Phosphoric Acid Solution Research Articles

Purification of Crude Glycerol Recovered From Fish Processing Waste Biodiesel Process

Biodiesel and crude glycerol are byproducts of the esterification and transesterification reactions that occur between triglyceride molecules and alcohol in the presence of acid and base catalysts. Purification of crude glycerol is necessary to increase the economic sustainability of the biodiesel industry. This study was carried out for pre-treatment of crude glycerol sourced from fish processing waste during biodiesel manufacturing, treated through an acidification process using phosphoric acid (H3PO4), and then using further purification treatment with Jatropha curcas bio-adsorbent. Based on the measurement, the quantity of 0.1% phosphoric acid (H3PO4) solution was required to treat the crude glycerin. The reaction conditions include heating solution to 60°C and stirring it at 40 rpm for varying treatment periods such as 15, 30, 45, and 60 min. The crude glycerol's pH was adjusted to begin the acidification process, and soap was then converted into fatty acids and salts using phosphoric acid. The maximum purified glycerol yield of 76.6% by weight was obtained with treatment time of 15min using vacuum distillation at 120°C. The crude and purified glycerol’s density was measured as 1.013 g/mL and 1.001 g/mL, respectively. However, after bio-adsorbent treatment at temperature of 50°C and 10% loading weight of the Jatropha curcas bio-adsorbent, the best impurity elimination was accomplished in 15 min. The research findings demonstrated that, following acidification and bio-adsorbent treatments, the FFA% decreased from 2.82% to 2.24%, while its density increased from 1.002 g/mL to 1.032 g/mL, respectively. The purified glycerol properties were found in accordance with BS 2621-1979 standard, showing that the acidification method for purifying of crude glycerol, in conjunction with bio-adsorbent treatment is efficient in enhancing the glycerol purity. It also improves glycerol's application in generating high-value products that enhance revenue streams for the biodiesel production.

Proton transport mechanisms in aqueous acids: Insights from abinitio molecular dynamics simulations.

The solvation and transport of protons in aqueous solutions of phosphoric acid (PA), sulfuric acid (SA), and nitric acid (NA) were studied using abinitio molecular dynamics simulations. Systems with acid-to-water ratios of 1:1 and 1:3 were examined to understand the similarities and differences in transport mechanisms. The solvation structure of H3O+ in these systems is similar to that in slightly acidic water, with variations in the strength of hydrogen bonds (H-bonds) accepted by acid molecules. In aqueous PA systems, strong H-bonds between PA molecules are slightly affected by water, leading to significantly greater H3O+ diffusion compared to aqueous SA and NA systems. This enhanced diffusion is attributed to the participation of PA molecules in H3O+ transport, where the PA molecule can shuttle a proton for H3O+, facilitating a large displacement via collective proton hopping. This shuttling mechanism is prominent in aqueous PA but rare in aqueous SA and absent in aqueous NA. Moreover, the decomposition of H3O+ diffusion into vehicular and structural components indicates that the higher diffusion in aqueous PA is primarily due to the structural mechanism with the aid of PA molecules. In the aqueous NA systems, the vehicular diffusion is dominant at low water contents and the increase in water content improves the structural diffusion by forming connected H-bonds within water molecules. Our findings elucidate the role of acid molecules in proton transport within their aqueous solutions, thereby advancing the fundamental understanding of proton transport mechanisms.

Setting reaction of a olivine-based Mg-phosphate cement

The cementitious properties of natural Mg-rich olivine when reacted with a phosphoric acid solution are investigated, as a function of acid concentration and liquid/solid mass ratio. The obtained cements are composed of residual olivine crystals and amorphous silica nanoparticles dispersed in a dense and compact newberyite (MgHPO4∙3H2O) matrix. The latter was mostly formed by packed micrometric tabular crystals, although evidence of the presence of a fraction of amorphous MgHPO4 was also found. Water content in the raw mix was observed to play a pivotal role on the reaction pathway, either promoting porosity or hindering the crystallization of the products. Up to 57 % of olivine reactivity, whose dissolution was promoted by the curing temperature (60 °C) and low pH, was achieved. All in all, these results indicate that the industrial mineral olivine may serve a viable source of Mg for the production of phosphate cements.

