Real-World Disproportionality Analysis of the Food and Drug Administration Adverse Event Reporting System Database for Asciminib.

INTRODUCTION: Asciminib is primarily utilized for treating Philadelphia chromosome-positive chronic myeloid leukemia in its chronic phase among patients harboring the T315I mutation or those who have been previously treated with at least two tyrosine kinase inhibitors. The safety profile of asciminib across a broad patient population over an extended timeframe remains unverified. This study uses a real-world pharmacovigilance database to evaluate the adverse events (AEs) linked with asciminib, providing valuable insights for clinical drug safety. METHODS: Data from the FDA Adverse Event Reporting System (FAERS) database, spanning from October 2021 to December 2023, served as the basis for this analysis. The extent of disproportional events was assessed using sophisticated metrics such as the reporting odds ratio, proportional reporting ratio, information component, and empirical Bayesian geometric mean. RESULTS: Within the specified period, the FAERS database documented 3,913,574 AE reports, with asciminib being associated with 966 incidents. Reactions to asciminib spanned 27 system organ categories. Utilizing four distinct analytical algorithms, 663 significant preferred terms exhibiting disproportional frequencies were identified. Notably, this investigation uncovered 26 significant AEs linked to off-label asciminib use, encompassing conditions such as gynecomastia, nephrotic syndrome, orchitis, pyelonephritis, hepatotoxicity, and pancreatitis. The median onset time for asciminib-related AEs was 52.5 days, ranging from 17 to 122.75 days. CONCLUSION: The study sheds light on additional potential AEs associated with asciminib use, warranting further research to confirm these findings.

Variability of internal standard method calibration factors estimated with a multifactorial Taguchi experiment in the analysis of alcoholic products by gas chromatography with flame ionization detection.

This study compares the variability of relative response factors (RRFs) using Taguchi's multifactorial analysis for two internal standard (IS) methods in gas chromatography (GC) for quality control of alcoholic products. Methods where either ethanol or pentan-1-ol was used as an IS were compared. For ten volatile substances prescribed by legislation, the RRFs of both methods were compared under 27 different experimental conditions. The influence of parameters (control factors) such as ethanol content in the matrix, analyte concentration, injected volume, injector temperature, split ratio, and flame ionization detector temperature was evaluated. The selected control factors had values at one of the three levels to cover the commonly used ranges of their settings in the measuring system and to characterize the majority of alcoholic products commonly analyzed in practice. The obtained results showed that the biggest differences in the variability of the results between the two methods were found for the most strictly controlled substances in alcoholic products, acetaldehyde, and methanol, where the application of ethanol as an IS provides clearly better results. For both methods, the way control factors affect the repeatability of GC measurements expressed in the form of relative deviation was also evaluated.

[Determination of perchlorate and chlorate in drinks by ultra-performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish a method for determination of perchlorate and chlorate in drinks by ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) based on isotopic internal standard method. METHODS: The perchlorate and chlorate residue in liquid drinks were extracted with methanol, in solid drinks with acetic acid solution, then centrifuged. The supernatant was cleaned-up with PSA/C18 cleanup tube. The separation of perchlorate and chlorate was carried out on a Acquity CSH fluorophenyl column(100 mm×2.1mm, 1.7 µm) and the detection was performed with tandem mass spectrometry with internal standard method for quantification. RESULTS: The peak area ratio of perchlorate and chlorate had a good linear relationship with their mass concentration within their respective linear ranges, with correlation coefficients(r) greater than 0.999. The limits of detection of perchlorate and chlorate were 0.2and 1 µg/L respectively and the limits of quantification were 0.5 and 3 µg/L respectively. The mean recoveries of two compounds were from 84.0% to 105.5% with relative standard deviations from 4.2% to 17.0% and 82.7% to 112.1% with relative standard deviations from 5.5% to 18.4%(n=6), respectively. The perchlorates in 11 kinds of beverage samples were 0.53-4.12 µg/L, chlorates were 3.27-61.86 µg/L. CONCLUSION: This method is simple, sensitive, accurate and reliable, which is suitable for the determination of perchlorate and chlorate in drinks.

[Quality control method for phenolic acid components in abandoned stems and leaves of Artemisia selengensis based on UPLC fingerprint combined with quantitative analysis of multi-components by single marker (QAMS)].

