Apparent Absorption Coefficient Research Articles

Arsenazo III-spectrophotometry for the determination of thorium content

ABSTRACT The complexation interaction between arsenazo III chromogenic agent and tetravalent thorium ion (Th4+) is the theoretical basis for the determination of thorium by spectrophotometry. In this paper, the effects of the acidity, temperature, interfering ions and Th4+ concentration on the absorbance and stability of arsenazo III-Th4+ solution by spectrophotometry were systematically studied. The results showed that the solutions to be tested had high absorbance values and stability only when the concentration of hydrochloric acid was greater than 6 mol·L−1. The absorbance decreased only 0.02 when the temperature was changed from 15°C to 40°C. The absorbance of arsenazo III-Th4+ solution at 662 nm showed a good linear relationship with the concentration of Th4+ under the same experimental environment (R2 = 0.9986), and the apparent molar absorption coefficient was 9.95 × 104 L·mol−1·cm−1, showing that thorium can be accurately quantitatively measured according to the Lambert-Beer law under these conditions.

Wavelength-dependent photoelectrochemical response demonstrated by the determination of acetaminophen and rutin in differential molecularly imprinted polymers strategy

Herein, the excitation wavelength-dependent responses of the molecularly imprinted polymer (MIP) photoelectrochemical (PEC) sensors were investigated, using acetaminophen (AP), rutin (RT) and perfluorooctanoate (PFOA) as the model templates, pyrrole as functional monomer, CuInS2@ZnS/TiO2 NTs as the basic photoelectrode. With wavelength λ > 240 nm, the photocurrent of MIPPFOA enhanced at higher concentrations of PFOA. With increasing AP concentration, the photocurrents of MIPAP could decline with λ < 271 nm, not change at λ = 270 nm, or increase with λ > 270 nm. As RT concentration increased, the photocurrents of MIPRT could decrease (λ < 431 nm), not change (λ = 431 nm) or increase (λ > 431 nm). The PEC responses depend on the comprehensive interaction of two contrary mechanisms from the template molecules within the MIP membrane. The photocurrent is enhanced by the role of the electron donor for photo-generated holes but attenuated due to the steric hindrance effect and the excitation light intensity loss via absorption or scattering. The apparent molar absorption coefficient of AP and RT within MIP membranes are 9.1–19.4 folds of those measured from dilute solutions. By using a routine UV lamp as the light source, the photocurrents of MIPRT at 254 nm and MIPAP at 365 nm were used to determine RT and AP, with the detection limits of 5.3 and 16 nM, respectively. The interference from the non-specific adsorption of interferents on the surfaces of MIPAP and MIPRT was reduced by one order of magnitude via a differential strategy.

Application of SPAC method and electromagnetic wave CT in karst detection of Wuhan Metro Line 8

In recent years, karst construction projects in the built-up area of Wuhan (capital of Hubei Province, China) are increasing, and the karst geological disasters have aroused social concerns. The actual engineering projects usually use shallow geophysical exploration methods to explore karst. This paper uses Spatial Auto-Correlation Method (SPAC) and electromagnetic Computerized Tomography (CT) to detect karst in urban built-up areas. Depending on the different physical properties of rock and soil, the SPAC method can better reveal the interface between soil and rock strata and the interface between soil layers. The electromagnetic CT method can identify strata according to the apparent absorption coefficient, which can better reveal the interface between soil and rock, the interface between the more intact and weathered rock. The SPAC method is mainly qualitative to measure the low-speed area, namely, the wrong geological body i.e., karst cave, but also can detect the fracture zone or filling mode of karst cave, and at the same time, cannot use exploration holes or logging observation. The electromagnetic CT method can accurately detect the location and scale of the karst caves and has a higher accuracy detecting karst bands. In addition, exploration holes or well logging observations are also expected to be conducted, and their detection effect is greatly affected by lithology.

