Akademiai Kiado Zrt.

A method developed for quantitative determination of the total amount of polyaromatic hydrocarbons (PAH) in human hair has been applied to the analysis of smokers’ hair. The procedure involves washing the hair with dichloromethane, acid decomposition of the hair matrix, micro-liquid extraction, and HPTLC determination of total PAH concentrations in the whole extract. The concentrations of PAH in human hair were in the range 0.005–0.3 μg g–1 hair.

High performance thin-layer chromatography (HPTLC) combined with densitometry has been used for analysis of the triterpenoid content of acetone and ethyl acetate extracts of the leaves of Jovibarba sobolifera (Sims.) Opiz. After optimization of the extraction process, HPTLC separation was successfully standardized, using silica gel plates washed with methanol and dichloromethane, dichloromethane-ethyl acetate 18.5:1.5 as mobile phase, and 8% H2SO4 in ethanol (m/m) as spray reagent. Triterpenoids in the leaves of Jovibarba sobolifera were quantified by measurement of absorbance. Three spots were observed on chromatograms - the sum of α and β-amyrin, oleanolic acid, and an unidentified compound. All of the triterpenoid components were analyzed for the first time in this plant. The triterpenoid content was calculated statistically.

Bài báo nghiên cứu này mô tả một phương pháp lập phương giản đơn và nhạy cảm với kỹ thuật sắc ký lớp mỏng (TLC) phân tích định lượng đồng thời guaifenesin (GUF) và pseudoephedrine HCl (PSH) trong các hỗn hợp nhị nguyên và trong sự có mặt của tạp chất guaifenesin và chất liên quan, guaiacol. Phương pháp sắc ký đề xuất đã được phát triển sử dụng các tấm silica gel 60 F254 làm pha tĩnh với hệ phát triển gồm hỗn hợp hexan-acetone-ethyl acetate-triethylamine-nước (3:4:3:0.1:0.3, theo thể tích), sau đó thực hiện đo mật độ quang tại 208 nm (cho pseudoephedrine HCl và guaifenesin) và 278 nm (cho guaiacol). Các điều kiện thực nghiệm đã được tối ưu hóa để đạt được sự phân tách và độ nhạy mong muốn. Đường chuẩn cho ba thành phần được nghiên cứu đã được xây dựng bằng phương trình bậc 2 chiếm ưu thế hơn so với phương trình bậc nhất về hệ số tương quan và khoảng định lượng (14–25, 2–12 và 0.1–1.1 µg band−1) cho pseudoephedrine HCl, guaifenesin và guaiacol, tương ứng. Phương pháp phát triển đã được áp dụng thành công để xác định pseudoephedrine HCl và guaifenesin trong siro Triaminic® Chest Congestion mà không phát hiện được sự nhiễu từ các phụ gia trong siro. Dữ liệu thu được từ việc xác nhận phương pháp đã khẳng định tính đặc hiệu, nhạy bén và độ chính xác của phương pháp. So sánh thống kê giữa kết quả thu được từ phương pháp sắc ký được đề xuất và các kết quả thu được từ kỹ thuật hóa phân tích đã công bố cho thấy không có sự khác biệt đáng kể ở mức độ tin cậy 95%.

A simple, accurate and precise high-performance thin-layer chromatography (HPTLC) method was developed and validated for the simultaneous determination of quercetin and kaempferol in the methanolic extract of leaves of Centella asiatica. Leaves of two different chemotypes of Centella asiatica were obtained from two different regions viz. Maharashtra and Gujarat state, and a comparative study was performed for the presence of both the standards — quercetin and kaempferol. The HPTLC of flavonoids was performed on F254 TLC plates with toluene-ethyl acetate-chloroform-formic acid (6:4:4:1, v/v) as a mobile phase. Densitometric determination of flavonoids was performed at λ = 240 nm in reflectance/absorbance mode. The linear regression analysis data for the calibration plots showed a good linear relationship in the concentration range of 100–1000 ng/band with r2 = 0.9764 and 0.9823 for quercetin and kaempferol, respectively. The accuracy of the method was confirmed by conducting recovery studies at three different levels using the standard addition method. The average recovery for quercetin was 98.60% and for kaempferol was 90.08%. The proposed HPTLC method provides good resolution of quercetin and kaempferol from other constituents present in methanolic extract of leaves of Centella asiatica and can be used for quantification of quercetin and kaempferol present in the extract. Statistical analysis of the data showed that the method is sensitive and selective for determination of flavonoids.

Physochlaina praealta samples were studied macromorphologically and cytomorphologically along with their detailed phytochemical investigation. The concentration of phytoconstituents showed a strong positive correlation with the ploidy level and altitudinal gradients. The total phenol content was detected maximum in the methanolic extract of leaves and stem of higher altitudinal plants in both cytotypes (2x, 4x). The maximum content of flavonoids was detected in the methanolic extract of root and leaves. Root organ from higher elevation possessed the highest DPPH radical scavenging activity, with the maximum percentage of inhibition being obtained in methanolic extracts. The plants of both cytotypes from higher elevations accumulate an abundant quantity of secondary metabolites. The two cytotypes differ from each other with respect to various morphometric characters thereby depicting the drastic affect of polyploidy.

Quantification of bioactive markers through modern analytical methods is very essential for establishing the authenticity and creditability of prescription and usage of herbal drugs formulations. In the present study, simultaneous quantification of rosmarinic acid (RA), quercetin (Q), glycyrrhizin (G) and betulinic acid (BA), in polyherbal formulation by high-performance thin-layer chromatography (HPTLC) method was developed. Mobile phase of ethyl acetate‒toluene‒methanol‒formic acid (7:1:0.5:0.5, V/V) was used on pre-coated plate of silica gel 60F254 and quantified by densitometric method. Validation of the method was done to demonstrate its selectivity, linearity, precision and accuracy as per the International Council for Harmonization (ICH) guidelines. Intra-day assay and inter-day assay precision of the analytes were less than 2%, and the average recovery rates obtained were in the range of 98.11‒101.14% for all with percent relative standard deviation (%RSD) below 2%. Correlation coefficient shows that the developed method was accurate and precise. This method can be used in the routine analysis of polyherbal formulations.

This review describes the application of thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) in the separation and identification of vitamins from their mixtures using different kinds of mobile phases such as isocratic and mixed solvents as well as mobile phases containing various modifiers. TLC has long been used for the separation and semiquantitative determination of biomolecules including vitamins. HPTLC is the modified version of TLC, and it offers the advantages of better resolution, smaller sample size, and lesser volumes of mobile phases. In recent years, the emergence of advanced and fully automated chromatographic techniques such as high-performance liquid chromatography (HPLC) and gas chromatography (GC) has reduced the application of TLC/HPTLC for vitamins analysis. However, due to the inherent simplicity and cost-effectiveness, both TLC and HPTLC continue to be the methods of choice in small laboratories of developing countries. In this short review, the literature survey on TLC/HPTLC of vitamins covering the period 2011‒2019 has been encapsulated in a tabular form.