Spectrophotometric Analysis of Caffeine

Table 1

Different spectrophotometric methods for the determination of caffeine.

S. number	Method	Linearity range for caffeine	UV-vis spectral range	Sample	Solution	Reference
1	Chemometric methods for spectral investigation; (1) Inverse least square; (2) Principal component analysis	12–56 μg/mL	225–285 nm	Pharmaceuticals; (Metamizol, acetaminophen, and caffeine)	0.1 M HCl	[12]
2	Simple and derivative spectrophotometry	12–28 g/mL	200–350 nm	Pharmaceuticals; (Phenylpropanolamine HCl, caffeine, and diazepam)	Water, chloroform, and petroleum ether	[13]
3	Derivative ratio spectra-zero crossing procedure	1–5 μg/mL	244.8–276.9 nm	Pharmaceuticals; (Paracetamol, propyphenazone, and caffeine)	0.1 M HCl	[18]
4	Ratio spectra spectrophotometry and chemometric methods viz, classical least squares, and inverse least squares	4–40 μg/mL	225–285 nm	Pharmaceuticals; (Chlorphenoxamine hydrochloride and caffeine)	0.1 M HCl	[14]
5	Multivariate calibration and N-way partial least squares (PLS)	2–6 μg/mL	210–300 nm	Pharmaceuticals; (Acetylsalicylic acid, paracetamol, and caffeine)	Water	[15]
6	Multivariate calibration method and chemometric methods viz, partial least squares, and principle component regression	.05–20 μg/mL	190–300 nm	Pharmaceuticals; (Phenytoin, barbital, and caffeine)	Water/methanol (1 : 1, v/v)	[16]
7	Continuous wavelet transform and derivative transform (using Savitzky-Golay filters)	2–50 μg/mL	220–300	Pharmaceuticals; (Paracetamol and caffeine)	0.1 M HCl	[17]
8	H-point standard addition method	0.1–3.0 μg/mL	453 nm	Pharmaceuticals; (Paracetamol and caffeine)	Water	[24]
9	Simultaneous equation method and Q-absorbance equation at isosbestic point	2–32 μg/mL	200–400 nm	Pharmaceuticals; (Paracetamol and caffeine)	Water	[19]
10	Isoabsorption assay method	—	200–300 nm	Pharmaceuticals; (Caffeine and sodium benzoate)	Water	[20]
11	Simultaneous equation method and absorbance ratio method	0–25 μg/mL	200–400 nm	Pharmaceuticals; (Acetylsalicylic acid and caffeine)	0.1 N NaOH	[21]
12	Simultaneous equation method and absorbance ratio method	1.14–2.05 μg/mL	200–400 nm	Pharmaceuticals; (Acetylsalicylic acid and caffeine)	0.1 N HCl	[22]
13	Partial least squares regression, genetic algorithm coupled with PLS, and principle component-artificial neural network	1–18 μg/mL	200–400 nm	Pharmaceuticals; (Paracetamol, ibuprofen, and caffeine)	Methanol/0.1 N HCl (3 : 1, v/v)	[23]
14	Simple spectrophotometric method with coupling reagent	0.1–1 μg/mL	500–750 nm	Alkaloids (caffeine and theophylline)	Water	[25]
15	First-derivative spectrophotometry	4–40 μg/mL	220–360 nm	Pharmaceuticals; (Chlorpheniramine maleate and caffeine)	Ethanol	[26]
16	Derivative spectrophotometric methods (first, second, and third-order spectra)	2–10 μg/mL	190–350 nm	Beverages (caffeine)	Water	[27]
17	Simple spectrophotometric method	5–25 μg/mL	271 nm	Paullinia cupana var. sorbilis (tannins and caffeine)	Sulfuric acid (2.5%)	[28]
18	Simple spectrophotometric method (Solvent study)	0–20 μg/mL	180–400 nm	Tea (caffeine)	Water, ethyl acetate, chloroform, and methanol	[34]
19	UV-spectrophotometry	10–60 μg/mL	200–600	Soft and energy drinks (caffeine)	Carbon tetrachloride	[35]
20	Simple spectrophotometric method	10–50 μg/mL	200–400 nm	Drugs (caffeine)	Water	[36]