Calibration Line Research Articles

Bioluminescence assay for rapid detection of live Staphylococcus aureus based on the enrichment of egg yolk antibody modified magnetic metal organic framework immunobeads.

Specific and rapid detection of live Staphylococcus aureus (S.A) in environmental and food samples is critically important for protecting human health. In order to fulfill this purpose, two kinds of novel egg yolk antibody (IgY) immobilized immunomagnetic beads (IMBs; mSiO2-IgY and mMOF-IgY), with core-shell mSiO2 and mMOF as substrate, were prepared for selectively enriching S.A from samples. Furthermore, the IMBs with captured S.A were collected and re-dissolved in 0.5 mL PBS. After that, a cotton swab coated with sodium dodecylsulfate (SDS) was put in the solution to lyse S.A cells and emit ATP bioluminescence of the luciferin/luciferase system. Finally, a portable bioluminescence detector was used for quantification of ATP corresponding to S.A concentration. The results demonstrated that mMOF-IgY can enrich more S.A than mSiO2-IgY and emit a stronger signal. The reasons may be due to the higher immobilization amount of IgY on the IMBs. Under optimal conditions, the calibration line of S.A concentration was 10-105 CFU mL-1 by mMOF-IgY within 30 min. The low detection limit of S.A was 3 CFU mL-1. The results demonstrated that the assay takes much shorter time than plate counting. Its portability and excellent detection capability are suitable for rapid monitoring of specific pathogens in foods.

2 in 1 versus 1 plus 1 – Outcomes of the transformation of adsorptive stripping method for the Ni2+ and Co2+ determination

AbstractDue to the similar chemical properties of Ni2+ and Co2+, several dozens of adsorptive stripping voltammetric (AdSV) methods have been developed for their simultaneous determination. The question was would there be some benefits if a stripping method made for simultaneous determination of Ni2+ and Co2+ will be optimized for the determination of only one of them (Ni2+). It was found that the optimized method has for an order of magnitude lower LOQ (1.89×10−10 M), an order of magnitude lower influence of Co2+, and the applicability of one calibration line for four orders of magnitude of Ni2+ concentration. The influence of some common anions and cations has been examined. The developed method was successfully applied for nickel content determination in real samples. The suitability of the developed method for the determination of Co2+ from the same solution in the second run, upon optimizations of deposition potential and time, was also explored. The LOQ obtained for Co2+ (3.61×10−11 M) is almost two orders of magnitude lower than LOQ of the method for simultaneous determination of both cations and, its LOD and LOQ are among few lowest obtained by AdSV methods for Co2+ determination. The developed method for Ni2+ and Co2+ determination from the same solution in two successive runs has significantly better analytical performances than the starting method for their simultaneous determination in one run.

Identification of the Mixing Ratios of Beer-Mixed Beverages by UV/VIS Spectroscopy

UV/VIS spectroscopy was used in conjunction with a calibration method to determine the mixing ratio of samples of beer-mixed drinks with mineral water (sour Radler beers) from the food service industry. For this purpose, calibration lines were constructed based on absorptions at the two wavelengths 380 nm and 430 nm. To create these calibration lines, blending ratios were prepared from beers from three southwestern German brands and mineral water. The samples of the sour Radler beers were taken from restaurants and bars, which are all located in Baden-Württemberg. It has been shown that the calibration lines can be used to determine mixing ratios with an average deviation of approximately 7% and 9%. Thereby, the calibration line based on the absorption at 430 nm represents a higher accuracy. Using this calibration line, the sour Radler beer samples have percentage ranges of beer of approximately 50% to 90%. This method could serve as a rapid quantitative quality control of the mixing ratios of sour Radler or other beer-mixed drinks. It could be used in breweries for routine control.

Determination of ketamine using melamine-modified gold nanoparticles.