Изучение реакции ионов Cu(II) с N-(бензоил)-N'-(фенилсульфонил)гидразином в аммиачных средах спектрофотометрическим методом

The reaction of complexation of N-(benzoyl)-N'-(phenylsulfonyl)hydrazine with Cu(II) ions in an ammonia medium has been studied. The absorption spectra of the reagent and its complex with Cu(II) ions have been recorded and analyzed. The optimal conditions for the formation of the complex compound were found: the pH range of complex formation; optimal time for color development; amount of photometric reagent. Under optimal conditions for the complex formation of BPSH with Cu(II) ions, a calibration graph was constructed. The Bouguer-Lambert-Beer law is fulfilled in the range from 0,5 to 1,75 mg Cu(II) in 25 ml of solution. The true (19389) and apparent (4708) molar light absorption coefficients were calculated. The methods of saturation, equilibrium shift, curve intersection, isomolar series, and conductometric titration were used to determine the molar ratios in a solution of a complex compound – [Сu(II)]:[BFSH] = 1:1 and 1:2. According to the Babko method, the conditional stability constant of the complex was calculated – 2,45∙1013. The convergence and correctness of the spectrophotometric technique were determined by the method of mathematical statistics.

Infrared intensities of methyl acetate, an interstellar compound - comparisons of three organic esters

The mid-infrared (IR) spectra of the simplest aliphatic esters have been studied in the past in the solid, liquid, and gas phases with an emphasis on vibrational frequencies and peak assignments. However, relatively little has been published on the IR intensities of the amorphous forms of these compounds. These IR intensities are of particular interest to the astrochemical community as they are needed to help quantify laboratory measurements of the formation and destruction of extraterrestrial molecules, including esters. Here we report and compare IR intensities of three organic esters: methyl formate, methyl acetate, and methyl propionate, all studied with the same equipment and procedures. Of these three esters, our main interest is with methyl acetate, for which little quantitative IR work is available. For each ester, we report apparent absorption coefficients and band strengths, and compare them to earlier work. We also have calculated the first IR optical constants for both amorphous and crystalline methyl acetate. We use our new results to measure vapor pressures and a sublimation enthalpy for methyl acetate and to comment on a radiation-chemical experiment with methyl acetate and how it can be better quantified.

Спектрофотометрическое определение ионовCo(II) сN-(2-гидроксибензоил)-N'-(п-тозил)гидразином в аммиачных средах

A technique has been developed for the spectrophotometric determination of Co(II) ions with N-(2-hydroxybenzoyl)-N'-(p-tosyl)hydrazine (GBSH) in an ammonia medium. The absorption spectra of the reagent and its complex with Co(II) ions have been recorded and analyzed. The optimal conditions for the formation of the complex compound were found: the pH range of complex formation; optimal time for color development; amount of photometric reagent. Under optimal conditions for the complexation of GBSG with Co(Ⅱ) ions, a calibration graph was constructed. The Bouguer-Lambert-Beer law is fulfilled in the range from 0.3 to 2.4 mg Co(II) in 25 ml of solution. The true and apparent molar light absorption coefficients were calculated. The true molar coefficient of light absorption of the complex compound GBSG with Co(Ⅱ) ions in an ammonia medium is 750. The molar ratios in the solution of the complex compound [Co(Ⅱ)]:[GBSG] = 1:1 and 1:2. The conditional stability constant of the GBSG complex with Co(Ⅱ) ions was calculated using the Babko method and it is 3.24∙1012. The convergence and correctness of the spectrophotometric technique were determined by the method of mathematical statistics.

Solvated Electron in Acetonitrile: Radiation Yield, Absorption Spectrum, and Equilibrium between Cavity- and Solvent-Localized States.