Supercritical CO2 Extraction and HPLC Quantification of Carnosic Acid from the leaves of Rosemary Officinalis: A Green Approach to Bioactive Compound Purification

This study explores the extraction and purification of carnosic acid, a potent antioxidant found in rosemary (Rosmarinus officinalis), using a green and sustainable method involving supercritical CO₂. The extraction was conducted at 45°C and 350 bar, with three cycles lasting 45 minutes each. The process resulted in the collection of 75 grams of oleoresin from 1 kg of dried rosemary leaves which is an optimal yield. The oleoresin underwent further purification via hexane precipitation, yielding a carnosic acid powder with a purity of 40% as determined by Gradient elution of Mobile phase A: Methanol: Water + Phosphoric acid solution, Mobile phase B: Methanol: Acetonitrile + Phosphoric acid solution by high-performance liquid chromatography (HPLC). Comparisons with a 60% purity standard highlight the potential of supercritical CO₂ extraction in obtaining bioactive compounds, though additional optimization is necessary to achieve higher purity.

Soil ammonia volatilization after fertilization using antibiotic-contaminated swine wastewater

The application of wastewater from pig farming is an alternative to fertilize crops using the effluent produced in the activity. However, in addition to nutrients capable of meeting the needs of crops, this effluent also has residues of antibiotics for livestock use in its composition, which can interfere with the activity of soil microorganisms and reduce the enzymatic activity, leading to nitrogen losses into the atmosphere. Hence, this study evaluated ammonia volatilization behavior after adding swine wastewater with tetracycline-class antibiotics. Pots containing soil received doses of raw and digested wastewater (0.06 and 0.09 L), combined or not with doses of tetracycline (35 µg L-1), chlortetracycline (40.9 µg L-1), and doxycycline (14.9 µg L-1 volatilized NH3 was collected by foam absorbers containing phosphoric acid solution on the soil, which were changed every 48 h, totaling 11 collections at a time. The NH3 volatilization significantly increased when the swine wastewater (raw or digested) was added. The presence of antibiotics reduced NH3 losses, showing that they can inhibit urease activity. Our findings showed that tetracycline-class antibiotics can inhibit urease activity, contributing to the continuity of nitrogen in the soil.

Synthesis of poly(terphenyl-co-dibenzo-18-crown-6 methylimidazole) copolymers for high-performance high temperature polymer electrolyte membrane fuel cells

This study focuses on the development of high temperature polymer electrolyte membranes (HT-PEMs), which are essential components for HT-PEM fuel cells (HT-PEMFCs). While phosphoric acid (PA) doped polybenzimidazole (PBI) has been recognized as a successful HT-PEM, it faces several challenges, including the use of carcinogenic monomer, complex synthesis processes, and poor solubility in organic solvents. To produce more cost-effective, easily synthesized, and high-performance alternatives, this study utilizes a straightforward superacid-catalyzed Friedel-Crafts reaction to synthesize a series of poly(terphenyl-co-dibenzo-18-crown-6 methylimidazole) copolymers, referred to as Co-x%TP-y%CE-Im, using p-terphenyl, dibenzo-18-crown-6 and 1-methyl-1H-imidazole-2-formaldehyde as monomers. The copolymerized hydrophilic and bulky crown ether units introduce substantial free volume and multiple interaction sites with PA molecules, as indicated by theoretical calculations. Additionally, the formation of microphase separation structures, confirmed by atomic force microscope (AFM) and transmission electron microscope (TEM), contributes to the enhanced performance of these membranes. For instance, after immersion in 85 wt% and 75 wt% PA solutions, the Co-90%TP-10%CE membrane achieves PA doping contents of 200 % and 169 %, achieving high conductivities of 0.092 S cm−1 and 0.054 S cm−1 at 180 °C, while maintaining tensile strengths of 6.5 MPa and 7.5 MPa at room temperature. Without the need for humidification or backpressure, the peak power density of an H2-O2 cell equipped with Co-90%TP-10%CE/169%PA membrane with a thickness of 79 μm reaches an impressive 1018 mW cm−2 at 210 °C. These results demonstrate new materials and insights for the development of high-performance HT-PEMs.

Protection of steel in solutions of sulfuric and phosphoric acid by inhibitors based on pharmaceuticals

Protection of steel in solutions of sulfuric and phosphoric acid by inhibitors based on pharmaceuticals

Development and Validation of a Stability Indicating RP-HPLC Method for Simultaneous Estimation of Metformin, Tenegliptin, and Pioglitazone in bulk and its Pharmaceutical Dosage Form .

