Reagent Blanks Research Articles

Sustainable Spectrophotometric Quantification of Lansoprazole Through Mixed Hydrotropy Approach

Solubility is the property of a substance to dissolve in or form a homogeneous mixture with another substance. One of the most common problems associated with making a solution is poor solubility. There are many drugs that are sparingly soluble or insoluble in water, and lansoprazole is one of them. Aqueous solubility of lansoprazole is 0.05 mg/ml at room temperature. The current study aims to improve lansoprazole solubility using a mixed hydrotropy method. The purpose of the mixed hydrotropic solubilization approach is to increase the solubility of weakly water-soluble drugs in hydrotropic agent blends. To avoid the use of organic solvents, the mixed hydrotropy idea may be a good option. In this current research attempt, a novel method for spectrophotometric estimation of lansoprazole using a mixed solvent blend (containing 10% SC and 20% SB) as the solvent was developed. By observing the absorbances of the drug's standard solutions, the calibration curve for lansoprazole was drawn. The absorbances were measured at 275 nm compared to the corresponding reagent blanks. The percent label claims were found to be very near to 100, showing that the proposed approach is accurate. The suggested method estimates percent recoveries to be near 100 with significantly low percentage deviation and standard error values. As a result, the proposed process is simple, safe, and precise, and it does not require the use of harmful chemical solvents.

Extractive Spectrophotometric Detection of Sn(II) Using 6-bromo-3-hydroxy-2-(5-methylfuran-2-yl)-4H-chromen-4-one.

For the determination of tin(II) traces, an extractive spectrophotometric approach is devised. The applied method serves a powerful tool for determination of tin(II), involves the formation of yellow colored complex after thebinding of 6-bromo-3-hydroxy-2-(5-methylfuran-2-yl)-4H-chromen-4-one (BHMF) and tin(II) in 1:2 stiochiometry in a slightly acidic medium (HCl). The complex shows absorbance at 434nm with respect of the blank reagent. The outcomes of spectral investigation for complexation showed a Beer's range of 0-1.3μg Sn mL-1, molar absorptivity, specific absorptivity and Sandell's complex sensitivity are 9.291 × 104 L mol-1cm-1, 0.490mLg-1cm-1 and 0.002040μgcm-2 at 434nm that was stable for two days. The interferences studyresults showed that this method is free from interferences, when tested with metal ions including Ag,Be, Bi, Ca,Cd, Ce, Co,Hg, Mo,Re,Pt, Se,Ti,U,V, W and other common cations, anions, and complexing agents. Theapplied method is quite simple, highly selective, and sensitive with good re-producibility. This method has been satisfactorily by utilizing the proposed procedure, and its applicability has been tested by analyzing synthetic samples and an alloy sample of gunmetal. The procedure assumes this because of the scarcity of better methods for determining tin(II). The results are in good agreement with the certified value.

Determination of Folic Acid in both Pure and Pharmaceutical Preparations via Oxidative Coupling Reaction

In this study, the development of an indirect spectrophotometric method for the determination of folic acid in pure and pharmaceutical preparations is described. The method is based on the oxidation of pyrocatechol with iron (III) in an acidic medium, followed by the reaction with folic acid (FA) to produce a stable, water-soluble orange compound with maximum absorption at 350 nm versus the blank reagent. The complex of charge transfer was studied under optimal conditions; the titration graph was linear over the range of 0.5-25 μg/mL with a relative error of 1.2-2.8 and a relative standard deviation of 2.43-1.45 depending on the concentration level.

Anti-fatigue effect of Lubian on kidney Yin deficiency and kidney Yang deficiency mice and mechanism based on PI3K-Akt pathway

