Value of High-Resolution MRI in the Diagnosis of Brachial Plexus Injury in Infants and Young Children.

Purpose: To investigate the value of high-resolution MRI based on 3D-short inversion time inversion recovery sampling perfection with application-optimized contrasts (3D-STIR SPACE) sequence for the diagnosis of brachial plexus injury in infants and young children. Methods: Physical examination, electromyography (EMG) and MRI data of 26 children with brachial plexus injury were retrospectively analyzed. Sensitivity, specificity, and accuracy were calculated for the three tests. The agreement among these examinations was analyzed with the Kappa test. P<0.05 was considered statistically significant. Results: Of the 26 children, 3 cases had normal MRIs, 23 cases had unilateral brachial plexus injury diagnosed with MRI, and a total of 73 nerve roots and/or sheaths were involved. Among the 23 cases with aberrant MRI findings, there were 19 cases of nerve root thickening (42 nerve roots), 4 cases of nerve root sleeve expansion (5 nerve roots), 17 cases of pseudomeningeal cysts (34 nerve roots), 2 cases of nerve root loosening (2 nerve roots), 8 cases of nerve root dissection (11 nerve roots), 19 cases with increased nerve signal (43 nerve roots), and 9 cases with an increased signal of the muscles on the affected side. As for the diagnosis of brachial plexus injury, the sensitivity and the accuracy of physical examination, EMG and MRI were 0.92, 0.86, and 0.88, respectively. The agreement between MRI and physical examination was substantial (κ=0.780, P=0.000), as did the agreement between MRI and EMG (κ=0.611, P=0.005). Conclusion: High-resolution MRI based on 3D-STIR SPACE sequence plays a role in the diagnosis and evaluation of brachial plexus injury in infants and young children. It can accurately identify the injured nerve and characterize related pathological alterations. Besides EMG and physical examination, it can be used as a valuable tool for screening and monitoring of brachial plexus injury in infants and children.

Modified Look-Locker Inverse-Recovery (MOLLI) Sequence of Quantitative Imaging in Dirty Magnetic Resonance Longitudinal Relaxation Time Diagnostic Value of GE Combined with Longitudinal Relaxation Time Quantitative Imaging for Myocardial Amyloidosis.

The pathological changes of myocarditis include degeneration and necrosis of myocardial cells and infiltration of inflammatory cells in the myocardial interstitium, accompanied by obvious myocardial fibrosis. Myocardial fibrosis is a determinant of ventricular remodeling and an important indicator of the classification of clinical risk factors and has an important value in evaluating the prognosis of heart disease. Cardiac magnetic resonance (CMR) is the "gold standard" for evaluating the shape and function of the heart, and it can show the characteristic pathological changes of myocardial tissue. The traditional gadolinium imaging agent delays the enhanced sequence images to visually show the extent of the affected myocardial fibrosis, but it cannot effectively identify small focal fibrosis or widespread diffuse fibrosis. The CMR longitudinal relaxation time quantitative technique can directly measure the relaxation time (T1) determined by the myocardial tissue and does not depend on the signal strength of the reference tissue and can quantitatively analyze the affected myocardium. In this study, the initial and enhanced quantitative imaging techniques of CMR were used to measure the magnetic value of the myocardium in patients with myocarditis, to explore the diagnostic value of myocardial fibrosis, and to analyze the correlation between cardiac fibrosis and cardiac function.

Gastric calcifying fibrous tumors: Computed tomography findings and clinical manifestations.

