ethyl acetate. Further the ethyl acetate was evaporated, residue resuspended in Milli-Q water, defatted with n-hexane, and solid phase extracted using BondELUT C18 cartridges. Separation was carried out on a C6 phenyl column with a mobile phase consisting of 0.1% formic acid in Milli-Q water and acetonitrile. The detector response was linear over the tested concentration range from 100 to 1000 µg kg−1. The recovery values for all analytes in feed were higher than 79% with RSD for repeatability and reproducibility in the ranges of 4.5–10.9% and 8.4–13.5%, respectively. CCα and CCβ varied between 76.8 and 86.1 µg kg−1, and between 111.3 and 159.9 µg kg−1, respectively. The results showed that this method is effective for the quantification of phenicols in non-target feed.

Identification and Validation of Synthetic Phenolic Antioxidants in Various Foods Commonly Consumed in Malaysia by HPLC

This study was conducted in order to identify the presence of four synthetic phenolic antioxidants (SPAs): propyl gallate (PG), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) in various food stuffs that are commonly consumed in Malaysia. The identification method was optimized and validated before it was applied to the analyses of eighty three food samples which include chewing gum, chili sauce, cereal-based snack food, noodles, potato snack, cereal breakfast, oat, biscuit, cookie, coffee, junk food, seaweed, nut, chocolate, apple juice, orange juice and blackcurrant juice. Twenty nine food samples contained SPAs either singly or in combination. The chromatography conditions such as elution method, flow rate and wavelength were optimized. Good linearity ranges (1–300 mgL–1) were found for all the four phenolic antioxidants. RSD for repeatability and reproducibility ranged from 0.15–0.84% for both precision analyses. LOD and LOQ ranged from 0.02–0.67 and 0.06–2.03 mgL–1, respectively. Recoveries of the four SPAs ranged from 80.4 to 119.0% when selected food items spiked at 10, 50, and 100 mgL–1.

Development and validation of multi-residue analysis for tetracycline antibiotics in feed by high performance liquid chromatography coupled to mass spectrometry

ABSTRACTA new multi-residue method for the analysis of the tetracycline antibiotics oxytetracycline, tetracycline, chlortetracycline, and doxycycline was developed and validated for animal feed. After extraction with 0.1M Na2EDTA-McIlvaine buffer (pH 4), the samples were centrifuged, purified by SPE (Strata-X-CW cartridges) and analysed by HPLC-MS. Validation of the method was performed according to the guidelines indicated in European Commission Decision 2002/657/EC. The procedure was validated by spiking feed samples at three different levels (300, 1000, and 5000 µg/kg). Average recoveries for tetracyclines were in the range 79.70–98.8%, with RSD for repeatability and reproducibility in the ranges of 5.0–9.5% and 6.5–11.0%, respectively. The method was successfully validated and proved to be efficient, precise, and useful for quantification of tetracyclines in animal feed. The validated method was successfully applied to 65 suspect feed samples collected from different regions of Poland in 2015–16 and obtained from farms and feed manufactures. Of these 65 purportedly non-medicated feeds, eight (12.3%) were positive for the presence of doxycycline or chlortetracycline.

Determination of ochratoxin A in Capsicum spp. (paprika and chili) by immunoaffinity column cleanup and liquid chromatography: collaborative study.

A method validation study for the determination of ochratoxin A in Capsicum spp. (paprika and chili) was conducted according to the International Union of Pure and Applied Chemistry harmonized protocol. The method is based on the extraction of samples with aqueous methanol, followed by an immunoaffinity column cleanup. The determination is carried out by RP-HPLC coupled with a fluorescence detector. The study involved 21 participants representing a cross-section of research, private, and official control laboratories from 14 European Union (EU) Member States and Singapore. Mean recoveries reported ranged from 83.7 to 87.5%. The RSD for repeatability (RSDr) ranged from 1.7 to 14.3%. The RSD for reproducibility (RSDR) ranged from 9.1 to 27.5%, reflecting HorRat values from 0.4 to 1.3 according to the Horwitz function modified by Thompson. The correction for recovery of results from naturally contaminated samples further improved the reproducibility of the method. The method showed acceptable within-laboratory and between-laboratory precision for each matrix, and it conforms to requirements set by current EU legislation.

WEFTA Interlaboratory Comparison on Total Lipid Determination in Fishery Products Using the Smedes Method

Lipid determination by the Smedes method was tested in an interlaboratory trial performed by nine laboratories from seven countries belonging to the West European Fish Technologists Association Analytical Methods Working Group. Five samples of fish and fishery products with different lipid contents, including two blind duplicates, were distributed among the participants. All laboratories applied a slightly modified Smedes method, which included extraction of lipids by cyclohexane and isopropanol, transfer of lipids to the cyclohexane phase by addition of water, phase separation by centrifugation, and gravimetric lipid determination. The results indicate that the RSD for reproducibility (RSD(R)) was between 4.11 and 6.31% for samples with moderate (7%) and high (14%) lipid content, depending on the sample. Larger SDs among the laboratories were obtained for a cod sample with low lipid content of 0.5%. The method is judged to be suitable as a routine method for lipid determination in fish and fishery products.