This study established an ultra-performance liquid chromatography(UPLC) fingerprint of abandoned stems and leaves of Artemisia selengensis and quantitative analysis of multi-components by single marker(QAMS) for five phenolic acid components. Waters Acquity UPLC BEH C_(18) chromatography column(2.1 mm×100 mm, 1.7 µm) was used. The gradient elution was carried out with the mobile phase composed of 0.1% phosphoric acid water and acetonitrile at a flow rate of 0.3 mL·min~(-1) and a column temperature at 30 ℃. The detection wavelength was 330 nm, and the injection volume was 2 µL. Similarity evaluation and cluster analysis were conducted on the fingerprint data, and 15 common components in 13 batches of abandoned stems and leaves of A. selengensis were identified. The relative correction factors of ferulic acid, isochlorogenic acid A, isochlorogenic acid B, and isochlorogenic acid C were calculated using chlorogenic acid as the internal reference. The QAMS for determining five components in the abandoned stems and leaves of A. selengensis was established. At the same time, the content of these five components was determined using the external standard method(ESM), and the results showed that there were no significant differences in their content determined by the QAMS and the ESM. The results indicated that the content of phenolic acid components in the abandoned stems and leaves of A. selengensis from different varieties and different origins had obvious differences. In addition, the content of phenolic acid components in the abandoned stems and leaves of lignified A. selengensis was significantly higher than that of non-lignified A. selengensis. In summary, QAMS established in this study can be quickly, accurately, and economically used to determine the content of five phenolic acid components in abandoned stems and leaves of A. selengensis, laying a foundation for the resource development and utilization of abandoned stems and leaves of A. selengensis.

Trace determination of imidacloprid and its major metabolites in wheat-soil system.

Trace analysis method is a reliable basis for studying the translocation and metabolism of imidacloprid used as an insecticide in wheat, and it clarifies whether biologically active metabolites including residual imidacloprid, have long-lasting insecticidal potency against wheat aphids under seed treatment during the entire growth period. In this study, a highly sensitive analytical method was established to determine the residues of imidacloprid and its six metabolites (5-hydroxy imidacloprid, imidacloprid olefin, imidacloprid guanidine, imidacloprid urea, 6-chloronicotinic acid, and imidacloprid nitrosimine) in wheat-soil systems, such as in wheat leaves, wheat ears, wheat grains, roots, and soil. All the compounds were extracted using an ACN:water (8:2, v/v) mixture and purified by dispersive solid-phase extraction. The average recoveries ranged from 74.4% to 109.5% for all matrices, with intra- and inter-day variations of less than 14.9%. The limit of quantitation was in the range of 0.001-0.005 mg/kg. The method is demonstrated to be sensitive and accurate for monitoring imidacloprid and its metabolites at trace levels during the entire growth period under field conditions.

[Simultaneous determination of glucosinolates and flavonoids in leaves of Moringa oleifera by quantitative analysis of multi-components by single-marker (QAMS)].

To establish a method for simultaneously determining the content of four glucosinolates and five flavonoids in leaves of Moringa oleifera via quantitative analysis of multi-components by single-marker(QAMS) and verify the feasibility and applicability of the established method. The glucosinolates and flavonoids were analyzed via Waters Acquity UPLC HSS T_3 column(2.1 mm × 100 mm, 1.8 µm). The gradient elution was carried out with the mobile phase composed of 0.1% formic acid-acetonitrile and 0.3% formic acid at the flow rate of 0.4 mL·min~(-1) and the column temperature of 40 ℃. The wavelengths for the detection of glucosinolates and flavonoids were 225 nm and 260 nm, respectively. With 4-O-(α-L-rhamnoyloxy)-benzyl glucosinolate and vecenin-2 as internal reference substances, the relative correction factors of four glucosinolates and five flavonoids were respectively calculated for determining the content of the 9 ingredients in leaves of M. oleifera. To verify the accuracy and feasibility of QAMS, we used internal standard method(ISM) and external standard method(ESM) to determine the content of glucosinolates and flavonoids, respectively. The t-test results showed that there was no significant difference in the content of glucosinolates obtained by ISM and QAMS methods or in the content of flavonoids obtained by ESM and QAMS methods. The content of glucosinolates and flavonoids varied among M. oleifera of different varieties and from different producing areas. The total glucosinolates and total flavonoids had the highest content in the Indian variety while the lowest content in the variety ■Honghe No. 1'. The established QAMS method is rapid, simple and accurate and can be used for simultaneous determination of glucosinolates and flavonoids in the leaves of M. oleifera. This study provides experimental data for the quality control and utilization of M. oleifera leaves.