This study aimed to investigate the anti-fatigue effect and mechanism of Lubian(Cervi Penis et Testis) on kidney Yin deficiency and kidney Yang deficiency mice. After one week of adaptive feeding, 88 healthy male Kunming mice were randomly divided into a blank group, a kidney Yin deficiency model group, a kidney Yin deficiency-Panacis Quinquefolii Radix(PQR) group, kidney Yin deficiency-Lubian treatment groups, a kidney Yang deficiency model group, a kidney Yang deficiency-Ginseng Radix et Rhizoma(GR) group, and kidney Yang deficiency-Lubian treatment groups, with eight mice in each group. The kidney Yin deficiency model and kidney Yang deficiency model were prepared by daily regular oral administration of dexamethasone acetate and hydrocortisone, respectively, and meanwhile, corresponding drugs were provided. The mice in the blank group received blank reagent. The treatment lasted 14 days. The exhaustive swimming time was measured 30 min after drug administration on the 14th day. On the 15th day, blood was collected from eyeballs and the serum was separated to determine the content of lactic acid(LD), blood urea nitrogen(BUN), lactate dehydrogenase(LDH), cyclic adenosine monophosphate(cAMP), and cyclic guanosine monophosphate(cGMP). The liver was dissected to determine the content of liver glycogen and the protein expression of phosphoinositide 3-kinase(PI3K) and protein kinase B(Akt). Compared with the kidney Yang deficiency model group, the kidney Yang deficiency-Lubian treatment groups showed increased body weight(P<0.05), relieved symptoms of Yang deficiency, decreased cGMP content(P<0.01), increased cAMP/cGMP(P<0.01), prolonged exhausted swimming time(P<0.01), reduced LD(P<0.01), elevated BUN content(P<0.01), increased liver glycogen content(P<0.01), and increased protein expression of PI3K and Akt in the liver(P<0.05). Compared with the kidney Yin deficiency model group, the kidney Yin deficiency-Lubian treatment groups showed increased body weight(P<0.01), relieved symptoms of Yin deficiency, increased content of cGMP(P<0.01), decreased cAMP/cGMP(P<0.01), prolonged exhausted swimming time(P<0.01), decreased LD(P<0.01), decreased BUN content(P<0.01), increased liver glycogen content(P<0.01), and increased protein expression of PI3K(P<0.05) and Akt in the liver(P<0.05). To sum up, Lubian can regulate Yin deficiency and Yang deficiency and increase glycogen synthesis by affecting the PI3K-Akt pathway, thereby exerting an anti-fatigue role.

Rapid, sensitive analysis method for determining the nitrogen stable isotope ratio of total free amino acids in soil.

The amino acid-nitrogen (AA-N) isotope analysis of naturally abundant or isotope-labeled samples is indispensable for tracing nitrogen transfer in soil nitrogen biogeochemical cycling processes. Despite the usefulness of AA-N isotope analysis, the preparation methods are complex and time-consuming, and necessitate the use of toxic reagents. We present an improved, rapid method for AA-N isotope analysis with high precision. At a high pH, AA-N was released and oxidized to N2 O using ClO- under vacuum. Additionally, purge-and-trap isotope ratio mass spectrometry was used to analyze N2 O. Moreover, we investigated the effect of various factors on the N2 O conversion process with glycine and applied the results to seven representative single-N AAs (alanine, serine, cysteine, aspartic acid, glutamic acid, leucine, and phenylalanine) and five poly-N AAs (lysine, arginine, histidine, tryptophan, and asparagine), as well as side-chain analogs, blank reagent, and other N forms. The concentration of ClO- and the pH were determined to be crucial factors for achieving desirable AA-N to N2 O conversion efficiencies. Glycine-N had the highest N2 O yield of 70%, with isotopic results consistent with those of the reference values at a high precision (within 0.5‰ for natural abundance and 0.01 atom% for 15 N-enrichment) at the nanomolar N level. Additionally, the α-NH2 AAs were labile, and the single-N AAs were more easily converted to N2 O than poly-N AAs. With the exception of γ-aminobutyric acid, the N2 O conversion efficiencies of the side-chain N analogs were very low (below 5%). This method was also applicable to the 15 N analysis of the total free AAs in complex soil samples without interference from analytical blanks and other forms of N. Our method is highly selective for the α-NH2 groups of an amino acid, and the oxidation of the side chain is difficult. In addition, the method is sensitive, rapid, and convenient, and does not require toxic reagents.

Ultra-trace determination of mercury by platinum-coated tungsten coil trapping cold vapour atomic absorption spectrometry