ABSTRACT: To retrospectively analyze the computed tomography (CT) findings and clinical manifestations of gastric calcifying fibrous tumor (CFTs).The features of 7 cases with pathologically proven gastric CFTs who had undergone CT were assessed, including tumor location, contour, growth, degree of enhancement, calcification and clinical data. In addition, the size and CT value of each lesion were measured. The mean values of these CT findings and clinical data were statistically analyzed only for continuous variables.Four patients were female and three were male (mean age: 33.3 years; range: 22 ∼ 47 years). Nonspecific clinical symptoms: abdominal pain and discomfort were observed in four cases and the CFTs were incidentally detected in the other three cases. Regarding tumor markers, lower ferritin levels were observed in three female patients. All of the gastric CFTs were solitary and mainly located inside the body; they were in round or oval shape and exhibited endophytic growth. Gastric CFTs are usually small sized and could contain confluent and coarse calcifications; cyst, necrosis, ulcer, bleeding and surrounding lymphadenopathy were not found in any of the cases. Unenhanced CT values of gastric CFTs were higher than those of same-transect soft tissue. Mild-to-moderate enhancement in the arterial phase and progressive enhancement in the portal venous phase were mainly noted.A gastric mass with a high unenhanced CT attenuation value, confluent and coarse calcifications and mild-to-moderate enhancement could prompt a diagnosis of gastric CFT. In addition, (1) being young- or middle-aged, (2) having relatively low ferritin levels, and (3) tumor located in the gastric body have critical reference value for diagnosis of gastric CFT.

Computed tomography characteristics of adrenal ganglioneuroma: a retrospective analysis of 30 pathologically-confirmed cases.

OBJECTIVE: To investigate the computed tomography (CT) characteristics of adrenal ganglioneuromas (AGNs) and to determine the ability of CT scanning to distinguish between large (>3 cm) and small (≤3 cm) AGNs. METHODS: This retrospective study searched the electronic medical record system of a hospital between January 2008 and July 2019 in order to identify patients with pathologically-confirmed AGNs that underwent three phases of CT scanning. The CT features were compared between large and small AGNs. RESULTS: A total of 30 patients with pathologically-confirmed AGNs were included in the study. The majority of patients (76.7%; 23 of 30) were asymptomatic and there were nonspecific symptoms in seven patients. The 'pointed peach' sign appeared in more than half of the patients (53.3%; 16 of 30). The CT value of the arterial phase, progressive enhancement, morphology and calcification in the CT images were found to be significantly different between large and small AGNs. Progressive enhancement was more likely to occur in small AGNs. Most large AGNs had irregular shapes, while small AGNs were likely to be round or oval with a smooth border. Calcifications were noted in large AGNs (42.9%; six of 14). CONCLUSION: CT scanning can show many of the key imaging characteristics of AGNs used to distinguish between large and small AGNs.

Multifocal neuroendocrine cell hyperplasia accompanied by tumorlet formation and pulmonary sclerosing pneumocytoma: A case report.

BACKGROUND: Pulmonary tumorlets are nodular hyperplastic neuroendocrine cells (NECs) that extend beyond the basement membrane. They often coexist with other lung diseases such as fibrosis and bronchiectasis, but rarely accompanied by pulmonary sclerosing pneumocytoma (PSP), which has not been reported in the literature. CASE SUMMARY: A 54-year-old woman was admitted to the hospital because she had symptoms of bloody sputum for more than 4 mo and hemoptysis for 1 wk. Computed tomography images showed atrophy accompanied by infections in the middle lobe of her right lung. Moreover, numerous nodules were identified in the middle lobe of the right lung. The patient underwent thoracoscopic pneumonectomy of the middle lobe of the right lung, and the resected mass was pathologically confirmed to have bronchiectasis, multifocal NEC hyperplasia accompanied by tumorlet, and PSP. CONCLUSION: Our report presents a rare clinical case of bronchiectasis complicated with multifocal NEC hyperplasia, tumorlet, and PSP.

Differentiation of gastric glomus tumor from small gastric stromal tumor by computed tomography.