Simultaneous determination of both kavalactone and flavokawain constituents by different single-marker methods in kava.

Kava, the rhizomes and roots of Piper methysticum Forst, is a popular edible medicinal herb traditionally used to prepare beverages for anxiety reduction. Since the German kava ban has been lifted by the court, the quality evaluation is particularly important for its application, especially the flavokawains which were believed to be responsible for hepatotoxicity. Now, by employing two different standard references and four different methods to calculate the relative correction factors, eight different quantitative analyses of multicomponents by single-marker methods have been developed for the simultaneous determination of eight major kavalactones and flavokawains in kava. The low standard method difference on quantitative measurement of the compounds among the external standard method and ours confirmed the reliability of the mentioned methods. A radar plot clearly illustrated that the contents of dihydrokavain and kavain were higher, whereas flavokawains A and B were lower in different kava samples. Only one of eight samples did not detect flavokawains that may be related to hepatotoxicity. In summary, by using different agents as an internal standard reference, the developed methods were believed as a powerful analytical tool not only for the qualitative and quantitative of kava constituents but also for the other multicomponents when authentic standard substances were unavailable.

Determination of ascorbic acid using electrochemiluminescence sensor based on nitrogen and sulfur doping graphene quantum dots with luminol as internal standard.

A novel internal standard electrochemiluminescence (ECL) sensor has been designed for the detection of ascorbic acid (AA). The adopted dual-emission luminophore (NSGQDs-PEI-luminol-Pt) is composed of nitrogen and sulfur double-doped graphene quantum dots (NSGQDs, as the main luminophore), luminol (as the auxiliary luminophore and internal standard), platinum nanoparticles (Pt NPs, as the co-reaction accelerator), and polyetherimide (PEI, as the linker of NSGQDs and luminol). The results suggest obviously enhanced  ECL intensities by the Förster resonance energy transfer (FRET) between luminol (donor) and NSGQDs (acceptor). In this sensing system, the cathodic ECL intensities of NSGQDs (ECL-1, -1.8 V vs. Ag/AgCl) gradually decrease with increasing concentration of AA, while the anodic ECL intensities of luminol (ECL-2, 0.3 V vs. Ag/AgCl) almost remain essentially constant at a potential window from -2.0 to 0.4 V. The natural logarithm of the ratio between ECL-1 and ECL-2 (ln I (ECL-1/ECL-2)) shows a good linear relationship with AA concentration ranging from 10 to 360 nM. The regression equation is ln I (ECL-1/ECL-2) = - 0.0059 cAA + 3.55 (R2 = 0.992) with a limit of detection of 3.3 nM. Such sensor has also been applied for monitoring AA in human serum. The recovery range was 96.5-105.3% and the relative standard deviation was  1.3-3.3%.

Rapid Analysis for Staphylococcus aureus via Microchip Capillary Electrophoresis.

Staphylococcus aureus (S. aureus) is one of the most common pathogens for nosocomial and community infections, which is closely related to the occurrence of pyogenic and toxic diseases in human beings. In the current study, a lab-built microchip capillary electrophoresis (microchip CE) system was employed for the rapid determination of S. aureus, while a simple-to-use space domain internal standard (SDIS) method was carried out for the reliable quantitative analysis. The precision, accuracy, and reliability of SDIS were investigated in detail. Noted that these properties could be elevated in SDIS compared with traditional IS method. Remarkably, the PCR products of S. aureusnuc gene could be identified and quantitated within 80 s. The theoretical detection limit could achieve a value of 0.066 ng/µL, determined by the using SDIS method. The current work may provide a promising detection strategy for the high-speed and highly efficient analysis of pathogens in the fields of food safety and clinical diagnosis.

[Determination of manganese in urine by direct dilution-inductively coupled plasma mass spectrometry].