A straightforward, reliable, and thorough approach was created for contemporaneously estimating Teneligliptin, Metformin, and Pioglitazone in solid dosage form. It was conducted by means of Agilent C18 150x4.6mm, 5µ. The mobile phase comprising buffer, acetonitrile, and Methanol (55:35:10 v/v) passed across the column at a pace of 0.9ml/min. The procedure relied on a 0.01N K2HPO4 buffer having a pH of 3.5, which was achieved by diluting an orthophosphoric acid solution. The temperature was kept constant at 30°C—optimized wavelength for Teneligliptin. Metformin and Pioglitazone were 220.0 nm. Retention times of Teneligliptin, Metformin, and Pioglitazone were 2.970 min, 2.395 min, and 3.642 min. %RSD of a system for Teneligliptin, Metformin, and Pioglitazone were 1.3, 0.6, and 1.0, respectively. %RSD of a method for Teneligliptin, Metformin, and Pioglitazone was 0.6 for each drug. The % recovery was 100.43, 100.45, and 100.22% for Teneligliptin, Metformin, and Pioglitazone, accordingly. The regression equations are used to generate the LoD and LoQ values of Teneligliptin, Metformin, and Pioglitazone, and LoD values were 0.016 ppm, 0.26 ppm, 0.42ppm, while LOQ values of Teneligliptin, Metformin and Pioglitazone were 0.048 ppm, 0.78 ppm,1.28 ppm respectively. The regression equation of Teneligliptin was y = 56655x + 920.87. Metformin was y = 14194x + 3082.1 and of Pioglitazone was y = = 41330x + 792.61.Reduced retention durations make the new approach easy and cost-effective for use in routine industrial quality control testing.

Quantitative Interpretation of Potentiodynamic Polarization Curves Obtained at High Scan Rates in Scanning Electrochemical Cell Microscopy.

Scanning electrochemical cell microscopy is becoming the tool of choice for the investigation of localized metal corrosion. Typically, potentiodynamic polarization measurements in scanning electrochemical cell microscopy are performed at high potential scan rates. However, Tafel extrapolation applied to high-scan-rate potentiodynamic polarization curves would yield inaccurate corrosion kinetics due to the interference of double-layer charging current or mass transport of species in the metal oxide. Instead, the high field model was used to simulate the potentiodynamic polarization curves of pure aluminum at 25, 50, 100, and 200 mV/s in neutral and acidic phosphate solutions, thus enabling quantitative analysis of local corrosion kinetics by fitting the potentiodynamic polarization curve.

Determination of Four Compositions of Lonicerae japonicae flos Based on UPLC–MS/MS Method

Background Lonicerae japonicae flos, a representative kind of traditional Chinese medicine (TCM) for clearing heat and detoxifying, is known as Jinyinhua in China. The determination of multiple components’ content, especially multiple pharmacological components’ content, is often used to evaluate the quality of TCM, which could objectively evaluate the quality of TCM. Purpose The ultra high-performance liquid chromatography–mass spectrometry/mass spectrometry (UPLC–MS/MS) method was used to determine the content of chlorogenic acid, isochlorogenic acid A, isochlorogenic acid C, and luteoloside in the current study. Methods 15 batches of Lonicera japonica flos were collected from different sources. 75% methanol was taken as a solvent, and the solution ratio was 1 (mg:mL). The ultrasonic method was utilized to prepare the sample solution for 30 min, which was centrifuged for 10 min at 10,000 rpm. Then, the supernatant was taken for reserve. C18 was chosen as the fixed phase, and acetonitrile (A)–0.1% phosphate acid solution (B) was chosen as the mobile phase. The flow rate was 0.3 mL.min−1. The column temperature was 40°C, and the sample injection was 1 µL. In the negative ion mode, data were collected using multiple reaction monitoring (MRM) scan mode. Results The scope of chlorogenic acid, isochlorogenic acid A, isochlorogenic acid C, and luteoloside was in the range of 62.5–6,250 ng. mL−1, which had good linearity ( r2 = 0.9997). The content of the four components showed some differences among different sources. Conclusion The method was fast and sensitive, which could effectively evaluate and control the quality of Lonicera japonica flos.

