Development of certified reference material of methamphetamine hydrochloride

1H quantitative NMR (1H qNMR) is known as a powerful tool for determination of analytes without the need for their identical standards, which is eligible to a primary rate method. 1H qNMR has been already stipulated to an assay for purity determination in Japanese Pharmacopoeia (JP), and then this technique has been also applied in several fields such as pharmaceutical and food sciences. However, there is little information about the accuracy of 1H qNMR so that the further applications into other fields such as industrial chemistry could be constricted. In this study, in order to assess the reliability of 1H qNMR, we designed the round-robin test of 1H qNMR under the basis of the measurement conditions described in JP. 1,4-Bis(trimethylsilyl)benzene-d4 [1,4-BTMSB-d4, 99.9±0.6% (w/w)] and 3,5-bis(trifluoromethyl)benzoic acid [3,5-BTMFBA, 99.96±0.06% (w/w)], which are certified reference materials (CRMs), were adopted to analyte and qNMR reference standard respectively for the accurate evaluation in this test. Six NMR instruments in 5 institutions optimized to 1H qNMR conditions provided the purity 1,4-BTMSB-d4 within acceptable error range. This result represented that 1H qNMR has the capability to determine precisely the value of analyte in practical analytical field and to be set as official analytical method for purity determination or assay of concentration of organic compounds.

Certified reference material (CRM) plays a vital role for quality control assurance in environmental analysis, because the quality of data arising from measurements has crucial importance. This article presents the results from studies carried out for certification of a candidate reference material composed by sixteen polycyclic aromatic hydrocarbons (PAHs) dissolved in toluene (naphthalene, acenaphthylene, acenaphtene, fluorene, anthracene, phenanthrene, fluoranthene, chrysene, benzo[a]anthracene, pyrene, benzo[k]fluoranthene, benzo[b]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthacene, indeno[123-cd]pyrene and benzo[ghi]perylene). This is the first Brazilian PAH CRM developed by Inmetro. The certification procedure includes validation of the GC/IDMS method (isotopic dilution mass spectrometry coupled to gas chromatography), homogeneity study, stability studies under transport and storage conditions and estimation of measurement uncertainties.

Study of an egg powder certified reference material for accurate measurement of florfenicol residue

A paste‐type certified reference material (CRM) of tomato was developed for accurate elemental analysis of canned foods. Accurate mass fractions of cadmium (Cd), lead (Pb), and tin (Sn) in the tomato paste CRM were determined by isotope dilution inductively coupled plasma mass spectrometry. The certified values and their expanded uncertainties (k=2 at approximately 95% level of confidence) for Cd, Pb, and Sn were (0.297 ± 0.015) mg/kg, (0.213 ± 0.010) mg/kg, and (221.2 ± 9.5) mg/kg, respectively. Homogeneity of the CRM was 0.3%, 1.8%, and 0.2% for Cd, Pb, and Sn, respectively, which were estimated using the relative standard deviation of the measurement results of 10 separate sample bottles from one batch of the CRM. Major contributions to the measurement uncertainties for Cd and Sn were the uncertainties of the isotope ratios of Cd and Sn in the sample and the elemental standards. The uncertainty for Pb was mainly affected by sample homogeneity. Stability tests were conducted for 6 and 12 months at −20, 4, and 25°C, and the storage temperature for the CRM was determined to be −20°C. To investigate long‐term storage, the mass fractions of Cd, Pd, and Sn in the CRM were re‐determined after storage for 7 years. The results were in good agreement with the certified results implying that this CRM is stable for 7 years if kept at an appropriate storage condition with vacuum packaging the amber glass bottles in aluminum‐coated polymer bag.