The equilibrium between a solvent cavity-localized electron, ecav-, and a dimeric solvent anion, (CH3CN)2•-, which are the two lowest energy states of the solvated electron in acetonitrile, has been investigated by pulse radiolysis at 233-353 K. The enthalpy and entropy for the ecav- to (CH3CN)2•- conversion amount to -11.2 ± 0.3 kcal/mol and -39.3 ± 1.2 cal/(mol K), corresponding to a 0.44 ± 0.35 equilibrium constant at 25 °C. The radiation yield of the solvated electron has been quantified using a Co(II) macrocycle that scavenges electrons with a 1.55 × 1011 M-1 s-1 rate constant. The apparent yield increases without saturation over the attainable scavenger concentration range, reaching 2.8 per 100 eV; this value represents the lower limit for the acetonitrile ionization yield in pulse radiolysis. The apparent molar absorption coefficient of (20.8 ± 1.5) × 103 M-1 cm-1 at 1450 nm and 20 °C for the solvated electron and individual vis-near-infrared (NIR) absorption spectra of ecav- and (CH3CN)2•- are derived from the data. Variances with previous reports are thoroughly discussed. Collectively, these results resolve several controversies concerning the solvated electron properties in acetonitrile and furnish requisite data for quantitative pulse radiolysis investigations in this commonly used solvent.

Effect of Boron Supplementation on Nutrient Utilization and Productive Performance of Peripartum Murrah Buffaloes.

Boron (B) has been established as a beneficial micronutrient for some farm animals. However, its impact on coping negative energy balance during transition and subsequent production performance needs critical perusal. Therefore, the present study was undertaken to determine the effect of B supplementation on productive performance, apparent nitrogen (N), and mineral utilization in peripartum Murrah buffaloes. Thirty advanced pregnant buffaloes (60days prior to expected date of calving) were allocated into three groups, i.e. control, B-200, and B-400, and supplemented with pharmacological concentration of B at 0, 200, and 400ppm, respectively, from 45days prior to expected date of calving till 120days post calving. Two metabolism trials were conducted (with animals having similar expected date of calving), one during prepartum (30days prior to the expected date of calving) and another during postpartum (90days post calving) phase to evaluate nutrient utilization and balance of N as well as minerals. Results revealed that B supplementation decreased (P < 0.05) overall plasma nonesterified fatty acids (NEFA), whereas plasma level of β-hydroxybutyric acid, insulin, triglyceride, and glucose did not differ (P > 0.05) among the groups. Dry matter intake, nutrient digestibility, and N balance remained unaffected with B supplementation. Higher (P < 0.05) apparent absorption coefficient for magnesium (Mg) and zinc (Zn) was observed in pregnant animals, while during lactation, absorption coefficient of calcium, Mg, and Zn was increased (P < 0.05) in B-supplemented groups. Hence, it can be concluded that alteration in NEFA concentration and variation in apparent absorption coefficient of minerals with B supplementation suggest its role in energy and mineral metabolism. However, further investigations are required to determine the underlying mechanism of action for the present findings.

Experimental investigation of a light extinction based sensor assessing particle size and distribution in an oil system

Optical particle counters (OPCs) based on the light extinction measurement scheme are widely used in the industry for monitoring the level of wear debris in lubricating oil systems. In this work it is investigated how model-based size estimation and OPC output data can be correlated. Spherical metal coated 5–20 μm diameter particles were used in a laboratory oil system and monitored using an OPC. The raw OPC output data were extracted with the purpose of estimating the true particle size. Distribution parameters has been deducted from detected minima in output signals for each particle diameter using a half-normal fit centered at the detected kernel peak. Experiments with different sized particles showed that signal minima amplitude distributions differ between particle diameters thus, clearly showing the discrimination ability of the OPC. Furthermore, to obtain OPC based true size determination, the apparent absorption coefficient of the micrometer sized particles must be considered. Thus, reducing the maximum deviation between true and OPC determined diameter to 13%.