OBJECTIVE: This study was performed to investigate the value of computed tomography (CT) in the differentiation of gastric glomus tumors (GGTs) and small gastric stromal tumors (GSTs). METHODS: Fifty-nine patients with pathologically confirmed GGTs (n = 11) and GSTs (n = 48) from 2006 to 2019 were retrospectively evaluated. All patients' preoperative CT imaging features were analyzed. RESULTS: The following features were significantly different between GGTs and small GSTs: location in the antrum, endophytic growth, heterogeneous enhancement in the arterial phase, CT value in the arterial phase of ≥60.7 Hounsfield units (HU), CT value in the portal phase of ≥87.6 HU, degree of enhancement in the arterial phase of ≥29.9 HU, and degree of enhancement in the portal phase of ≥49.0 HU. A model including four randomly selected features among these seven criteria was built to differentiate GGTs from small GSTs with a sensitivity and specificity of 90.9% (10/11) and 100% (48/48), respectively. CONCLUSION: We identified seven features that are useful for differentiating GGTs from small GSTs. A combination of four of these seven criteria may increase the diagnostic accuracy.

Clinical and CT findings of COVID-19: differences among three age groups.

BACKGROUND: The novel coronavirus pneumonia (coronavirus disease 2019, COVID-19) has spread around the world. We aimed to recapitulate the clinical and CT imaging features of COVID-19 and their differences in three age groups. METHODS: The clinical and CT data of patients with COVID-19 (n = 307) that had been divided into three groups (Group 1: < 40 years old; Group 2: 40 ≤ age < 60 years old; Group 3: ≥ 60 years old) according to age were analyzed retrospectively. RESULTS: Of all patients, 114 (37.1%) had histories of epidemiological exposure, 48 (15.6%) were severe/critical cases, 31 had hypertension (10.1%), 15 had diabetes mellitus (4.9%), 3 had chronic obstructive pulmonary disease (COPD, 1%). Among the three groups, severe/critical type, hypertension and diabetes occurred more commonly in the elderly group compared with Group 1&2 (P < 0.05, respectively). Cough and chest tightness/pain were more commonly appeared in Group 2&3 compared with Group 1 (P < 0.05, respectively). Compared with Group 1 and 2, there were more abnormal laboratory examination indexes (including CRP increase, abnormal percentage of lymphocytes, neutrophils and monocytes) in Group 3 (P < 0.05, respectively). CT images revealed that more lobes were affected and more subpleural lesions were involved in the elderly group, besides, crazy paving sign, bronchodilatation and pleural thickening were more commonly seen in the elderly group, with significant difference between Group 1&2, Group 2&3 (P < 0.05, respectively). CONCLUSIONS: COVID-19 presented representative clinical manifestations, laboratory examinations and CT findings, but three age groups possessed their own specific characteristics. Grasping the clinical and CT features stratified by age will be helpful for early definite diagnosis of COVID-19.

Comparing the diagnostic value of 18F-FDG-PET/CT versus CT for differentiating benign and malignant solitary pulmonary nodules: a meta-analysis.

BACKGROUND: This quantitative meta-analysis was conducted to provide an indirect comparison of the diagnostic value of computed tomography (CT) with positron emission tomography (PET)/CT for differentiating benign and malignant solitary pulmonary nodules (SPNs). METHODS: PubMed, Embase, and the Cochrane Library were searched to identify eligible studies throughout November 2018, which differentiated benign and malignant SPNs using CT or PET/CT. The summary sensitivity, specificity, positive and negative likelihood ratio (PLR and NLR), diagnostic odds ratio (DOR), and area under the receiver operating characteristic curve (AUC) were calculated using bivariate generalized linear mixed model and random-effects model. The diagnostic value of CT with PET/CT was indirectly evaluated using the ratio for diagnostic parameters. RESULTS: The sensitivity, specificity, PLR, NLR, DOR, and AUC for CT were 0.94 [95% confidence interval (CI): 0.87-0.97], 0.73 (95% CI: 0.64-0.80), 3.45 (95% CI: 2.60-4.58), 0.09 (95% CI: 0.04-0.17), 32.01 (95% CI: 15.10-67.86), and 0.89 (95% CI: 0.86-0.91), respectively. The pooled sensitivity, specificity, PLR, NLR, DOR, and AUC for PET/CT were 0.89 (95% CI: 0.85-0.92), 0.78 (95% CI: 0.66-0.86), 3.97 (95% CI: 2.57-6.13), 0.15 (95% CI: 0.10-0.20), 24.04 (95% CI: 12.71-45.48), and 0.91 (95% CI: 0.89-0.94), respectively. No significant differences were observed between CT and PET/CT for sensitivity, specificity, PLR, NLR, DOR, and AUC. CONCLUSIONS: This study used both CT and PET/CT with a moderate-to-high diagnostic value for differentiating benign and malignant SPNs and showed no significant differences in diagnostic parameters between CT and PET/CT.