Interlaboratory Comparison of an Analytical Method for the Determination of Semduramicin in Poultry Feed at the Authorized Level Using High-Performance Liquid Chromatography Coupled to Postcolumn Derivatization and Spectrophotometric Detection

The performance characteristics of a method based on HPLC with postcolumn derivatization and spectrophotometric detection for the quantification of semduramicin in poultry feedingstuffs have been determined via a collaborative study. Semduramicin is a feed additive that is authorized for fattening chickens within the European Union at a minimum and maximum content of 20 and 25 mg/kg in feedingstuffs, respectively. The target concentration of semduramicin in the test samples ranged from 11.5 to 45.0 mg/kg. The study has been conducted with two different types of test material, namely, feedingstuff samples that have been previously ground in our laboratory and pelleted feedingstuffs. In the latter case, the laboratories participating in the study had to grind the samples prior to analysis. The obtained RSD for repeatability (RSD(r)) ranged from 2 to 10% for the ground materials, and from 2 and 7% for the pelleted materials. The RSD for reproducibility (RSDR) varied between 11 and 16% for the ground materials, and between 12 and 15% for the pelleted materials. These data indicated that grinding as an additional step in the analytical procedure did not influence the precision profile of the method. In addition, the HorRat values for all test materials were below or equal to 1.5, thus demonstrating that the obtained precision data were acceptable for the purpose of the method. Furthermore, an estimation of trueness based on statistical treatment of the results reported from the laboratories for spiked samples revealed acceptable mean recovery values of 88 +/- 4%. Based on the obtained performance profile, the method can be considered fully validated and transferable to control laboratories to be used within the framework of official control.

Extension of the Validation of AOAC Official MethodSM 2005.06 for dc-GTX2,3: Interlaboratory Study

AOAC Official Method(SM) 2005.06 for the determination of saxitoxin (STX)-group toxins in shellfish by LC with fluorescence detection with precolumn oxidation was previously validated and adopted First Action following a collaborative study. However, the method was not validated for all key STX-group toxins, and procedures to quantify some of them were not provided. With more STX-group toxin standards commercially available and modifications to procedures, it was possible to overcome some of these difficulties. The European Union Reference Laboratory for Marine Biotoxins conducted an interlaboratory exercise to extend AOAC Official Method 2005.06 validation for dc-GTX2,3 and to compile precision data for several STX-group toxins. This paper reports the study design and the results obtained. The performance characteristics for dc-GTX2,3 (intralaboratory and interlaboratory precision, recovery, and theoretical quantification limit) were evaluated. The mean recoveries obtained for dc-GTX2,3 were, in general, low (53.1-58.6%). The RSD for reproducibility (RSD(r)%) for dc-GTX2,3 in all samples ranged from 28.2 to 45.7%, and HorRat values ranged from 1.5 to 2.8. The article also describes a hydrolysis protocol to convert GTX6 to NEO, which has been proven to be useful for the quantification of GTX6 while the GTX6 standard is not available. The performance of the participant laboratories in the application of this method was compared with that obtained from the original collaborative study of the method. Intralaboratory and interlaboratory precision data for several STX-group toxins, including dc-NEO and GTX6, are reported here. This study can be useful for those laboratories determining STX-group toxins to fully implement AOAC Official Method 2005.06 for official paralytic shellfish poisoning control. However the overall quantitative performance obtained with the method was poor for certain toxins.

Determination of Phytase Activity in Feed: Interlaboratory Study

An interlaboratory study was conducted to determine the performance characteristics of a new method for the determination of phytase activity in feed samples. The method is based on the principle that inorganic phosphate is released from the substrate phytate under defined assay conditions and has been validated for its suitability to measure the enzyme activity of various phytase products. Two different experimental designs of the study were applied, allowing for the estimation of the precision of the method under repeatability, intermediate precision and reproducibility conditions, respectively. The relative standard deviation for repeatability (RSDr) ranged from 2.2 to 10.6% and the RSD for reproducibility (RSDR) ranged from 5.4 to 15%. The suitability of the validated method for the intended purpose was demonstrated. The obtained performance profile of the method validated in this study was comparable to that of similar methods that were exclusively validated for one phytase product.