Preparation and In Vitro and In Vivo Evaluation Of Panax Notoginseng Saponins-loaded Nanoparticles Coated with Trimethyl Chitosan Derivatives

In this study, novel Panax notoginseng saponins (PNS)-loaded nanoparticles coated with the Trimethyl chitosan (TMC) derivatives TMC-VB12 and TMC-Cys (PPTT-NPs) were developed to improve the oral absorption of the constituents. PPTT-NPs were prepared by the double emulsion method and showed different encapsulation effects on the major components, including Rg1, Rb1, and R1, in PNS. In vivo, the absorption rate constant and apparent absorption coefficient of PPTT-NPs were higher than PNS solution. These findings preliminarily proved that PPTT-NPs can promote intestinal absorption to a certain extent. The pharmacokinetic results indicated that the blood concentration and the area under the curve of Rg1 and Rb1 in the PPTT-NPs were higher than Xueshuantong capsules. The cell viability of PPTT-NPs was above 90% within 25-150 μg/mL. PPTT-NPs promoted the cellular uptake of PNS by receptor-mediated endocytosis. In summary, NPs coated with TMC-VB12 and TMC-Cys can be used as promising drug delivery systems.

Frequency-dependent analysis of ultrasound apparent absorption coefficient in multiple scattering porous media: application to cortical bone

The effect of matrix viscoelastic absorption on frequency-dependent attenuation in porous structures mimicking simplified cortical bone is addressed in this numerical study. An apparent absorption is defined to quantify the difference between total attenuation (resulting from both absorption and scattering) and attenuation exclusively due to scattering. A power-law model is then used to describe the frequency-dependent apparent absorption as a function of pore diameter and density. The frequency response of the porous structures to a Gaussian pulse is studied to determine the frequency range over which the system can be considered linear. The results show that for low scattering regimes (normalized frequency 0.80), the system and its apparent absorption can be considered linear. Hence, the total attenuation coefficient results from the summation of scattering and absorption coefficients. However, for highly scattering regimes, the system can no longer be considered linear, as the apparent absorption vs. frequency deviates from a linear trend. As the pore density increases, the apparent absorption coefficient increases as well.

Growth performance, bioavailability of toxic and essential elements and nutrients, and biofortification of iodine of rainbow trout (Onchorynchus mykiss) fed blends with sugar kelp (Saccharina latissima)

Aquaculture production is demanding novel feed ingredients that reflect natural marine nutrient levels, that are also essential to humans. In this regard, biofortification through addition of iodine-rich sugar kelp in feed formulations was assessed in a 12 week rainbow trout trial. Yttrium inclusion in feed allowed determinations of apparent absorption coefficients of essential and potentially toxic elements and apparent digestibility coefficient of nutrients. E.g. apparent absorption coefficients in trouts fortified feed with 1–4% dw kelp were 67–61% As, 32–40% Cd, <5% Fe; 80–83% I; 66-58% Se. Iodine concentrations in feed up to 239 mg/kg (~4% kelp) was proportional to iodine accumulation in trout fillets (R2 = 1.00) with 0.5% transfer ratio. Feed iodine concentrations up to 117 mg/kg (~2% kelp) did not affect growth performance negatively, but increased significantly protein efficiency ratio after eight weeks feeding. However, 4% kelp meal inclusion affected final growth and hepato somatic index, and caused histomorphological changes in the intestine. All fillets had low toxic element concentrations (As, Cd, Hg, Pb). The potential applicability of Saccharina latissima as feed ingredient to tailor iodine concentration in farmed fish is evident. Consuming of a 160 g fillet (2% kelp) contributes ~60% of recommended daily iodine intake for adults.