[Determination of cylindrospermopsin, nodularin and microcystins in freshwater fish by dispersive solid phase extraction-liquid chromatography-tandem mass spectrometry].

A method was developed for the determination of cylindrospermopsin (CYN), nodularin (NOD), microcystin-RR (MC-RR), microcystin-YR (MC-YR) and microcystin-LR (MC-LR) in freshwater fish by dispersive solid phase extraction-liquid chromatography-tandem mass spectrometry (DSPE-LC-MS/MS). The analytes were extracted from fish tissues with acetonitrile-water-formic acid (89:10:1, v/v/v), and purified by DSPE using C18 as the adsorbent. The separation of analytes was performed on an Agilent ZORBAX Eclipse XDB C18 column with the gradient elution of acetonitrile and water as mobile phases. Qualitative analysis was performed using the multiple reaction monitoring (MRM) mode. The analytes were quantified by matrix-matched external standard curves. The chromatographic and MS parameters were optimized. Major factors affecting the extraction and cleanup efficiencies including the type of extraction solvent and cleanup sorbent were investigated. The linear correlation coefficients (R2) of the five target compounds were no less than 0.9954. The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) of the five target compounds were 5-10 µg/kg and 15-40 µg/kg, respectively. The spiked recoveries of the five target compounds ranged from 62.3% to 101.2%. The developed method is simple, rapid, accurate, sensitive, and is suitable for the determination of cylindrospermopsin, nodularin and microcystins in freshwater fish.

Primary hepatic melanoma: A case report of computed tomography and magnetic resonance imaging findings.

RATIONALE: Malignant melanoma predominantly develops in middle-aged and older adults, most commonly occurring on the skin and rarely on internal organs. Malignant melanoma originating in the liver is extremely rare. Imaging findings of primary hepatic melanoma (PHM) are scarce in relevant literature. PATIENT CONCERNS: The patient was a 69-year-old woman from Zhejiang, China, who was admitted to the hospital because of upper abdominal pain that persisted for >10 days. DIAGNOSES: Computed tomography (CT) findings indicated the presence of a circular low-density shadow of approximately 7.5 × 8.0 cm in the hepatic hilar region. Magnetic resonance imaging (MRI) indicated a heterogeneous solid cystic mass in the hepatic hilar region. The mass exhibited heterogeneous low-signal intensity on a T1-weighted image (T1WI) and slightly higher signal intensity on a T2-weighted image (T2WI). The tumor appeared as multiple irregular strips with high-signal intensity on T1WI and low-signal intensity on T2WI. The diffusion-weighted image revealed increased signal intensity. The tumor continued to be enhanced after enhancement. Clinical data suggested that the tumor was a malignant liver tumor. INTERVENTIONS: The patient underwent a CT guide puncture hepatic biopsy. The tumor was located in the hepatic hilar region adjacent to the large blood vessels and invaded the portal vein. Because a resection was highly risky, conservative treatment was conducted. OUTCOMES: Postoperative pathology and clinical examination confirmed that the tumor was malignant PHM. The patient has been followed up for 6 months. The patient underwent CT reexamination 2 months after conservative treatment, the results of which revealed that the tumor progressed. Multiple lesions were identified; moreover, the tumor size had increased and the tumor had invaded the portal vein and intrahepatic bile duct. The patient was reexamined by CT in another hospital 6 months after conservative treatment. The results revealed peritoneal, omental metastases and multi bone metastases. LESSONS: To our best knowledge, this is the first reported case of a PHM with complete imaging data, including preoperative CT and MRI examinations and a follow-up CT examination. From compiling the CT and MRI findings of this patient and those of relevant studies, this study can serve as a reference for the preoperative diagnosis and differential diagnosis of PHM.

