[An epigenetic clock model for assessing the human biological age of healthy aging].

Objective: To construct an epigenetic clock model for assessing and calibrating human biological age. Methods: Convenience sampling was used to select 186 subjects from the longevity cohort of Guangxi Zhuang Antonornous Region from July 1 to November 30, 2019, and 124 subjects from the physical examination population of the Seventh Medical Center of the PLA General Hospital from October 1 to December 31, 2020. Self-designed questionnaire was applied to collect demographic characteristics and family history of disease. Physical examination was applied to determine heart rate and blood pressure. Fasting peripheral venous blood was drawn for determination of fasting plasma glucose, plasma total cholesterol, triglyceride, plasma high-density lipoprotein cholesterol, plasma low-density lipoprotein cholesterol and telomere length. Methylation levels of EDARADD cg09809672, IPO8 cg19722847, NHLRC1 cg22736354, P2RX6 cg05442902 and SCGN cg06493994 were detected by targeted methylation site sequencing. A total of 54 subjects with unqualified quality control of DNA methylation and telomere length were excluded, and 256 subjects' data were finally analyzed. Trend test was used for the change of methylation level among different ages groups, multiple linear regression method was used to build prediction models of biological age. Kendal rank correlation analysis was used to evaluate the correlation of age gap (Gregorian calendar age minus biological age) with telomere length. Independent sample t-test was used to compare the health-related indicators between subjects with different age gap within different age groups. Results: The M(Q1, Q3)of age of subjects were 67 (51, 91) years old, including 166 females (64.84%). With increase of age, the methylation levels of gene loci were decreased (EDARADD cg09809672, IPO8 cg19722847 and P2RX6 cg05442902) and increased (NHLRC1 cg22736354 and SCGN cg06493994) (all P values<0.05). The established biological age prediction model was as follows: Y=-53.121×EDARADD cg09809672-137.564×IPO8 cg19722847+141.040×NHLRC1 cg22736354-67.893×P2RX6 cg05442902+149.547×SCGNcg06493994+4.592×sex+64.185 (R2=0.86, P<0.001), where Y was the biological age, and the items in the equation were methylation level, sex (male =1, female =2) and intercept in sequence. The Kendall rank correlation coefficient between age gap and telomere length was 0.731 (P<0.001). Compared with the subjects whose age gaP<0, the subjects with age gaP≥0 had higher systolic blood pressure in adolescence [(88.50±8.89) and (109.83±9.48) mmHg, respectively, 1 mmHg=0.133 kPa]; lower TC [(5.48±0.23) and (3.98±0.54) mmol/L, respectively, ] and TG [(3.51±0.32) and (3.41±0.20) mmol/L] in young adults; lower fasting blood glucose in middle age [(6.17±0.67) and (5.37±0.79) mmol/L, respectively, ] and higher diastolic blood pressure in nonagenarian age [(76.99±6.78) and (83.97±9.36) mmHg, respectively, ] (all P values<0.05). Conclusion: The constructed epigenetic clock model can be used to evaluate and calibrate human biological age.

[Assessment of cognitive function of the elderly by serum metabolites of brain-gut axis].