Evaluation of effectiveness of silicoorganic treatments using hydric properties

In this work, the effectiveness of silicoorganic treatments for the consolidation, with or without waterproofing, of silicified stones (one conglomerate and four sandstones) from Zamora is analyzed, provided that these treatments are applied in the same way. Changes in the following properties have been monitored: total and free porosity, real and apparent density, absorption coefficient, imbibition coefficient, and capillary absorption coefficient. These intrinsic stone properties and the treatments employed have a significant effect on changes in these variables and lead to differences in the transport of fluid in the stone. This is the first time that the Canonical Biplot has been applied to this type of data to determine the control of the effectiveness of silicoorganic treatments applied to rocks. It was observed that the double action treatment RC80, which includes both waterproofing and consolidating, is more effective than the consolidating treatment RC70.

Effect of Evening Primrose Oil-Based Polyol on the Properties of Rigid Polyurethane⁻Polyisocyanurate Foams for Thermal Insulation.

The article presents the results of research on the synthesis of a new biopolyol based on evening primrose oil, and its use in the production of rigid polyurethane–polyisocyanurate foams intended for thermal insulation. The obtained biopolyol was subjected to analytical, physicochemical, and spectroscopic tests (Fourier transform infrared (FTIR), 1H NMR, 13C NMR) to confirm its suitability for the synthesis of polyurethane materials. Then, it was used for the partial replacement of the petrochemical polyol in the polyurethane formulation. Obtained rigid polyurethane–polyisocyanurate foams are characterized by a lower apparent density, brittleness, water absorption, and thermal conductivity coefficient λ. In addition, foams modified by biopolyols had a higher content of closed cells and higher aging resistance. The results of the conducted research showed that the use of the biopolyol based on evening primrose oil may be an alternative to petrochemical polyols. The research presented herein is perfectly consistent with the trends of sustainable development and the philosophy of green chemistry.

Evaluating ultraviolet (UV) based photochemistry in optically complex coastal waters using the Hyperspectral Imager for the Coastal Ocean (HICO)

Knowledge of light partitioning into different optically active constituents, particularly chromophoric dissolved organic matter (CDOM) in the ultraviolet (UV) is indispensable for understanding UV dependent biogeochemical issues including photochemical processes in optically complex waters. Herein a new approach is presented to investigate photochemistry by blending two ocean color algorithms, namely the composite SeaUV (Cao et al., 2014) and the SeaCDOM (Cao and Miller, 2015) algorithms, and applying them to visible remote sensing reflectance (Rrs) measured using the Hyperspectral Imager for the Coastal Ocean (HICO). As illustrated using photochemical carbon monoxide (CO) production from CDOM, this model approach allows high resolution examination of UV optical details with estimates of both depth-specific and depth-integrated photoproduction rates in a dynamic estuarine/coastal environment. Decoupled retrievals of inherent and apparent optical properties (i.e. diffuse attenuation coefficient (Kd) and CDOM absorption coefficient (ag)) using two distinct ocean color algorithms over the entire UV spectrum allow a synoptically dynamic view of CDOM's contribution to light attenuation (ag/Kd). This provides new potential to probe UV processes in complex coastal waters on regional as well as global scales using remote sensing of ocean color.

Effect of scattering and porosity on the apparent absorption in porous biphasic structures—Application to cortical bone

In this in-silico study, the attenuation coefficient in porous structures mimicking simplified cortical bone is calculated both in presence and absence of absorption, to isolate the effect of scattering on attenuation. Pore distributions with various pore concentrations (5–25 pore/mm2) and diameters (40–120 μm) are generated. The propagation of 8 MHz plane waves is simulated using a 2D FDTD package. The attenuation coefficient is measured by fitting the exponential decay of the signal amplitude in the frequency domain during propagation in the absence or presence of absorption (coefficient of 10 dB/cm/MHz to mimic bone tissue), for different pore concentrations and sizes. The difference between total attenuation and scattering attenuation coefficients (obtained with no absorption) is defined as the apparent absorption coefficient. For ka 1, increasing porosity leads to a higher apparent absorption, indicating a higher impact of absorption, even though the absorption coefficient and the overall volume fraction of absorbing material (solid phase) were kept constant. This suggests complex interactions between the wave and the structure, and could be attributed to longer propagation paths in the solid phase due to multiple scattering by the pores.In this in-silico study, the attenuation coefficient in porous structures mimicking simplified cortical bone is calculated both in presence and absence of absorption, to isolate the effect of scattering on attenuation. Pore distributions with various pore concentrations (5–25 pore/mm2) and diameters (40–120 μm) are generated. The propagation of 8 MHz plane waves is simulated using a 2D FDTD package. The attenuation coefficient is measured by fitting the exponential decay of the signal amplitude in the frequency domain during propagation in the absence or presence of absorption (coefficient of 10 dB/cm/MHz to mimic bone tissue), for different pore concentrations and sizes. The difference between total attenuation and scattering attenuation coefficients (obtained with no absorption) is defined as the apparent absorption coefficient. For ka 1, increasing porosity leads to a higher appa...