Fire resistance of phosphoric acid activated metakaolin geopolymer

Fire resistance is a key advantage of geopolymer (GP) materials. While most research focuses on alkali-activated GPs, this study examines the fire resistance of phosphoric acid-activated GPs with varying phosphorus-to-aluminum (P/Al) molar ratios. By activating metakaolin with different ortho-phosphoric acid (H3PO4) solutions, it was found that GPs with P/Al > 0.59 exhibited intumescence during fire tests, resulting in a 110 °C lower backside temperature (310 °C) compared to non-intumescent GPs (420 °C). Physico-chemical changes were analyzed before and after fire tests using DMA, TGA NMR, EPMA, and XRD. The study revealed dehydration, crystallization, and rheological changes, with NMR showing transitions from Al(VI) to Al(IV), full condensation of phosphorus species, and Si-O-Al to Si-O-Si bonds. Intumescence was linked to GP softening between 100 and 160 °C, achievable only with a P/Al ratio ≥ 0.74, with no additional benefits from excess phosphorus.

Study of the Production of Wet-processing Phosphoric Acid by Clinker Method on Base of Mineralized Mass

The article presents the results of the study of extractive phosphoric acid extraction processes from the mineralized mass (MM) - mineralized mass (MM) produced during the thermal processing of Central Kyzylkum (CK) phosphorite. Effects of sulfuric acid concentration on the quality parameters of the obtained wet-processing phosphoric acid (WPPA), processes of WPPA extraction through different concentrations of phosphoric acid solution from phosphoric acid-gypsum porridge were studied. The optimal parameters of these processes have been determined. In the composition of WPPA obtained in acceptable parameters 19,30-19,59% Р2О5, 0,08-0,09% F will be. Filtration rates of phosphatic-acid-gypsum porridges during extraction with different concentrations of WPPA are equal to 1096-1192 kg/m2·h. It was also determined that the main composition of the resulting phosphogypsum is as follows: 2,44-2,59% Р2О5total (t.)., 29,93-30,09% CaOtotal (t.), 41,29-41,50% SO3 and 1,16-1,21% F.

(Invited) Preparation of N-Type and P-Type Doped Single Crystal Diamonds with Laser-Induced Doping and Microwave Plasma Chemical Vapor Deposition

In this study, n-type doped single crystal diamonds were successfully prepared under normal temperature and pressure conditions using laser-induced doping. 248nm pulsed laser beams with nanosecond duration were irradiated on the single crystal diamond substrate immersing in an 85% phosphoric acid solution and it introduced phosphorus doping to form an n-type doped thin layer. The resistivity of the doped region significantly decreased compared to that of the single crystal diamond. After depositing a titanium electrode, the resistivity of the doped film obtained by Van der Pauw Technique was determined to be 1.3×10-6 Ω·m. Raman spectroscopy confirmed the absence of carbon or graphite phases in the laser-induced doped diamond, indicating that the enhanced conductivity was due to phosphorus incorporation.Furthermore, p-type doped single crystal diamonds were successfully prepared by introducing boron during the growth process using Microwave Plasma Chemical Vapor Deposition（MPCVD）. It was demonstrated that the proposed technique can introduce impurities into single crystal diamonds to form doped conductive thin layers, which has potential applications in the field of microdevices and integrated circuits.

Investigation of mild steel corrosion inhibition in acidic media by Viola extract based on bulk and nanometer size

In the present work, the inhibition performance of Viola extract based on bulk and nano size as a green corrosion inhibitor on mild steel in 0.5 M phosphoric acid and 1M hydrochloric acid solutions is investigated using different techniques (potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and Optical microscopy). The gained results demonstrated that various concentrations of Viola Extract (bulk and nano) inhibited the corrosion of the alloy in both of the acid solutions. The temperature impact on corrosion rate without/with this extract was examined. Certain thermodynamic parameters were determined based on the temperature impact on inhibition and corrosion processes. The adsorption mechanism of the extract on the alloy was explored using the Langmuir adsorption isotherm. A mixed mode of adsorption was observed, wherein the nano-sized extract in 1.0 M HCl predominantly underwent chemisorption, while the bulk-sized extract in 1.0 M HCl and both bulk and nano-sized extracts in 0.5 M H3PO4 were primarily subjected to physisorption. Scanning electron microscopy (SEM) and Optical microscopy analyses were employed to scrutinize alloys’ surface morphology.