Ketamine is used in medicine because of its anaesthetic and antidepressant effects at low doses. Unfortunately, due to its narcotic effect when used at high doses, its abuse among young people is increasing. It is also one of the most common drugs used in rape. Therefore, there is a need for fast and inexpensive tests that can be performed on-site. With the advancement of nanotechnology, nanoparticle-based approaches have found their place in selective analyses as in many fields. In the developed method, firstly gold nanoparticles were modified with melamine (AuNPs@Mel). Under optimized conditions, hydrogen bonds formed between ketamine and AuNPs@Mel cause the red colour of AuNPs@Mel to shift to blue-purple (i.e. aggregation-induced surface plasmon absorption shift). The association between absorbance and concentration produced a calibration line (curve) having a linearity correlation coefficient of 0.9981 for ketamine concentrations ranging from 4.76 to 47.6 mg L-1. The detection limit of the proposed method was 1.5 mg L-1 and the RSD (relative standard deviation) values of concentrations were changed ranging from 5.2% to 8.2%. The intra-assay and inter-assay measurements using the suggested method resulted in coefficients of variation (CVs) of 5.7% and 8.5%, respectively. Scan transmission electron microscopy (STEM), UV-vis spectrophotometry and FTIR spectroscopy were used to characterize the synthesized and modified AuNPs. Additionally, the procedure was successfully carried out with some interference materials and a real sample of fetal bovine serum. Lastly, using the Student t-test and F tests, the suggested technique was compared to and confirmed against an LC-MS/MS procedure previously published.

127 How to Best Calculate Acid Binding Capacity at pH 4 in Feed Ingredients for Weanling Pigs

Abstract The value of acid binding capacity at pH 4 (ABC-4) of feed ingredients can be used to formulate weanling pig diets for improved feed efficiency and free of ZnO. In practice, it is expensive and time consuming to analyze all ingredients used in pig diet formulation. Therefore, the objective of this study was to determine the most efficient and cost-effective method to accurately predict ABC-4 in feed ingredients used in weanling pig diets. Variation of the ABC-4 value is low in most feed ingredients, and the average value of ABC-4 is accurate enough for use in feed formulation [Lawlor et al. (2005)]. However, limestone and soybean meal (SBM) were studied because of their contribution to dietary ABC-4, and their inherit variability in ABC-4. Results showed that when ABC-4 of limestone and SBM is analyzed, the error in ABC-4 of final feed decreases by 58%. Therefore, if SBM and limestone are analyzed for ABC-4, and fixed values are used for all other ingredients, the value of ABC-4 in the final diet will be +/-20 mEq/kg of the target ABC-4 (P < 0.05). When ingredients are not analyzed for ABC-4, the variability increases and value in final feed will vary between +/- 48 mEq ABC-4/kg (P < 0.05). Next, 39 samples of SBM were collected from the US, Brazil, and Argentina to develop a prediction equation of ABC-4 for SBM from its macro-nutrient composition. Values of ABC-4 of SBM ranged between 773 and 878 mEq/kg, with an average of 824 mEq/kg and STD of 28 mEq ABC-4/kg. No significant relationships between the analyzed macro-nutrients and ABC-4 of SBM were observed (R2 = 0.01, with cross-validation). Therefore, the accuracy and precision of predicting ABC-4 of SBM were not improved by developing a derivative formula to estimate ABC-4 in SBM from its macro-nutrients. Next, 24 samples of limestone were collected from Canada to develop methods to predict ABC-4 accurately and quickly. The value of ABC-4 ranged between 20,823 and 23,412 mEq/kg, with an average of 22,117 mEq/kg and STD of 431 mEq/kg. A good correlation was obtained between ABC-4 and near infrared spectroscopy calibration (NIR) lines (R2 = 0.79, unground, with cross-validation). We conclude that for accurate and rapid determination of ABC-4, and ease of application in nursery diet formulation, ABC-4 can be analyzed in limestone using NIR, in SBM using wet chemistry, and for all other ingredients fixed values can be used. Additionally, for accurate formulation of nursery diets, a safety margin of 20 mEq/kg can be applied to the target ABC-4 value in the final diet.

