Determination of genotoxic impurities of aromatic aldehydes in pharmaceutical preparations by high performance liquid chromatography after derivatization with N-Cyclohexyl-4-hydrazino-1,8-naphthalenediimide.

The detection of aromatic aldehydes, considered potential genotoxic impurities, holds significant importance during drug development and production. Current analytical methods necessitate complex pre-treatment processes and exhibit insufficient specificity and sensitivity. This study presents the utilization of naphthalenediimide as a pre-column derivatisation reagent to detect aromatic aldehyde impurities in pharmaceuticals via high-performance liquid chromatography (HPLC). We screened a series of derivatisation reagents through density functional theory (DFT) and investigated the phenomenon of photoinduced electron transfer (PET) for both the derivatisation reagents and the resulting products. Optimal experimental conditions for derivatisation were achieved at 40 °C for 60 min. This approach has been successfully applied to detect residual aromatic aldehyde genotoxic impurities in various pharmaceutical preparations, including 4-Nitrobenzaldehyde, 2-Nitrobenzaldehyde, 1,4-Benzodioxane-6-aldehyde, and 5-Hydroxymethylfurfural. The pre-column derivatisation method significantly enhanced detection sensitivity and reduced the limit of detection (LOD), which ranged from 0.002 to 0.008 µg/ml for the analytes, with relative standard deviations < 3 %. The correlation coefficient (R2) >0.998 demonstrated high quality. In chloramphenicol eye drops, the concentration of 4-Nitrobenzaldehyde was measured to be 8.6 µg/mL below the specified concentration, with recoveries ranging from 90.0 % to 119.2 %. In comparison to existing methods, our work simplifies the pretreatment process, enhances the sensitivity and specificity of the analysis, and offers comprehensive insights into impurity detection in pharmaceutical preparations.

Rapid Analysis of Estrogens in Meat Samples by High Performance Liquid Chromatography with Fluorescence Detection.

A novel reagent named 4-(N-methyl-1,3-dioxo-benzoisoquinolin-6-yl-oxy)benzene sulfonyl chloride (MBIOBS-Cl) for the determination of estrogens in food samples by high-performance liquid chromatography (HPLC) with fluorescence detection has been developed. Estrogens could be easily labeled by MBIOBS-Cl in Na2CO3-NaHCO3 buffer solution at pH 10.0. The complete labeling reaction for estrogens could be accomplished within five minutes, the corresponding derivatives exhibited strong fluorescence with the maximum excitation and emission wavelengths at 249 nm and 443 nm, respectively. The derivatization conditions, such as the molar ratio of reagent to estrogens, derivatization time, pH, temperature, and buffers were optimized. Derivatives were sufficiently stable to be efficiently analyzed by HPLC with a reversed-phase Agilent ZORBAX 300SB-C18 column with a good baseline resolution. Excellent linear correlations were obtained for all estrogen derivatives with correlation coefficients greater than 0.9998. Ultrasonic-Assisted extraction was used to optimize the extraction of estrogens from meat samples with a recovery higher than 82%. The detection limits (LOD, S/N = 3) of the method ranged from 0.95 to 3.3 µg· kg-1. The established method, which is fast, simple, inexpensive, and environment friendly, can be successfully applied for the detection of four steroidal estrogens from meat samples with little matrix interference.

Phragmites australis + Typha latifolia Community Enhanced the Enrichment of Nitrogen and Phosphorus in the Soil of Qin Lake Wetland.

Aquatic plants play an essential role and are effective in mitigating lake eutrophication by forming complex plant-soil system and retaining total nitrogen (TN) and phosphorus (TP) in soils to ultimately reduce their quantities in aquatic systems. Two main vegetation types (Phragmites australis community and P. australis + Typha latifolia community) of Qin Lake wetland were sampled in this study for the analysis of TN and TP contents and reserves in the wetland soils. The results showed that (1) the consumption effect of Qin Lake wetland on soluble N was much more significant than on soluble P. (2) The efficiency of TN enrichment in wetland soil was enhanced by vegetation covering of P. australis and T. latifolia. (3) Wetland soil P was consumed by P. australis community and this pattern was relieved with the introduction of T. latifolia. (4) According to the grey relativity analysis, the most intensive interaction between plants and soil occurred in summer. In addition, the exchange of N in soil-vegetation system primarily occurred in the 0-15 cm soil layer. Our results indicated that vegetation covering was essential to the enrichment of TN and TP, referring to the biology-related fixation in the wetland soil.

[Effects of nitrogen fertilization on fine root lifespan of Fraxinus mandshurica and Larix gmelinii].

Root observation tubes (minirhizotrons) were used to study the effects of nitrogen addition on the fine root growth of Fraxinus mandshurica and Larix gmelinii, with the correlations between the fine root lifespan and nitrogen availability analyzed. After the nitrogen addition, the fine root number of F. mandshurica and L. gmelinii had a decreasing trend, but the fine root diameter became larger and the branching ratio decreased. The survival rate of F. mandshurica fine roots increased, and the median root lifespan prolonged 105 days, compared with the control. No significant responses to the nitrogen addition were observed in the survival rate of L. gmelinii fine roots. The first-order fine roots with smaller diameter, the roots in surface soil (0-15 cm), and the fine roots newly born in spring and summer were vulnerable to extend their lifespan by nitrogen addition, suggesting that the fine roots with higher physiological activity were easily to be affected by nitrogen fertilization.

