Ongoing procedure performance verification (OPPV) of an analytical procedure is the process of ensuring it continues to meet its intended use after completion of validation. On the basis of previous studies, this paper further discussed the indicators of ongoing procedure performance verification (including system suitability indicators and reported values, etc.) and the implementation of analysis tools (control charts), and demonstrated the specific operation steps of ongoing procedure performance verification with examples. It is hoped that this paper will provide new ideas for the accurate and standardized procedure verification in the pharmaceutical field, especially in the enterprises and regulatory departments.

Long-acting injectable formulations are preferred over conventional formulations for the treatment of chronic diseases. The regulatory guidelines and pharmacopoeia have remained silent on dissolution methods for long-acting injectable formulations due to their diverse nature. The lack of compendial method for dissolution testing increases the duration of approval process for long-acting injectable formulations. This article reviews various dissolution methods used to study in vitro drug release profile of long-acting injectable formulations. Compendial as well as noncompendial methods, such as-flow-through cell method, sample and separate method, the dialysis method are used by researchers for drug release profile of long-acting injectable formulations. This review article also highlights the advantages and disadvantages of reported dissolution methods. The compiled work will help the researchers in designing the bio-relevant dissolution method and expedite the development of long-acting injectable formulations.

Objective: To establish an HPLC method of the content and related substances of compound amino acid injection(3AA). Methods: RP-HPLC was adopted to determine compound amino acid injection(3AA), combining with the use of two-dimensional column switching-LC/MSⁿ method was applied to separate and identify the impurities. The determination was performed on Capcell PAK AQ C₁₈(250 mm×4.6 mm, 3 μm) column with 0.2 mol·L^-1 sodium dihydrogen phosphate solution (adjusted pH to 2.8 with phosphoric acid) -acetonitrile (98∶2) as mobile phase at the flow rate of 1.0 mL·min^-1. The column temperature was 40 ℃, and the detection wavelength was 210 nm. And the injection volume was 20 μL. The LC/MSⁿ method was performed on a Thermo Accucore AQ C₁₈ (100 mm×4.6 mm, 2.6 μm) column with 0.1% formic acid solution as mobile phase A, 0.1% formic acid solution-acetonitrile as mobile phase B, at a flow rate of 0.4 mL·min^-1, and at a column temperature of 40 ℃. The mass spectrometry conditions were performed using an ESI ionisation source in the positive-ion scanning mode with a scan range of m/z 100-1 000, and the secondary mass spectrum was carried out by data-dependent scanning. Results: The related substances were completely separated from the main constituents in RP-HPLC. The standard curve of valine was linear over the range of 1.263-5.050 mg·mL^-1, with the average recovery of 99.0% (n=9). The standard curve of isoleucine was linear over the range of 1.350-5.402 mg·mL^-1, with the average recovery of 99.4%(n=9). The standard curve of leucine was linear over the range of 1.647-6.588 mg·mL^-1, with the average recovery of 99.5%(n=9). The main impurities in the three batches of samples were all process impurities introduced from the raw materials, with methionine content of 4.344 μg·mL^-1, 3.751 μg·mL^-1, 4.503 μg·mL^-1, respectively, phenylalanine content of 4.636 μg·mL^-1, 4.889 μg·mL^-1, 4.753 μg·mL^-1, respectively. The maximum single impurity contents were 0.01%, 0.02% and 0.01%, respectively. Conclusion: The method is proved by the methodology validation that it can be used for the quality control of compound amino acid injection(3AA).

Bioassays play a key role in the development and quality control of biological products, and the research on them has also made great progress in recent years. Here, the historical process of bioassays was reviewed. Then- the current contents about bioassays in pharmacopoeia and technical guidelines weresorted out. At last, the latest progress related to bioassays was summarized and analyzed including the introduction of new concepts such as analytical procedure, method life cycle and analytical target profile.This paper might provide a systematical reference for the people work in the biopharmaceutical field to fully understand the bioassays and related guidelines. Meanwhile, it can also provide a theoretical support for drug researchers to establish scientific and reliable bioassays.

The change of analytical procedure, a part of the entire lifecycle of a method, is increasingly valued with the emergence of new technologies, the increasing demand for product quality, 3R, environmental protection, and cost reduction requirements. This paper refers to the latest progress in the study of counterpart law at home and abroad, systematically classifies changes of analytical procedures from the perspective of methodology, and discusses the differences between different types of changes and the evaluation criteria and implementation approaches of analytical procedures after procedure changes.

