Potassium Phosphate Research Articles

High-Performance Liquid Chromatographic Method Development and Validation for Analysis of Expired and Marketed Doxofylline Tablets.

The objectives of the study were to develop a simple, reliable, sensitive and accurate high-performance liquid chromatography (HPLC) method for doxofylline pure and pharmaceutical dosage forms. HPLC method was developed for the estimation of doxofylline in pure and marketed, recently expired, and 1-year expired tablet formulations. Chromatographic separation of the drug was achieved on a stainless steel column 25 cm × 4.6 mm, packed with octadecylsilane bonded to porous silica (5 µm), Cosmosil® C18, column using a mobile phase of Potassium dihydrogen orthophosphate buffer: Acetonitrile pH 5.1 (60:40 v/v) at a flow rate of 1-mL/min. The drug eluted was monitored at 274 nm and the retention time of doxofylline was found to be 3.575 minutes, respectively. The validation of developed methods was done according to ICH Q2 (R1) guidelines. The calibration curve was linear over the range of 5 to 50 µg/mL. The correlation coefficient was found to be 0.9943 for doxofylline. The average retention time was found to be 3.538 minutes. The results were reproducible, showing the effectiveness of the system. The plate number was found to be 4909, which is also within the limit, i.e. ≥ 2000 prescribed in I.P. The dissolution studies of all three marketed, recently expired and 1-year expired formulations were carried out by using 0.01 M HCl and the results showed almost a similar rate of release profile and all three formulations accomplished the drug release within the limit. The developed and validated HPLC method offers a precise, accurate, and efficient analytical tool for the determination of doxofylline in pharmaceutical formulations.

QbD-Driven Approach to Cleaning Method Development and Validation for Darunavir Analysis in Oral Films.

The current investigations involve developing a high-performance liquid chromatographic method that’s simple to operate, fast to establish, accurate, precise, and economical through design-enabled methods. A positive experimental design is offered to utilize the central composite design of pH and the mobile phase, two crucial components of the RP-HPLC technology. The chromatographic conditions were optimized with the release of Design Expert software version 13.0. Symmetry C18 column (4.6×150mm, 5µm) was used in the procedure, along with acetonitrile (20:80 v/v) and potassium dihydrogen orthophosphate buffer pH 4.0 as the mobile phase. There was a 0.70 ml/min flow rate. 263 nm is the wavelength of detection. Darunavir’s sharp, resolved peak was seen 2.3 minutes after swabbed samples from the 10*10 cm SS plate were injected. A linear calibration curve with an R2 of 0.9991 was observed in the concentration range of 0.25 to 25µg/ml. For precision %RSD is 1.03,1.48. Accuracy % concentration 50%,100%,150% mean recovery 99.43-100.53.LOD & LOQ 1.12µg/ml, 3.39µg/ml. Robustness was tested with modest modifications to the wavelength and flow rate. Forced degradation studies were carried out and found to be within the limits. the degradation parameters such as Acid, Base, Oxidative, Photolytic, and thermal degradation parameters are according to the ICH guidelines. % Assay was done for oral films and it was found to be within the limits. Thus, the outcomes unequivocally demonstrated that the QbD technique could be effectively used to enhance the HPLC method for the measurement of darunavir in production settings.

Graphene-Based Nano Drug Delivery of Curcumin for the Treatment of Dengue Fever.