Determination of arsenic compounds in reference materials by HPLC-(UV)-HG-AFS

The certified reference materials (CRMs) of emodin in rhubarb and its alcohol extract, water extract were developed by using quantity transfer technology from single chemical composition to the complex systems. The CRM of emodin was used for quantity transfer, and high performance liquid chromatography (HPLC) method was used to determine the contents of emodin in different matrix composition. By establishing mathematical model and calculating the parts of uncertainty, the uncertainty values were finally gotten. CRMs of emodin in rhubarb, alcohol extract and water extract were accomplished. The content values of emodin were 0.40% ±0.03%, 1.15%±0.18%, 0.16%±0.08% (k=2,P=0.95), respectively. The established method for quantity transfer has successfully solved the technical problems that the value of active ingredient of traditional Chinese medicine can't be traced to SI units. The series of CRMs are assigned as grade primary reference materials, which are useful for quality control of the emodin content, also provide the accurate and reliable CRM, materials standard and standard methods.

Heterocyclic aromatic amines (HAAs) are carcinogenic and mutagenic compounds formed by the cooking of meat and combustion of biomass. There are relatively few data on HAAs in atmospheric particulate matter (PM). We developed an analytical method using high performance liquid chromatography – tandem mass spectrometry (tandem quadrupole, HPLC-MS/MS(QqQ)) to analyze PM samples for 12 HAAs. We applied this method to an urban air standard reference material and wildfire-impacted PM2.5 from the 2018 wildfire season in Northern California. The PM sample matrix adversely impacted the MS/MS response, with high levels of ion suppression for sample masses >4 mg and higher ion suppression in wildfire-impacted particulate matter compared with the standard reference material. Despite detection limits at the low ng level, no HAAs were detected in the standard reference material, but β-carboline norharman (0.34 ng/m3) was detected in one wildfire sample.

Reference materials (RMs) and certified reference materials (CRMs) are essential for ensuring compliance of food products with international standards. In fish, mercury content is closely monitored due to associated human health risks. This study developed and certified a CRM for total mercury (Hg) and methylmercury (MeHg) in striped catfish (Pseudoplatystoma fasciatum) from the Colombian Amazon. The process involved raw material selection, sample preparation, homogeneity, and stability, resulting in the CRM INM-039–1. Total Hg was measured using inductively coupled plasma-mass spectrometry (ICP-MS) and cold vapor atomic absorption spectrometry (CV-AAS), while MeHg was analyzed by gas chromatography-mass spectrometry (GC–MS). Calibration methods varied: ICP-MS used gravimetric standard addition, CV-AAS employed bracketing calibration, and GC–MS applied matrix-matched calibration. Method validation was performed using CRMs DORM-4 and ERM-CE464. The total Hg results were combined using the Levenson approach, yielding a relative standard uncertainty of 1.8%, while MeHg was 2.9%. Other uncertainty components included long-term stability (2.5%), homogeneity (1.8%), and short-term stability under transport conditions (0.02%). The CRM was certified with a total Hg mass fraction of 3.94 mg/kg (relative expanded uncertainty 7.1%, k = 2) and an informative MeHg mass fraction of 3.79 mg/kg (relative expanded uncertainty 8.3%, k = 2). This CRM is a valuable tool for assessing mercury in similar matrices, supporting compliance with safety standards for small and mid-size fish producers in the region.Graphical

The long-term stabilities of arsenobetaine (AsB), arsenate (As(V)), and dimethylarsinic acid (DMA), which are arsenic (As) compounds in certified reference materials (CRMs), namely, NMIJ CRMs 7901-a, 7912-a, and 7913-a, were monitored. The CRMs were developed and certified by the National Metrology Institute of Japan (NMIJ) and the National Institute of Advanced Industrial Science and Technology (AIST) in 2009 to prepare a calibrant for the speciation analysis of As species. The CRMs were prepared from high-purity reagent powders as raw materials, and each reagent was dissolved in water or diluted acid. The certification of the CRMs for AsB, As(V), and DMA was conducted by NMIJ. The concentration of total As was determined by more than three independent analytical techniques. Then, the obtained As concentrations were converted into the concentration of each chemical species, and the mass fractions of each certified value were certificated. The long-term stability of As species in the CRMs under storage was performed by liquid chromatography-inductively coupled plasma-mass spectrometry, and this report presents data on long-term stability that occurred approximately 13years. The obtained monitoring results were evaluated using both measurement results with uncertainty and a statistical parameter method, complying with ISO Guide 35. According to the results, the long-term stability of all mass fractions was confirmed.