Objective: To investigate the feasibility of assessing cognitive function of the elderly by serum metabolites of brain-gut axis. Methods: Convenience sampling was used to select 100 and 60 participants from the healthy population cohort and microecological balance cohort of the longevity population in Guangxi, to constitute subset of healthy population and longevity population, respectively. A questionnaire was used to investigate the demographic characteristics of the subjects, 2-5 ml of fasting venous blood was collected from the subjects, and the serum untargeted metabolomics was determined by liquid chromatography tandem mass spectrometry. The biomarkers related to the brain-gut axis were collected through literature retrieval, and the results were intersected with the untargeted metabolites and annotated. Spearman correlation analysis was used to screen serum metabolites of brain-gut axis associated with aging, and multiple linear regression method was used to construct biological age model. The mini mental status examination was used to evaluate the cognitive function of longevity population subsets. The differences of biological age and chronological age of longevity population subsets with different cognitive function were compared. Results: The M (Q1, Q3) of subset of healthy population and longevity population were 64 (38, 72) and 97 (95, 99) years old, respectively, and there were 50 (50.0%) and 44 (73.3%) females, respectively. Nine serum metabolites of brain-gut axis were obtained by initial screening, which were propionic acid, glutamic acid, γ-aminobutyric acid (GABA), lactic acid, 5-hydroxytryptamine (5-HT), tryptophan, trimethylamine oxide, dopamine and canine urea. Spearman correlation analysis showed that glutamic acid and dopamine were positively correlated with aging (r values were 0.208 and 0.524, respectively, all P values<0.05), and tryptophan, 5-HT and GABA were negatively correlated with aging (r values were -0.308, -0.533 and -0.213, respectively, all P values<0.05). The biological age model was constructed as: y=49.81-1.18×10-5× GABA-1.82×10-4×5-HT+1.99×10-3×dopamine+1.65×10-6×glutamic acid -2.04×10-6×tryptophan+2.36×gender, where y was the biological age (years), the items on the right were the intercept item, the relative concentration of each metabolite, and gender (male=1, female=2). The coefficient of determination of model was 0.50 (P<0.001). The M (Q1, Q3) of the chronological age of the subset of longevity population with poor, moderate and good cognitive function were 97 (94, 100), 97 (93, 101) and 96 (94, 101) years old, respectively, and there was no statistical significance in pairwise comparison (all P values>0.05). The M (Q1, Q3) of the biological age of the subjects with better cognitive function was 51 (38, 54) years old, which was lower than that of the subjects with poor cognitive function [57 (47, 61)] (P=0.040). Conclusion: The biological age model can be constructed based on serum metabolites of brain-gut axis and used to evaluate the cognitive function of the elderly.

[The study on the distribution characteristics and relevant factors of healthy and long-lived people in multiple regions of Guangxi Zhuang Autonomous Region].

Objective: To investigate the epidemiological characteristics and relevant factors among individuals characterized by their longevity in multiple regions of Guangxi Zhuang Autonomous Region, and provide a valuable scientific perspective for the research in health and longevity of the elderly in Guangxi. Methods: Registration and face-to-face questionnaire on a door-to-door basis were adopted to collect the demographic characteristics of the long-lived individuals (≥90 years old) in Bama of Hechi city, Yongfu of Guilin city, Dongxing of Fangchenggang city, Guangxi. Then, among the local general population, individuals within the age group between 40 and 85 years old were selected randomly as controls. Correlations were then analyzed between the relative health and longevity of the subjects and their gender, ethnicity, family history, disease history, marital status, the number of family generations, the number of children, smoking, drinking, outdoor activities, sleep and other health-related factors, then the result was subject to further analysis by comparing the long-lived population and the control population respectively. Results: Among 691 500 of the permanent residents of Bama, Yongfu and Dongxing city, 1 005 cases were 90 years old and over with a ratio of 145.34 out of 100 000 persons; within the 1 005 cases, 944 were aged between 90 and 100 (longevity rate: 136.51/100 000) with an average age of (93.28±2.57); 61 cases were aged 100 or over, arriving at a centenarian rate of 8.82/100 000 with an average age of (102.00±3.05) years. Significant differences were found just among three particular factors - regional distribution (P=0.014), history of disease (P=0.002), four generations of family (P=0.008) between nonagenarians and centenarians (P<0.05), while the other 15 indicators did not show anything noteworthy. The result indicated that longevity and centenarians might be the same group and then we combined both groups into one. By cross-comparison between the longevity-plus- centenarians and the control group in the region, factors listed below exhibited significant correlation with health and longevity: marital status (OR=26.469, 95%CI: 13.208-53.045), number of generations within the family (OR=5.419, 95%CI: 3.418-8.592), number of male offspring (OR=2.013, 95%CI: 1.555-2.607), number of female offspring (OR=1.380, 95%CI: 1.122-1.696), and the frequency of outdoor activities (OR=10.226, 95%CI: 3.164-33.045). Conclusions: The longevity rate is higher in the general natural population in Bama, Yongfu and Dongxing of Guangxi. The phenomenon may owe to favorable family structure, atmosphere within or out of the family or other elements related with social surrounding. Among them all, mentality, inclination to physical exercise and regular rhythm of life may all exert tremendous contributory influence here.