Objective: To establish the HPLC characteristic chromatogram for Gujing Maisiha tablets, and evaluate the quality using chemical pattern recognition. Methods: The Welch Xtimate C₁₈ column (250 mm × 4.6 mm, 5 μm) was used and the mobile phases were acetonitrile (A) and 0.1% formic acid (B) in gradient elution (0-10 min,5%A→15%A;10-20 min,15%A;20-40 min,15%A→40%A;40-65 min,40%A→70%A; 65-66 min,70%A→90%A;66-80 min,90%A;80-81 min,90%A→5%A;81-85 min,5%A). The detection wavelength was 254 nm. The column temperature was 35 ℃ and the flow rate was 1.0 mL·min^-1. Gujing Maisiha tablets were analyzed to construct characteristic chromatogram. The quality of Gujing Maisiha tablets was assessed through similarity evaluation, cluster analysis, principal component analysis (PCA), and partial least squares discriminant analysis (PLS-DA). Results: The characteristic chromatogram of Gujing Maisiha tablets was established, which contained the twenty-eight distinct peaks, and seven compounds identified as gallic acid, chlorogenic acid, picrocrocin, isoquercitrin, crocin-Ⅰ, crocin-Ⅱ, eugenol. The similarities for the ten batches of Gujing Maisiha tablets were more than 0.98, with no significant difference observed. Cluster analysis segregated the samples into two distinct groups according to the Euclidean distance of 10, which was consistent with the results of PCA analysis. PLS-DA analysis screened out five components from Flos Caryophylli, Rosae Rugosae Flos, Olibanum that may cause differences between samples. Conclusion: The method of HPLC characteristic chromatogram of Gujing Maisiha tablets is effective, feasible and reproducible, which can provide reference for the study of quality standard of this product.

Objective: To compare the quality of wild and cultivated Arnebiae Radix,using macroscopic investigation and chemometric analysis of the different components in wild and cultivated Arnebiae Radix from three different habitats. Methods: Wild and cultivated Arnebiae Radix were collected and their macroscopic features were compared. Using the ACQUITY UPLC BEH C₁₈ (2.1 mm×100 mm, 1.7 μm) column, with acetonitrile-0.05% formic acid water as the mobile phase, the contents of D-shikonin, acetylshikonin, β-acetoxyisovalerylshikonin, isobutyrylshikonin, β,β’-dimethylacrylalkannin and isovalerylshikonin in 48 batches of wild and cultivated Arnebiae Radix were determined. The detection wavelength was 275 nm and the flow rate was 0.2 mL·min^-1. PCA and OPLS-DA were performed to reveal the differential components of wild and cultivated Arnebiae Radix. Results: There were great differences in macroscopic features of wild and cultivated Arnebiae Radix, and the linear relationship between the contents of six naphthoquinone components was good. The correlation coefficients were above 0.999, the average recovery rates were 93.4%-102.9%, and the RSDs were less than 3.0%. The contents of six components in different batches of wild and cultivated Arnebiae Radix were quite different, and the contents of D-shikonin and acetylshikonin in wild products were significantly higher than those in cultivated products, indicating that there were still certain differences between wild products and cultivated products. The PCA model established could distinguish wild products and cultivars, and two differentiating components in wild products and cultivars were revealed by OPLS-DA, namely isobutyryl shikonin, β,β’-dimethylacrylalkannin. Conclusion: By comparing the core size, cork curl degree and specific odor of wild and cultivated products, the two can be identified. The established content determination method is repeatable, specific, stable and feasible. The differential components in wild and cultivated Arnebiae Radix in three different regions are identified, which provides a basis for the quality control of Arnebiae Radix and provides ideas for expanding the source of Arnebiae Radix.

Stem cells have varying degrees of proliferation, self-renewal, and differentiation potential, and can be applied in regenerative medicine and the treatment of various diseases. To ensure safety and effectiveness of stem cell products, it is important to establish quality control methods and standards. Herein, we review the regulations and guidelines for stem cell products, and provide an overview of the detection assays on the basic biological characteristics, microbiological safety, biological safety, biological effectiveness and other conventional testing methods and quality research methods for stem cells. We further describe the quality research methods for genetically modified stem cell products, functional cells derived from stem cells, and extracellular vesicles, etc.