Precise Determination of the Temperature Gradients in Laser-irradiated Ultrathin Magnetic Layers for the Analysis of Thermal Spin Current

We investigated the temperature distribution induced by laser irradiation of ultrathin magnetic films by applying a finite element method (FEM) to the finite difference time domain (FDTD) representation for the analysis of thermal induced spin currents. The dependency of the thermal gradient (∇T) of ultrathin magnetic films on material parameters, including the reflectivity and absorption coefficient were evaluated by examining optical effects, which indicates that reflectance (R) and the apparent absorption coefficient (α*) play important roles in the calculation of ∇T for ultrathin layers. The experimental and calculated values of R and α* for the ultrathin magnetic layers irradiated by laser-driven heat sources estimated using the combined FDTD and FEM method are in good agreement for the amorphous CoFeB and crystalline Co layers of thicknesses ranging from 3~20 nm. Our results demonstrate that the optical parameters are crucial for the estimation of the temperature gradient induced by laser illumination for the study of thermally generated spin currents and related phenomena.

Effects of Small-Scale Gold Mining Tailings on the Underwater Light Field in the Tapajós River Basin, Brazilian Amazon

Artisanal and Small-scale Gold Mining (ASGM) within the Amazon region has created several environmental impacts, such as mercury contamination and changes in water quality due to increased siltation. This paper describes the effects of water siltation on the underwater light environment of rivers under different levels of gold mining activities in the Tapajós River Basin. Furthermore, it investigates possible impacts on the phytoplankton community. Two field campaigns were conducted in the Tapajós River Basin, during high water level and during low water level seasons, to measure Inherent and Apparent Optical Properties (IOPs, AOPs), including scattering (b) and absorption (a) coefficients and biogeochemical data (sediment content, pigments, and phytoplankton quantification). The biogeochemical data was separated into five classes according to the concentration of total suspended solids (TSS) ranging from 1.8 mg·L−1 to 113.6 mg·L−1. The in-water light environment varied among those classes due to a wide range of concentrations of inorganic TSS originated from different levels of mining activities. For tributaries with low or no influence of mining tailings (TSS up to 6.8 mg·L−1), waters are relatively more absorbent with b:a ratio of 0.8 at 440 nm and b660 magnitude of 2.1 m−1. With increased TSS loadings from mining operations (TSS over 100 mg·L−1), the scattering process prevails over absorption (b:a ratio of 10.0 at 440 nm), and b660 increases to 20.8 m−1. Non-impacted tributaries presented a critical depth for phytoplankton productivity of up to 6.0 m with available light evenly distributed throughout the spectra. Whereas for greatly impacted waters, attenuation of light was faster, reducing the critical depth to about 1.7 m, with most of the available light comprising of red wavelengths. Overall, a dominance of diatoms was observed for the upstream rivers, whereas cyanobacteria prevailed in the low section of the Tapajós River. The results suggest that the spatial and temporal distribution of phytoplankton in the Tapajós River Basin is not only a function of light availability, but rather depends on the interplay of factors, including flood pulse, water velocity, nutrient availability, and seasonal variation of incoming irradiance. Ongoing research indicates that the effects of mining tailings on the aquatic environment, described here, are occurring in several rivers within the Amazon River Basin.

