ABSTRACT
Background Diacetyl (DC) is widely used in the food flavoring industry and excessive occupational exposure to DC can cause serious respiratory diseases. However, there is no corresponding national standard method for the determination of DC in the air of workplace. Objective To establish a method for the determination of DC in workplace air by high performance liquid chromatography using 4-nitro-o-phenylenediamine (NPDA) as precolumn derivatization. Methods DC in the air of workplace was collected by solution absorption method. This experiment used NPDA as the derivatization reagent. By adjusting acidity of solution and optimizing concentration ration of DC/NPDA, derivatization temperature, and time, a method for the determination of DC in workplace air was proposed, and its performance indexes such as linearity, detection limit, and lower limit of quantification were obtained. Sampling efficiency was evaluated by relative comparison method, and sample stability was evaluated by sample preservation test. Accuracy and precision of the method were evaluated by standard addition recovery test with blank samples, and an interference test was carried out by adding standard samples. The established method was applied to actual samples to evaluate its adaptability. Results A combination of 60 °C for 2 h was selected for derivatization because a higher derivatization reaction temperature and a longer reaction time associated with a higher derivatization efficiency. The solution was separated by SB-C18 column (250 mm×4.6 mm, 5 μm) at 30 ℃, using a mixture of methanol and water (v/v, 65%/35%) as mobile phase with an elution flow rate of 1.0 mL·min−1, and was detected with a variable wavelength detector (λmax=257 nm) by qualitative analysis based on retention time and quantitative analysis based on external standard method. In terms of the proposed method, the linear range of detection was from 5 μg·L−1 to 2000 μg·L−1, with a correlation coefficient of 0.9999, and a detection limit of 1.3 μg·L−1, the quantitative detection of the lower limit was 4.3 μg·L−1, with a sampling volume V0 of 3.0 L, the minimum detection concentration was 4.3 μg·m−3, and the minimum quantitative concentration was 14.3 μg·m−3. The recovery rate was 99.1%-100.8%, the intra-batch precision was 0.5%-3.0%, and the inter-batch precision was 1.2%-2.0%. The average sampling efficiency of this method was 94.5%, and the sample could be stored at 4 °C for at least 14 d. The coexisting components in the air of the workplace did not interfere with the determination of DC. The DC content in the air of a flavor workplace was 5.86-8.85 mg·m−3. Conclusion A determination method for DC in workplace air by high performance liquid chromatography using NPDA as precolumn derivatization after being collected by 1.0% phosphoric acid absorbent is proposed and has the advantages of simple operation, high sensitivity, and good accuracy. With no DC loss and degradation, the method may satisfy the request for DC determination in the air of workplace.
ABSTRACT
@#Abstract: Objective - - To establish a pre column derivatization high performance liquid chromatography method for detecting Methods dimethyl sulfate (DMS) in workplace air. DMS in workplace air was collected with mercaptopyridine impregnated （ silicone tube. The derivative of DMS and mercaptopyridine was eluted by mobile phase phase A: water, phase B: acetonitrile, ∶ the volume ratio was 40 60) , and separated with a C18 column, then detected with diode array detector and quantitated by a Results - standard curve. The linear range of DMS was 0.17 40.00 mg/L, with the correlation coefficient of 0.999 95. The detection limit and the lower limit of quantitation were 0.05 and 0.17 mg/L respectively. The minimum detection concentration and minimum quantitation concentration were 0.02 and 0.04 mg/m³, respectively (air sample volume of 4.5 L, 1.0 mL sample - - - solution). The average desorption efficiency was 98.40% 102.00%. The within run and between run relative standard deviations - - were 0.61% 3.92% and 1.71% 6.00%, respectively. The samples could be stored at room temperature for at least 14 days. Conclusion This method can be used to detect DMS in workplace air.
ABSTRACT
Objective To study the pharmacokinetic features of reactive sulfide in rats after oral administration of Cinnabaris. Methods An HPLC coupled with precolumn derivatization method was developed for the pharmacokinetic features study on reactive sulfide in rats after oral administration of Cinnabaris. Results Good linearity (r>0.99) was found for reactive sulfide in plasma in the concentration range of 0.25–15 μmol/L (r>0.99). The LOQ and LOD of the method were 0.1 μmol/L and 0.02 μmol/L, respectively. The intra- and inter-day precision was less than 4.4% and 3.5% respectively, and the accuracy was -9.9%–6.0%. The average recovery rate was 74.9%. 0.6 g/kg Cinnabaris was given the rats for gavage, and the time-course pharmacokinetics parameters were as follows:Cmax(1.33±0.13) μmol/L, tmax(150±34) min, t1/2(323±62) min, AUC0-∞ (5743±297) ng/mL?h. Conclusion A sensitive, robust and accurate precolumn derivatization-HPLC method for the determination of plasma reactive sulfide is developed and validated. The method is successfully applied in the pharmacokinetic features study on reactive sulfide in plasma of rats after administration of Cinnabaris.