A non-invasive method for measuring time-series of moisture concentrations in mycelial blocks during shiitake mushroom development using magnetic resonance imaging

The moisture concentration in mycelial block is an important factor for increasing the yield of high-quality shiitake mushrooms (Lentinula edodes) with a pileus of 4–5cm or more in mycelial block cultivation. Here, we show a novel way to measure moisture concentration in mycelial blocks using magnetic resonance imaging (MRI). The culture medium was inoculated with Hokken No. 607 and mycelial blocks were incubated and their moisture concentration was measured using MRI. A method was developed to calculate the spatial distribution of moisture concentration inside the mycelial blocks by measuring the total water mass in the mycelial block using mass method and creating a calibration line. During the maturation phase of the mycelial block (46–98 days of incubation), the moisture concentration in the top region of the mycelial block decreased once at 66 days of incubation and then gradually increased. The increase in moisture concentration was due to mycelia decomposing the culture medium and producing water. During the growth period of the fruiting body, the moisture concentration in the periphery of the fruiting body increased and, conversely, the moisture concentration in the whole mycelial block decreased because water in the mycelial block moved into the fruiting body.

Determination of ticagrelol in rat plasma and tablets by micellar electrokinetic chromatography coupled with large volume sample stacking: Application to a pharmacokinetic study.

A method using micellar electrokinetic chromatography coupled with large-volume sample stacking for the determination of ticagrelol was developed and validated. The analysis was performed in a fused silica capillary (41.5cm effective length, 50μm diameter) with ultraviolet detection at 195nm. The background electrolytes were 30mM phosphate buffer of pH 3.0 with 120mM sodium dodecylsulfate and 10 % (v/v) acetonitrile (120 s X 50mbar; 20°C; -18kV) and 30mM borate buffer of pH 8.5 with 75mM sodium dodecylsulfate (120 s X 50mbar; 20°C; 25kV); under acidic and alkaline conditions, respectively. The method was found to be reliable with respect to specificity, linearity of the calibration line (R2 >0.99), repeatability (relative standard deviation 2.56%-3.34%), and accuracy (recovery in the range 101.21%-102.67%). The limits of detection and quantitation were 0.032, 0.071, and 0.087, 0.188μg/mL, respectively. The method was successfully applied for the determination of ticagrelol concentrations in rat plasma and tablets with good recoveries and reproducibility. The presented method proved to be suitable for monitoring ticagrelor in rat plasma.

Correcting Gain Drift in TES Detectors for Future X-Ray Satellite Missions

Changes in the operating environment of transition-edge sensor (TES) microcalorimeters can cause variations in the detector gain function over time. If not corrected, this can degrade the spectral resolution, and cause systematic errors in the knowledge of the absolute energy. The non-linear nature of the TES energy scale function and the potential for multiple, simultaneous sources of drift can make effective corrections extremely challenging. Satellite instruments typically employ an on-board calibration source to provide known reference X-ray lines. This allows real-time monitoring of the detector gain stability and provides information that can be used to correct for drifts. Here we discuss progress towards demonstrating that the energy scale requirements can be met for future instruments such as Athena X-IFU. We present measurements (from ∼ 1-12 keV) on ∼ 200 pixels in a prototype X-IFU array. We use a non-linear drift correction algorithm that uses two fiducial calibration lines (5.4 keV and 8.0 keV) to track gain and interpolate a new, corrected gain between a set of three pre-calibrated gain functions that span the anticipated range of induced drifts. We demonstrate this algorithm is effective at correcting the full gain scale in the presence of multiple sources of environmental drift.

Rapid and non-invasive estimation of total polyphenol content and antioxidant activity of natural corks by NIR spectroscopy and multivariate analysis

The use of near infrared spectroscopy (NIRS) coupled with multivariate data analysis has been evaluated for the rapid and non-invasive estimation of total polyphenol content (TPC) and antioxidant activity of natural corks. A total of 132 samples were used, using two-thirds and one-third of spectra for calibration and external validation sets, respectively. Regression models were developed by partial least squares (PLS) regression analysis. The best models were achieved by different spectral preprocessing approaches with 7 latent variables for TPC and 9 for antioxidant activity, a variance explained by the models between 64.7 % and 72.0 %, and a standard error of calibration (SEC) between 3.6 and 6.8, respectively. Good relationships between chemical values measured by conventional assays and NIRS predicted values were obtained, with standard error of prediction (SEP) of 5.0 and 5.8 for ABTS and DPPH antioxidant activity, and 5.8 for TPC. Regression lines for calibration and external validation presented good correlation coefficients (r2) from 0.80 to 0.85, and from 0.62 to 0.76, respectively. The models obtained showed that it is possible to estimate rapidly and simultaneously, the TPC and antioxidant activity of natural corks by combining the NIRS with different multivariate analysis tools.

