Detection of Multiple Antibiotic Residues in Turkish Pine and Blossom Honeys Using LC-MS/MS Method.

Due to the high demand for honey, beekeepers often feed the bees with antibiotics to protect honeybees against illnesses; the determination of veterinary drugs and their residues in bee products especially in honey is gaining importance. In this study, commercially available 15 different brands, a total of 22 honey (14 blossoms and 8 pines) samples obtained from 5 chain supermarkets in the city of Bingöl and Diyarbakir, Turkey were analysed for 29 antibiotic residues. These antibiotics belong to 10 different categories, including tetracyclines, aminoglycosides, macrolides, sulfonamides, fluoroquinolones, benzimidazoles, anthelmintic, amphenicols, quinolines, and oxazolidines. For the qualitative and quantitative determination of the antibiotics, a triple quadrupole liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used. A total of 10 out of 22 honey (8 blossom, 57.14 % and 2 pine, 25 %) samples were found to be positive for antibiotics. Among the tested antibiotics, tetracycline, dihydrostreptomycin, streptomycin, erythromycin, and sulfadimidine were detected in the honey samples. Dihydrostreptomycin and sulfadimidine were detected in 6 samples, erythromycin was determined in 4 samples, streptomycin was found in 2 samples, and lastly, tetracycline was detected only in one sample. The highest and the lowest concentrations of antibiotics detected in the samples were dihydrostreptomycin and erythromycin found at the amount of 992.58 µg/kg and 0.77 µg/kg respectively. The proposed method was validated with a limit of quantification (LOQ) and limit of detection (LOD) ranging between 0.42 and 3.22 µg /kg and 0.13-0.97 µg /kg respectively. Good linearities were also achieved ranging between R2 =0.987 and 0.999.

Single pot in situ aqueous derivatization and subsequent determination of streptomycin and dihydrostreptomycin residues in honey by means of mass spectrometry.

Streptomycin (STR) and dihydrostreptomycin (DSTR) are the typically encountered aminoglycoside (AMG) residues in honey. For AMG analysis, studies in literature involve impractical and expensive applications such as ion-pairing chromatography, immunoassays, pre and post column derivatizations, or SPE approaches. Pretreatments of these methods are toilsome and costly. Herein, one-pot, aqueous in-situ derivatization method was presented as a superior protocol. Time and cost-efficient UHPLC-MS/MS method has been developed, and practical sample preparation was introduced. Satisfactory results were reported in method verification studies. The mean recovery values were 102.6% for STR and 101.3% for DSTR. Average values between 1.5% and 9.9% RSDs were found at intra and inter-day precisions. CCα (5.7 and 5.8 µg/kg) and CCß (6.2 and 6.4 µg/kg) values were calculated for STR and DSTR respectively. AMG residues were found in 29 out of 110 analyzed samples using validated method. Described novelty enabled comprehensive analysis in an inexpensive and straightforward manner.

[Determination of streptomycin and dihydrostreptomycin in grapes by liquid chromatography-tandem mass spectrometry].