Objective: To establish a direct dilution-inductively coupled plasma mass spectrometry method for the determination of manganese in urine. Methods: Using 1% nitric acid solution as diluent, the urine dilution factor and internal standard elements were determined by single factor rotation experiment. The linear range, correlation coefficient, precision, accuracy and detection limit of the direct dilution-inductively coupled plasma mass spectrometry for the determination of manganese in urine were evaluated. Results: The linear range of this method was 0.0-20 µg/L, the correlation coefficient was 0.999 9, the detection limit was 0.02 µg/L, the recoveries were 84.65%-103.40%, the relative standard deviations were 0.26%-8.17%. Conclusion: This method has the advantages of simple operation, high sensitivity and low detection limit. It can be used for the determination of urine manganese at the same time with other elements. It is suitable for the determination of urine manganese in workers and ordinary people.

[Status analysis of standard methods for detecting metals and metalloids in the air of workplace in China].

To provide basis for improving the detection standard methods and improve the quality and applicability of the occupational health detection standard methods. This paper is based on occupational health standards and experimental data at home and abroad. Analysis the detection standard methods of metal and metalloid in the air of workplace through data collection, investigation and experiments.

Direct vs. standard method of insertion of an intrauterine contraceptive device: insertion pain and outcomes at 6 months.

Objectives: The direct method is a procedure designed to cause less pain during insertion of an intrauterine contraceptive device (IUCD). It was first reported in 2005 and differs from the standard method of insertion recommended by IUCD manufacturers. In France, the direct method is well known and used by experienced practitioners, but it has never been evaluated against the standard method of insertion. The aim of the study was therefore to compare the direct method with the standard method in terms of pain experienced during insertion and the side effects and satisfaction rates over 6 months. Methods: A prospective observational study was conducted in France between June and December 2016 to compare the direct and standard methods of IUCD insertion. Results: The study included 535 women: 281 in the direct method group (DM group) and 254 in the standard method group (SM group). Women in the DM group reported less pain. This difference was assessed by multilevel multivariate analysis (-8.3 mm, 95% confidence interval (CI) -14.3, -2.3). There was no difference in the occurrence of infection (1.4% vs. 2.8%; p = .366) and 6-month continuation rates (89.4% vs. 89.2%; p = .936). Satisfaction rates at 6 months were higher in the DM group (93.6% vs. 87.4%; p = .019). Conclusions: The results of the study suggest that the direct method of IUCD insertion is associated with less pain and does not increase the risk of adverse effects. Widespread adoption of the direct method could improve women's comfort and lead to a higher uptake of the IUCD as a form of contraception.

[Determination of ochratoxin A and ochratoxin alpha in wine by ultra-performance liquid chromatography tandem mass spectrometry].

OBJECTIVE: To establish a method for determination of ochratoxin A and ochratoxin alpha in wine by ultra-performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS) based on isotopic internal standard method. METHODS: The wine sample was adjusted to pH 9. 0 by 5% ammonia and concentrated by a MAX solid phase extraction cartridge. The UPLC separation was performed on a ACQUITY BEH C_(18) column(100 mm×2. 1 mm, 1. 7 µm)with a isocratic elution program of acetonitrile and 5 mmol/L ammonium acetate as the mobile phase. Electrospray ionization was applied and operated in the positive ion mode. The concentration of wine was quantified by isotope internal standard. RESULTS: The calibration curves were linear in the concentration range of 1. 0-50. 0 µg/L, the coefficients of correlation were 0. 9996 and 0. 9993, respectively. The limits of detection(LODs) of both were 0. 10 µg/kg, and the limits of quantitative were 0. 35 µg/kg. The average recoveries at the spiked levels of 0. 35, 2. 00 and 10. 00 mg/kg were 88. 6%-108. 0%, and the relative standard deviations(RSDs) were 2. 1%-9. 2%, respectively. CONCLUSION: This method is simple, sensitive, accurate and reliable, which is suitable for the determination of ochratoxin A and ochratoxin alpha in wine.