Investigating the Applicability of a Global Average Calibration Line for Ambient Size-Resolved Cloud Condensation Nuclei (CCN) Measurements: A Technical Note

Abstract Aerosol–cloud–precipitation interaction represents the largest uncertainty in climate change’s current and future understanding. Therefore, aerosol properties affecting the cloud and precipitation formation and their accurate estimation is a first step in developing improved parameterizations for the prognostic climate models. Over the last couple of decades, a commercially available Cloud Condensation Nuclei Counter (CCNC) has been deployed in the field and laboratory for characterizing CCN properties of ambient or atmospherically relevant laboratory-generated aerosols. However, most of the CCN measurements performed in the field are often compounded with the erroneous estimation of CCN concentration and other parameters due to a lack of robust and accurate CCNC calibration. CCNC is not a plug-and-play instrument and requires prudent calibration and operation, to avoid erroneous data and added parameterization uncertainties. In this work, we propose and demonstrate the usability of a global calibration equation derived from CCNC calibration experiments from 8 contrasting global environments. Significant correlation was observed between the global calibration and each of the 16 individual experiments. A significant improvement in the correlation was observed when the calibration experiments were separated for high-altitude measurements. Using these equations, we further derived the effective hygroscopicity parameter and found lower relative uncertainty in the hygroscopicity parameter at higher effective supersaturation. Our results signify that altitude-based pressure change could be of importance for accurate calibration at high-altitude locations. Our results are consistent with previous studies emphasizing the criticality of the accurate CCN calibration for the lower supersaturations.

Quantitative analysis of Li, Na and K in single-element standard solutions using portable laser-induced breakdown spectroscopy

Laboratory-based laser-induced breakdown spectroscopy (LIBS) instruments have proven themselves for trace element analysis of an extensive range of elements. As portable devices have evolved greatly in recent years, new areas of field application are opening up. However, no portable LIBS (pLIBS) has yet been used for quantitative inorganic water analysis. The aim of this study was to explore whether pLIBS combined with a surface-enhanced liquid-to-solid conversion method can quantify light alkali element concentrations in standard solutions. Multivariate calibrations were performed with single-element standard solutions at detection limits of 0.006, 0.011 and 0.007 mg l −1 for Li, Na and K, respectively. Coefficients of determination ( R 2 ) for the calibration lines from 0.1 to 100 mg l −1 for Li and Na, and 0.1 to160 mg l −1 for K were between 0.96 and 0.99. It has been shown that the surface preparation technique used improves the homogeneity of the spread and shape of the evaporation residue and thus the accuracy and precision of the analysis. Hence, this study demonstrates that it is possible to quantify light alkali metals in single-element standard solutions in the range of 0.1 to 160 mg l −1 using handheld LIBS.

Rapid enantiomeric analysis of zopiclone in serum by supercritical fluid chromatography-tandem mass spectrometry.

Zopiclone (ZOP) is a hypnotic drug prescribed to treat insomnia. Due to the chiral nature of ZOP, the psychologically active S-form and inactive R-form need to be determined enantiomerically in a forensic drug analysis. In the present study, a supercritical fluid chromatography (SFC) method was designed with a faster analysis ability than that of previously reported techniques. The SFC-tandem mass spectrometry (SFC-MS/MS) method was optimized using a column with a chiral polysaccharide stationary phase (Trefoil CEL2). ZOP was extracted from pooled human serum using solid-phase extraction (Oasis HLB) and analyzed. The developed SFC-MS/MS method achieved the baseline separation of S-ZOP and R-ZOP within 2 min. The fit-for-purpose method validation indicated that the optimized solid-phase extraction achieved near complete recovery and approximately 70% of the matrix effect. Both the retention time and peak area showed sufficient precision. The lower and upper limits of quantification (LOQ) were 5.7 × 10-2 ng/mL and 25 ng/mL for R-ZOP, and 5.2 × 10-2 ng/mL and 25 ng/mL for S-ZOP. The calibration line was linear in the range from lower LOQ to upper LOQ. The stability test indicated that ZOP in serum stored in a refrigerator (4°C) degraded and about 55% remained in 31 days. The quick analysis of the SFC-MS/MS method makes it a valid option for the enantiomeric analysis of ZOP.