Molecularly imprinted solid-phase extraction for rapid screening of mycophenolic acid in human plasma

A molecularly imprinted solid-phase extraction coupled with high performance liquid chromatography (MISPE–HPLC) method was developed for rapid screening of mycophenolic acid (MPA) in human plasma. MPA imprinted polymers (MPA-MIP) were synthesized and then tested for their performance both in organic and in aqueous solution. MPA was selectively trapped and preconcentrated on the MPA-MIP sorbent using different loading and washing conditions. The good selectivity of MPA-MIP enabled further clean-up of the interfering components in human plasma. For the proposed MISPE–HPLC method, the linearity between responses (peak area) and concentration was found over the range of 1–100 μg/ml with a linear regression coefficient ( R 2) of 0.9989. The limit of detection (LOD) and theoretical limit of quantification (LOQ) for MPA in plasma were 0.10 and 0.32 μg/ml, respectively. The precisions were 7.3, 3.5 and 4.7% RSD for intra-day assay and 9.2, 4.1 and 5.5% RSD for inter-day reproducibility, respectively, at three concentration levels of MPA in spiked plasma (1, 10 and 100 μg/ml). Both recoveries for the extraction (more than 74%) and for the analytical method (more than 87%) were acceptable for screening MPA in plasma samples. Twelve-hour pharmacokinetic profile of MPA for a renal transplant recipient receiving chronic oral dosing of 500 mg mycophenolate mofetil (MMF) was investigated. Results indicated that this method could be applied for therapeutic drug monitoring of mycophenolic acid in patient plasma.

Gas chromatography–electron capture detection determination of Dacthal and its di-acid metabolite in soil after ultrasound-assisted extraction and in situ focused microwave-assisted derivatization

A quantitative method for the determination of Dacthal and its di-acid metabolite in soil has been developed by coupling ultrasound-assisted extraction and microwave-assisted derivatization of the analytes prior to gas chromatography-electron capture detection for individual separation and measurement. The main factors affecting both extraction efficiency and derivatization were optimized by experimental design methodology. The proposed approach allows extraction of these pollutants from spiked sediment and soil with efficiencies similar to those provided by the reference method but with a drastic reduction of both the extraction and derivatization times. The repeatability of the analyses, expressed as RSD, of Dacthal and its di-acid metabolite was 4.6% and 5.4%, respectively; meanwhile, the RSD for within-laboratory reproducibility was 8.7% and 9.2%, respectively.

Organotin analysis by gas chromatography?pulsed flame-photometric detection (GC?PFPD)

Monobutyltin (MBuT), dibutyltin (DBuT), and tributyltin (TBuT) mixtures have been separated and quantified by gas chromatography with pulsed flame-photometric detection (GC-PFPD). The compounds were first derivatized with NaBEt4, then extracted with hexane and injected into the GC in splitless mode. Optimum GC and detector conditions were established. For GC, various injector temperatures and oven temperature programs were tested. For the PFPD detector, gate settings (gate delay and gate width) and detector temperature were optimized. A very good linearity was obtained up to 100-150 ppb for all organotin compounds. The detection limits obtained were: MBuT (0.7 ppb), DBuT (0.8 ppb), and TBuT (0.6 ppb). RSD for repeatability and reproducibility were well below 20% when the instrument was in routine operation. A biological sample (CRM 477) was also analyzed for organotins. Extraction from the biological matrix was performed with TMAH. Besides the increased risk of contamination, the derivatization step seemed to be critical. pH and amount of derivatizing agent were tested. When using an internal standard (TPrT) between 90% and 110% of the certified amounts of organotin were recovered.

Analysis of neuroactive amino acids from microdialysate samples by fluorescence detection using a modification of the 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate method

A sensitive and rapid reversed-phase high-performance liquid chromatographic method using pre-column derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) and fluorescence detection is reported. By directly derivatizing microdialysate samples with AQC, an automatic and rapid simultaneous measurement of aspartate, serine, glutamate, glycine and histidine was developed. Excellent linearity (r2 > or = 0.998) was achieved for the standard mixture used for the validation experiments. Within-day and between-day precision was less than 6.2%, and the accuracy ranged from 95 to 105.2% in standards. This method is suitable for single run analysis of a high number of small volume microdialysate samples from rat hippocampus. Amino acids from microdialysate samples were quantified with RSD for reproducibility below 2%, and at approximately 0.1% for retention time.

Oxidability Determination in Waste Waters Using an Automatic Titrator Based on a Multicommutated Unsegmented Flow System

The automatic titrator based on a multicommutated unsegmented flow system was applied to redox titrations and used for oxidability determination in waters analysis. This automatic titrator allows the attainment of complete titration curves, being the determination of titrand concentration performed without requiring any prior calibration. After sample treatment (oxidation step), the oxidability determination in waste water samples was accomplished by the automatic flow titrator (titration step). Repeated determinations of standard solutions gave a 3.5% RSD (n=10, 0.010M) for repeatability and a 3.2% RSD (n=2, 0.057M) for reproducibility. Samples results (n=9) were in good agreement (t-test) with those obtained with a reference procedure.