Study of a new matrix certified reference material for simultaneous measurement of two plant growth regulators residues in tomato

A procedure was developed for simultaneous determination of 21 synthetic antibacterials in fish and meat products by high performance liquid chromatography with a photodiode array detector. The antibacterials were extracted with acetonitrile-0.2% metaphosphoric acid (7:3), followed by liquid-liquid partition with dichloromethane. High performance liquid chromatography was carried out on a TSK-gel ODS-80Ts column using gradient elution with acetonitrile-sodium dihydrogenphosphate. The recoveries of antibacterials from fish and meat products spiked at 1.0μg/g were over 70% except in the cases of sulfisomidine and carbadox. The detection limits were 0.05-0.10μg/g for each antibacterial except thiamphenicol (0.25μg/g).

셀레늄은 다양한 화학종으로 존재하며 그 농도와 형태에 따라 활성도나 생물학적 이용도가 달라지므로 식품에 대한 셀레늄 화학종의 정확한 분리 및 정량이 필요하다. 본 연구에서는 역상 (RP; reversed phase) 고성능 액체 크로마토그래피 (HPLC; high performance liquid chromatography)와 유도결합 플라즈마 (ICP; inductively coupled plasma) 질량분석법 (MS; mass spectrometry)을 사용하여 해산물 시료 중 셀레늄 화학종을 분리 검출 한 뒤에 후 컬럼 동위원소희석법 (post column isotope dilution)으로 정확히 정량 하였다. 시료 중 <TEX>$^{80}Se$</TEX>의 간섭요인인 <TEX>$^{79}Br$</TEX>을 제거하기 위해 고체상 추출법을 사용하여 대부분의 <TEX>$^{79}Br$</TEX>을 제거하였고 남아있는 <TEX>$^{79}Br$</TEX>은 수학적 보정식을 이용하여 보정해주었다. CRM (certified reference material) DOLT-4를 사용하여 셀레늄의 총량을 분석한 결과는 인증치와 잘 일치하였지만 각 화학종에 대한 정보는 비교할 수 없었다. 한국인 식탁에 오르는 대표적인 해산물 시료인 갈치, 삼치, 오징어, 등을 분석한 결과, 주된 셀레늄 화학종은 SeCys (selenocysteine)와 SeMet (selenomethionine)이었으며 각각은 0-661.6 mg/kg and 137.3-462.7 mg/kg의 농도로 존재함 을 알 수 있었다. Selenium exists in various forms of chemical species. The activity and bioavailability is strongly dependent on its chemical form and concentration. Consequently the information on each selenium species and its concentration must be exactly determined for the food we take in. In this study, selenium species in seafood were separated and quantified by RP (reversed phase) HPLC (high performance liquid chromatography) coupled with ICP-MS (inductively coupled plasma mass spectrometry) using post-column isotope dilution. <TEX>$^{79}Br$</TEX>, which interferes on <TEX>$^{80}Se$</TEX>, has mostly been removed by solid phase extraction and then mathematical correction has been applied for the more accurate correction. The experimental result for CRM (certified reference material) DOLT-4 agreed well with the certified value but each selenium species could not be compared. SeCys (selenocysteine) and SeMet (selenomethionine) were the major species detected in seafood such as belt fish, spanish mackerel, and squid that have been serving as Korean diet. The concentrations found in Korean sea food for SeCys and SeMet were in the range of 0-661.6 mg/kg and 137.3-462.7 mg/kg, respectively.

The present study explains the in situ growth of Cu cluster-based metal-organic framework on copper substrate for thin film microextraction approach. Cu cluster-based metal-organic framework has been growth via a hydrothermal method on electrochemically anodized copper substrate. After thin film microextraction, some polycyclic aromatic hydrocarbons were quantified via high performance liquid chromatography- photo diode array detection. The influence of effective parameters such as extraction time, extraction temperature, agitator speed and ionic strength of the sample was investigated and the optimum conditions were chosen. Calibration curves were obtained in 0.0001–10 µgL−1 range with acceptable linearity as R2 > 0.986. The range of 1 and 3 pgL−1 was calculated as limits of detection, with the relative standard division below 5.1% in the optimal condition. For evaluating the model, samples from river water and wastewater were used and investigated. It was found that relative recoveries were between 96-104%. The proposed method provided a simple, efficient and environmental approach for the rapid and convenient determination of polycyclic aromatic hydrocarbons in real samples.