Graphene, which is defined as a single-layered sp2 hybridized carbon atoms placed in a honeycomb-like crystal lattice when converted to graphene oxide, has proven its worth by showing its tremendous capacity in controlling the release rate of drugs by entrapping in the numerous pockets present inside it through π-π stacking interaction when used as a nanocarrier. In this experiment graphene oxide was synthesized through traditional Hummer’s method and was used as a nanocarrier to target nanosized drugs, which was prepared by loading curcumin drug into the PVP functionalized graphene oxide by using necessary procedures. After the successful confirmation of the stability, functionalization, and compatibility through various characterization procedures and effective drug loading into the systems, the release behavior of the formulations has been checked through dialysis bag diffusion technique using potassium phosphate buffer saline (pH 7.2, 4.0 and 9.2) for selection of the best medium for determination of the successful sustained-release behavior of the drugs through the dialysis membrane which concluded with satisfactory, sustained and constant drug release phenomenon in the acidic environment reflecting an idea of the fact its favorable release in acidic pH. It is a fact known that dengue fever causes systemic acidosis i.e., reduction of the pH of blood below 7. Thus, when used in-vivo there is a possibility that the formulation has easy access to its target and, performs the desired mechanism of action and can be used as a therapeutic delivery system against the Dengue virus.

Optimized analysis for related substances in spiramycin based on high performance liquid chromatography with hybrid particle column and characterization of its impurities by single heartcut two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometer

This article described the development and validation of a method for spiramycin related substances based on hybrid particle column. The chromatographic conditions were as follows: water - 0.2 mol/L dipotassium hydrogen phosphate (the pH value adjusted to 9.5 using a 1 mol/L KOH solution) - acetonitrile - methanol (10: 60: 28.5: 1.5, v/v/v/v) as mobile phase A, water - 0.2 mol/L dipotassium hydrogen phosphate (pH 9.5) - acetonitrile - methanol (10: 30: 57: 3, v/v/v/v) as mobile phase B and gradient elution was performed. Compared with previous analytical methods, this method has strong specificity, excellent sensitivity and stability, which could be used for the daily testing of related substances of spiramycin. Furthermore, impurities above 0.1 % were characterized using two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometer (2D LC-QTOF-MS/MS) and there were 6 impurities reported for the first time.

Anomalous relaxation and polarization switching in a nanocomposite based on potassium dihydrogen phosphate combined with silicon dioxide nanoparticles and multiwalled carbon nanotubes

Anomalous relaxation and polarization switching in a nanocomposite based on potassium dihydrogen phosphate combined with silicon dioxide nanoparticles and multiwalled carbon nanotubes

Influence of slag on water resistance of magnesium silicon potassium phosphate cement

The poor water resistance of traditional magnesium phosphate cement (MPC) limits its wider application in engineering fields. So far, research on enhancing the water resistance of MPC has been relatively limited. Therefore, this paper optimizes the slag content based on magnesium silicon potassium phosphate cement to prepare slag-magnesium silicon potassium phosphate cement (S-MSPPC). The research results indicate that slag contains various active components, and its appropriate addition can refine the pore structure of the paste. With the increase in slag replacement rate, the paste setting time increases, and the fluidity decreases slightly. The hydration of silica fume to produce SiO(OH)3‐ and SiO2(OH)22‐ ions significantly enhances the alkalinity of the paste and provides conditions for activating the activity of the slag. The S-MSPPC hardened paste can maintain alkalinity for the long term. Moreover, the water resistance of the S-MSPPC paste was significantly improved while ensuring mechanical properties. The water resistance coefficients of S-20 with 20 % slag increased by 49.23 % and 40.64 % at 28 days and 56 days compared to the reference group S-0. This improvement was due to the participation of silica fume and slag in the hydration reaction to form M-S-H and C-(A)-S-H gels in the paste. These gel products fill the pores and microcracks in the paste, optimize the pore size distribution, reduce porosity, and enhance density. In addition, the alkaline environment within the paste effectively slows the dissolution rate of K-struvite in water, further enhancing the water resistance of S-MSPPC.