Objective: To explore the biological function methods of mesenchymal stem cells(MSCs) for quality analysis. Methods: The surface markers of MSCs were detected by flow cytometry. MSCs osteogenic differentiation was induced by ascorbic acid and β-glycerophosphate sodium, etc., followed by Alizarin Red S staining. MSCs adipogenic differentiation was induced by IBMX, Rosiglitazone, etc., followed by Oil Red O staining. MSCs could differentiate into chondrocytes with treatment of ITS and TGFβ3, etc., followed by Alcian Blue staining. Cell co-culture of THP-1-macrophage with MSCs and ELISA assay were applied to detect the effects of MSCs on macrophage polarization. The expression levels of IL-10 and TNF α in the cell co-culture supernatant were detected by ELISA. To observe the effects of MSCs on lymphocyte proliferation, MSCs cultured with PBMCs, which were labeled with CFSE and activated by CD3/CD28, followed by flow cytometry. Results: The expression of MSCs surface markers, CD105, CD73, and CD90, was more than 95% respectively, while the expression of CD45, CD34, CD14, CD19, and HLA-DR expression was less than 2%. MSCs osteogenic differentiation assay showed red calcium nodules. Red lipid vacuoles were observed in MSCs adipogenic induction differentiation. Furthermore, MSCs have the differentiation potential to chondrocyte spheroids, and typical cartilage pits were observed. Co-culture of MSCs with THP-1 macrophages, an increase in IL-10 expression and downregulate TNFα secretion were observed. MSCs played inhibitory effects on the proliferation of PBMC activated by CD3/CD28, with an inhibition rate of 76.4%. Conclusions: This study established some of biological activity detection methods for MSCs, including MSCs surface markers, differentiation abilities, promotion of macrophage polarization, and inhibitory effects on lymphocyte proliferation. It provides a potential application for MSCs products quality control.

Metabolomics, as a branch of systems biology, utilizes high-throughput omics technology to investigate metabolite changes within organisms, which enable us to explore the relationship between such alterations and disease etiology or evolution, thereby providing novel research insights for identifying relevant biomarkers and screening of diseases. In recent years, metabolomics has been widely used in the field of cancer research. At the same time, the changes of metabolic pathways can be deeply discussed by using the network shared database. Given that colorectal cancer ranks as the second most prevalent malignant tumor in China, it is crucial to search for clinically valuable tumor markers. This article will highlight the progress of recent five-year metabolomics studies in different matrices to identify potential biomarkers associated with colorectal cancer(CRC), so as to provide references for early screening of CRC.

Liposome is a drug delivery system which has been successfully transformed for clinical application. In the past few decades, liposome as a drug delivery system has been extensively and deeply studied in the field of therapy. A variety of liposome drugs have been marketed at home and abroad, but there are few reports on the systematic quality detection and evaluation methods. In this paper, the preparation technology and systematic quality evaluation methods of liposome drugs were reviewed based on domestic and foreign literature and relevant technical guidelines, so as to provide reference for the development and evaluation of liposome drug delivery technology.

Human chorinonic gonadotropin (hCG) is an important regulator of reproductive and metabolic processes in the human body. hCG can be used for assisted reproduction and treatment of infertility. It is also used to treat sexual dysfunctions such as impotence, cryptorchidism, and dwarfism. hCG plays an irreplaceable role as an endocrine system drug. This article briefly describes the applications, molecular structure, receptor structure, signaling pathways and bioactivity assays of hCG. In addition, an outlook on the development of hCG drugs and bioactivity detection menthods is presented.

This article focuses on the key experimental operations in the study about the applicability of microbial limit testing methods for drugs, summarizing literature and experience from the preparation of test solution, design of methods for microbial counting and control bacteria inspection, operation of microbial recovery test, bacterial liquid concentration counting, and operational methods for controlling bacterial & fungal purity. Emphasis was placed on the preparation methods of water-soluble test samples with strong antibacterial effects, non-oil and fat test samples that were not easily soluble and dispersed, and the test solution for oil and fat test samples. Detailed introduction of the sequential experimental plan for methods of aerobic bacterial count, mold & yeast count, and control bacterial inspection were introduced. Four operational methods for adding bacteria about membrane filtration were explained, and the impact of different ways of adding bacteria on the results of the method was analyzed. Summarized three counting methods for bacterial & fungal concentrations. Detailed sharing of operational experience on controlling the purity of bacterial solution. Summarized the current status about research on the applicability of microbial limit testing methods of drugs. Four suggestions for the future development of research on the applicability of microbial limit testing methods for drugs have been proposed:(1) Unify the operation about bacteria adding method in membrane filtration,scientific and reasonable;(2)Strengthen supervision of pharmaceutical production enterprises and review of microbial limit testing methods for drugs;(3)Unify the microbial limit testing methods for the drugs of the national sampling plan,and gradually collect and bind into a book;(4)Strengthen the research on the applicability of microbial limit testing methods for excipients.