Primary hyperparathyroidism characterized by diffuse homogeneous metastatic pulmonary calcification: A case report.

RATIONALE: Primary hyperparathyroidism (PHPTI) with respiratory tract symptom is extremely rare. It is caused by autonomic oversecretion of parathyroid hormone (PTH) owing to parathyroid adenoma, hyperplasia, or tumor. The diagnosis of PHPTI often needs to be made based on medical history, clinical manifestation, laboratory tests, and imaging examination. Moreover, no study has reported PHPTI with diffuse metastatic pulmonary calcification (MPC) as the characteristic. PATIENT CONCERNS: A 49-year-old female from Zhejiang, China, had a fever of unknown origin, cough with white crude sputum, and asthma after activity for 1 month. DIAGNOSIS: The computed tomography (CT) examination revealed a homogeneous and diffuse high-density shadow in both lungs. The pathologic examination with CT-guided lung biopsy (left lung puncture) suggested interstitial inflammation of the lung tissue, combined with fibroblast proliferation as well as calcification. B-ultrasonography identified a lump in the right parathyroid gland, with a size of 4.1 × 1.7 × 1.9 cm. Color Doppler sonography indicated rich blood flow inside the lump. Whole-body bone emission computed tomography imaging showed the enhancement of bone metabolism in bilateral lower extremities and a diffuse enhancement of radioactive distribution in both lungs. Tc-methoxyisobutyl isonitrile imaging suggested significantly increased MIBI uptake in the right superior pole of the thyroid gland and indicated adenoma of the right superior parathyroid. The diagnosis of PHPTI was confirmed by postoperative pathology. INTERVENTIONS: The patient received a resection of the right parathyroid adenoma. OUTCOMES: After surgery, the symptom such as fever, coughing, and white crude sputum were significantly alleviated. LESSONS: This novel case reported the case of a patient with PHPTI having respiratory tract infection as the 1st symptom and diffuse MPC as the symptom characteristic PHPTI, the findings of this case study might improve the recognition of PHPTI on diffuse pulmonary calcification for clinical doctors.

[Levels of phthalate internal exposure levels in pregnant women and influencing factors].