[Analysis of distribution characteristics and influencing factors of healthy and long-lived people in Shanglin area of Nanning, Guangxi Zhuang Autonomous Region].

Objective: To explore the epidemiologic characteristics of long-lived population and influencing factors in Shanglin county of Guangxi and provide scientific basis for the study of health and longevity in Guangxi. Methods: We collected and analyzed the general demographic cross-sectional data of the long-lived individuals (≥90 years old) in 11 villages and towns by multi-source registration and face-to-face interview. The age group control design was adopted to conduct a comparison among the longevity group (90-100 years old), centenarian group (≥100 years old), the longevity plus centenarian group and control group (local population aged 40-85 years), and identify the factors related to longevity. Results: Among the 496 007 people registered in Shanglin, 1 533 were aged ≥90 years, including 1 453 in the longevity group, with an average age of (92.84±2.46) years, and 80 in the centenarian group, with an average age of (102.67±2.60) years. The spatial distribution of long-lived individuals and centenarians was mainly in the north and central areas, and sparse in southwest area. Analysis on factors related to health and longevity indicated that old people with Zhuang ethnic (OR=1.551,95%CI:1.308-1.838), married (OR=55.507,95%CI:36.087-85.377) and moderately high waist-to-hip ratio (OR=258.056,95%CI:27.775-2 397.569), and SBP (OR=1.019,95%CI:1.013-1.026) tended to live longer. Conclusions: We found that the rate of longevity in Shanglin was higher than the average level in Guangxi and China. Longevity in Shanglin country had unique spatial and population distribution characterics of female longevity more than male longevity, mainly Zhuang ethnic and so on. Being women, married, family history of longevity, appropriate high waist-to-hip ratio, SBP and blood sugar level might be positive factors for longevity in Shanglin, but the impacts of other factors on longevity need further study.

[Efficacy and safety of Kangbingdu granules in the treatment of influenza: a randomized, double-blind, double-dummy, positive-drug parallel control multicenter clinical trial].

Objective: To observe the efficacy and safety of Kangbingdu granules (KBD) in the treatment of influenza. Methods: A multicenter, randomized, double-blind, double-dummy, and positive-drug parallel control trial was conducted in 27 Grade ⅢA hospitals in China and the subjects were randomly assigned to the KBD test group or the oseltamivir phosphate capsule control group at a ratio of 1∶1. 200 subjects were planned to be enrolled in each group. The experimental group was given KBD (18g each time, 3 times a day) and oseltamivir phosphate simulator orally, while the control group was given oseltamivir phosphate capsule (75 mg each time, twice a day) and KBD simulator orally for 5 days. The primary efficacy indicators included the remission time of major clinical symptoms and the time of complete defervescence. The secondary efficacy indicators included dosage of acetaminophen, the change of traditional Chinese medicine (TCM) syndrome score and the remission time of other important clinical symptoms. The efficacy of KBD in the test group and Oseltamivir phosphate control group were compared. Adverse events or adverse reactions were observed at the same time to evaluate the safety of KBD Granules. Results: A total of 393 subjects from 27 Grade ⅢA hospitals in China were enrolled. The experimental group included 195 subjects and 191 subjects (97.95%) completed the trial, While the control group included 198 subjects and 195 subjects (98.48%) completed the trial. There was no significant difference in the shedding rate and rejection rate between the two groups (P>0.05). In the Full Analysis Set (FAS), the mean age of the experimental group was (34.9±14.4) years old, with 83 males (42.78%). The mean age of the control group was (33.3±13.5) years old, with 78 males (39.59%). There were no statistically significant differences between the two groups in demographic data, physical examination, viral pathogen detection, total score of TCM syndromes and scores of each symptom at baseline (P>0.05). In the FAS, the remission time M (Q1, Q3) of major clinical symptoms was 3.0 (3.0, 4.0) days in the experimental group and 3.0 (3.0, 4.0) days in the control group, and the difference was not statistically significant (P>0.05). The time M (Q1, Q3) of complete defervescence was 34.0 (20.3, 49.0) hours in the experimental group and 36.5 (19.6, 48.8) hours in the control group, and the difference was not statistically significant (P>0.05). KBD granules had the same effect as Oseltamivir phosphate capsule (P>0.05) in terms of acetaminophen dosage, TCM syndrome effect and disappearance rate of most important clinical symptoms. Meanwhile, the disappearance rate of dizziness and chest distress on day 3 in the KBD granules group was better than that of oseltamivir phosphate capsule (P<0.05). Conclusion: KBD granules have the same efficacy as Oseltamivir Phosphate capsule in the treatment of influenza and the drug safety is good.