ABSTRACT Within the scope of this study, a simple, highly sensitive and rapid trapping method for the determination of mercury (Hg) was developed. In this method, the surface of the tungsten coil (W-coil) was coated with platinum using the electrolytic deposition technique. Scanning electron microscopy–energy-dispersive X-ray analyses were performed to examine the surface morphology of Pt-coated W-coil. During the experiment, firstly, Hg vapour generated by tetrahydroborate, used as a reducing agent, was efficiently trapped on the Pt-coated W-coil at collection temperature in hydrochloric acid medium. Subsequently, Hg trapped on the surface of the Pt-coated W-coil was revolatilised by the effect of releasing-stage gases at the optimised releasing temperatures and transported to quartz T-tube atomiser. The experimental conditions have been optimised. Under the optimised conditions, a limit of detection (LOD) of 8.8 ng L−1 was obtained using three times the standard deviation of blank values using Pt-coated W-coil trap cold vapour atomic absorption spectrometry (CVAAS) system. The precision of the measurements was evaluated by relative standard deviation of 4.4%, which is obtained by 11 consecutive measurements of reagent blanks for a collection volume of 6.83 mL corresponding to 90 s collection. The enhancement factors for both LOD (3 s) and characteristic concentration (Co) were found to be 5.09 and 5.02 when compared with the regular CVAAS system without trap. The accuracy of the proposed method was evaluated by analysing BCR 146 R (Sewage sludge), RTC (Sandy Loam 7), ERM-BD151 (skimmed milk powder) and NIST 1641e (mercury in water) certified reference materials (CRMs). There was a good agreement between certified and found values for all CRMs. The results of the application of the developed method in seawater showed the spike recovery ranges from 94.2% to 102.4%.

Occurrence and Characterization of Small Microplastics (

This study is the first to investigate the ingestion of microplastics (MPs), plasticizers, additives, and particles of micro-litter < 100 μm by larvae of Simuliidae (Diptera) in rivers. Blackflies belong to a small cosmopolitan insect family whose larvae are present alongside river courses, often with a torrential regime, up to their mouths. Specimens of two species of blackfly larvae, Simulium equinum and Simulium ornatum, were collected in two rivers in Central Italy, the Mignone and the Treja. Small microplastics (SMPs, <100 μm), plasticizers, additives, and other micro-litter components, e.g., natural and non-plastic synthetic fibers (APFs) ingested by blackfly larvae were, for the first time, quantified and concurrently identified via MicroFTIR. The pretreatment allowed for simultaneous extraction of the ingested SMPs and APFs. Strong acids or strong oxidizing reagents and the application of temperatures well above the glass transition temperature of polyamide 6 and 6.6 (55–60 °C) were not employed to avoid further denaturation/degradation of polymers and underestimating the quantification. Reagent and procedural blanks did not show any SMPs or APFs. The method’s yield was >90%. Differences in the abundances of the SMPs and APFs ingested by the two species under exam were statistically significant. Additives and plasticizers can be specific to a particular polymer; thus, these compounds can be proxies for the presence of plastic polymers in the environment.

Potentials of N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol as novel charge transfer acceptors in pharmaceutical analysis of some quinolones and cephalosporins

BackgroundQuinolones and cephalosporins are antibiotic agents with activity against Gram-positive and Gram-negative bacteria. They contain chromophores and amine groups which are electron-rich centres capable of donating electrons to electron-deficient compounds. A survey of the literature revealed that 2, 4-dinitro-1-naphthol, a nitroaromatic useful in chemical synthesis, can accept electrons in charge transfer reactions. This work investigates N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol in the formation of charge transfer complexes by accepting electrons from selected quinolones and cephalosporins. Five other nitroaromatics (i.e. 4-nitro-1-naphthylamine, 2-nitro-1-naphthol, 2,4-dinitro-1-naphthylamine, 1-nitronaphthalene and 1,4-dinitronaphthalene) were screened in addition to the aforementioned and compared for charge transfer complexes formation. Spot test was used to establish charge transfer complex formation at room and elevated temperatures with determination done by visual inspection and thin layer chromatographic analysis of the reaction mixture. Ultraviolet visible absorption spectroscopy was used to estimate the extent of complexes.ResultsOnly solutions of adducts of N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol gave instant and distinct colour with each drug used at room and elevated temperature. While the former gave deep golden yellow, the latter gave golden yellow against their blank reagent solutions which were, lemon and greenish yellow respectively. Visual inspections of 2-nitro-1-naphthol adduct solutions showed no colour change from the yellow colour of the blank reagent solution, even though the Ultraviolet visible absorption spectra revealed the formation of charge transfer complexes. The adducts solutions of 4-nitro-1-naphthylamine, 2,4-dinitro-1-naphthylamine, 1-nitronaphthalene and 1,4-dinitronaphthalene showed no colour change from their blank reagent solutions and their Ultraviolet visible absorption spectra revealed no formation of charge transfer complexes.ConclusionUltraviolet visible absorption spectral analysis shows superiority of N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol in charge-transfer complex formation over other nitroaromatics screened. N-(2, 4-dinitro-1-naphthyl)-p-toluenesulphonamide and 2, 4-dinitro-1-naphthol are good acceptors of electrons from these drugs, hence could be useful as charge transfer reagents in ultraviolet visible spectrophotometric analysis of these drugs.