ABSTRACT
OBJECTIVE: To establish a method for detecting thiocyanate in human urine by high performance liquid chromatography( HPLC) with 2,3,4,5,6-pentafluorobenzyl bromide as precolumn derivatization reagent.METHODS: Thiocyanate in human urine was derived with 2,3,4,5,6-pentafluorobenzyl bromide, and separated by poroshell 120EC-C18 column with acetonitrile:deionized water( 60:40,V/V) as mobile phase.detected by HPLC,Liquid chromatography-UV detector was used for determination.The wavelength was 212.00 nm.RESULTS: Good linearity was obtained in the range of 0.05-10.32 mg/L with the correlation coefficient of 0.999.The detection limit was 6.31 μg/L and the minimum detection concentration was 63.10 μg/L( 0.1 mL urine).The recovery rate was 95.1%-102.9%.The within-run relative standard deviation( RSD) and the between-run RSD were 0.9%-1.0% and 0.9%-2.1%,respectively.The urine samples could be stored at 4 ℃ for 7 days.CONCLUSION: This method has high sensitivity,good specificity and sample preparation,which can be used for detecting urine thiocyanate in occupational population.
ABSTRACT
OBJECTIVE: To establish a method for detecting human urinary thiocyanate by gas chromatographic and pre-column derivatization with 2,3,4,5,6-pentafluorobenzyl bromide( PFB-Br). METHODS: A total of 20. 0 μL of urine was taken and 1. 0 m L of acetonitrile and 100. 0 μL of PFB-Br were added for derivative reaction. The gas chromatography was directly used for measurement. RESULTS: The urinary thiocyanate concentration showed a good linear range of 1. 000-10. 000 mg/L. The linear correlation coefficient was 0. 999 6. The minimum detection concentration was 0. 112 mg/L,and the minimum quantitative concentration was 0. 411 mg/L( 20. 0 μL urine sample). The standard recovery rate was 97. 22%-102. 04%.The within-run relative standard deviation( RSD) of this method was 1. 56%-5. 35%. The between-run RSD was 1. 46%-5. 10%. Hydrocyanic acid ions interfered with the measurement. Other common inorganic ions such as chloride,sulfate,and nitrate ions did not interfere with the measurement results. The samples can be stored at 4 ℃ for at least 15 days. CONCLUSION: This method is suitable for detecting human urinary thiocyanate.
ABSTRACT
OBJECTIVE: To establish a quantitative method of determining the contents of 15 kinds of free amino acids in the Hericium erinaceus mycelium. METHODS: The HPLC analysis was performed after derivatization by using phenyl isothiocyanate (PITC) as a derivative reagent. The chromatographic column was Ultimate Amino Acid(4.6 mm×250 mm, 5 μm). The mobile phase A was acetonitrile-water (80∶20), and mobile phase B was sodium acetate buffer (pH 6.5). Gradient elution was performed at the flow rate of 1.0 mLmin-1. The detection wavelength was set at 254 nm, and the column temperature was maintained at 40℃. RESULTS: The correlation coefficients of 15 kinds of free amino acids ranged from 0.999 7 to 0.999 9. The average recovery rate (n=6) was between 96.83%-98.60%, and the RSD was between 0.67%-2.67%. CONCLUSION: This method is simple, accurate and can be used to determine the contents of 15 kinds of free amino acids in the Hericium erinaceus mycelium.
ABSTRACT
Objective: To analyze the free and hydrolyzed amino acids in Sojae Semen Preparatum (SSP) and Glycine max (GM) by pre-column derivatization RP-HPLC. Methods: Free amino acids extracted in HCl (0.1 mol/L) by ultrasonic method and hydrolyzed amino acids extracted in HCl (6 mol/L) by hydrolysis method were both derivated by the agent phenylisothiocyanate so as to analyze them by gradient elution. Results: There were 16 kinds of amino acids in both SSP and GM. The 16 kinds of amino acids had good linearity in the range of 0.031-1.750 μmol/mL with the coefficients of correlation all over 0.9979. The average recoveries were 91.02%-102.04% and the RSD values were between 1.01% and 4.81%. Conclusion: The method is not only sensitive and accurate, but also has the high repeatability and stability, and the 16 kinds of amino acids could be separated in the case of the samples with more impurities. The common C18 column is widely used for the determination of many other samples riched in amino acids at lower cost.