A Novel Reversed Phase HPLC Assay Method for Simultaneous Estimation of Glucose, Sodium Citrate and Chlorides in Pharmaceutical Formulations and Drug Solution for Oral Rehydration

A rapid, straightforward, sensitive, efficient, and cost-effective reverse-phase high-performance liquid chromatographic method was employed to simultaneously determine Glucose, Sodium Citrate, and chloride in a drug solution for oral solution. Glucose, Sodium Citrate, and Chlorides are all listed in the USP monograph. While various assay methods are available, titrimetric methods are ineffective for trace-level quantification. Although IC, AAS, and ICP-MS offer high accuracy, they are expensive and often inaccessible to many testing facilities. When selecting methods, it’s crucial to consider quality control requirements and user-friendly techniques. A simple proprietary HPLC method has been developed to simultaneously quantify Chlorides, Glucose, and Sodium Citrate, with a shorter run time. The separation was carried out using a Shim-pack SCR-102(H) ion exclusion analytical column (7.9 mm x 300 mm, 7 µm) with a flow rate of 0.6 mL/min. The column compartment was kept at 40°C, and the injection volume was 10 µL, with detection at 200 nm. All measurements were performed in a 0.1% phosphoric acid solution. The analytical curves showed excellent linearity (r > 0.9999) within the concentration ranges of 0.74 to 1.74 mg/mL for Sodium Citrate (SC), 1.0 to 2.5 mg/mL for Sodium Chloride (SC), and 3.0 to 7.3 mg/mL for Glucose. The method was validated according to the guidelines of the International Conference on Harmonization (ICH Q2B) and USP<1225>. The method demonstrated precision, robustness, accuracy, and selectivity. During accelerated stability testing over six months, no significant variations were observed in organoleptic analysis and pH. Consequently, the developed method is considered suitable for routine quality control analyses, enabling the simultaneous determination of Sodium Citrate, Chloride, and Glucose in pharmaceutical formulations and solutions for oral rehydration.

Influence of Current Duty Cycle and Voltage of Micro-Arc Oxidation on the Microstructure and Composition of Calcium Phosphate Coating

The micro-arc oxidation (MAO) technique was employed to produce calcium phosphate coatings on titanium surfaces using an electrolyte composed of hydroxyapatite and calcium carbonate in an aqueous solution of orthophosphoric acid. The coatings’ morphology and composition were regulated by adjusting electrical parameters, specifically the duty cycle and voltage. This study examined the effects of the duty cycle and voltage during the MAO process on the microstructure and composition of calcium phosphate coatings on VT1–0 titanium substrates. Scanning electron microscopy (SEM) was utilized to analyze the microstructure and thickness of the coatings, while X-ray diffraction (XRD) was employed to determine their phase composition. The findings reveal that the surface morphology of the calcium phosphate coatings transitions from a porous, sponge-like structure to flower-like formations as the duty cycle and voltage increase. A linear increase in the voltage within the applied duty cycles led to a rise in the size of the forming particles of amorphous/crystalline structures containing phases of monetite (CaPO3(OH)), monocalcium phosphate monohydrate (Ca(H2PO4)2·H2O), and calcium pyrophosphate (γ–Ca2P2O7).

Process of Magnetite Dissolution in Orthophosphoric and Sulfuric Acid Solutions According to Kinetic and Electrochemical Methods

Process of Magnetite Dissolution in Orthophosphoric and Sulfuric Acid Solutions According to Kinetic and Electrochemical Methods

Preparation and optimization of dummy molecularly imprinted polymer-based solid-phase extraction system for selective enrichment of p-toluene sulfonate esters genotoxic impurities