Estimation of ferulic acid from selected plant materials by Spectrophotometry and High performance liquid chromatography

Ferulic acid is an abundant phytophenolic compound present in plant cell wall. Ferulic acid possess anticancer, antioxidant, and anti-aging properties. A simple, sensitive and reproducible spectrophotometric method has been developed for quantitative estimation of ferulic acid from selected plant materials such as rice bran, wheat bran and bamboo shoot. The blue coloured chromogen obtained after the reaction was measured at wavelength of 718 nm for ferulic acid against the blank reagent. The chromogen obeyed linearity over the range of 1?g/ml - 8?g/ml. An HPLC method was also developed for the estimation of ferulic acid from selected plant materials.

Study on protective mechanism of Tibetan medicine Ershiwuwei Songshi Pills on cholestatic liver injury in rats based on FXR signaling pathway

This paper aimed to investigate the protective effect and mechanism of the Tibetan medicine Ershiwuwei Songshi Pills on α-naphthalene isothiocyanate(ANIT)-induced cholestatic liver injury in rats based on the farnesol X receptor(FXR) signaling pathway. SD rats were randomly divided into blank group, model group, ursodeoxycholic acid(UDCA) group, Tibetan medicine Ershiwuwei Songshi Pills low, medium and high dose groups(0.09, 0.18, 0.36 g·kg~(-1)). A prophylactic dosing regimen was used in the experiment. From the 1 st to 4 th days, the UDCA group and the Tibetan medicine Ershiwuwei Songshi Pills suspension groups received prophylactic gavage administration; on the 5 th day, the blank control group was given an equal volume of olive oil blank reagent, and the remaining groups were given ANIT modeling reagent. Administration was continued on day 5 to 6 in each administration group. Forty-eight hours after modeling on the 7 th day, blood was collected from the femoral artery of rats. Serum alkaline phosphatase(ALP), alanine aminotransferase(ALT), aspartate aminotransferase(AST), direct bilirubin(DBIL), total bilirubin(TBIL), and total bile acid(TBA) levels were detected, and liver histopathological changes were observed. The relative expression changes of FXR, SHP, CYP7 A1, MRP2, MRP3, NTCP, BSEP mRNA in liver tissues were detected by Real-time fluorescence quantitative method, and the expression changes of FXR, SHP, UGT2 B4 protein in liver tissues were detected by Western blot. The results showed that the Tibetan medicine Ershiwuwei Songshi Pills significantly reduced the levels of ALT, ALP, DBIL, TBIL and TBA in the serum of the ANIT mo-del rats(P&lt;0.01, P&lt;0.05), significantly up-regulated the mRNA expressions of SHP and NTCP(P&lt;0.01, P&lt;0.05), significantly down-regulated the mRNA expression of CYP7 A1 and MRP3(P&lt;0.01, P&lt;0.05); and significantly up-regulated the protein expressions of FXR and SHP(P&lt;0.01, P&lt;0.05). The Tibetan medicine Ershiwuwei Songshi Pills have an obvious protective effect on ANIT-induced cholestatic liver injury in rats, and its mechanism may be related to the bile acid metabolism mediated by the FXR signaling pathway.

Determination of Sulfur Amino Acids in Milk and Plant Proteins

A method for the determination of the sulfur amino acids methionine and cysteine in milk- and plant-derived protein powders and in protein-based nutritional products is described. Samples and calibration standards are prepared by acid hydrolysis (6-M HCl, 110 °C, 24 h) with 3,3’dithiopropionic acid, evaporation, and resuspension. The released methionine and cysteine mixed disulfide are quantified by direct LC/UV, without pre- or post-column chromophore/fluorophore derivatization. Since tyrosine is also released by the acid hydrolysis and elutes in the same chromatogram, it was included in all determinations. Method performance has been defined by assessments of linearity (R2 averaged > 0.999, n = 10, for 5-point plots of each analyte), intermediate precision (within-day RSD < 2%, n = 3, and day-to-day RSD < 3%, n = 3 days, for each analyte), accuracy (cystine spike recovery = 101%; measured methionine, cystine, and tyrosine concentrations were 95–111% of published concentrations), selectivity (reagent blanks and peak purity found analyte bias ≤ 2%), and quantitation limit (25 mg of methionine and tyrosine, and 50 mg of cystine, per 100 g of protein powder). The method provides a relatively simple means for the accurate and precise determination of both sulfur amino acids in protein powders and in nutritional products, and may be performed by conventional LC/UV, without specialized amino acid analysis instrumentation.