Streptomycin (STR) and dihydrostreptomycin (DSTR) are two of the most common aminoglycoside antibiotics used in veterinary medicine. STR is produced by some streptomyces griseus strains, and DSTR is a derivative of STR. In recent years, STR has been widely used in grapes to induce denuclearization. However, high levels of STR may have adverse effects like serious ototoxicity and nephrotoxicity. Therefore, to ensure the quality of grapes and the health of consumers, the regulation of STR and DSTR levels in grapes is required. An analytical method was developed for the identification and quantification of STR and DSTR in grapes by liquid chromatography-tandem mass spectrometry (LC-MS/MS). STR and DSTR are highly polar compounds due to the presence of various amino and hydroxyl groups in their structure. The determination of STR and DSTR poses a considerable analytical challenge, both during sample preparation and instrument analysis. In this study, the main factors governing the response, recovery, and sensitivity of these compounds, such as the type of chromatographic column, the type and proportion of the mobile phase and extraction solvent, the dosage of sodium 1-hexane sulfonate solution, and elution solvent and its volume, were investigated during sample pretreatment and instrument analysis. The STR and DSTR residues in the grape sample were extracted by ultrasonication with a phosphoric acid solution (pH 2), and cleanup and enrichment was performed using an Oasis HLB solid phase column. The analysis was performed using a UPLC Waters HSS T3 column (100 mm×2.1 mm, 1.8 µm) at the column temperature of 35℃. The injection volume was 2 µL. The mobile phase consisted of 0.1% formic acid aqueous solution and methanol with a volume ratio of 60:40. ESI-MS/MS was operated in multiple reaction monitoring (MRM) mode. External standard calibration curves were used for quantification. Based on the optimized method, both analytes displayed good linearity between 2 and 400 µg/L. The correlation coefficients were 0.9991-0.9997. Recoveries in spiked blank grape samples (5, 10, 20, and 40 µg/kg) ranged from 76.8% to 91.9%, with the relative standard deviations (RSDs) less than 10.2%, in compliance with the current legislation. The limits of detection and the limits of quantification of both analytes were 1 µg/L and 5 µg/kg, respectively. To assess the feasibility and potential of the proposed approach for routine analyses of STR and DSTR in other kinds of grape samples, the developed method was applied to the analysis of these compounds in red grapes, xinyu grapes, and xiahei grapes. The recoveries of STR and DSTR in the three kinds of blank grape samples were 77.2%-83.9% and 70.8%-78.9%, respectively, and the RSDs ranged from 3.0% to 15.6%. The results showed that the optimized methods can yield satisfactory recoveries for the analytes in grapes. In this method, the combination of Waters HSS T3 column to overcome the difficulties of the retention and separation of these highly polar compounds in the reverse phase, avoids the use of an ion-pair additive in the mobile phase to increase their retention, which is known to cause severe contamination of the column and serious ion suppression with electrospray ionization detection. In addition, the ideal enrichment and purification effect can be achieved by adding a sodium 1-hexane sulfonate solution to the superstratum extract with the use of only Oasis HLB for sample treatment. The method described herein has the advantages of easy operation, accuracy, and selectivity, making it feasible for the identification and quantification of STR and DSTR residues in grapes.

[Determination of streptomycin and dihydrostreptomycin residues in honey by hydrophilic interaction liquid chromatography-tandem mass spectrometry].

An analytical method was developed for the determination of streptomycin and dihydrostreptomycin in honey using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The streptomycin and dihydrostreptomycin residues in the test samples were extracted with 20 g/L trichloroacetic acid aqueous solution (including 50 mmol/L phosphate, pH 6.8) and cleaned on an Oasis HLB solid phase extraction column. The products were separated on a SIELC Obelisc R column with gradient elution using 0.5% (v/v) formic acid aqueous solution and acetonitrile as mobile phases. Streptomycin and dihydrostreptomycin were detected by liquid chromatography-tandem mass spectrometry in the positive ion mode using the external standard method. Under the optimal conditions, streptomycin and dihydrostreptomycin showed good linearity (r>0.99) in the range of 2.5-100 µg/L. The LOD and LOQ of the method was 2.0 µg/kg and 5.0 µg/kg, respectively. The spiked recoveries of the analytes from blank honey samples at the three levels of 5.0, 20.0 and 100.0 µg/kg were in the range of 86.9%-113.2% with the relative standard deviations less than 10%. With the advantages of convenience, rapidity, sensitivity and good repeatability, the method is suitable for the detection of streptomycin and dihydrostreptomycin in honey.

Investigation of the Persistence of Penicillin G and Dihydrostreptomycin Residues in Milk of Lactating Buffaloes ( Bubalus bubalis) Using Ultra-High-Performance Liquid Chromatography and Tandem Mass Spectrometry.