Water-soluble organic carbon (WSOC) and its brown carbon (BrC) components in the cryosphere have significant impact on the biogeochemistry cycling and snow/ice surface energy balance. In this study, snow samples were collected across regional area of northern Xinjiang, China to investigate the chemical composition, optical properties, and radiative forcing (RF) of WSOC. Based on the geographic differences and proximity of emission sources, the sampling sites were grouped as urban (U), remote (R), and soil-influenced (S) sites, for which WSOC concentrations were measured as 1968&amp;#177;953 ng g-1 (U), 885&amp;#177;328 ng g-1 (R), and 2082&amp;#177;1438 ng g-1 (S), respectively. The S sites showed the higher mass absorption coefficients at 365 nm (MAC365) of 0.94&amp;#177;0.31 m2 g-1 compared to those of U and R sites (0.39&amp;#177;0.11 m2 g-1 and 0.38&amp;#177;0.12 m2 g-1, respectively). Molecular-level characterization of WSOC using high-resolution mass spectrometry (HRMS) provided further insights into chemical differences among samples. Specifically, much more reduced S-containing species with high degree of unsaturation and aromaticity were identified in U samples, suggesting an anthropogenic source. Aliphatic/proteins-like species showed highest contribution in R samples, indicating their biogenic origin. The WSOC components from S samples showed high oxygenation and saturation levels. The WSOC-induced RF were estimated as 0.04 to 0.59 W m-2, which contribute up to 16% of that caused by BC, demonstrating the important influences of WSOC on the snow energy budget. Furthermore, the molecular composition and light-absorbing properties of BrC chromophores were unraveled by application of a high-performance liquid chromatography (HPLC) coupled to photodiode array (PDA) detector and HRMS. The chromophores were classified into five major types, i.e., (1) phenolic/lignin-derived compounds, (2) flavonoids, (3) nitroaromatics, (4) oxygenated aromatics, and (5) other chromophores. Identified chromophores account for ~23% &amp;#8211; 64% of the total light absorption measured by the PDA detector in the wavelengths of 300 &amp;#8211; 370 nm. In the representative U and R samples, oxygenated aromatics and nitroaromatics dominate the total absorbance. Phenolic/lignin-derived compounds are the most light-absorbing species in the S sample. Chromophores in two remote samples exhibit ultraviolet-visible features distinct from other samples, which are attributed to flavonoids. Identification of individual chromophores and quantitative analysis of their optical properties are helpful for elucidating the roles of BrC in snow radiative balance and photochemistry.

Introduction: The aim of this work was to control the quality of some antibiotics cartridges (ampicillin, amoxicillin-clavulanic acid, ciprofloxacin and vancomycin) used for antibiotic susceptibility testing by disk diffusion method. Antibiotics were determined in disks and two techniques were compared for this purpose, chromatographic and microbiological method.&#x0D; Methods: Chromatographic method (High-Performance Liquid Chromatography: HPLC) was used for determining ampicillin, amoxicillin-clavulanic acid and ciprofloxacin, and microbiological method for vancomycin and ampicillin. We used the European Pharmacopoeia 8th edition monographs and a simple and adapted method published in 2015 by Ramli Y. et Al.&#x0D; Results: Dosage results reveal that 35% of unexpired cartridges had low content and all the expired AB’s disks gave low results.&#x0D; Conclusion: Our study demonstrated that the content of antibiotics in disks could decrease if the storage and transport conditions (temperature and relative humidity) of disk cartridges were not respected. Therefore, properly performed quality control of antibiotic disks before use in laboratories would aid in providing accurate and reproducible results of dosage.&#x0D; Keywords: Antibiotic disks, Quality control, Antibiogram, High Performance Liquid Chromatography, Microbiological method.