Objective: To establish an HPLC fingerprint of Zuoyu’an San and conduct quality control by combining chemometrics and quantitative analysis of multi-components with a single-marker(QAMS). Methods: HPLC was used to establish the fingerprint spectra of 12 batches of Zuoyu’an San and perform similarity evaluation. Cluster analysis (CA), principal component analysis (PCA), and orthogonal partial least squares discriminant analysis (OPLS-DA) were combined to perform chemical pattern recognition analysis on different batches of Zuoyu’an San. At the same time, QAMS method was established using rhein as the internal standard reference. The relative correction factors between the internal reference and jatrorrhizine, palmatine, berberine, aloe-emodin, emodin, chrysophanol, and physcion were established. The external standard method (ESM) and QAMS method were used to determine jatrorrhizine, palmatine, berberine, aloe-emodin, rhein, emodin, chrysophanol, and physcion in Zuoyu’an San, respectively. To verify the reliability of QAMS metod results, the contents of 8 components of physcion were determined. Results: A total of 23 common peaks were calibrated in the fingerprint, and 8 components were identified by comparing with the mixed reference solution. The similarity between the samples and the control spectrum was between 0.952 and 0.994; CA divided 12 batches of Zuoyu’an San samples into 3 categories; PCA showed that there were certain differences in the chemical composition of different batches of Zuoyu’an San, and extracted 5 principal components that affected the quality evaluation of Zuoyu’an San; OPLS-DA screened out 13 potential marker components (VIP>1) among 23 common peaks that caused quality differences between different batches of Zuoyu’an San samples; There was no significant difference between the QAMS method calculated value and the ESM measured value. Conclusion: The established HPLC fingerprint and multi-index component determination method was accurate and simple, and combined with chemometric methods, could provide reference for the quality control and evaluation of Zuoyu’an San.

Objective: To establish an ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) for the simultaneous determination of daidzein, formononetin, genkwanin, quercetin, rutin, apigenin, kaempferol, luteolin and puerarin in Tongfu Jingyaotong tincture. Methods: The Waters ACQUITY UPLC HSS T3 Column (100 mm×2.1 mm,1.8 μm) was used with methanol and 0.1% formic acid (gradient elution) as the mobile phase at a flow rate of 0.3 mL·min^-1. Column temperature was 45 ℃, and injection volume was 2.0 μL. Electrospray ion source was adopted with positive and negative ion modes and multi-reaction monitoring and acquisition. Results: Apigenin, genkwanin and daidzein had good linearity in the range of 0.2-1 000 ng·mL^-1, puerarin, rutin, luteolin, kaempferol and formononetin in the range of 0.2-2 000 ng·mL^-1, and quercetin in the range of 1.0-5 000 ng·mL^-1. The resolution was good, and the RSDs of precision, repeatability, reproducibility and stability test were all below 5% (n=6). The average recoveries ranged from 82.7% to 111.8% with RSDs (n=6) of 2.0%-5.4%. The contents of daidzein, formononetin, genkwanin, quercetin, rutin, apigenin, kaempferol, luteolin and puerarin in 6 batches of Tongfu Jingyaotong tincture were 8.46-17.97 μg·mL^-1, 0.62-1.67 μg·mL^-1, 0.03-0.08 μg·mL^-1, 1.34-2.22 μg·mL^-1, 0.70-1.14 μg·mL^-1, 0.48-0.99 μg·mL^-1, 0.20-0.90 μg·mL^-1, 0.10-0.16 μg·mL^-1 and 167.95-227.75 μg·mL^-1, respectively. Conclusion: This method has strong specificity, wide linear range, accuracy and efficiency, and can detect the contents of 9 active ingredients in Tongfu Jingyaotong tincture at the same time, which offers an effective quality control method for Tongfu Jingyaotong tincture.