The purpose of this research was to evaluate the persistence of penicillin G and dihydrostreptomycin in milk of lactating buffaloes following intramuscular injection of procaine penicillin G (200000 IU/mL) and dihydrostreptomycin sulfate (250 mg/mL) every 24 h for 3 days. Milk samples were collected twice daily up to the 13th milking post-treatment and analyzed by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry. The analytical method has been validated according to Commission Decision 2002/657/EC. The highest concentrations of penicillin G (275 µg kg-1) and dihydrostreptomycin (220.5 µg kg-1) were detected in the milk of the first milkings post-treatment, and levels were below the maximum residue limit of 4 and 200 µg kg-1 in all treated buffaloes at milkings 12 and 2, respectively. The results of this study demonstrate that a nine-milking withdrawal time set for bovine milk was not adequate for depletion of penicillin G in lactating buffaloes.

[Determination of streptomycin and dihydrostreptomycin residues in tomato ketchup by UPLC-MS/MS].

OBJECTIVE: To develop a method for simultaneous determination of streptomycin and dihydrostreptomycin residues in tomato ketchup by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). METHODS: The sample was dissolved with phosphorus solution (pH 2) and extracted by ultrasonic. The pigment was removed with n-hexane. Then, the sample was cleaned up by HLB SPE. The HILIC chromatographic column (100 mm x 2.1 mm, 1.7 µm) was used to complete the separation under gradient elution. The mixed solution of 0.1% formic acid solution and acetonitrile was used as mobile phase. The detection of streptomycin and dihydrostreptomycin were carried out by MS/MS under multiple reaction monitoring (MRM) mode. The external standard method was used for quantitative analysis. RESULTS: The calibration curves for streptomycin and dihydrostreptomycin were indicated in the range of 0.005 - 0.100 mg/kg, and the detection limits were both 0.005 mg/kg. The recoveries of streptomycin and dihydrostreptomycin were ranged from 79.5% to 93.9% with relative standard deviations no more than 10%. CONCLUSION: The method is simple and accurate to meet the requirements for determination of streptomycin and dihydrostreptomycin residues in tomato ketchup.

Use of experimental design to optimize a triple-potential waveform to develop a method for the determination of streptomycin and dihydrostreptomycin in pharmaceutical veterinary dosage forms by HPLC-PAD.

An HPLC-PAD method using a gold working electrode and a triple-potential waveform was developed for the simultaneous determination of streptomycin and dihydrostreptomycin in veterinary drugs. Glucose was used as the internal standard, and the triple-potential waveform was optimized using a factorial and a central composite design. The optimum potentials were as follows: amperometric detection, E1=-0.15V; cleaning potential, E2=+0.85V; and reactivation of the electrode surface, E3=-0.65V. For the separation of the aminoglycosides and the internal standard of glucose, a CarboPac™ PA1 anion exchange column was used together with a mobile phase consisting of a 0.070 mol L(-1) sodium hydroxide solution in the isocratic elution mode with a flow rate of 0.8 mL min(-1). The method was validated and applied to the determination of streptomycin and dihydrostreptomycin in veterinary formulations (injection, suspension and ointment) without any previous sample pretreatment, except for the ointments, for which a liquid-liquid extraction was required before HPLC-PAD analysis. The method showed adequate selectivity, with an accuracy of 98-107% and a precision of less than 3.9%.

[Determination of streptomycin and dihydrostreptomycin in pollens by high performance liquid chromatography-tandem mass spectrometry].

A method was established for the determination of streptomycin (STR) and dihydrostreptomycin (DHS) in pollens based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted and cleaned-up by a C18 solid phase extraction cartridge. The separation was carried out on a Protemix WCX-NP5 column (100 mm x 2.1 mm, 5 microm) with a gradient elution using 5% (v/v) formic acid, 20 mmol/L ammonium acetate and methanol as mobile phases. The analysis of streptomycin and dihydrostreptomycin was performed under electrospray positive ionization mode. The limits of detection (LOD, S/N = 3) and limits of quantification (LOQ, S/N = 10) for the both were 5 microg/kg and 10 microg/kg, respectively. Good linearities (r > 0.99) were achieved for the target compounds over the range of 10-200 microg/L. The recoveries at three spiked levels (10, 20, 50 microg/kg) in the blank matrices, such as pollen pini, corn pollen, camellia pollen, sunflower pollen, rape pollen and bee pollen, were from 76.8% to 100.3% with the relative standard deviations varied from 3.70% to 12.6%. The method is accurate, practical, and can be applied to most of the contaminated matrices. With this method, heptafluorobutyric acid is not required as mobile phase which is harmful to MS spectrometer.