Cobalt (III)-EDTA dissociates and chromium (III)-EDTA is slightly more stable under in vitro reducing conditions comparable to those in the rumen

Ideal digesta markers used for feeding studies are inert, unabsorbable, and move with the digesta they are intended to mark. Both chromium (III) and cobalt (III) salts of EDTA (CrEDTA and CoEDTA, respectively) are used as markers of liquid digesta in dairy cattle research. A small portion is absorbed and excreted in urine, but the markers are assumed to remain unreactive and as inert salts in the digesta and animal. The degree to which these colored salts remain bound in solution can be estimated through spectrophotometric measurement at their wavelength (λ) of peak absorbance. The objective of this in vitro study was to evaluate whether CrEDTA and CoEDTA dissociate under reducing conditions that could be experienced in the rumen. In a completely randomized design with 2 replicate analytical runs and samples in duplicate within run, approximately 26 mg/L Cr from CrEDTA or Co from CoEDTA was incubated in a 26-mL reaction volume containing 20 mL of Goering and Van Soest medium without tryptone, 3 mL of CoEDTA or CrEDTA solutions, or water (reagent blanks), and 3.0 mL of a combination of distilled water with 0, 0.25, 0.50, 0.75, or 1.00 mL of reducing solution (RedSol). After incubation for 0.5 h at 39°C, absorbance was read at λ = 535, 465, and 560 nm, the peak λ for EDTA salts of Co(III), Co(II), and Cr(III), respectively. Mean reagent blank values were subtracted from CoEDTA and CrEDTA data. The absorbance data at peak λ were analyzed by marker in models that included RedSol with analytical run as a random variable. Contrasts were used to detect linear through quartic effects of RedSol. Samples with RedSol had redox potentials of -250 to -328 mV, which are within the range of reported ruminal measures. As RedSol increased, CoEDTA showed a linear decline of 75% in ABS at 535 nm and a quadratic 4-fold increase followed by a 60% decline at 465 nm. These responses indicate a reduction of Co(III) to Co(II) and subsequent dissociation of Co(II)EDTA. The absorbance of CrEDTA at 560 nm showed a tendency for an 8% linear decrease as RedSol increased. Wavescans from λ = 330 to 700 nm showed CrEDTA retaining its characteristic 2-peak pattern as RedSol increased, whereas CoEDTA curves deformed entirely. We conclude that CoEDTA is not a stable, inert digesta marker under reducing conditions achievable in the rumen and is therefore unsuitable for use in studies with ruminants. Reexamination of the suitability of available liquid digesta markers is advised.

Second Laboratory Validation of β-N-Methylamino-L-Alanine, N-(2aminoethyl)Glycine, and 2,4-Diaminobuytric Acid by Ultra-Performance Liquid Chromatography and Tandem Mass Spectrometry.

The analysis of β-N-methylamino-L-alanine (BMAA) has been validated according to AOAC international standards by a single laboratory (Glover et al. 2015). Using the same validated method, we add a second laboratory validation optimizing for different equipment. Given publicized concerns about standardizing methods across laboratories and recent reviews indicating superior results using 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate derivatization for the separation of BMAA and its isomers N-(2aminoethyl)glycine (AEG), and 2,4-diaminobuytric acid (DAB) (Bishop and Murch 2019), we add a second laboratory validation to this method demonstrating that the method is robust across laboratories using different equipment. Using the US Food and Drug Administration (FDA 2018) method for evaluating instrument parameters, we calculated a limit of detection (LOD) of 10pg/ml for BMAA, AEG, and DAB and lower limits of quantification (LLOQ) of 37pg/ml based on reagent blanks. In biological matrices, a higher LLOQ may be warranted for AEG and DAB. We demonstrate that the endogenous BMAA in mussel tissue can be lost by drying the hydrolyzed preparation and suggest sample preparation parameters be evaluated for robustness.