Shape-controllable synthesis of lignin-derived boron-doped nanoporous carbons for dye adsorption and electrochemical H2O2 production

Lignin-derived nanocarbon materials (LNCMs) have attracted intense attention due to their excellent properties and promising applications in renewable energy technologies. However, lignins tend to melt and agglomerate during pyrolysis, make it difficult to control the morphology and pore structure of the resulting carbon. In this study, boron-doped porous nanocarbon (BFC) in various shapes (sphere, band, and sheet) were synthesized using ammonium borate as a crosslinking agent to prevent lignin melting, assisted by liquid nitrogen freeze-drying and potassium phosphate (KP) templating. The effects of BFC structure on methylene blue adsorption and electrochemical generation of H2O2 were investigated. The results show that KP-1/1-8BFC exhibits a high specific surface area (912.89 m2/g) and a hierarchical micro-mesoporous structure, achieving a remarkable adsorption capacity of 473.9 mg/g for methylene blue and rapid kinetics. The selectivity of KP-1/20-8BFC for electrochemical production of H2O2 reaches 85 %. This study offers theoretical guidance for the controllable synthesis of LNCMs, contributing to the advancement of sustainable energy solutions.

Physical properties of tween 20 + di-potassium hydrogen phosphate anhydrous (or tri-potassium phosphate 1,5-hydrate) + water from 288.15 K to 318.15 K

ABSTRACT The present study investigates the characterisation of binary and ternary mixtures involving a surfactant such as Tween 20 and various potassium salts in aqueous solutions. The ternary mixtures can form two distinct immiscible liquid phases. Several physical properties, including refractive index, density, and speed of sound, were measured, and derived properties such as excess molar volume and isentropic compressibility were calculated. The research focuses on the behaviour of aqueous binary and ternary mixtures composed of Tween 20, salts (di-potassium hydrogen phosphate anhydrous and tri-potassium phosphate 1,5-hydrate), and water in their homogeneous phases. It examines the influence of the surfactant and salts and the effect of temperature on these physical properties for homogeneous mixtures. Additionally, the physical properties of the equilibrium phases were determined to cover all the homogeneous zones comprehensively.

Development and Validation of Novel RP-HPLC Method for the Simultaneous Estimation of Itraconazole and Secnidazole in Bulk and Pharmaceutical Formulations

Simple, accurate and precise RP-HPLC method for the simultaneous estimation of Itraconazole (ITZ) and Secnidazole (SEC) in bulk and pharmaceutical formulations has been developed and validated. The chromatographic analysis was performed on Shimadzu model equipped with SPD-20 AD UV detector, isocratic pump LC- 20 AD and loop injector. The chromatographic separation was performed using C18 column (250mm x 4.6mm i.d. and 5µm particle size). The analytes were monitored at 257nm using methanol: potassium dihydrogen phosphate buffer (PDP) pH 5.5 in the ratio of 90:10v/v with a flow rate of 1.5ml/min. The retention time was found to be 6.037 min for ITZ and 3.788 min for SEC. The linearity was found to be in the range of 10-50µg/ml for both ITZ and SEC with a regression coefficient of 0.999 and 0.998 for ITZ and SEC respectively. The method was validated in accordance with ICH guidelines for its linearity, precision, accuracy, robustness, ruggedness, LOD and LOQ. The recovery studies were carried out which confirmed the accuracy of the proposed method. LOD values for ITZ & SEC was found to be 0.583µg/ml and 0.241µg/ml, respectively. LOQ values for ITZ and SEC was found to be 1.749µg/ml and 0.732µg/ml, respectively. The developed method was also found to be precise and robust for the simultaneous determination of ITZ and SEC in bulk and pharmaceutical formulations.

Low‐Temperature Flexibility of Chiral Organic Crystals with Highly Efficient Second‐Harmonic Generation

Flexible crystals with unique mechanical properties have presented enormous applications in optoelectronics, soft robotics and sensors. However, there have been no reports of low‐temperature‐resistant flexible crystals with second‐order nonlinear optical properties (NLO). Here, we report the flexible chiral Schiff‐base crystals capable of efficient second harmonic generation (SHG). Both enantiomers and racemic modifications of these crystals are mechanically flexible in two directions at both room temperature and at ‐196 °C, although their mechanical responses differ. The enantiomers display SHG with an intensity of up to 12 times that of potassium dihydrogenphosphate (KDP) when pumped at 980 nm, and they also have high laser‐induced damage thresholds (LDT). Even when bent, the crystals retain strong second harmonic generation, although with a different intensity distribution depending on the polarization, compared to when they are straight. This work describes the first instance of flexible organic crystal with NLO properties and lays the foundation for the development of mechanically flexible organic NLO materials.