[Effects of fertilization on fine root diameter, root length and specific root length in Larix kaempferi plantation].

With 16 years old Larix kaempfersoil plantation in the mountainous area of eastern Liaoning Province as test object, this paper studied the effects of fertilization on the fine root diameter, root length, and specific root length (SRL) of the first to fifth order roots. The results showed that with ascending root orders, the mean fine root diameter and root length increased, while the SRL decreased significantly. Among the five order roots, the first order roots were the thinnest in diameter, the shortest in length, and the highest in SRL, but the fifth order roots were in reverse. The variance coefficients for the fine root diameter, root length, and SRL increased from the first to the fifth order roots. Except for the first order roots, soil depth had no significant influence on the fine root diameter, root length and SRL. Fertilization affected the fine root diameter, root length, and SRL of the first and the second order roots significantly, hut had little effects on other order roots. N fertilization decreased the mean diameter of the first and the second order roots significantly, and N or N + P fertilization decreased the mean length of the first order roots in surface soil (0-10 cm) significantly. The SRL of the first order roots in surface soil increased significantly under N fertilization.

[Effects of fertilization on fine root biomass of Larix kaempferi plantation].

With 16 years old Larix kaempferi plantation in eastern mountain area of Liaoning Province as test object, this paper studied its total fine root biomass, fine root biomass at different soil depths, and biomass of different root orders under effects of fertilization. The results showed that compared with no fertilization, applying N decreased the total fine root biomass significantly (P < 0.05), while the difference between applying P and N + P was not significant. The fine root biomass in top soil (0-10 cm) was significantly (P < 0.01) higher than that in subsoil (10-20 cm), and in all treatments, it accounted for 64%-73% of the total. The effects of fertilization on fine root biomass varied with soil depth and root orders. In top soil, N fertilization decreased five orders (except the second order) fine root biomass significantly (P < 0.05), while P and P + N fertilization had no significant effects (P > 0.05), except the fifth order root in treatment P, and the second order root in treatment P + N (P < 0.05). In subsoil, treatments N and P had no effects on five orders fine root biomass (P > 0.05), while treatment N + P increased the first order fine root biomass significantly (P < 0.05).

[Application of minirhizotron in fine root studies].

Due to the production, death, and decomposition of fine root, its turnover plays an important role in carbon allocation and nutrient cycling in terrestrial ecosystems. Some methods such as sequential root coring, compartmental flow model, and ingrowth core have been widely used in collecting root biomass data and estimating fine root turnover, but failed in monitoring the dynamics of fine root due to its simultaneous production and death. Minirhizotron is a nondestructive in situ method for studying the dynamics of fine root, which allows the simultaneous measurement of fine root growth and mortality. This paper reviewed the application of minirhizotron in fine root studies, with the focus on minirhizotron tube installation, image collection, data extraction, and calculation parameters. In a case study, the total fine root length, fine root length density per unit volume, fine root length density per unit area, fine root biomass density, and fine root production and mortality of Fraxinus mandshurica and Larix gmelini were calculated, and the results showed that minirhizotron method was feasible in studying the processes of fine root development, eclipse, death, and decomposition. The factors affecting fine root measurement and its precision mainly included the quality and quantity of tube installation, sampling interval and quantity, and analysis technique of images, etc. Soil texture, tube material, and disturbance of light on root were also the factors affecting the precision of the method. How to improve the measurement precision of minirhizotron would be the critical problem in future study.

[Productivity and species diversity of artificial broad-leaved Korean pine forests in eastern Liaoning mountainous areas].

An investigation in the typical plots of 20-yr artificial broad-leaved Korean pine forests in eastern Liaoning mountainous areas showed that the productivity of mixed forests Pinus koraiensis-Betula platyphylla, P. koraiensis-Alnus tinctoria, and P. koraiensis-Fraxrinus mandshurica was 6.529, 4.966 and 5.682 t x hm(-2) x yr(-1), respectively, much higher than that of pure Korean pine forest (3.812 t x hm(-2) x yr(-1)), while mixed forests P. koraiensis-Kalopanax septemlobus and P. koraiensis-Tilia amurensis had a productivity of 2.945 and 2.84 t x hm(-2) yr(-1), respectively, lower than that of pure Korean pine forest. The plant species diversities of arbor, shrub and herb layers of artificial broad-leaved Korean pine forests were all higher than those of pure Korean pine forests. The plant species number in pure Korean pine forests only accounted for 42%-52% of artificial broad-leaved Korean pine forests, and the tree number of vegetation only accounted for 11%-37% of mixed forests. These results suggested that artificial broad-leaved Korean pine forests could provide the chances for the succession of secondary forest systems to regional climax, but it would take a long time to reach the climax.