Objective: To conduct odor analysis of the main effective components, namely volatile oils, contained in two varieties, Notopterygium incisum Ting ex H.T.Chang and Notopterygium franchetii H.de Boiss, to provide a feasible method for promptly and accurately distinguishing between the differences in volatile oils of these two varieties of Notopterygii Rhizoma et Radix. This enriches the traditional evaluation content and serves as a reference for assessing the quality of extracts predominantly governed by volatile oils. Methods: The flavors of two samples of Notopterygii Rhizoma et Radix volatile oil were analyzed using electronic nose technology and sensory evaluation. The electronic nose data obtained were subjected to analysis and identification through principal component analysis (PCA) and linear discriminant analysis (LDA). Additionally, two nondestructive testing models-Fisher discrimination and multilayer perceptron (MLP) neural network discrimination were established for sample differentiation. Results: Sensory evaluation results indicated that pine resin flavor, cool flavor and woody flavor were the primary odor characteristics of both Notopterygii Rhizoma et Radix volatile oils. Additionally, the key flavor attribute influencing acceptance and differentiation was identified as spoiled yuba flavor, with the Notopterygium franchetii H. de Boiss volatile oil exhibiting a stronger presence of this attribute than the Notopterygium incisum Ting ex H. T. Chang volatile oil. The electronic nose results revealed that the nitrogen oxides’ response values in Notopterygium franchetii H. de Boiss volatile oil were significantly higher than those in Notopterygium incisum Ting ex H. T. Chang volatile oil. Meanwhile, the response values of hydrides, alcohol ether aldehydes, and ketones were slightly lower in Notopterygium franchetii H. de Boiss volatile oil compared to Notopterygium incisum Ting ex H. T. Chang volatile oil. The Fisher discriminant model demonstrated overall discrimination rates of 93.8% for the training set and 87.5% for the prediction set of the two volatile oils. In contrast, the MLP model achieved discrimination rates of 89.3% for the training set and 91.7% for the prediction set. Notably, the MLP model proved effective for identifying volatile oils, while the Fisher model exhibited greater suitability for discriminating volatile oils with broad-leaved characteristics. Conclusion: The combination of artificial senses and intelligent senses can be characterized from both subjective and objective perspectives, elucidating the flavor differences between the two kinds of Notopterygii Rhizoma et Radix volatile oils. The established Fisher discriminant function and MLP discriminant models can rapidly and accurately distinguish between the two kinds of Notopterygii Rhizoma et Radix volatiles. This lays a preliminary foundation for quality control in Notopterygii Rhizoma et Radix volatiles and offers new ideas and directions.

Objective: To screen the suitable monitoring method applicable to oligotrophs and review the bioburden and microbial species of oligotrophic environments in pharmaceutical water systems and cleanrooms. Methods: The culture conditions and detection methods suitable for microorganisms under oligotrophic conditions were optimized by comparing the counting results of microorganisms in laboratory pure water with R₂A and TSA media at different temperatures, media, and incubation times. In addition, monitoring of oligotrophs in pharmaceutical environments using both the traditional and oligotrophic assays were conducted, combining with the techniques of 16s rDNA sequencing and MALDI-TOF MS for multiphase microbial identification and analysis of the isolated microorganisms under oligotrophic conditions. Results: The colony counting methods, the type of culture media, and the incubation intervals significantly affected microbial enumeration. The isolation method using oligotrophic medium R₂A was more effective than the TSA medium in this study. The profiles of microorganisms isolated from the R₂A and TSA media were unique. The isolation rate of Gram-negative bacteria in the R₂A medium reached 37.0%, however, that of Gram-negative bacteria in the TSA medium was only 14.0%. In addition, several strains of potential pathogens initially isolated from the R₂A medium grew slowly in the TSA medium and were easily missed by the traditional monitoring method. Conclusion: With the development of the pharmaceutical industry, the contamination proportion of human-associated Gram-positive cocci might gradually decrease, the oligotrophic culture method as a powerful supplement to traditional monitoring techniques can help to detect potential objectionable microorganism contamination risks at an early stage.

Scientific design of experiment (DOE) is the main tool to ensure the accuracy of test results and the reliability of conclusions. It is discussed the validation design for bioassay with many influencing factors and great variation, and the calculation method of sample size in method validation design is elaborated in detail here. It is hoped that it could provide theoretical reference for bioassay valiadation to accurately understand the experimental design of method validation.

Growth hormone is a protein hormone with a single peptide chain produced and released by the anterior pituitary, which is the most important hormone for growth promotion after birth. In order to exert biological effects, growth hormone first binds to a specific receptor on the cell surface, and then activates the down stream signaling pathways of the non-receptor tyrosine kinase JAK2 and Src family kinases. An in-depth understanding of the mechanism of action of growth hormone is required for its biological activity measurement. In this paper, we reviewed the recent research progress on growth hormone, including the mechanism of action of growth hormone receptor, the activation of STATs, PI3K-Akt and MEK-Erk signaling pathways by the binding of growth hormone to the receptor, and the regulatory mechanism of growth hormone action pathways. We also summarized and prospected the research on the determination methods of growth hormone activity, in order to provide a reference for the quality control of the biological activity of growth hormone drugs.