[Determination of streptomycin and dihydrostreptomycin residues in tomato paste by tandem dual solid phase extraction column-liquid chromatography-tandem mass spectrometry].

The method was specifically developed for the simultaneous determination of streptomycin and dihydrostreptomycin residues in tomato paste by tandem dual solid phase extraction (SPE) column cleanup-liquid chromatography-tandem mass spectrometry. The residues were extracted from the samples with phosphate buffer solution (pH 4). The cleanup was performed by the way of dispersive solid phase extraction and tandem dual solid phase extraction column. The polar chromatographic column was used to complete the separation of the analytes under gradient elution and the analytes were detected in multiple reaction monitoring (MRM) mode via positive electrospray ionization (ESI +). The external standard calibration curves were used for the quantification. The linear ranges were from 0.01 to 0.2 mg/L with a good linear relationship (r > 0.999) for streptomycin and dihydrostreptomycin. The limit of quantification (LOQs) was 0.02 mg/kg for the both analytes. The recovery range was from 71% to 101% with the relative standard deviations (RSDs) between 2.3% and 15%. It was indicated that this method is accurate, easier, more sensitive, and has a better purification effect in the monitoring and analysis. The method is accurate and specific to monitor and analyze of streptomycin and dihydrostreptomycin residues in tomato paste and its products.

Hydrophilic interaction vs ion pair liquid chromatography for the determination of streptomycin and dihydrostreptomycin residues in milk based on mass spectrometric detection.

Streptomycin (STR) and dihydrostreptomycin (DHSTR) are two of the most common aminoglycoside antibiotics used in veterinary medicine. The physicochemical properties of both substances, make their determination challenging. In the present study the development of methods based on ion-pair chromatography (IPC) and on hydrophilic interaction chromatography (HILIC), for the determination of the above mentioned aminoglycosides in the range of 100-1000 µg L(-1) is described. The two methods were validated according to EU requirements for residues in food. The recoveries for the IPC method were 69.3% and 56.5% of STR and DHSTR, respectively, and for HILIC method 85.5% and 72.3%, respectively. The intra- and inter-day precision, studied at 100, 200 and 300 µg kg⁻¹ levels in milk samples, gave %RSD ≤ 13 for both methods. LOQs for the HILIC method were 14 µg kg⁻¹ for both analytes and for the IPC method were 109 and 31 µg kg⁻¹, for STR and DHSTR, respectively. The sensitivity of the HILIC method is 80 and 210 times greater than that of the ICP method, for STR and DHSTR, respectively.

Development and validation of an LC-APCI-MS-MS analytical method for the determination of streptomycin and dihydrostreptomycin residues in milk.

An analytical method for the quantification and identity confirmation of streptomycin and dihydrostreptomycin residues in pasteurized milk using liquid chromatography (LC)-atmospheric pressure chemical ionization (APCI)-tandem mass spectrometry (MS-MS) was developed and validated. Method validation was performed according to the recommendations of the international agencies European Community and IUPAC, and the following parameters were evaluated: analytical curve, linearity, sensitivity, precision (intra- and inter-day repeatability), accuracy, and the limit of detection (LOD) and limit of quantification (LOQ). Simple sample preparation was followed by the LC-APCI-MS-MS analysis. The method presented adequate linearity with correlation coefficients above 0.99 for both analytes in the dynamic range of 50-400 microg/kg, and average accuracies between 84-110%. The LOD and LOQ were, respectively, 25 microg/kg and 50 microg/kg for both analytes. Method selectivity was verified by the absence of interfering peaks in the retention regions of the analytes and the internal standard when a blank sample was tested. The results qualified the method for the quantification and confirmation of the analytes in milk at concentrations inferior to the established maximum residue limits (200 microg/kg).