Multi-residue method for the determination of 450 pesticide residues in honey, fruit juice and wine by double-cartridge solid-phase extraction/gas chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry.

A multi-residue method was developed for the determination of 450 pesticide residues in honey, fruit juice and wine using double-cartridge solid-phase extraction (SPE), gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS-MS). The method development was based on an appraisal of the characteristics of GC-MS and LC-MS-MS for 654 pesticides as well as the efficiency of extraction and purification from honey, fruit juice and wine. Samples were first diluted with water plus acetone, then extracted with portions of dichloromethane. The extracts were concentrated and cleaned up with graphitized carbon black and aminopropyl cartridges stacked in tandem. Pesticides were eluted with acetonitrile + toluene, and the eluates were concentrated. For 383 pesticides, the eluate was extracted with hexane twice and internal standard solution was added prior to GC-MS determination. For 67 pesticides, extraction was with methanol prior to LC-MS-MS determination. The limit of detection for the method was between 1.0 and 300 ng g(-1) depending on each pesticide analyte. At the three fortification levels of 2.0-3000 ng g(-1), the average recovery rates were between 59 and 123%, among which 413 pesticides (92% of the 450) had recovery rates of 70-120% and 35 pesticides (8% of the 450) had recovery rates of 59-70%. There were 437 pesticides (97% of the 450) with a relative standard deviation below 25%; there were 13 varieties (3% of the 450) between 25.0 and 30.4%.

Determination of clopidol residues in chicken tissues by liquid chromatography: part I. Optimization of analytical conditions and comparison with AOAC gas chromatography method.

A simple and specific liquid chromatographic method was developed for determination of clopidol in chicken tissues. Samples were extracted with acetonitrile. The extracts were cleaned up on an alumina column and an anion exchange column. The clopidol was separated on a column (30 cm x 3.9 mm) of microBondapak C18 (10 microm) by using acetonitrile-water (20 + 80, v/v) as mobile phase, and determined quantitatively at 270 nm. Recoveries were 86.0-97.6%, with relative standard deviations of 2.14-9.42% at 0.010-2.0 mg/kg from 4 spiked matrixes of chicken muscle, egg, liver, and kidney. The limit of detection was 0.005 mg/kg. Compared with the modified AOAC gas chromatographic method, the present method is simple and fast to operate. Its results are accurate and reliable, making it favorable for environmental protection and meeting requirements for human safety. Thus, it is suitable for routine analysis of large quantities of samples.

Determination of clopidol residues in chicken tissues by liquid chromatography: part II. Distribution and depletion of clopidol in chicken tissues.

A study was made of the distribution and depletion of clopidol residues at different tissue locations in chickens fed with feeds incurred with clopidol. Experiments showed that the residue levels were not identical at 5 different tissue locations in each chicken. The sequence of residue levels from high to low was livers, kidneys, upper breast, lower breast, and leg meat. The maximum residue values after suspension of the drug for 8 h were (mg/kg): livers, 4.600; kidneys, 3.619; upper breast, 1.742; lower breast, 1.641; leg meat, 1.525. The averages were taken after values for 10 chickens were determined. After suspension of the drug for 3 days, >80% residue clopidol was depleted, and the depletion was nearly completed within 7 days. The speed of depletion varied at different tissue locations in each chicken, with the sequence from fast to slow being equivalent to that of the residue levels. Analytical results of 350 samples during 7 days showed that the proposed method is specific for determination of clopidol in chickens.

Determination of clopidol residues in chicken tissues by liquid chromatography: part III. Quality control analysis of export chickens.