Sulfonate esters, one class of genotoxic impurities (GTIs), have gained significant attention in recent years due to their potential to cause genetic mutations and cancer. In the current study, we employed the dummy template molecular imprinting technology with a dummy template molecule replacing the target molecule to establish a pretreatment method for samples containing p-toluene sulfonate esters. Through computer simulation and ultraviolet–visible spectroscopy analysis, the optimal functional monomer acrylamide and polymerization solvent chloroform were selected. Subsequently, a dummy template molecularly imprinted polymer (DMIP) was prepared by the precipitation polymerization method, and the polymer was characterized in morphology, particle size, and composition. The results of the adsorption and enrichment study demonstrated that the DMIP has high adsorption capability (Q = 7.88 mg/g) and favorable imprinting effects (IF = 1.37); Further, it could simultaneously adsorb three p-toluene sulfonate esters. The optimal adsorption conditions were obtained by conditional optimization of solid-phase extraction (SPE). A pH 7 solution was selected as the loading condition, the methanol/1 % phosphoric acid solution (20:80, v/v) was selected as the washing solution, and acetonitrile containing 10 % acetic acid in 6 mL was selected as the elution solvent. Finally, we determined methyl p-toluene sulfonate alkyl esters, ethyl p-toluene sulfonate alkyl esters, and isopropyl p-toluene sulfonate alkyl esters in tosufloxacin toluene sulfonate and capecitabine at the 10 ppm level (relative to 1 mg/mL active pharmaceutical ingredient (API) samples) by using DMIP-based SPE coupled with HPLC. This approach facilitated the selective enrichment of p-toluene sulfonate esters GTIs from complex API samples.

Multi‐step heating strategy during thermal stabilization of polyacrylonitrile multi‐filament bundle before carbonization

AbstractA polyacrylonitrile (PAN) multi‐filament bundle underwent a multi‐step heat treatment following impregnation with a solution of ammonium bromide, phosphoric acid and urea (A‐P‐U). The multi‐step thermal stabilization process was conducted in an air atmosphere at temperatures ranging from 200 to 245 °C for various stabilization times spanning from 10 to 70 min. Comprehensive analysis of physical and mechanical properties, infrared (IR) spectroscopy, X‐ray diffraction (XRD) and thermal analysis (DSC and TGA) revealed the significant influence of stabilization time on the structure and properties of thermally stabilized PAN multi‐filament bundle. The fiber thickness and linear density of the stabilized fibers decreased by approximately 29.5% and 10.6%, respectively, after 70 min of heat treatment. However, the fiber density value increased from 1.18 to 1.38 g cm−3 during the same stabilization time. Additionally, the carbon yield value obtained using TGA increased from 31% to 73% at 850 °C. The presence of A‐P‐U markedly reduced the time needed for the conversion of the PAN polymer into a cyclized structure through its nitrile groups, thereby accelerating the stabilization reactions. Furthermore, the IR spectra exhibited the appearance of CC bonds, signaling the creation of a crosslinked ladder‐like structure. The XRD traces confirmed the decrease in crystallinity with increasing stabilization time, consistent with the findings from IR spectra. The findings showed that the A‐P‐U integrated system is notably successful and proficient in promoting the cyclization of nitrile groups, thereby decreasing the time needed to establish a thermally stable structure capable of withstanding elevated carbonization temperatures. © 2024 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Development of HPLC method for isomeric impurities of key starting material of novel oral anticoagulant drug; Edoxaban Tosylate Monohydrate

Reverse-phase high-performance liquid chromatography method has been developed for the determination of EDO-S1 stereoisomeric impurities such as isomer 1, isomer 2, isomer 3, isomer 4, isomer 5, isomer 6 and isomer 7 with good resolution using the column, Bakerbond C18 (150 × 4.6 mm; 3 μm). The separation was achieved with mobile phase-A (10 mM dipotassium hydrogen phosphate pH-7.0 with 10% orthophosphoric acid solution in Milli-Q water) and mobile phase-B (n-Propanol: Acetonitrile ratio of 20:30 % V/V), which consisted of mobile phase mixture in the combination of moilephase-A: mobile phase-B (85:15). The total run time was 30 min at 0.8 mL/min flow rate, 20 µL injection volume and 30 ℃ column oven temperature. The column eluate was monitored at 210 nm to quantify the impurities The method showed adequate specificity, sensitivity, linearity, accuracy, precision, and robustness inline to ICH tripartite guidelines. The limit of detection and quantification limits were 0.1 and 0.3 μg mL−1, respectively, for all isomeric impurities and EDO-S1. The developed method was found to be linear over the concentration range of LOQ to 150% of specification range for isomeric impurities with a correlation coefficient >0.999. The method was precise (%RSD < 5.0), robust, and accurate (with 85%–115% recovery).