Analysis of impurities in streptomycin and dihydrostreptomycin by hydrophilic interaction chromatography/electrospray ionization quadrupole ion trap/time-of-flight mass spectrometry.

Impurities in streptomycin (STR) and dihydrostreptomycin (DHS) were investigated by hydrophilic interaction chromatography/electrospray ionization quadrupole ion trap/time-of-flight mass spectrometry (HILIC/ESI-QIT/TOFMS). Samples were separated on a fused-core silica column (100 mmx2.1 mm i.d., particle size: 2.7 microm) with isocratic elution using 200 mM ammonium formate buffer (pH 4.5) and acetonitrile as mobile phase. Constant neutral loss survey in accurate mass measurement was carried out by QIT/TOFMS. Formulae, chemical structures of impurities in an STR sample were suggested with supporting results on the probable pathways of STR biosynthesis by Streptomyces griseus.

Monitoring of streptomycin and dihydrostreptomycin residual levels in porcine meat press juice and muscle via solid-phase fluorescence immunoassay and confirmatory analysis by liquid chromatography after post-column derivatization.

A solid-phase fluorescence immunoassay (SPFIA) that was primarily developed for detection of antibiotic residues in milk was qualitatively applied for the pre-screening of the residues of aminoglycoside antibiotics, streptomycin and dihydrostreptomycin, in meat press juice. The confirmation of both analytes was performed using a validated method of highperformance liquid chromatography with post-column derivatization. The analytical performance was demonstrated by the analysis of pork meat samples spiked at three concentration levels, ranging from 0.25 to 2.5 ppm for each analyte. In general, the recoveries ranged from 80.4 to 81.5% and from 79.6 to 84.4% for streptomycin and dihydrostreptomycin, respectively, with relative standard deviations lower than 6%. The limits of detection were 0.1 and 0.15 ppm for streptomycin and dihydrostreptomycin, respectively, and the limits of quantification of 0.35 and 0.5 ppm are below the maximum residue limits of Codex, the European Union, and the Korean Food and Drug Administration (ranging from 0.5 to 0.6 ppm). Eight real samples collected from the Seoul area were first monitored using SPFIA, and none of them were found positive. These findings are in good accordance with those observed by HPLC analysis. To the best of our knowledge, this is the first report to monitor the aminoglycoside residues in pork meat press juice using SPFIA.

A high-throughput analytical method for determination of aminoglycosides in veal tissues by liquid chromatography/tandem mass spectrometry with automated cleanup.

A liquid chromatographic/tandem mass spectrometric (LC/MS/MS) method was developed for determining dihydrostreptomycin, gentamicin C1, and neomycin in veal kidney, liver, and muscle. The extraction prior to injection on the automated cleanup/analysis system is very simple, permitting preparation of 24 veal samples for analysis in half a day of work. The extracts are purified online on a reversed-phase column, with the help of an ion-pairing agent, and the analytes are separated on a Nucleosil C18 column prior to analyses by electrospray MS/MS. The cleanup is sufficient to minimize ion suppression/enhancement phenomena and permits quantification of the analytes extracted from veal tissues. Four secondary ions were measured for every analyte, which gives unambiguous identification of the compounds under analysis. Calibration curves were linear for all analytes between 50 and 5000 ppb, and recoveries in kidney were 76, 57, and 51%, respectively, for dihydrostreptomycin, gentamicin C1, and neomycin. Estimated limits of detection for kidney were, respectively, 0.1, 0.1, and 0.4 ppb. When compared to an LC method with fluorescence detection, the method gave equivalent results for kidneys incurred with neomycin. This rugged method has been applied to the analysis of more than 1000 veal samples over a 1-year period.