Objective: To establish an innovative analytical method based on high resolution sampling two-dimensional chromatography (HiRes 2D-LC) for determination of the content of vitamin D₃ in vitamin D drops. Methods: Two-dimensional liquid chromatography was used. Thermo HYPERSIL Gold Silica (100 mm×2.1 mm, 1.9 μm) column was used in the first dimension with n-hexane-n-amyl alcohol (996∶4) as mobile phase. The flow rate was 0.2 mL·min^-1. The samples were injected and tested at the wavelength of 265 nm. The column temperature was 40 ℃. In the second dimension liquid chromatography, ShimPack Velox Hilic (50 mm×2.1 mm, 2.7 μm) was used as the column with n-hexane-n-pentanol-isopropanol (98∶1∶1) as the mobile phase. The flow rate was 0.5 mL·min^-1. The samples were injected and tested at the wavelength of 265 nm. The column temperature was 40 ℃. A six-position 14-way valve and was equipped with 2 multi-center cutting valves was equipped to make multiple consecutive cuts of the pre-vitamin D₃ peak and vitamin D₃ peak. Results: The calibration curves showed a good linearity at the range of 1.018 4-5.092 mg·mL^-1(r≥0.999 8). The precision test showed the RSDs of the peak area of pre-vitamin D₃ and vitamin D₃ were 0.95% and 0.40%, respectively. The repeatability test showed the RSD of vitamin D₃ content was 0.41%. The average recovery rate (n=9) was 101.4%. The test solution was stable at 4 ℃ and 10 ℃ for 12 h, and the RSDs were 0.58% and 0.66%, respectively. The contents of vitamin D₃ in the samples of vitamin D drops measured by this method were 100.4%, 101.6%, 100.9%, 101.6%, 102.7% and 101.6%, which was basically consistent with the results measured by the fourth method in General Chapter 0722 of ChP 2020 Vol Ⅳ. Conclusion: This method has a good specificity and high sensitivity to accurately determine the content of vitamin D₃ in vitamin D drops.

Objective: To establish a stable and reliable gas chromatography-tandem mass spectrometry method for the determination of N-nitrosodimethylamine (NDMA) in metformin hydrochloride sustained-release tablets, and to optimize extraction conditions by investigating the effects of isopropyl alcohol and thioglycerin on the stability of the tested solution. Methods: Separation was achieved on AB-InoWax capillary column (30 m×0.25 mm×0.25 μm) with polyethylene glycol as the stationary phase. Electron ion(EI) source and multiple reaction monitoring (MRM) mode were used. Quantitative determination was performed by both external standard and internal standard. Results: The addition of thioglycerin could significantly improve the stability of the test solution. NDMA showed good linearity within the concentration range of 0.25-50 ng·mL^-1(r>0.999). The detection limit of the method was 0.1 ng·g^-1 and the quantification limit of the method was 0.2 ng·g^-1. The average recoveries (n=9) were 97.3% and 94.9% while using external standard and internal standard, respectively. Precision, repeatability and stability were good with RSD less than 8%. Ninety batches of metformin hydrochloride sustained release tablets were tested. NDMA content in all detected samples were all less than 30% of the acceptable limit set by the National Medical Products Administration and FDA. Conclusions: This method shows satisfactory sensibility, specificity, accuracy, stability and durability, which is suitable for quantitative analysis of NDMA in metformin hydrochloride sustained-release tablets, providing technical support for the quality and safety of related products.

Thin layer chromatography (TLC) has been widely used for the separation and analysis of various constituents across multiple fields, owing to its advantages of cost-effectiveness, flexibility, high-throughput, and intuitiveness. Among the factors influencing TLC results, the choice of stationary phase critical. Currently, the main stationary phases used in TLC for identifying Chinese materia medica and Chinese patent medicines recorded in Chinese Pharmcopoeia, are silica gel, polyamide, and cellulose. This article reviews the characteristics and application of these three stationary phases in the analysis of Chinese herbal medicines. Using Chrysanthemi Indici Flos, Descurainiae Semen and Lepidii Semen, Oroxyli Semen, Cistanches Herba, Typhae Pollen, and Catechu as examples where traditional method are suboptimal, silica gel plates were employed to develop TLC identification methods with well-defined and abundant spots. These results highlight the clear advantages and feasibility of silica gel as a stationary phase in analyzing flavonoids and phenolic acid components. The findings offer alternative approaches to improve the national standards of these traditional Chinese medicines. Additionally, the article discusses the future development trend of TLC technology.

Objective: To establish a simple and efficient method for detecting telomerase activity for evaluating tumorigenic risk of cell products. Methods: Specific primers and probes were designed for the conserved domain of telomerase catalytic subunit (TERT), and the primers and probes of TERT gene were optimized and screened, and the primers and probes of internal reference genes were set up. Multiple quantitative PCR reaction was performed using two-color fluorescent probes in a reaction system, and RT-qPCR probe method was established. The expression of TERT gene in human mesenchymal stem cells HMSC was used to determine whether telomerase activity existed in the cells indirectly. Results: TERT gene of 293T/17 positive control cells could be stably and specifically detected by this method, with a mean Ct value of 23.96 and a RSD of 1.5. The internal reference gene GAPDH could be detected successfully, the mean Ct value was 14.13, the RSD was 1.3%. The reference gene GAPDH in MRC-5 could be detected in negative control cells, the mean Ct value was 12.81, the RSD was 0.46%, the TERT gene was not detected, and the telomerase activity was negative. The reference gene GAPDH in HMSC could be detected, the Ct mean value was 13.01, and the RSD was 3.8%, whereas, the telomerase activity of HMSC was negative. Conclusion: The real-time fluorescent quantitative RT-qPCR probe method established in this study can accurately detect the expression of catalytic subunit mRNA in telomerase positive cells with good repeatability and high specificity. It can be used to analyze telomerase activity of stem cells and indirectly evaluate tumorigenic risk of cell products derived from stem cells.