[Determination of 25-hydroxyl vitamin D in serum by isotope dilution ultra-fast liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To establish a rapid and accurate method for determination of 25-hydroxyl vitamin D2, 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3 in serum by isotope dilution ultra-fast liquid chromatography-tandem mass spectrometry(UFLC-MS/MS). METHODS: The serum sample was extracted by nhexane after methanol/acetonitrile precipitation protein, and then the extract was concentrated by nitrogen and volumed with the primary mobile phase. The chromatographic separation was carried out on a Phenomenex Kinetex F5 column(2. 1 mm × 150 mm, 1. 7 µm) by using 0. 1%(V/V) formic acid and 0. 1%(V/V) formic acid/methanol solution as the mobile phase with the gradient elution. Detection was performed in positive multi-reaction monitoring(MRM) mode with the isotope internal labeling method for quantification. RESULTS: The baseline separation was obtained within 6 min for the epimer 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3, and the accurate qualification was obtained for the simultaneous determination of 25-hydroxyl vitamin D2, 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3. The three analytes showed good linear relationship within the range of 0. 5-50. 0 µg/L with a correlation coefficient r >0. 9995. The limits of detection(LODs) and the limits of quantitation(LOQs) of the method were 0. 15 µg/L and 0. 5 µg/L, respectively. The recoveries of the method were84. 3%-109. 0%(n = 11) at the three spiked levels of 1. 0, 10. 0 and 30. 0 µg/L, and the relative standard deviations(RSDs) were between 0. 8%-6. 8%. At the same time, the certified standard reference materials(SRM) of the America National Institute of Standards and Technology(NIST) Level 1, Level 2, Level 3 and Level 4(SRM 972 a)were used as the quality control samples for verification, the relative deviations of the measurement result were less than 5% compared with the reference values. CONCLUSION: The developed method has the characteristics of simplicity, rapidity, sensitivity and accuracy, and is suitable for the simultaneous rapid determination of 25-hydroxyl vitamin D2, 25-hydroxyl vitamin D3 and 3-epi-25-hydroxyl vitamin D3 in serum.

[Determination of 9 isoflavonoids in Puerariae Lobatae Radix with quantitative analysis of multi-components by single marker].

A method for determination of 9 isoflavones in Puerariae Lobatae Radix was established and the accuracy and feasibility of the method were verified. The relative correction factors of eight isoflavonoids,3'-hydroxy puerarin,puerarinapioside,3'-methoxy puerarin,puerarin 6″-O-xyloside,daidzin,genistin,formononetin and daidzein were determined by HPLC method with puerarin as the internal standard. The contents of 9 isoflavonoids in 11 batches of samples were determined by external standard method and QAMS.The accuracy and feasibility of the methods were evaluated by comparison of the quantitative results between external standard method and QAMS. The reproducibility of the relative correction factors was good under different experimental conditions,and there was no significant difference between the external standard method of the 9 compounds and the content of QAMS method. The results showed that using puerarin as an internal standard to simultaneously determine the 8 isoflavonoids mentioned above is accurate and feasible. Thus,it can be used as quality control of Puerariae Lobatae Radix.

[Extraction kinetics of volatile oil from galangal by steam distillation].

To reveal the extraction regularity of volatile oil from galangal by GC-MS analysis. The volatile oil in galangal was extracted by steam distillation. The extract was collected every 30 min, the oil part and the water part were separated. GC-MS was used to analyze the extraction liquid collected at different time periods. A total of 140 volatile components were obtained by GC-MS analysis. Among them, the main components were eucalyptus oil alcohol, alpha-pine oil alcohol and 4-terpene alcohol; 22 special components were dissolved in water, 77 special components were dissolved in oil and 41 components were dissolved in both oil and water. With the increase of specific components in water, the content of Eucalyptus in water increased in a linear manner. The increase of eucalyptus oil further promoted the dissolution or dispersion of alpha PN in water, and the change of specific components in oil was positively correlated with the content of Eucalyptus and alpha-terpilenol in oil. The results of principal component analysis show that the physical and chemical properties of the compounds were important factors affecting the distribution of components. PC1 (molecular weight, melting point, boiling point positive correlation), PC2 (negative correlation of refractive index) and PC3 (positive correlation of water solubility) were the main components that lead to the differences in composition distribution. The process of extracting volatile oil from galangal through steam distillation was affected by the physical and chemical properties of volatile components. Some components were specifically distributed in the fragrance and volatile oil system. The endemic components of aromatic water increased the content of the main components in the water system, which may lead to the "emulsification", reduction of the yield and low quality of the volatile oil.

The Application of Quantitative ¹H-NMR for the Determination of Orlistat in Tablets.

