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Simple, accurate and sensitive spectrophotometric, chemometric and chromatographic methods were used for the simultaneous determination of emtricitabine (ETC) and tenofovir disoproxil fumarate (TDF) in tablets. In 1st derivative spectrophotometry, the first derivative spectra of the solution of ETC and TDF in water were recorded as Δλ = 4 nm and the first derivative absorbances were measured at the zero-crossing points at 297.3 and 281.2 nm for ETC and TDF, respectively. In ratio of the 1st derivative spectrophotometry measurements were recorded at 239.0 and 270.2 nm for ETC and TDF, respectively. Then analytical signals were measured at the wavelengths corresponding to either maximum or minimum for both drugs. For these spectrophotometric methods Beer’s law is obeyed in the concentration range of 2–15 μg mL-1 for both drugs. As chemometric method, the PLS technique was used. In chromatographic method, the separation was achieved on a C18 column with DAD (262 nm) and isocratic elution of methanol, acetonitrile and 0.1 % orthophosphoric acid in the volume ratio of 40:40:20, respectively, containing the mobile phase. The mean recovery and the relative standard deviation of the methods were found as 97.51–100.17 % and 0.55–1.26 % respectively. All these methods were statistically compared, and they were successfully applied to a pharmaceutical preparation.

Different administration approaches were investigated for the selection of bupivacaine administration type and a sensitive high-performance liquid chromatographic (HPLC) method has been developed. Developed method was validated and applied for the determination of bupivacaine in rabbit aqueous humor. The separation was achieved using a XTerra, C8 (250 × 8 mm i.d. particle size 5 μm) analytical column with a mobile phase consisted of acetonitrile and sodium dihydrogen phosphate (pH = 3.0, 20 mM; 30:70, v/v). Bupivacaine detection was performed by Diode Array detector (DAD) at 220 nm. The retention times for bupivacaine is 15.886 min. HPLC-DAD method was linear in the range of 75–4000 ng/mL. The limit of detection was 25 ng/mL and the limit of quantification of bupivacaine was found to be 75 ng/mL (relative standard deviation, RSD ≤ 15%, n  = 6). In intra-day and inter-day precision and accuracy analysis, the RSD was found to be in the range of 0.96 and 7.98%, the bias values were 0.64 and 3.33%. Method was carried out for three different type of bupivacaine application because of the investigation of effective drug administration. Twenty aqueous humor samples were in the range of 0.642 and 5.124 μg/mL. [ABSTRACT FROM AUTHOR]

Objective: Aflatoxins are a group of mycotoxin with potent carcinogenic, teratogenic, mutajenic and toxigenic effects are produced by certain species of Aspergillus flavus and Aspergillus parasiticus and may occur in various agricultural commodities. When aflatoxin B1 contaminates the food of lactating animals, milk from these animals contains aflatoxin M1, the principal metabolite arising from biotransformation of aflatoxin B1 in liver and it is secreted into milk in the mammary gland. In this study we aimed to determination and investigattion of aflatoxin M1 concentrations in cheese samples by HPLC. Samples were obtained from various regions of Turkey (Urfa, Civil, Mihalıç, Otlu cheese and Kars cheddar; n=100). Method: Aflatoxin M1 concentrations in cheese samples determined by using HPLC-RP fluorescence system (λex=365 nm and λem=435 nm) which were consisted of Phenomenex, Nucleosil, 100 A, C18 (4.6x250 mm, 5μm) analytical column and mobile phase composition with water:acetonitrile (75:25 v/v) at 1 ml/min, 40 ºC). Results: Aflatoxin M1 was determined only ten samples of Urfa cheese, which were under the acceptable limits of dairy products. In the other groups of cheese samples (Civil, Mihalıç, Otlu cheese and Kars cheddar) Aflatoxin M1 was not determined. Conclusion: In this study, Aflatoxin M1 was determined only ten samples of Urfa cheese which were under the acceptable limits of dairy products. All other samples from different part of the country were suitable for human consumption. Ancak bu konudaki çalışmaların daha geniş kapsamlı örneklerle tekrarlanması yanısıra gerek üreticilerin gerekse tüketicilerin konu hakkında bilgilendirilmesi önerilir. [ABSTRACT FROM AUTHOR]