Objective: To establish the RP-UPLC-PDA method for simultaneous determination of triptolide, triptonide, triptophenolide, wilforine, wilforlide A and celastrol in Tripterygii Radix. Methods: Tripterygii Radix were extracted with ethyl acetate and the extracts were dissolved and separated by methanol. The six components were determined by RP-UPLC-PDA method. The chromatographic column was Acquity^TM UPLC BEH C₁₈ column (100 mm×2.1 mm, 1.7 μm), the column temperature was 30 ℃, the injection volumn was 2 μL, the flow rate was 0.4 mL·min^-1 and the mobile phase was acetonitrile (A)-0.1% formic acid (B). Results: The linear relationship of six components was good (0.999 2≤r≤0.999 7) in the concentration ranges. The average recoveries were 99.2%-103.1% and RSDs were 1.2%-2.9%. The contents in 10 batches of Tripterygii Radix from different habitat were determined. The results showed that the contents of Tripterygii Radix in prepared pieces from different producing areas were different. The highest content of triptolide was 140.2 μg·g^-1, and the lowest content was 103.2 μg·g^-1. The highest content of triptonide was 224.7 μg·g^-1 and the lowest content was 112.2 μg·g^-1. The highest content of triptophenolide was 306.7 μg·g^-1 and the lowest content was 189.6 μg·g^-1. The highest and lowest contents of wilforine were 283.2 μg·g^-1 and 211.2 μg·g^-1. The highest content of wilfhabitat was 31.2 μg·g^-1 and the lowest content was 16.8 μg·g^-1. The highest content of celastrol was 87.6 μg·g^-1, and the lowest content was 52.1 μg·g^-1. Conclusion: The RP-UPLC-PDA method can simultaneously determine six components in Tripterygii Radix. The method is reliable and stable, which is suitable for quantitative analysis and determination of Tripterygii Radix.

Objective: To establish an HPLC characteristic chromatogram of Xifeng Huoluo capsules, and to determine the contents of gastrodin, amygdalin, strychnine, hydroxysafflower yellow A, brucine, paeoniflorin, ferulic acid, salvianolic acid B, cryptotanshinone, tanshinone Ⅰ, and tanshinone ⅡA. Methods: Extraction of 75% methanol was analyzed by a Venusil MP C₁₈ chromatographic column (250 mm×4.6 mm, 5 μm) using 0.1% phosphoric acid (A) -acetonitrile (B) as the mobile phase with gradient elution at a flow rate of 1.0 mL·min^-1. The column temperature was 30 ℃. The detection wavelengths were variable. The characteristic chromatograms of 10 batches of Xifeng Huoluo capsules were evaluated by similarity evaluation, and the eleven identified index components were quantitatively determined. Results: There were thirty-one common peaks in the characteristic chromatograms of eleven batches of samples and the similarities were all above 0.99. The common peaks could ascribed to twelve medicinal materials, and eleven of them were identified. Eleven components showed good linearity within their respective ranges (r≥0.999 4), and the average recoveries were 99.3%-103.0% with RSDs of 1.5%-2.4%. Conclusion: The established method has high sensitivity and strong specificity. The HPLC characteristic chromatogram combined with multi-component quantitative determination can fully reflect its inherent quality and can be used for the quality control of Xifeng Huoluo Capsules.