OBJECTIVE: To investigate the levels and influencing factors of phthalate internal exposure in pregnant women (gestation age ≤ 16 weeks). METHODS: During April to June in 2013, 1 020 pregnant women (gestation age ≤ 16 weeks) who had established the maternal care manual were recruited in maternal and child health hospital of Siming District, Xiamen city. Participators were asked to complete a questionnaire to obtain information on socio-demographic characteristics, lifestyle behaviors, and antenatal examination and to provide a urine sample. Finally, 998 pregnant women who provided a urine sample and completed the questionnaire were enrolled. Adopting systematic sampling method, 100 ones were selected randomly among 998 pregnant women. High performance liquid chromatography-electrospray ionization-tandern mass was used to determine the concentration of five phthalate monoesters in each urine, including mono-n-methyl phthalate (MMP), mono-ethyl phthalate (MEP), mono-butyl phthalate (MBP), mono-benzyl phthalate (MBzP), mono-ethylhexyl phthalate (MEHP). Based on the measurements and questionnaire data, multivariate logistic regression was used to analyze the association between the phthalate monoester levels and potential influential factors. RESULTS: The detection rates of MMP, MEP, MBP, MBzP and MEHP in 100 pregnant urine samples were 94%, 93%, 87%, 83%, 99%, respectively. And the urinary median uncorrected concentrations of MMP, MEP, MBP, MBzP and MEHP in 100 urine samples were 20.56, 17.62, 10.15, 2.03, and 5.12 ng/ml, respectively. Specific gravity-corrected concentration were 20.81, 20.36, 12.88, 2.58, 5.00 ng/ml, respectively. The results of multivariate logistic regression analysis indicated that: education degree was negatively associated with urinary concentration of MMP, MEP, MBP, MBzP and MEHP, OR (95% CI) were 0.495 (0.253-0.966), 0.380 (0.191-0.755), 0.379 (0.186-0.774), 0.401 (0.196-0.819), 0.373(0.183-0.762), respectively. Participants who had hair permed and dyed during pregnancy had higher urinary level of MBP and MBzP, OR (95% CI) were 12.867 (1.240-133.525), 15.982 (1.367-186.911), respectively; Participants who use cosmetics during pregnancy had higher urinary level of MEP and MBP, OR (95% CI) were 2.977 (1.012-8.757), 4.440 (1.485-13.272), respectively; plastic bottled water consumption was positively associated with urinary concentrations of MEP and MEHP, OR (95% CI) were 3.780 (1.417-10.083), 2.699 (1.039-7.010), respectively; annual household income was negatively associated with urinary concentration of MMP, OR (95% CI) was 0.597 (0.372-0.959); individuals who took medications during pregnancy had higher urinary level of MEHP than non-takers, OR (95% CI) was 4.853 (1.084-21.732). CONCLUSION: Pregnant women whose gestation age was less than 16 weeks are generally exposed to phthalate. Phthalate internal exposure levels are significantly associated with most measured factors and the influencing factors with different phthalates internal exposure levels are different.

A novel method for the rapid detection of benzo(a)pyrene in liquid milk by dimethyl sulfoxide selectively enhanced synchronous fluorescence spectrometry.

Based on the high solubility efficiency and strong fluorescence response of benzo(a)pyrene (BaP) in dimethyl sulfoxide in combination with the high-performance derivative constant-energy synchronous fluorescence spectroscopic (DCESFS) technique, a simple, sensitive and economic method was developed for the determination of BaP in liquid milk. This method comprises ultrasound-assisted solvent extraction, solvent replacement and DCESFS detection. No saponification or other tedious clean-up procedures were needed. The recoveries of BaP in different milk samples were greater than 82%. Detection limits in full- and low-fat milk were 0.03 and 0.04 µg kg(-1), respectively.

[Determination of migration level of benzo(a) pyrene from paper cups into food simulants].

This paper quantitatively determined the migration level of benzo(a)pyrene (BaP) from paper cups into aqueous food simulants or fatty stimulants, under different conditions by second derivative constant-energy synchronous fluorescence spectrometry (DCESFS), which proved to be a method with high sensitivity and spectral resolution. The influences of food simulants, time and temperature on the relative migration percent(%) of benzo(a) pyrene were discussed. Results showed that the recoveries of this method ranged from 89.2% to 104.3%. The migration percent(%) of fatty stimulants was higher than that of aqueous simulants. Migration into hot water was also observed, while the migration into cool water was almost negligible. The relative migration percent(%) increased with the increase of time and temperature.

A novel synchronous fluorescence spectroscopic approach for the rapid determination of three polycyclic aromatic hydrocarbons in tea with simple microwave-assisted pretreatment of sample.

Many polycyclic aromatic hydrocarbons (PAHs) are carcinogenic, and some have been reported to be present in tea. People can be exposed to PAHs through tea consumption. Therefore, there is real importance for the determination of PAHs in tea. Because of the complex matrix of tea, it is hard to detect PAHs in tea without cleanup and chromatographic separation procedures. In this research, for the first time, a novel synchronous fluorescence spectroscopic approach coupling nonlinear variable-angle synchronous and matrix-isopotential synchronous scanning modes has been developed for the rapid determination of benzo(a)pyrene (BaP), benzo(k)fluoranthene (BkF), and anthracene (AN) in tea with simple microwave-assisted pretreatment of samples. This novel technique is able to resolve the spectra of the three PAHs well, even with interference from other EPA PAHs. The detection limits for BaP, BkF, and AN in tea were 0.18-0.28, 0.55-0.89, and 0.64-3.58 µg/kg, respectively, depending on various teas, with satisfactory recoveries ranging from 77.1 to 116%. The relative standard deviations achieved for BaP, BkF, and AN were 1.5, 6.6, and 8.5% for green tea; 2.9, 7.4, and 2.1% for oolong tea; and 5.6, 5.4, and 5.8% for black tea, respectively. Our results showed good correlation with those of gas chromatography-mass spectrometry. The approach developed is simple, reliable, and cost-efficient, providing an attractive alternative for the rapid selective screening of PAHs in tea.