A summary is presented of the liquid chromatographic (LC) determination of clopidol residues in export chickens from 1992 to 1999. Over the past 8 years, we analyzed >7000 chicken samples. A total of 0.66% of samples contained clopidol residues, ranging from 0.005 to 0.79 mg/kg; however, none exceeded 3 mg/kg, the Chinese maximum residue limit. In comparison with 1992, the number of samples multiplied 70-fold, and the frequency of clopidol found in samples decreased 148-fold in 1999. The chickens inspected were exported to foreign countries; all were cleared by the buyers with no disputes. This report also introduces the critical control points of the proposed LC method as well as identification of false-positive procedures by both experience and LC/mass spectrometric confirmation. Our experiences over the past 8 years have demonstrated that the ruggedness of the proposed LC method is quite good.

Determination of clopidol residues in chicken tissues by high-performance liquid chromatography-mass spectrometry.

A high-performance liquid chromatographic-mass spectrometric (HPLC-MS) method has been developed for determination of clopidol residues in chicken tissues. Samples are extracted with acetonitrile. The extracts are cleaned up on an alumina column followed by an anion-exchange column. The clopidol is separated on a column (150 cmx4.6 mm) of Intertsil by using acetonitrile-water (20:80) as mobile phase. The clopidol was qualitatively identified by molecule mass and determined quantitatively by selected ion monitoring mode at 190 m/z. The recoveries with RSDs ranged from 91.6+/-10.1 to 97.3+/-5.7 at 0.010 to 10.0 mg/kg by spiking three matrices (chicken muscle, liver, and kidney). The limit of detection was 0.005 mg/kg, and the limit of quantification was 0.010 mg/kg.

Interlaboratory study of identification and quantitation of multiresidue pyrethroids in agricultural products by gas chromatography-mass spectrometry.

This paper deals with the different GC-MS analytical conditions adopted by four laboratories in an attempt to confirm the accuracy of the GC-electron-capture detection (ECD) analytical results during the international collaborative study for the establishment of the AOAC Official Method 998. 01. What is especially noted is that two laboratories have conducted comparative analysis of the respective 12 blind samples with both methods of GC-ECD and GC-MS, and the analytical results of the two methods turn out to be basically identical. This fully demonstrates that GC-MS is not only an effective confirmation tool in the analysis of the pyrethroid residues but also of sufficient sensitivity regarding the maximum residue limit of determination prescribed by FAO/WHO. Moreover, its selectivity is better than GC-ECD.

Multiresidue gas chromatographic method for determining synthetic pyrethroid pesticides in agricultural products: collaborative study.

Fourteen laboratories from 6 countries and regions participated in an international collaborative study to evaluate a multiresidue gas chromatographic (GC) method for determining 8 synthetic pyrethroid pesticides in grains, fruits, and vegetables. The study design was based on Youden's matched-pairs principle for collaborative tests of analytical methods. Each laboratory analyzed 12 collaborative samples of wheat, oranges, and tomatoes as blind samples. Wheat samples were extracted with acetonitrile-water (2 + 1), while orange and tomato samples were extracted with acetone. Residues were partitioned into hexane, evaporated to dryness with a rotary evaporator, and then dissolved in hexane. The hexane extract was partitioned with acetonitrile and cleaned up on a 5% water-deactivated Florisil column with 6% ethyl ether in hexane as eluant. Residue concentrations were determined by GC with electron capture detection with splitless injection by comparison with single-point calibration standards. The appropriate standard concentration was determined by screening sample extracts before analysis. The multiresidue method was tested over the concentration range of 0.095-1.909 mg/kg depending on the 8 different of pesticides and agricultural products analyzed in the collaborative study. Statistical analysis of data from 13 laboratories showed weighted average recoveries for 8 pyrethroids in wheat, oranges, and tomatoes at 0.105-1.909, 0.095-1.909, and 0.105-0.954 mg/kg, respectively, ranging from 91.8 to 100.2%, from 88.1 to 100.6%, and from 88.2 to 101.5%, respectively. Reproducibility relative standard deviation values ranged from 6.46 to 17.74%, from 5.94 to 18.13%, and from 5.59 to 10.48%, respectively. Repeatability relative standard deviation values ranged from 6.34 to 10.84%, from 5.19 to 11.72%, and from 3.20 to 8.09%, respectively. The multiresidue GC method for determining synthetic pyrethroid pesticides in agricultural products has been adopted first action by AOAC INTERNATIONAL.