Objective: To establish a method for related substances determination in timolol maleate by ultra-high performance liquid chromatography-quadrupole/orbitrap high resolution mass spectrometry(UPLC-Q/Orbitrap HRMS), by which the impurities both in active pharmaceutical ingredients(APIs) and preparations can be recognized and determined. Methods: An ACE Excel3 C₁₈-AR column(150 mm×4.6 mm, 3 μm)was used for the separation and a mixture of 0.01 mol·L^-1 ammonium acetate solution with 0.02% formic acid and methanol was employed as the mobile phase by gradient elution, at a flow rate of 0.6 mL·min^-1. The detection wavelength for UV detector was 295 nm, an HESI(heated ESI)ion source was employed in both the positive mode and negative mode. The possible fragmentation patterns prediction was conducted with the help of Mass Frontier 8.0 and Compound Discover 3.3. The related substances could be recognized and determined by means of the forced degradation of the APIs, with the calibration by the correction factors and confirmation by the mass spectrum data from UPLC-Q/Orbitrap HRMS. Results: The timolol impurity B[3-(tert-butylamino)-2-(4-morpholino-1, 2, 5-thiadiazol-3-yloxy)propan-1-ol], timolol impurity D(4-morpholino-1,2,5-thiadiazol-2-ol), timolol impurity E((S,Z)-4-(｛1-(tert-butylamino)- 3-[(4-morpholino-1, 2, 5-thiadiazol-3-yl) oxy] propan-2-yl｝oxy)-4-oxobut-2-enoic acid maleate salt) and timolol impurity C[N-(tert-butyl)-2, 3-bis (4-morphloline-1, 2, 5-thiadiazol-3-yloxy) propan-1-amine maleate] were produced from the APIs under selected conditions and separated well in the specified HPLC condition, the limit of quantitation was 0.05 μg·mL^-1 and the limit of detection was 0.015 μg·mL^-1 for HPLC-UV. The contents of individual impurities were between 0.000 4%-0.09% and the results of total impurities were between 0.02%-0.12% for the samples from 4 different manufactures. The probable chemical structures of the 6 unspecified impurities were speculated according to the fragmentation pattern of fragment ions, combined with the fragment information, chemical structure of API and the references. Conclusion: The system solution can be obtained by the degradation of the API, and be implied in the impurity analysis for the timolol maleate. The results can be used as a reference for the quality control of timolol maletae.

Objective: To explore the definition and systematic taxonomy of bioassay method, to provide ideas for better understanding the essence of bioassay. Methods: According to the attribute characteristics of bioassay, the classification framework of bioassay was established and the meaning for the classification was explained. Results: (1) The definition of bioassay has different emphases, mainly due to the different focus in various fields, but the theme was basically the same. (2)Potency and its derivative terms had their definitive connotations and extents in bioassay, and accurate use of these terms could make the expression more professional and clearer. (3) Bioassays could be classified according to many attributes, such as whether directness or not of the biological effect detected, the type of the biological subsector used for assay, the nature and mechanism of the bioassay, and the data type of reportable value of the bioassay. Conclusion: Accurate and standardized definition and classification of bioassay are not only conducive to the standardization of expression for use, but also provide theoretical basis and technical support for further understanding, application and improvement of bioassay.

Objective: To establish the substances benchmarks fingerprint of Daqinglong decoction and determine the content and transfer rate of 6 index components, and study the transfer rule of Daqinglong decoction substances benchmarks value, which laid the foundation for the study of Daqinglong decoction compound preparation and quality standard. Methods: Fifteen batches of substances benchmarks of Daqinglong decoction were prepared, and the paste rate was determined. To determine the contents of ephedrine, pseudoephedrine, amygdalin, and cinnamic acid, HPLC method was performed on a Dikma Platisil C₁₈ column (250 mm×4.6 mm, 5 μm). And 0.15% phosphoric acid water (A) and acetonitrile (B) were used as mobile phases with gradient elution at a flow rate of 1 mL·min^-1. The column temperature was 25 ℃, the detection wavelength was 207 nm, and the injection volume was 10 μL. To determine the contents of liquiritin and glycyrrhizic acid, 0.05% phosphoric acid water (A) and acetonitrile (B) were used as mobile phases with gradient elution. The detection wavelength was 237 nm. The transfer rate was calculated, and the transfer analysis from the decoction pieces to the substances benchmarks was carried out. Results: The fingerprint similarities of 15 batches of Daqinglong decoction substances were ≥0.921. Fifteen common peaks were identified, including 8 from Ephedrae Herba, 3 from Cinnamomi Ramulus, 2 from Glycyrrhizae Radix et Rhizoma(fried), and 2 from Armeniacae Semen Amarum(here). The contents of ephedrine, pseudoephedrine, amygdalin, liquiritin, cinnamic acid and glycyrrhizic acid were 0.94%-1.30%, 0.56%-1.02%, 0.70%-1.25%, 0.18%-0.32%, 0.05%-0.10% and 0.46%-1.23%, respectively. The transfer rates were 41.67%-59.47%, 42.66%-59.74%, 17.59%-36.34%, 21.48%-44.75%, 31.06%-48.89% and 12.95%-25.15%, respectively. The paste yields of substances benchmarks were 11.98%-13.38%. Conclusion: The fingerprint combined with the determination of paste rates and index component contents are used to study the quantitative value transfer of Daqinglong decoction substance benchmarks, and initially establish a scientific and stable substance benchmarks quality evaluation method, which can provide reference for the future research on compound preparation.