Influence of Ca-substituted K-induced cluster defects on the electronic structure and optical properties of KDP crystals

Compensation mechanism following Ca substitution in K sites was computed using GULP. Utilizing density functional theory for three charge states, the impact of defect clusters CaK + VK/CaK + VH on potassium dihydrogen phosphate (KDP) crystals in both phases was assessed. Corrections to the band edge and defect formation energies were made employing hybridization floods HSE06 and FNV. Neutral and −1 valence defect states emerged. Cluster defects induced pronounced lattice distortion in PE-KDP. Notably, PE-KDP exhibited an additional photoemission of 2.89 eV, signifying a substantial structural impact. Comparative stability analysis favored FE-KDP, offering theoretical guidance for KDP crystal utilization.

Impact of PGRs, polyamines and potassium to improve pomegranate flowering behaviour, fruit set and fruit quality

Ever changing climate is affecting the flowering pattern in pomegranate worldwide. It is the need of the hour to find out some chemicals that can not only enhance hermaphrodite flowers and fruit set but also enhance fruit quality. The present investigation aimed to evaluate the effect of plant growth regulators (three), polyamines (two) and other chemicals (five) on photosynthesis, flowering ratio, fruit set and quality of pomegranate fruits. Pomegranate trees were treated at full leaf expansion stage. Potassium dihydrogen phosphate (5000 ppm), spermidine (1.5 ppm) and naphthalene acetic acid (NAA) (20 ppm) were the best treatments to significantly enhance hermaphrodite flowers, as the hermaphrodite to male flower ratio was 0.39, 0.37, and 0.35, respectively, compared to 0.22 in the control treatment. Except spermidine, NAA and paclobutrazol, all treatments increased the fruit setting significantly, with potassium dihydrogen phosphate (5000 ppm) being the most effective treatment with 66% fruit set compared to 43% in control trees. In mature fruits, compared to control, NAA enhanced total phenols, ascorbic acid and total antioxidants (3%, 15%, 7%, respectively) followed by ascorbic acid treatment (250 ppm); potassium dihydrogen phosphate (5000 ppm) and putrescine (44 ppm) enhanced the anthocyanin content and hence aril color significantly (11% and 10% respectively). Though the use of NAA in pomegranate production is commercial practice, two sprays of ascorbic acid can also be included to enhance the nutritional quality of fruits. Foliar application of potassium dihydrogen phosphate twice at flowering stage could be highly useful for quality pomegranate production due to the enhanced number of hermaphrodite flowers, fruit setting and fruit color. Overall, use of these chemicals can be beneficial to pomegranate farmers to get more remuneration from harvest.

Investigation into “hair” inclusions in large-sized KDP crystals grown by traditional method

Potassium dihydrogen phosphate (KDP) crystals are widely used in high-energy laser facilities for harmonic generation. An important defect observed in KDP crystals, known as "hair" inclusions in large-size crystals grown by traditional methods, was investigated using ultra-microscopy. Most of the "hair" inclusions within the crystals have a straight chain structure, while only a few displays a curved formation. The "hair" inclusions consist of multiple liquid inclusions and exhibit a chain-like structure with quasi-periodic features. The size of these liquid inclusions varies, ranging from 17.54 to 56.90 μm, and show a chain density between 0.90 mm−1 and 20.77 mm−1. The angles of the "hair" inclusion orientations about the c-axis range from 30° to 79°, corresponding to the dislocations in KDP crystals. Furthermore, the study examined the impact of "hair" inclusions on the transmittance of the crystals. This investigation aims to enhance the understanding of “hair” inclusions in traditionally grown KDP crystals and attempts to clarify the factors leading to the formation of these inclusions. It also offers a theoretical and experimental basis for reducing these inclusions in KDP crystals.