Comparing a two-dimensional liquid chromatography with a quick, easy, cheap, effective, rugged, and safe protocol-based liquid chromatography method for matrix removal in pesticide analysis using time-of-flight mass spectrometry

In this study, a clean-up approach using a two-dimensional liquid chromatography (2D-LC) consisting of a hydrophilic interaction liquid chromatography column and a reversed phase column was investigated. A fully automated 2D-LC system was used and compared with a traditional quick, easy, cheap, effective, rugged, and safe (QuEChERS) liquid chromatography (QuE-LC) method.The comparison was based on the results of a validation of selected analytes. It was investigated whether the detectability of analytes could be improved by the use of the 2D-LC. On the basis of these results, the relative detection rates were determined for every matrix. By means of those detection rates, the matrices were categorized regarding their complexity. Furthermore, the applicability of the 2D-LC was tested by participation in the European Proficiency Test in Fruits and Vegetables Screening Methods.In order to evaluate the separation and the elution profile of matrix components, multivariate data analysis was applied. For this purpose, ten matrices were processed in accordance to a QuEChERS protocol and the protocol for 2D-LC analysis. Moreover, the reagent blanks of the corresponding matrix were processed and analyzed by QuE-LC and 2D-LC. The results allowed evaluating the number of detected compounds for both methods. Additionally, the influence of compounds originating from reagent blanks can be estimated. In general, less compounds could be detected when 2D-LC was used. Especially, these were very polar compounds and compounds with m/z values >1500. These compounds seem to originate primarily from the used reagents especially from the citrate salts. However, the most of these compounds could be separated and were not detectable any more when 2D-LC was used. The results of the comparison based on validation and participation in the European Proficiency Test also show a better detectability for the most analytes with 2D-LC.

Stability of the liquid markers chromium (III) and cobalt (III)-EDTA in autoclaved, clarified rumen fluid

An ideal digesta marker for use in feeding studies is inert, unabsorbable, and moves with the portion of the digesta it is intended to mark. Both chromium (III) and cobalt (III) salts of EDTA (CrEDTA and CoEDTA, respectively) have been used as digesta liquid markers in studies with dairy cattle. Although a small portion of these markers is known to be absorbed and excreted in urine, the markers are assumed to remain ionically bound in the digesta. The degree to which these salts remain bound in solution can be determined through spectrophotometric measurement at the wavelength (λ) of peak absorbance of these colored compounds. The objective of this study was to evaluate whether CrEDTA and CoEDTA dissociate during incubation in autoclaved, clarified rumen fluid (ACRF), as indicated by changes in absorbance. In a complete block design with separate replicated analytical runs, approximately 40 mg/L of Cr from CrEDTA or Co from CoEDTA were incubated in 2 separate preparations of ACRF from 2 lactating Holstein cows, in water (CrEDTA), or in MES buffer (CoEDTA), and appropriate reagent blanks. Solution pH were approximately 6.0. Samples were incubated for 24 h at 39°C with absorbance measurements recorded at 0, 1, 2, 4, 6, 22, and 24. The CrEDTA was measured at λ = 541 nm, CoEDTA at λ = 535 nm, and both were measured with wavescans of λ = 330 to 700 nm. At their peak λ, both CrEDTA in water and CoEDTA in MES buffer maintained absorbance values throughout the incubation, whereas, in ACRF, CrEDTA absorbance decreased by 9% at 0 h, and by up to 14% by 24 h; CoEDTA showed a gradual decline over time, with approximately 4% loss in absorbance by 24 h. Responses differed by ACRF preparation. Both markers in ACRF showed increases and decreases over time in absorbance at λ = 330 and 380 nm, though the changes were more marked for CrEDTA; markers not in ACRF showed no change in absorbance at these λ. Changes in the absorbance values at λ = 330 and 380 nm suggest that soluble phenolic compounds may be involved in the exchange of metals with EDTA, but that does not preclude involvement of other components in rumen fluid. Both CrEDTA and CoEDTA incubated in ACRF showed declines over time in absorbance at their peak λ, suggesting that the metals dissociated from EDTA. The apparent dissociation indicates that these liquid markers are not inert as had been assumed.