Modification of AOAC multiresidue method for determining synthetic pyrethroid residues in fruits, vegetables, and grains. Part III: Studies of analyte stability and method ruggedness.

The stability of 8 synthetic pyrethroids in 9 crops during storage for 90 days were studied. The 8 pyrethroid insecticides were highly persistent in the 6 grains during storage. But their stabilities in 3 kinds of fruits and vegetables were different from those in the 6 grains: Most of them were degraded. Florisil purification conditions were studied with 6 batches of Florisil from 3 countries at various extents of deactivation and amounts. The best conditions of Florisil purification found in this present research agree with those found 1 year ago. The efficiencies of acetonitrile and acetone to extract the 8 pyrethroids from 6 fruit and vegetable samples were compared. The extraction efficiency of acetone was competitive with that of acetonitrile for the 6 fruit and vegetable samples. Method performance was evaluated by 6 analysts from different areas. The ruggedness tests demonstrate further that the proposed method is simple, accurate with good precision, and suitable for multiresidue analysis of pyrethroids in various agriculture products.

Multiresidue liquid chromatographic method for simultaneous determination of pyrethroid insecticides in fruits and vegetables.

A simple and rapid liquid chromatographic (LC) method has been developed for simultaneous determination of 9 pyrethroid insecticides (biphenthrin, cypermethrin, fenpropathrin, fenvalerate, flucythrinate, methothrin, permethrin, py-115, and tetramethrin) in fruits and vegetables. Residues are extracted from crops with methanol and partitioned with toluene. Extracts are cleaned up by Florisil-charcoal column chromatography. LC separation is performed on a muBondapak C18 stainless steel column with acetonitrile-deionized water as mobile phase. The insecticides are detected at 206 nm with 0.03 absorbance unit full scale. Recoveries of 9 pyrethroid insecticides from 6 crops (cucumbers, tomatoes, cabbages, apples, pears, and peaches) fortified at 0.5-5.0 mg/kg were 62.7-129.2%. Detection limits were about 0.05 mg/kg, except for py-115, for which detection limit was 0.10 mg/kg.

Modification of AOAC multiresidue method for determination of synthetic pyrethroid residues in fruits, vegetables, and grains. Part I: Acetonitrile extraction system and optimization of florisil cleanup and gas chromatography.

We present a multiresidue method for determination of synthetic pyrethroids in fruits, vegetables, and grains. The method is a modification of AOAC Method 970.52. Residues are extracted with acetonitrile (for fruits and vegetables) or acetonitrile-water (2 + 1) (for grains) and then transferred to hexane. Coextractives are removed by acetonitrile partitioning and open-column chromatography with deactivated Florisil. The final extract is analyzed by gas chromatography with electron capture detection (GC-ECD). An HP-17 wide-bore column is used to determine the individual isomeric contents of each insecticide. The method was used to recover 8 pyrethroids (biphenthrin, fenpropathrin, cyhalothrin, permethrin, cypermethrin, fluvalinate, fenvalerate, and deltamethrin) spiked at 0.01-4.0 mg/kg in 20 crops (apple, pear, peach, banana, grape, strawberry, potato, tomato, cucumber, pepper, cabbage, carrot, celery, polished rice, wheat, green gram, buckwheat, sorghum, maize, and barley). Recoveries of the 8 pyrethroid insecticides in 6 crops ranged from 83.8 to 112.8%, with a coefficient of variation (CV) of 2.00 to 12.09% for the narrow-bore capillary GC (n = 6) and from 82.8 to 106.4%, CV = 2.93-12.19%, for the wide-bore capillary GC (n = 6). The minimum detectable levels of 0.004-0.028 mg/kg (for fruits and vegetables) or 0.01-0.08 mg/kg (for grains) for the 8 pyrethroids are easy to detect.

Modification of AOAC multiresidue method for determination of synthetic pyrethroid residues in fruits, vegetables, and grains. Part II: Acetone extraction system.