Effect of Three Foliar Inhibitors on Accumulation of Cd and As in Rice Grains

This study investigated the impact of single and combined applications of three foliar inhibitors on the accumulation of cadmium （Cd） and arsenic （As） in rice grains. Two rice varieties, Songyazao 1 （for early rice） and Wuxiang Youyue （for late rice）, were selected for this experiment. We established nine treatments using a pot experiment method, including a control （CK） treated with no foliar inhibitor and three individual foliar inhibitors： cysteine （L-Cys）, potassium sulfide （K2S）, and dipotassium hydrogen phosphate （K2HPO4）. We then combined the applications of two foliar inhibitors： L-Cys with low/high concentrations of K2S, L-Cys with low/high concentrations of K2HPO4, and K2S with a low concentration of K2HPO4. The results showed that the single and combined applications of foliar inhibitors reduced Cd and As concentrations in rice grains. The Cd content in brown rice treated with L-Cys and K2S/K2HPO4 was reduced below the standard limit for food safety of 0.20 mg·kg-1. Compared to the CK, the content of inorganic arsenic （IAs） in early and late rice decreased by 4.68%-56.75% and 2.84%-16.91%, respectively. Foliar inhibitors applied individually or in combinations facilitated the transport of Cd and As from the stem to the leaf while inhibiting their transport from the leaf to the rice grain. This resulted in the sequestration of Cd and As within the leaf cell wall, ultimately reducing the content of these elements in rice grains. Among the combination treatments, the application of L-Cys and high-concentration K2S achieved the best results. The Cd content in early and late rice decreased by 37.64% and 26.37%, respectively, falling below 0.20 mg·kg-1. The IAs content in early and late rice was reduced to 0.10 mg·kg-1 （below 0.20 mg·kg-1） and 0.24 mg·kg-1, respectively. This study provides a valuable theoretical foundation and empirical data to support the achievement of safe rice production practices.

Unapproved potassium phosphates drug product: risk of aluminium toxicity in infants

Unapproved potassium phosphates drug product: risk of aluminium toxicity in infants

Effect of seed priming using potassium dihydrogen phosphate on seedlings emergence, growth and yield of Bambara groundnut (<i>Vigna subterranea</i> (L) Verdc.)

Effect of seed priming using potassium dihydrogen phosphate on seedlings emergence, growth and yield of Bambara groundnut (<i>Vigna subterranea</i> (L) Verdc.)

Efficacy of Potassium Iodide and Glutathione for Correlation of Dentin Discoloration Caused by Silver Diamine Fluoride.

This study aimed to investigate and contrast the degree of dentin discoloration resulting from the application of silver diamine fluoride (SDF) alone, SDF in combination with potassium iodide (KI), and SDF in combination with glutathione. The aim was to assess the effectiveness of these combinations in reducing the aesthetic issues associated with SDF treatment in minimally invasive dentistry and preventive procedures. We conducted this in-vitro study on 136 permanent molar teeth. The teeth were randomly assigned to two main groups of total-etch and self-etch and four subgroups of control, SDF, SDF plus KI, and SDF with glutathione. The teeth underwent colorimetry before and 1 week after applying materials to compare the color change. We mounted the teeth in acrylic resin 1 mm below their cementoenamel junction. A low-speed diamond saw and 600-grit silicon carbide abrasive paper eliminated the occlusal enamel for 10 seconds under water coolant, exposing the dentin. The teeth were then immersed in a demineralizing solution (pH of 4.4, 50 mmol acetate, 2.2 mmol potassium dihydrogen phosphate, and 2.2 mmol calcium chloride) for 7 days at 37°C to induce dentin demineralization and simulate demineralized dentin artificially. The teeth were then gently polished with 600-grit silicon carbide abrasive paper to create a standard smear layer and eliminate the demineralized dentin layer. 136 teeth were evaluated in the total-etch (n = 68) and self-etch (n = 68) groups. Glutathione and KI significantly decreased the discoloration caused by SDF (P<0.05). No significant difference was noted in color change between SDF/glutathione and SDF plus KI groups (P > 0.05). In self-etch groups, glutathione yielded an ∆E=4.12, while KI yielded an ∆E=4.44, with no significant difference. The application of glutathione and KI can significantly decrease dentin discoloration caused by SDF.