Quantitative determination of dihydrostreptomycin in bovine tissues and milk by liquid chromatography-electrospray ionization-tandem mass spectrometry.

Dihydrostreptomycin (DHS) is an aminoglycoside antibiotic used in veterinary medicine in combination with benzylpenicillin for the treatment of bacterial infections in cattle, pigs and sheep. A method to determine its residues in edible tissues of cattle, as well as in milk, was developed and validated. Extraction of DHS from the tissues was performed using a liquid extraction with a 10 mM phosphate buffer containing 2% (w/v) trichloroacetic acid, while milk samples were treated with a 50% (w/v) trichloroacetic acid solution, followed by a solid-phase clean-up procedure on a carboxypropyl (CBA) weak cation exchange column. Ion-pair chromatography, using a mixture of 20 mM pentafluoropropionic acid in water and acetonitrile as the mobile phase, was used to retain DHS and the internal standard streptomycin (STR) on a Nucleosil (5 microm) reversed-phase C18 column. The components were detected and quantified by electrospray ionization (ESI) tandem mass spectrometry. The method could be validated according to EC (European Community) requirements with respect to linearity, trueness and precision, the latter evaluated at the maximum residue limit (MRL) - 1000 ng g(-1) for kidney, 500 ng g(-1) for muscle, liver and fat, and 200 ng g(-1) for milk -, at one-half of the MRL and at one and a half times the MRL. A limit of quantification of 10 ng g(-1) and 1 ng ml(-1) was obtained for all tissues and for milk, respectively, which is far below one-half of the MRL as requested, while the limit of detection was in the low ppb range, varying between 1.9 and 4.2 ng g(-1) for the different tissues tested, and being 0.6 ng ml(-1) for milk. The method was used for the monitoring of DHS residues in incurred tissue and milk samples coming from cattle medicated with DHS in combination with benzylpenicillin by intramuscular injection, in order to evaluate withdrawal times.

Development of a novel method based on liquid chromatography-evaporative light scattering detection for the direct determination of streptomycin and dihydrostreptomycin in raw materials, pharmaceutical formulations, culture media and plasma.

A novel method for the non-derivatization liquid chromatographic determination of streptomycin (STR) and dihydrostreptomycin (DHSTR) was developed and validated based on evaporative light scattering detection (ELSD). Utilizing a ThermoHypersil BetaBasic C18 analytical column, evaporation temperature of 50 degrees C and pressure of nebulizing gas (nitrogen) of 3.5 bar, the optimized mobile phase was 1.25 mL L(-1) TFA aqueous solution, in an isocratic mode at a rate of 1.0 mL min(-1). STR was eluted at 5.6 min and DHSTR at 7.8 min with a resolution of 4.4. Linear calibration curves were obtained from 2 to 120 microg mL(-1) (r > 0.9990) for STR and 2-75 microg mL(-1) (r > 0.9994) for DHSTR, with a LOD equal to 0.7 and 0.5 microg mL(-1), respectively. The developed method was applied for the assay of STR and DHSTR (sulfate) in pharmaceutical raw materials and formulations, while the simultaneous direct determination of sulfate was feasible (tR = 2.5 min, LOD = 1.4 microg mL(-1), double logarithmic calibration curve in the range of 4-50 microg mL(-1), r > 0.9998). Modified isocratic mobile phase (H2O-ACN, 90:10, v/v, containing 1.25 mL L(-1) TFA), was used for the determination of streptomycin B impurity in STR sulfate raw material and a gradient mobile phase (H2O-ACN containing TFA) was used for the determination of DHSTR in the presence of penicillinG procaine. The developed method was also applied for the assay of commercial formulations (STR powder and DHSTR injection solution and suspension) (%recovery 98-102, %RSD < 1.3, n = 3 x 3), for the determination of STR in bacteria culture medium (%recovery 99.6, %RSD = 0.8, n = 3 x 3), and for the determination of DHSTR in human plasma (2.0-23.0 microg mL(-1)) after solid phase extraction using carboxylate cartridges (%recovery 98.4-101.8, %RSD = 3.2, n = 3 x 3).