ABSTRACT
A method was developed for the determination of sodium caprylate in human serum albumin by reversed phase high performance liquid chromatography(RP-HPLC) after pre-column derivatization. The caprylic acid, extracted from human serum albumin by hexane, was treated with ω-bromoacetophenone and 18-crown-6 for 30 min at 50 ℃, and analyzed on a Nova-Park C_(18)(150 mm×3.9 mm, 4 μm) column with methanol-water(75∶ 25, V/V) as the mobile phase. The internal standard was enanthic acid, the flow rate was 1.0 mL/min and the detection wavelength was 262 nm. The extraction yield of caprylic acid was 97.9% and that of enanthic acid was 98.2%. The linear range of sodium caprylate was 9.00×10~(-4)-1.44×10~(-2) mol/L(r=0.9995). The average recovery of caprylic acid was 99.7%, RSD was less than 0.9%. The present method is reliable and relatively simple and can be used for the determination of sodium caprylate in human serum albumin.
ABSTRACT
Objective To determin the amino acids in silkworm extract by High Performance Liquid Chromatography with Precolumn Derivatization.Methods With the technology of precolumn derivatization, along with high performance liquid DABS-CL and a high-efficiency YMC-Pack ODS-A column(250?4.6mm, 5 ?m), with mobile phase being A:25mol/L KH2PO4 and B: acetonitrile : methyl alcohol =70:30, at flow rate of 1.5 ml/min, peaks were detected at 436nm and column temperature being 35℃.Results All kinds of amino acids have a nice linear relations (r=0.9989~0.9999), precision (RSD
ABSTRACT
OBJECTIVE:To establish a HPLC method for determination of the plasma concentrations of isoniazid(INH)and its metabolite acetyl-isoniazid(AcINH).METHODS:Trichloroacetic acid was added to plasma to precipitate protein,then the supernatant was divided into 2 parts,distilled water was added to the first part;while HCl was added to the second one,after incubated at 80℃for 1 hour,1%cinnamaldehyde was added to perform precolumn derivatization.The column was Hypersil BDS C 18 ,the mobil phase was eluted with0.02mol/L NaH 2 PO 4 (pH=4.0)-acetontrile(69∶31)and detected wave-length was 340nm,the flow fate was1ml/min.RESULTS:INH detectable concentration showed a good linear correlation in the range of 0.57～145.88?mol/L,the average recoveries of INH and AcINH were 101.1% and 101.5% respectively,the average RSD within or between day was less than 10%.CONCLUSION:The present method is applicable to monitoring of INH plasma concentration and the study of metabolism capacity of N-acetyltransferase.
ABSTRACT
OBJECTIVE:To establish a RP-HPLC precolumn derivatization method for the content determination of argi-nine(Arg)and proline(Pro)in Folium Isatidis.METHOD:2,4-dinitro-fluorobenzene was undergone precolumn derivatization and the amino acids was determined directly under alkaline condition with Kromasil C 18 as chromatographic column,the mobile phase was composed of sodium acetate buffer solution(pH=6.4)-acetonitrile(850∶150)with detection wavelength at360nm,the content was calculated by external reference method.RESULTS:The linear ranges for Arg and Pro were0.627?g～5.016?g(r=0.9996)and0.874?g～7.000?g(r=0.9995),respectively.The average recovery was98.2%with RSD at2.3%and2.2%,respectively.CONCLUSION:The method is simple,accurate and reliable,and suitable for the assaying of amino acids in Folium Isatidis.
ABSTRACT
Objective To evaluate the pharmacokinetic parameters and bioavailability of Cyclobuxine D in transdermal patch in Newzealand rabbits by determining concentration-time curve and by comparing with the pharmacokinetics of Cyclobuxine Dinjection and suspension.Methods Precolumn derivatization RP-HPLC was used to detect the concentration of Clovirobuxine D in rabbits plasma at different time,and software 3p87 was used to analyze the pharmacokinetics parameter.Results In contrast to oral delivery,relatively steadily sustained blood concentration with minimal fluctuation and prolonged peak time were presented in the rabbits over a long period after transdermal administration.The absolute bioavailability of Cyclobuxine D was 30.472 %.Conclusion Cyclobuxine D Patch exhibits good controlled-release properties and maintains appropriate blood concentration for a prolonged time.
ABSTRACT
Therapeutic drug monitoring for serum Gentamicin is very useful for infectious patients. The most common methods for measuring concentration of Gentamicin in body fluids are microbiological assay, rasioimmunoassay (RIA), enzyme immunoassay (EMIT) and high pressure liquid chromatography (HPLC), The purpose of this study was to compare two new methods, an enzyme multiplied immunoassay test (EMIT; Suva Corp.) and high pressure liquid Chromatography with fluorescence detection precolumn derivatization, reversed Phase column. Forty serum samples were obtained from patients in the kidney disease unit, Department of Medicine, Siriraj Hospital. The two methods were evaluated on the basis of accuracy, limitation, specificity and cost. EMIT showed a high degree of accuracy and lesser limitation. But this method of HPLC could not determine values for serum gentamicin at levels below 4 ตg/ml. Total cost which included equipment for both procedures was similar. Unit cost for this method of HPLC was cheaper than EMIT but was time consuming and required experience. Both methods were specific for serum Gentamicin.