Highly sensitive and selective spectrofluorimetric approach for the rapid determination of trace benzo[α]pyrene in drinking water and in solutions leached from disposable paper cups.

Based on the excellent band narrowing and background suppressing features of second-derivative constant-energy synchronous spectrofluorimetry with a Δ⁻υ value of 1400 cm(-1) , the strong fluorescence intensity for benzo[α]pyrene (BaP) obtained in dichloromethane and the use of standard addition method, a highly sensitive and selective approach for the quantitative determination of trace amount of BaP in drinking water has been established in this study. The detection and quantification limits were 0.11 and 0.37 ng L(-1) , respectively, and the recoveries obtained from spiked Milli-Q water, bottled natural spring water, tank-purified water and tap water at different concentrations, ranged from 86.0 to 104.0%. This method has been applied for the determination of trace BaP in solution leached from disposable paper cups. The experimental results indicated that BaP was leached from paper cups when filled with hot water, but it was not detected when cool (unheated) water was used.

[Benzo (a) pyrene residue surveillance in retail food in the city of Xiamen, China: report from 121 samples].

OBJECTIVE: To investigate Benzo (a) pyrene (BaP) residue in retail food of Xiamen. METHODS: BaP residue in 121 retail food samples collected from Xiamen were determined by a rapid BaP detector based on derivative constant-energy synchronous fluorescence technique. RESULTS: BaP was detected in 84.3% samples and the concentration were ranged from 0.17 to 59.0 microg/kg. There were 49.6% samples exceeding 5.00 microg/kg, and most of them were roasting food (1.44 - 54.10 microg/kg), processed meat products (0.17 - 59.00 microg/kg) and aquatic products (2.79 - 36.80 microg/kg). The BaP concentration in 34 samples collected from roadside stands were 1.78 - 49.60 microg/kg, of which the rate of the samples exceeding 5.00 microg/kg was 88.2%. CONCLUSION: The BaP contamination in retail food samples from Xiamen is serious.

[Determination of tetrodotoxin in nassarius by solid-phase extraction, ultrafiltration and liquid chromatography-mass spectrometry].

A method for the determination and analysis of tetrodotoxin (TTX) in nassarius using liquid chromatography-mass spectrometry (LC-MS) has been developed. The homogenized sample was extracted with 0.03 mol/L acetic acid by heating in a boiling water-bath for 10 min and then was cleaned up on a Sep-Pak C18 cartridge column and filtered through a M(r) 3 000 cut-off ultrafree microcentrifuge filter. Chromatographic separation was performed on an Insertsil ODS-3 column using 30 mmol/L heptafluorobutyric acid in 1 mmol/L ammonia formate buffer-methanol (99 : 1, v/v) as mobile phase at a flow rate of 0.3 mL/min. TTX was identified by retention time in positive mode with selected ion monitoring (SIM). The results showed that TTX and its analogs can be separated with the method. The linear range was 0.01 - 10.0 mg/L and the correlation coefficients were greater than 0.995 with a detection limit of 2 microg/L (S/N = 3). The average recoveries were in the range of 72.5% - 80.4% and the relative standard deviations were 4.48% - 8.87%. TTX of 0.04 - 0.50 mg/kg was found in nassarius that was collected from Fujian Province after red tide.