Determination of streptomycin and dihydrostreptomycin in milk and honey by liquid chromatography with tandem mass spectrometry.

Two liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods were developed for the determination of streptomycin (STR) and its derivative dihydrostreptomycin (DHSTR) in milk and honey. These aminoglycoside antibiotics are used as veterinary drugs. In the EU, the presence of dihydro- and streptomycin residues in honey is forbidden, the maximum residue level (MRL) in milk is 200 microg/kg. The methods were optimised with regard to sensitivity and chromatographic efficiency, and validated by a procedure consistent with EU directive 2002/657. Average recoveries and accompanying standard deviations were satisfactory. The limit of quantification of STR was 2 microg/kg in honey and 10 microg/kg in milk, of DHSTR it was a factor two lower. The precision of the milk analysis was improved by using STR as the internal standard for DHSTR and vice versa. In a survey of 186 honeys available on the Dutch market, 26% of the honeys of foreign origin were positive for (DH)STR. This occurence rate was consistent with previous surveys, but lower concentrations were found.

Capillary electrophoresis method for simultaneous determination of penicillin G, procaine and dihydrostreptomycin in veterinary drugs.

Capillary electrophoresis method for identification and simultaneous determination of procaine, dihydrostreptomycin and penicillin G, present in multiantibiotic veterinary preparations, was elaborated. The influence of pH (5.0-9.75) and concentration of disodium tetraborate decahydrate in running buffers (0.02-0.1 M) as well as temperatures (25-40 degrees C) on separation efficacy were analyzed. For quantitative analysis, 0.08 M borate buffer (pH 8.0) at 35 degrees C and 15 kV were chosen. Method was validated, selectivity, precision, linearity, LOD, LOQ, accuracy and specificity of capillary zone electrophoresis (CZE) were evaluated.

[Determination of streptomycin and dihydrostreptomycin in meat by liquid chromatography/mass spectrometry].

A sensitive and selective method using liquid chromatography-electrospray mass spectrometry (LC-ESI-MS) for the determination of aminoglycoside antibiotics, streptomycin and dihydrostreptomycin, in meat has been developed. The LC separation was performed on a TSK-gel Super ODS column (10 cm x 2 mm i.d.) using 5 mmol/L heptafluoro-n-butyric acid (HFBA)-acetonitrile (88:12) as the mobile phase at a flow rate of 0.18 mL/min. The positive ionization produced typical [M + H]+ molecular ions of both drugs (streptomycin m/z 582; dihydrostreptomycin m/z 584). The calibration graphs for streptomycin and dihydrostreptomycin were rectilinear from 0.25 to 25 ng with selected ion monitoring (SIM). The drugs were extracted with 1% metaphosphoric acid, and the extracts were added to 2 mL of 0.1 mol/L heptanesulfonic acid. The solution was cleaned up on a Bond Elut C18 (500 mg) cartridge. The recoveries of streptomycin and dihydrostreptomycin from swine and bovine muscle fortified at 0.2 microgram/g were 73.2-82.6%, and the detection limits were 0.01 microgram/g for both drugs.

Liquid chromatographic analysis of dihydrostreptomycin sulfate.

The analysis of dihydrostreptomycin sulfate using a column packed with base deactivated reversed phase silica gel and ultraviolet detection at 205 nm is described. The mobile phase consists of an aqueous solution containing 4 g/l of sodium sulfate, 1.5 g/l of sodium octanesulfonate, 100 ml/l of acetonitrile and 50 ml/l of a 0.2-M phosphate buffer at pH 3.0. The method allows separation of streptidine, dihydrostreptomycin B, streptomycin, dihydrostreptomycin and deoxydihydrostreptomycin, as well as some other components which were not identified. The total time of analysis is 55 min. The effects of the different chromatographic parameters on the separation were also investigated. A number of commercial samples were analyzed using this method.