In vivo photothermal therapy monitored by multi-position calibrated photoacoustic thermometer

With the ability of monitoring both temperature and photothermal agents, the photoacoustic (PA) imaging is a promising guiding tool for the photothermal therapy (PTT). The calibration line which depicts the relative variation of PA amplitude with the temperature should be obtained before using PA thermometer. In existing study, a calibration line was generated based on the data from one spatial position, and used in the whole region of interesting (ROI). However, the generalization of this calibration line in ROI was not verified, especially for ROI with heterogeneous tissues. Moreover, the relationship between the distributions of photothermal agents and effective treatment area is not clear, hindering using photothermal agents’ distribution to optimize the administration-therapy interval. In this study, the distribution of effective photothermal agents and temperature in subcutaneously transplanted tumor mouse models were continuously monitored by 3D photoacoustic/ ultrasonic dual-modality imaging in 8 h after administration. With multiple micro-temperature probes in tumor and surrounding normal tissue, the PA thermometer was calibrated and evaluated at multiple spatial positions for the first time. The generalization in homologous tissue and tissue specificity in heterogeneous tissues of the PA thermometer calibration line were verified. Our study not only validated the effectivity of PA thermometer by proving the generalization of calibration line, but also removes a major obstacle that prevents applying the PA thermometer to a heterogeneous tissues ROI. The positive correlation between the proportion of effective treatment area and the proportion of effective photothermal agent area in the tumor was observed. Since the latter can be monitored with fast PA imaging, PA imaging can be employed as a convenient tool for seeking optimal administration-treatment interval.

Proton nuclear magnetic resonance (1H NMR) of flammable organic chemicals in radioactive high-level supernatant waste at the Savannah River Site (SRS).

The Savannah River Site stores approximately 36 million gallons of radioactive and hazardous waste that contains approximately 245 million curies. The waste is sent through various chemical processes to reduce its volume and to separate various components. The facility plans to replace formic acid (a chemical used to reduce soluble mercury) with glycolic acid. Recycle solution with glycolate may flow back to the tank farm, where the glycolate can generate hydrogen gas by thermal and radiolytic mechanisms. The current analytical method for detecting glycolate (ion chromatography) in supernatant requires a large dilution to reduce interference from the nitrate anions. Hydrogen nuclear magnetic resonance is an analytical method that requires less sample dilution. It takes advantage of the CH2 group in glycolate. Liquid samples were spiked with four different levels of glycolate to build a calibration line, as it is recommended in the standard addition method. The detection and quantitation limits determined were 1 and 5ppm, respectively, for 32 scans, which is well below the process limit of 10ppm. In one test, 800 scans of a supernatant spiked with 1ppm glycolate resulted in a -CH2 peak with a signal-to-noise ratio of 36.

Development and validation of nomograms for predicting overall survival and cancer-specific survival in elderly patients with locally advanced gastric cancer: a population-based study