The use of an RP-HPLC-UV method for the analysis of oxcarbazepine in the presence of its preservatives; stability studies and application to human plasma samples

AbstractA simple, sensitive, selective, accurate and precise method was developed and fully validated for determination of oxcarbazepine (OXC) in presence of their preservatives and determination of oxcarbazepine (OXC) in human plasma. A reversed phase liquid chromatography (RP-HPLC) with UV detection techniques were applied for separation and quantification of studied drug OXC. Successful separation of the drug from methyl paraben (M.P.), propyl paraben (P.P.) and potassium sorbate (P.ST.) was achieved on a Kromasil C18 column (5 μm particle size, pore size 300 Å, l × I.D. 250 × 4.6 mm). The mobile phase that contain aqueous 0.05M potassium dihydrogen phosphate buffer (pH 7): acetonitrile, (50: 50, %v/v). The method was linear over concentration ranges 5.0–50 μg mL−1 for OXC. Bioanalytical validation of the developed method was carried out according to US-FDA guidelines and revealed a good linear relations over a range of (5.0–50), (0.5–10), (0.05–0.15), and (1.0–10) μg mL−1 for OXC, M.P, P.P, and P.ST, respectively, with a correlation coefficient (R2) of more than 0.999. Limit of detection (LOD) were 1.15, 0.03, 0.01 and 0.04 μg mL−1 for OXC, M.P, P.P, and P.ST, respectively, Intra and inter-day precisions, calculated as percentage relative standard deviation (% RSD), were lower than 2.0%. The developed method can be applied for routine drug analysis, therapeutic drug monitoring and bioequivalence studies through the analysis of plasma samples taken from blood bank.

Зависимость кормовой ценности эспарцета песчаного от листовых подкормок

In the feed production system of the Lower Volga region, more than 60% of forage crops are located on irrigated lands. Only these lands can be considered a guaranteed source of sustainable food supply. More than 80% of the feed from their gross production is harvested from irrigated lands, therefore, studies on the dependence of the feed value of sandy esparcet on leaf fertilizing are certainly relevant. The aim of the research was to increase the efficiency of esparcet cultivation in the conditions of the Lower Volga region by improving the use of mineral fertilizers. Experiments to study the dependence of the feed value of esparcet in the form of green mass on leaf fertilizing with water-soluble mineral fertilizers were conducted from 2017 to 2023 on irrigation in the zone of light chestnut soils in the Prigorodnoye SEC of the Svetloyarsky district of the Volgograd region. Mineral fertilizers were applied in the form of leaf fertilizing during the period of active growth of the esparcet according to the following schemes: 1. Control (without leaf dressing); 2. Monophosphate at the rate of 0.5 kg/ha per top dressing; 3. Monophosphate with adhesive at the rate of 0.5 kg/ha per top dressing. As a result of the experiments conducted, it was found that in the variant using potassium monophosphate, the yield of the green mass of the Rusich variety was 8.2 t/ha, or 18.8% more, and in the variant using potassium monophosphate with an adhesive by 11.7 t/ha, or 26.8% more compared to the control variant. The largest accumulation of feed units of 12.8 t/ha was found in the Rusich variety on the variant of leaf fertilizing with potassium monophosphate with an adhesive, which turned out to be 0.6 t/ha more than in the experiment from 2017 to 2019. The highest content of digestible protein of 2.21 t/ha was found in the Rusich variety on a variant of leaf fertilizing with potassium monophosphate with an adhesive. The largest amount of metabolic energy of 101.7 GJ was contained in the Rusich variety on a variant of leaf fertilizing with potassium monophosphate with an adhesive. The lowest amount of metabolic energy was contained in the Sandy 22 variety in the control variant without leaf fertilizing and averaged 70.3 GJ for 2021-2023.