A quantitative nuclear magnetic resonance (qNMR) method to measure the content of Orlistat in tablets was studied and found to be efficient, accurate, reliable, and simple. In this paper, phloroglucinolanhydrous and dimethylsulfoxide-d6 (DMSO-d6) served as the internal standard and solvent, respectively. The qNMR methodology, including the linearity, range, the limit of detection (LOD) and quantification (LOQ), stability, precision, and accuracy, was validated seriatim, and the results were very favorable. The content determination results of three batches of Orlistat in tablets were almost identical upon comparing the qNMR method and the high-performance liquid chromatography (HPLC) method. The recommended method authentically compensated the deficiencies of the current HPLC method for determining Orlistat content, and proved to be a method complementary to traditional analysis for the purity measurement of Orlistat in some pharmaceutical preparations.

[Simultaneous determination of febrifugine and isofebrifugine in Dichroa febrifuga root by HPLC method].

To develop the HPLC method for simultaneous determination of febrifugine and isofebrifugine in Dichroa febrifuga root, and on the basis of this, the feasibility of quantitative analysis of multi-component by a single-marker (QAMS) model for the determination of the two alkaloids was investigated. The chromatographic separation was performed on an octadecyl bonded silica gel column with mixed solvent consisting of acetonitrile-water-glacial acetic acid-triethylamine (9∶91∶0.36∶0.745) as mobile phase at a flow rate of 1.0 mL•min⁻¹. The detection wavelength was set at 225 nm, and the column temperature was set at 30 ℃. The linear range of febrifugine and isofebrifugine were 10.7-426 ng and 10.6-424 ng, respectively. Their average recovery were 98.33% (RSD 2.7%) and 100.4% (RSD 1.8%), respectively. On the basis of this established method, febrifugine was used as the internal reference substance to calculate the relative correction factors (RCF) and the relative retention values (RRV) of isofebrifugine to febrifugine. Through a series of methodology evaluations, the two alkaloids were simultaneously assayed only by quantitative determination of febrifugine. This result played the part of demonstration role for the application of QAMS model in the determination of isomers.

Gene analysis of multiple oral bacteria by the polymerase chain reaction coupled with capillary polymer electrophoresis.

Capillary polymer electrophoresis is identified as a promising technology for the analysis of DNA from bacteria, virus and cell samples. In this paper, we propose an innovative capillary polymer electrophoresis protocol for the quantification of polymerase chain reaction products. The internal standard method was modified and applied to capillary polymer electrophoresis. The precision of our modified internal standard protocol was evaluated by measuring the relative standard deviation of intermediate capillary polymer electrophoresis experiments. Results showed that the relative standard deviation was reduced from 12.4-15.1 to 0.6-2.3%. Linear regression tests were also implemented to validate our protocol. The modified internal standard method showed good linearity and robust properties. Finally, the ease of our method was illustrated by analyzing a real clinical oral sample using a one-run capillary polymer electrophoresis experiment.

Application of internal standard method in recombinant luminescent bacteria test.

Mercury and its organic compounds have been of severe concern worldwide due to their damage to the ecosystem and human health. The development of effective and affordable technology to monitor and signal the presence of bioavailable mercury is an urgent need. The Mer gene is a mercury-responsive resistant gene, and a mercury-sensing recombinant luminescent bacterium using the Mer gene was constructed in this study. The mer operon from marine Pseudomonas putida strain SP1 was amplified and fused with prompterless luxCDABE in the pUCD615 plasmid within Escherichia coli cells, resulting in pTHE30-E. coli. The recombinant strain showed high sensitivity and specificity. The detection limit of Hg(2+) was 5nmol/L, and distinct luminescence could be detected in 30min. Cd(2+), Cu(2+), Zn(2+), Ca(2+), Pb(2+), Mg(2+), Mn(2+), and Al(3+) did not interfere with the detection over a range of 10(-5)-1mM. Application of recombinant luminescent bacteria testing in environmental samples has been a controversial issue: especially for metal-sensing recombinant strains, false negatives caused by high cytotoxicity are one of the most important issues when applying recombinant luminescent bacteria in biomonitoring of heavy metals. In this study, by establishing an internal standard approach, the false negative problem was overcome; furthermore, the method can also help to estimate the suspected mercury concentration, which ensures high detection sensitivity of bioavailable Hg(2+).