To optimize conditions and to evaluate further a multiresidue method for pyrethroids, various extraction solvents and partitioning conditions were examined. Acetone and acetonitrile (for fruits and vegetables) and acetone-water and acetonitrile-water (for grains) were used as solvents with or without acetonitrile partitioning. Twenty crops fortified with 8 pyrethroid insecticides at low, medium, and high levels were analyzed. For limit of detection (LOD) levels, repeatability tests were completed with acetone-water as extraction solvent. Recoveries of 8 pyrethroid insecticides at LOD levels were 76.2-99.6%, with coefficients of variation (CVs) of 2.08-10.90% for narrow-bore capillary gas chromatography (GC) (n = 6) and 80.1-107.3% with CVs of 3.76-15.38% for wide-bore capillary GC (n = 6). Both acetone or acetone-water extraction with acetonitrile partitioning and acetonitrile or acetonitrile-water extraction with acetonitrile partitioning are suitable for multiresidue analysis of pyrethroid insecticides. However, acetonitrile and acetonitrile-water as extraction solvents were better than acetone and acetone-water at LOD-fortified levels. This finding was confirmed chromatographically with pear, cucumber, and barley control samples.

Cleanup with two Florisil columns for gas chromatographic determination of multiple pyrethroid insecticides in products of animal origin.

A gas chromatographic method was developed for the simultaneous determination of 9 pyrethroid insecticides in products of animal origin. The multiresidues of the pyrethroids in different samples were extracted with acetone-petroleum ether (1 + 1), and extracts were cleaned up on a Florisil partition column and a Florisil adsorption column. Four animal tissue samples were examined at 0.05-0.25 ppm fortification levels. The average recoveries of all insecticides were 76.9-88.0%, and the coefficients of variation were < 4.6% for all insecticides except permethrin. The detection limits of the method were ca 5 ppb for all insecticides but permethrin, which had a detection limit of ca 10 ppb.

Packed-column gas chromatographic method for the simultaneous determination of 10 pyrethroid insecticide residues in fruits, vegetables, and grains.

A simple, rapid, packed-column gas chromatographic method was developed for simultaneous determination of 10 pyrethroid insecticide residues (allethrin, biphenthrin, cyhalothrin, permethrin, cyfluthrin, flucythrinate, fenvalerate, fluvalinate, deltamethrin, and py-115) in fruits, vegetables, and grains. These multiresidues are extracted from various crops with acetone-petroleum ether and cleaned up on a Florisil column (for the fruits and vegetables) or on a Florisil-charcoal-alumina column (for the grains) prior to their determination by gas chromatography with an electron capture detector. Recoveries of 10 pyrethroid compounds from 12 different crops (maize, soybeans, wheat, sorghums, paddy, potatoes, cucumbers, cauliflowers, spinaches, apples, bananas, and oranges) fortified at levels of 0.02-5.00 ppm ranged from 58 to 130%. In a separate precision study, coefficients of variation were 5.5-14.6% at 0.1-0.5 ppm (n = 10, maize), and 4.1-12.1% at 0.010-0.050 ppm (n = 10, apples). The detection limits of the method ranged from 2.0 to 10.0 ppb on a crop basis.

Rapid method for the determination of multiple pyrethroid residues in fruits and vegetables by capillary column gas chromatography.

A rapid and economical simplified multi-residue method is described for the determination of multiple pyrethroid insecticides in fruits and vegetables. The residues are extracted from crops with methanol and the crop co-extractives are removed by toluene partitioning and Florisil-charcoal minicolumn chromatography. The final extract is analysed by capillary column gas chromatography with electron-capture detection. The recoveries were determined by fortifying six different crops (apples, oranges, cabbages, pears, peppers and tomatoes) with eleven pyrethroids (Py-115, allethrin, biphenthrin, fenpropathrin, cyhalothrin, permethrin, cyfluthrin, flucythrinate, fluvalinate, fenvalerate and deltamethrin) at three levels, 0.01-0.07, 0.10-0.70 and 1.0-7.0 mg/kg. Three determinations were made at each level for each crop. Recoveries of the eleven pyrethroids ranged from 70.4 to 110.0% at the three different levels. The practical determination limit of the method was in the range 3.0-30.0 micrograms/kg for all the pyrethroid insecticides. The proposed method had major advantages that simplified steps were achieved for the extraction and the clean-up, the solvent consumption was reduced and the analysis time was shortened.