Rhamnolipids Enhance Bioremediation of Petroleum-Contaminated Soil

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 215952, “Enhancing Bioremediation of Petroleum-Contaminated Soil Using Rhamnolipids: A Combined Laboratory and Field Study,” by Pan Ni, Lehigh University; Yonglin Ren, SPE, Stepan Oilfield Solutions; and Derick G. Brown, Lehigh University, et al. The paper has not been peer reviewed. _ Hydrocarbon spills can occur at various stages of the oil and gas exploration and production process. Treating these spills onsite to avoid more-expensive excavation and incineration processes would be beneficial. The study outlined in the complete paper aims to optimize the use of rhamnolipid biosurfactants for enhancing the bioremediation of hydrocarbon-contaminated soil. The goal of this work was to explore the effects of rhamnolipid application on hydrocarbon degradation rate under both laboratory and field conditions and to examine the effects of this treatment on the indigenous soil microorganism population. Introduction The authors write that, to the best of their knowledge, previous research studies on rhamnolipid-based soil remediation focused on either laboratory or field tests and that comparison between laboratory-scale and field-scale tests is overlooked but necessary for practical applications. Materials and Methods Materials and Chemicals. The soil used for this work (23 kg for the laboratory test, 10 metric tons for the field test) was obtained from a contaminated site in Longford Mills, Canada. The soil properties are presented in Table 1 of the complete paper. The rhamnolipid stock solution featured 9.8 wt% rhamnolipid blends in deionized water. Another commercial remediation agent (enzyme-based) was used in the field test to compare with the performance of rhamnolipid. Ammonium chloride (NH4Cl) and potassium hydrogen phosphate (K2HPO4) also were used along with sodium hydroxide (NaOH). Experimental Setup. Both laboratory and field tests were ex-situ tests using simulated soil piles. The laboratory test was conducted for 193 days. For the laboratory experiments, an aerobic/anaerobic respirometer system equipped with a low-temperature incubator was used to monitor the in-situ oxygen uptake inside eight reactors (Fig. 1). Each reactor contained 250 g of soil with rhamnolipid doses of 0, 0.1, 0.5, and 1 g/kg. The temperature was set to 25°C. Inside each reactor was placed 10 mL of 4-M NaOH in a 20-mL glass beaker to adsorb the produced CO2. A parallel set of eight reactors was prepared and operated under the same conditions. The nutrients of nitrogen and phosphorous (NH4Cl and K2HPO4) were added at specific times based on the oxygen uptake rate monitored by the respirometer. To avoid the possible inhibition of the microbes in the soil as a result of high ionic strength (greater than 160 mM) in the soil pore water, NH4Cl and K2HPO4 were added so that the molar concentration in the soil pore water did not exceed 100 mM. The field test is being conducted in Longford Mills, Ontario, Canada, and is ongoing at the time of writing. For the field test, 10 metric tons of soil were mixed to achieve homogeneity before the preparation of the soil piles. Five different treatment conditions were examined using duplicate soil piles (10 piles total), with each consisting of 1 metric ton of soil. Nutrient addition was similar to that used in the laboratory tests. Temperature and moisture were monitored every few days at five points in each soil pile, and the pH was monitored once every month at five points.