ObjectiveTo evaluate the multiple factors influencing the survival of elderly patients with locally advanced gastric cancer (LAGC) and develop and validate the novel nomograms for predicting the survival.MethodsThe clinical features of patients treated between 2000 and 2018 were collected and collated from the Surveillance, Epidemiology, and End Results (SEER) database and three medical centres in China, and the patients were randomly divided into a training cohort (3494), internal validation cohort (1497) and external validation cohort (841). Univariate and multivariate analyses of the prognostic values were performed to identify independent prognostic factors associated with overall survival (OS) and cancer-specific survival (CSS), and two nomogram models were developed. Harrell’s concordance index (C-index) and calibration curves were employed to assess discrimination and calibration. Decision curve analysis (DCA) and receiver-operating characteristic (ROC) curves were utilized to investigate the clinical usefulness.ResultsIn the SEER database, the 5-year OS of the patients was 31.08%, while the 5-year CSS of the patients was 44.09%. Furthermore, in the external validation set, the 5-year OS of the patients was 49.58%, and the 5-year CSS of these patients was 53.51%. After statistical analysis, nine independent prognostic factors of OS and CSS were identified, including age, race, tumour size, differentiation, TNM stage, gastrectomy type, lymph node metastasis (LNM), lymph node ratio (LNR) and chemotherapy. The C‐index (approximately 0.7) and calibration curve (close to the optimal calibration line) indicated satisfactory discrimination and calibration of the nomogram. DCA and ROC curves showed that the developed nomogram was superior to TNM stage.ConclusionThe novel validated nomogram could accurately predict the prognosis of individual elderly patients with LAGC and guide the selection of clinical treatment measures.

Calibrating a Handheld LIBS for Li Exploration in the Barroso–Alvão Aplite-Pegmatite Field, Northern Portugal: Textural Precautions and Procedures When Analyzing Spodumene and Petalite

In pegmatites containing abundant petalite and spodumene, such as those from the Barroso–Alvão (BA) aplite-pegmatite field, calibrating a portable laser-induced breakdown spectroscopy (pLIBS) equipment to identify and analyze these minerals may be challenging. Forty-nine samples of spodumene, petalite and spodumene + quartz were collected from 22 aplite-pegmatites from the BA field and sent for inductively coupled plasma-mass spectroscopy analysis. One calibration for both spodumene and petalite has been proven to be impossible since almost all the LIBS intensity ratios, including for Li, overlapped on both minerals. Thus, three calibrations were developed: one qualitative to distinguish both minerals and two more quantitative, specifically made for each mineral. The first LIBS calibration only has Fe since it is the sole element with intensity ratios different enough to distinguish both minerals. Eleven calibration lines were created: Li, Al, Si, Be, Na, P, K, Mn, Fe, Rb and Cs; however, only the Li, Al, and Si have consistent errors below 20%. Thin sections were produced and observed with optical microscopy and cathodoluminescence (CL) to control the purity and mineral paragenesis of the samples. The petalite pellets were also controlled with cold CL since petalite crystals often present fine spodumene and quartz inclusions.

Evaluation of automated clean-up for large scope pesticide multiresidue analysis by liquid chromatography coupled to mass spectrometry

Clean-up step is essential during the multiresidue sample preparation process to remove undesired matrix components that may cause analytical interferences or suppression effect. However, its application generally by specific sorbents entails time-consuming work producing low recoveries for some compounds. Moreover, it usually needs to be adapted to the different co-extractives from the matrix present in the samples by using different chemical sorbents increasing the number of validation procedures. Therefore, the development of a more efficient and automated and unified clean-up procedure means a significant time reduction and laboratory work with improved performance.In this study, extracts from different matrices (tomato, orange, rice, avocado and black tea) were purified by manual dispersive clean-up (different procedures according to the matrix group) in parallel with an automated µSPE clean-up workflow, in both cases based on QuEChERS extraction. The latter procedure employed clean-up cartridges containing a mixture of sorbent materials (anhydrous MgSO4/PSA/C18/CarbonX) suitable for multiple matrices. All the samples were analysed by liquid chromatography mass spectrometry and the results obtained from both procedures have been compared in terms of the extract cleanness, performance, interferences, and sample workflow. At the levels studied, similar recoveries were achieved by both techniques (manual and automated) except for reactive compounds when PSA was used as the sorbent material producing low recoveries. However, the µSPE recoveries were between 70–120%. Furthermore, closer calibration line slopes were provided when µSPE was applied to the different matrix groups studied. It is important to note that up to 30% more samples per day can be analysed using an automated µSPE compared to the manual method (which requires shaking, centrifuging, then taking the supernatant and adding formic acid in ACN); it also provides good repeatability - an RSD (%) < 10%. Consequently, this technique is a very useful option for routine analyses, greatly simplifying the work of muti-residue methods.