Spectrophotometric analysis of tablets of nalidixic acid using melted niacinamide as solvent

In the current attempt of research, novel method for spectrophotometric estimation of nalidixic acid in tablets using melted niacinamide as solvent was developed. The main objective behind research is to show “SOLIDS ALSO POSSESS SOLUBILIZING POWER”. The current study deals with novel spectrophotometric analytical technique for quantitative estimation of nalidixic acid in tablets using melted niacinamide as solvent. According to the theory proposed by Maheshwari, each &amp; every substance possesses solubilising power; substance may be a gas, solid or liquid. Niacinamide imbibes large solubilizing power to nalidixic acid and having approximate solubility more than 80 mg per gm of melted niacinamide (135°C) whereas aqueous solubility of nalidixic acid is 0.21mg/ml at room temperature. Calibration curve of nalidixic acid was plotted by recording the absorbances of standard solutions of drug. The absorbances were observed at 330 nm against respective reagent blanks. The percentage label claims were found very close to 100 (100.93± 1.303 and 99.08±1.764) indicating accuracy of the proposed method. Percentage recoveries estimated by the proposed method are close to 100 (99.91±1.303 and 101.74±1.663) with significant low values of percentage deviation and standard error. Thus, it may be concluded that proposed method is simple, safe and precise and excludes use of toxic organic solvents.&#x0D; Keywords: Mixed Solvency, Solubilizing Power, Spectrophotometric Analysis, Niacinamide, Nalidixic Acid.

On the fluorometric measurement of ammonium in oligotrophic seawater: Assessment of reagent blanks and interferences

AbstractDynamically distributed at trace levels in the open ocean, ammonium is one of the most important and reactive nitrogen compounds in the marine environment. Obtaining reliable measurements of ammonium concentrations is thus a prerequisite to fully understand its role in marine biogeochemical processes, but remains challenging. Among others, quantification and identification of different sources of blanks is an outstanding issue, due partly to the fact that ammonium‐free water is very difficult to prepare and/or preserve. Building on a recently developed method using solid phase extraction combined with fluorescence detection (SPE‐Flu), we examined the kinetics of the ortho‐phthaldialdehyde‐sulfite‐ammonium reaction and introduce a new approach to quantifying reagent blanks via a “reagents addition” method. The reagent blank of the method, equivalent to 6.7 ± 1.5 nmol L−1 of ammonium under our experimental settings, accounted for up to 27% of the ammonium background in seawater samples collected from the oligotrophic ocean. We also showed that the SPE‐Flu method is highly specific, with negligible interference from three types of amines and 15 types of amino acids at nanomolar concentrations, which are typical of open ocean regimes. The determination of the reagent blank allowed for optimized data reduction, which was applied to a study in the oligotrophic South China Sea. Water column profiles showed a very well‐defined structure and smooth distribution of ammonium concentrations, consistent with the distribution of other parameters. We thus contend that our proposed approach provides a way to further optimize the quantification of ammonium concentrations in natural seawater via the SPE‐Flu method.

Sequential coprecipitation and matrix removal for determination of cadmium impurities from multivitamin supplements by inductively coupled plasma mass spectrometry and method validation by isotope dilution analysis of SRM 3280 multivitamin/multielement tablets

In this paper, we examined three different sequential coprecipitation schemes based on Mg(OH)2 and CaF2 precipitation using triethylamine (TEA) and hydrofluoric acid (HF), respectively, for determination of cadmium (Cd) impurities from multivitamin/mineral (MVM) supplements by isotope dilution (ID) inductively coupled plasma mass spectrometry (ICP-MS). The schemes involved three-step coprecipitation with either TEA alone or in combination with HF and are designated as Scheme 1 (TEA-TEA-TEA), Scheme 2 (TEA-HF-TEA) and Scheme 3 (HF-TEA-TEA) according to the addition sequence of each reagent. Experiments were carried out with MVM solutions spiked with 60μgL−1 Cd from a multielement standard solution. All schemes provided quantitative separation of Cd from MVM matrix. Scheme 1 was the least effective in removal of interfering concomitant elements, molybdenum (Mo) and tin (Sn). Scheme 2 performed better for Sn, but failed in eliminating Mo. Scheme 3 was the most effective in eliminating both Mo and Sn. Mo levels in test MVM solutions reduced from 4.3μgmL−1 to as low as 0.014μgmL−1 while that for Sn decreased from 0.5μgmL−1 to 0.018μgmL−1 allowing interference-free determination of Cd to be achieved. Salt-matrix due to Mg, Ca, P and K along with the essential elements (Mn, Fe, Cu and Zn) levels was also reduced significantly. Reagent blanks from HF and TEA were insignificant (0.008μgL−1) allowing a limit of detection of 0.004μgL−1 or 0.26ngg−1 Cd to be achieved (3σ, n=6). The performance of the coprecipitation method (Scheme 3) was validated by determination of Cd in multivitamin/multielement tablets certified reference material (SRM 3280) by ID-ICP-MS. Experimental results (ngg−1) and recoveries were 78.8±4.7 (98.5%), 77.9±5.2 (97.4%) and 76.5±4.8 (95.6%) for 110Cd, 111Cd and 114Cd isotopes, respectively. Several commercial MVM supplements were analyzed using the method. Mean Cd concentration ranged from 21.4ngg−1 to 93.3ngg−1. These values are much lower than those reported to date for various MVM supplements by ICP-MS determinations without chemical separation.