Estimating mineral requirements of Nellore beef bulls fed with or without inorganic mineral supplementation and the influence on mineral balance.

The objectives of this study were to quantify the mineral balance of Nellore cattle fed with and without Ca, P, and micromineral (MM) supplementation and to estimate the net and dietary mineral requirement for cattle. Nellore cattle ( = 51; 270.4 ± 36.6 kg initial BW and 8 mo age) were assigned to 1 of 3 groups: reference ( = 5), maintenance ( = 4), and performance ( = 42). The reference group was slaughtered prior to the experiment to estimate initial body composition. The maintenance group was used to collect values of animals at low gain and reduced mineral intake. The performance group was assigned to 1 of 6 treatments: sugarcane as the roughage source with a concentrate supplement composed of soybean meal and soybean hulls with and without Ca, P, and MM supplementation; sugarcane as the roughage source with a concentrate supplement composed of soybean meal and ground corn with and without Ca, P, and MM supplementation; and corn silage as the roughage source with a concentrate supplement composed of soybean meal and ground corn with and without Ca, P, and MM supplementation. Orthogonal contrasts were adopted to compare mineral intake, fecal and urinary excretion, and apparent retention among treatments. Maintenance requirements and true retention coefficients were generated with the aid of linear regression between mineral intake and mineral retention. Mineral composition of the body and gain requirements was assessed using nonlinear regression between body mineral content and mineral intake. Mineral intake and fecal and urinary excretion were measured. Intakes of Ca, P, S, Cu, Zn, Mn, Co, and Fe were reduced in the absence of Ca, P, and MM supplementation ( < 0.05). Fecal excretion of Ca, Cu, Zn, Mn, and Co was also reduced in treatments without supplementation ( < 0.01). Overall, excretion and apparent absorption and retention coefficients were reduced when minerals were not supplied ( < 0.05). The use of the true retention coefficient instead of the true absorption coefficient provided a better estimate of mineral requirements. Dietary mineral requirements were lower for P, Cu, and Zn and greater for Fe compared with previously published recommendations. This study provides useful information about mineral requirements and mineral supplementation to obtain adequate dietary mineral supply of Nellore cattle in tropical conditions.

Intestinal absorption of Ginseng Radix et Rhizoma extract combined with Acori Tatarinowii Rhizoma in rats

To investigate the changes in intestinal absorption of ginsenosides Rg₁, ginsenosides Re and ginsenosides Rd after combined administration of Ginseng Radix et Rhizoma extract and Acori Tatarinowii Rhizoma, in order to confirm whether the combined administration is scientific and rational, and provide experimental basis for pharmaceutical studies of the formula. An in vivo single-pass perfusion method was performed to study the effect of various concentrations of ginsenosides Rg₁, ginsenosides Re, ginsenosides Rd on the intestinal absorption at duodenum, jejunum, ileum and colon. The concentrations of ginsenosides Rg₁, ginsenosides Re, ginsenosides Rd were determined by RP-HPLC.The absorption rate constant (Ka) and the apparent absorption coefficient(Papp) of ginsenosides Rg₁, ginsenosides Re, ginsenosides Rd were calculated.The result showed that ginsenosides Rg₁, ginsenosides Re, ginsenosides Rd had a high absorption rate on upper portion of the small intestine. The drug concentration had not significantly impact on the absorption rate, suggesting that ginsenosides Rg₁, ginsenosides Re, ginsenosides Rd were absorbed via passive diffusion.Volatile oil of Acori Tatarinowii Rhizoma had obvious effect in enhancing intestinal absorption of ginsenosides Rg₁, ginsenosides Re, ginsenosides Rd, indicating that the combined administration of Ginseng extract and Acorus tatarinowii Schott is scientific and rational.