A New method for simultaneous qualitative and quantitative determination of amlodipine besylate and atorvastatin calcium in bulk and pharmaceutical formulations using transmission FT-IR spectroscopy

A simple, precise, rapid, and eco-friendly FTIR spectrophotometric method was developed and validated for simultaneous analysis of amlodipine (AML) and atorvastatin (ATV) in drug combination preparations. Firstly, synthetic mixtures were made and scanned with FTIR instrument. Then the result spectra were converted automatically to absorbance spectra. The calibration model was made depending on Beer's law which relates concentration to absorbance. Two characteristic bands corresponding to the carbonyl group at 1708-1688 cm−1 and 1660-1632 cm−1 for AML and ATV, respectively, were selected for quantification. The absorbance of a series of standards was measured as the AUC of the chosen bands. Then, the calibration line was obtained by plotting the measured AUCs and the actual concentrations against each other. Validation tests were performed per ICH recommendations. Specificity was evaluated by the separation of APIs and excipients from marketed preparations by methanol. Then, the spectra of extracted excipients, APIs, and pharmaceutical samples were taken and overlapped. The selected peaks were specific and did not interfere with each other or other peaks from the excipients used in the tablet's matrix. Linearity for AML and ATV was in the range of 0.1–1% w/w with excellent coefficients of determination (R2), 0.998 and 0.999 for AML and ATV, respectively. The proposed analytical method was accurate and precious, as the RSD values were less than 2%. The proposed FTIR method was successfully applied to estimate the exact quantity of APIs in pharmaceutical samples. Recoveries were accepted in accordance with USP and were in the range of 94.62–100.6% and 98.175–101.06% for AML and ATV, respectively. Likewise, the acquired results were compared with the HPLC method. And the t- and F- tests were calculated and compared with the theoretical values, which indicate the similarity of results in both developed and reported methods.

Apparently Seasonal Variations of the Seawater Sr/Ca Ratio Across the Florida Keys Reef Tract

AbstractA 4‐year time‐series of surface seawater Sr/Ca ratios was assembled across a section of the Florida Keys Reef Tract, in order to uncover any variability that might explain previously reported anomalies in regional calibrations of the coral aragonite Sr/Ca paleotemperature proxy. Samples were collected semiannually on a grid of 54 sites, from September of 2016 until January of 2020. The 325‐km2 grid extended from the ocean shore to the forereef wall and from the east end of Long Key to the west end of Marathon. A novel ICP‐AES method was used to measure the Sr/Ca ratio, with ratio calibration and normalization against an in‐house seawater reference, yielding a long‐term precision of better than 0.2%. Significant variations (2%–3%) of the seawater Sr/Ca ratio were found. While it was relatively constant offshore, near the coast the ratio alternated seasonally between higher and lower values, generally resulting in seaward Sr/Ca gradients that were markedly negative in summer but reversed in winter. Inshore seawater Sr/Ca ratios ranged from a summer high of 8.83 mmol/mol to a winter low of 8.54 mmol/mol, the difference corresponding to a potential bias of ∼5.5°C in terms of the coral Sr/Ca paleotemperature proxy. This seasonal variation should diminish the slope of empirical Sr/Ca–SST calibration lines, as has indeed been observed in prior studies with local coral species. Open ocean samples obtained from the Atlantic, Indian, and Pacific enlarge the published Sr/Ca data set for surface seawater and show a much smaller variability of 8.646 ± 0.018 mmol/mol (0.2%).

Unconstrained Bezier Calibration Method for Nonlinear Measurement Calibration Applications: A Comparison Study

The primary motivation of this paper is to present an accurate and universal method for the nonlinear system modeling. An Unconstrained Bezier Calibration Method (UBCM) is presented. By constraining the boundary freedom of the UBCM, it could become a constrained form called the Bezier Calibration Method (BCM), which is suitable for situations with an accurate boundary modeling requirement. A comparison study is performed to compare the presented method with the most widely utilized Polynomial Calibration Method (PCM) through several nonlinear behavior modeling examples, including sensor inherent nonlinearity calibration, sine wave, gauss nonlinearity and nonlinear broken line. A comparison study demonstrates that in the present verification examples the UBCM has better calibration performance than that of the BCM and PCM.