Performance evaluation of a mitogenome capture and Illumina sequencing protocol using non-probative, case-type skeletal samples: Implications for the use of a positive control in a next-generation sequencing procedure

Next-generation ancient DNA technologies have the potential to assist in the analysis of degraded DNA extracted from forensic specimens. Mitochondrial genome (mitogenome) sequencing, specifically, may be of benefit to samples that fail to yield forensically relevant genetic information using conventional PCR-based techniques. This report summarizes the Armed Forces Medical Examiner System’s Armed Forces DNA Identification Laboratory’s (AFMES-AFDIL) performance evaluation of a Next-Generation Sequencing protocol for degraded and chemically treated past accounting samples. The procedure involves hybridization capture for targeted enrichment of mitochondrial DNA, massively parallel sequencing using Illumina chemistry, and an automated bioinformatic pipeline for forensic mtDNA profile generation. A total of 22 non-probative samples and associated controls were processed in the present study, spanning a range of DNA quantity and quality. Data were generated from over 100 DNA libraries by ten DNA analysts over the course of five months.The results show that the mitogenome sequencing procedure is reliable and robust, sensitive to low template (one ng control DNA) as well as degraded DNA, and specific to the analysis of the human mitogenome. Haplotypes were overall concordant between NGS replicates and with previously generated Sanger control region data. Due to the inherent risk for contamination when working with low-template, degraded DNA, a contamination assessment was performed. The consumables were shown to be void of human DNA contaminants and suitable for forensic use. Reagent blanks and negative controls were analyzed to determine the background signal of the procedure. This background signal was then used to set analytical and reporting thresholds, which were designated at 4.0X (limit of detection) and 10.0X (limit of quantiation) average coverage across the mitogenome, respectively. Nearly all human samples exceeded the reporting threshold, although coverage was reduced in chemically treated samples resulting in a ∼58% passing rate for these poor-quality samples. A concordance assessment demonstrated the reliability of the NGS data when compared to known Sanger profiles. One case sample was shown to be mixed with a co-processed sample and two reagent blanks indicated the presence of DNA above the analytical threshold. This contamination was attributed to sequencing crosstalk from simultaneously sequenced high-quality samples to include the positive control. Overall this study demonstrated that hybridization capture and Illumina sequencing provide a viable method for mitogenome sequencing of degraded and chemically treated skeletal DNA samples, yet may require alternative measures of quality control.

Verification of 5-Methyltetrahydrofolic Acid in Nutritional Products

A simple method for the verification of supplemental (6R,S)-5-methyl-5,6,7,8-tetrahydrofolic acid, “5-MTHF,” in nutritional products is described. Nutritional product samples are prepared for the liquid chromatographic/fluorescence detection (LC/FLD) determination of 5-MTHF by buffer dilution, 10-min centrifugation, and syringe filtration. Method performance has been defined by assessments of 5-MTHF linearity (r 2 averaged 0.9999 ± 0.0001, and all relative calibration errors averaged ≤0.6%, for ten consecutive six-point standard curves), intermediate precision (rsd = 1.1%, n = 9, for three products fortified at ∼1.73 μmol/kg = ∼795 μg/kg, tested on each of 3 days), accuracy (spike recovery average = 92.8 ± 1.0%, n = 9, for nutritional products spiked with 5-MTHF at ∼1.73 μmol/kg, or ∼795 μg/kg), and selectivity (absence of interference from reagent blanks, and from four compounds structurally related to 5-MTHF). The 5-MTHF recovery, as % of unheated controls, from a simulated heat treatment (20 min at 120 °C) averaged 99.1 ± 0.6%, n = 4. The limits of 5-MTHF detection (S/N = 3) and quantification (S/N = 10) were experimentally determined to be 10 μg/kg (∼0.020 μmol/kg) and 30 μg/kg (∼0.060 μmol/kg), respectively (<10× the expected fortification rate). The method provides a simple and inexpensive means for verifying proper fortification, and for assessing the stability to processing and storage conditions, of free 5-MTHF in nutritional products. A finding of interest is the indication that liquid nutritional products may comprise a stable matrix for 5-MTHF fortification.